10-Q

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 10-Q

(mark one)
x	QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934
For the quarterly period ended March 31, 2013
OR
o	TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the transition period from          to          

Commission File Number: 1-10499

NORTHWESTERN CORPORATION

(Exact name of registrant as specified in its charter)

Delaware	46-0172280
(State or other jurisdiction of incorporation or organization)	(I.R.S. Employer Identification No.)
3010 W. 69th Street, Sioux Falls, South Dakota	57108
(Address of principal executive offices)	(Zip Code)
Registrant’s telephone number, including area code: 605-978-2900

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes x No o

Indicate by check mark whether the registrant has submitted electronically and posted on its corporate Web site, if any, every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files). Yes x No o

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non- accelerated filer or a smaller reporting company. See the definitions of “large accelerated filer,” “accelerated filer” and “smaller reporting company” in Rule 12b-2 of the Exchange Act.

Large Accelerated Filer x Accelerated Filer o Non-accelerated Filer o Smaller Reporting Company o

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act). Yes o  No x

Indicate the number of shares outstanding of each of the issuer’s classes of common stock, as of the latest practicable date:

Common Stock, Par Value $0.01

37,884,938 shares outstanding at April 19, 2013

1

NORTHWESTERN CORPORATION

FORM 10-Q

INDEX

		Page
SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS		3
PART I. FINANCIAL INFORMATION		4
Item 1.	Financial Statements (Unaudited)	4
	Condensed Consolidated Balance Sheets — March 31, 2013 and December 31, 2012	4
	Condensed Consolidated Statements of Income — Three Months Ended March 31, 2013 and 2012	5
	Condensed Consolidated Statements of Comprehensive Income — Three Months Ended March 31, 2013 and 2012	6
	Condensed Consolidated Statements of Cash Flows — Three Months Ended March 31, 2013 and 2012	7
	Notes to Condensed Consolidated Financial Statements	8
Item 2.	Management’s Discussion and Analysis of Financial Condition and Results of Operations	23
Item 3.	Quantitative and Qualitative Disclosures About Market Risk	39
Item 4.	Controls and Procedures	40
PART II. OTHER INFORMATION		41
Item 1.	Legal Proceedings	41
Item 1A.	Risk Factors	41
Item 6.	Exhibits	46
SIGNATURES		47

2

SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS

On one or more occasions, we may make statements in this Quarterly Report on Form 10-Q regarding our assumptions, projections, expectations, targets, intentions or beliefs about future events. All statements other than statements of historical facts, included or incorporated by reference in this Quarterly Report, relating to management's current expectations of future financial performance, continued growth, changes in economic conditions or capital markets and changes in customer usage patterns and preferences are forward-looking statements within the meaning of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934.

Words or phrases such as “anticipates," “may," “will," “should," “believes," “estimates," “expects," “intends," “plans," “predicts," “projects," “targets," “will likely result," “will continue" or similar expressions identify forward-looking statements. Forward-looking statements involve risks and uncertainties, which could cause actual results or outcomes to differ materially from those expressed. We caution that while we make such statements in good faith and believe such statements are based on reasonable assumptions, including without limitation, management's examination of historical operating trends, data contained in records and other data available from third parties, we cannot assure you that we will achieve our projections. Factors that may cause such differences include, but are not limited to:

• potential adverse federal, state, or local legislation or regulation, including costs of compliance with existing and future environmental requirements, as well as adverse determinations by regulators, could have a material effect on our liquidity, results of operations and financial condition;

• changes in availability of trade credit, creditworthiness of counterparties, usage, commodity prices, fuel supply costs or availability due to higher demand, shortages, weather conditions, transportation problems or other developments, may reduce revenues or may increase operating costs, each of which could adversely affect our liquidity and results of operations;

• unscheduled generation outages or forced reductions in output, maintenance or repairs, which may reduce revenues and increase cost of sales or may require additional capital expenditures or other increased operating costs; and

• adverse changes in general economic and competitive conditions in the U.S. financial markets and in our service territories.

We have attempted to identify, in context, certain of the factors that we believe may cause actual future experience and results to differ materially from our current expectation regarding the relevant matter or subject area. In addition to the items specifically discussed above, our business and results of operations are subject to the uncertainties described under the caption “Risk Factors” which is part of the disclosure included in Part II, Item 1A of this Report.

From time to time, oral or written forward-looking statements are also included in our reports on Forms 10-K, 10-Q and 8-K, Proxy Statements on Schedule 14A, press releases, analyst and investor conference calls, and other communications released to the public. We believe that at the time made, the expectations reflected in all of these forward-looking statements are and will be reasonable. However, any or all of the forward-looking statements in this Quarterly Report on Form 10-Q, our reports on Forms 10-K and 8-K, our other reports on Form 10-Q, our Proxy Statements on Schedule 14A and any other public statements that are made by us may prove to be incorrect. This may occur as a result of assumptions, which turn out to be inaccurate, or as a consequence of known or unknown risks and uncertainties. Many factors discussed in this Quarterly Report on Form 10-Q, certain of which are beyond our control, will be important in determining our future performance. Consequently, actual results may differ materially from those that might be anticipated from forward-looking statements. In light of these and other uncertainties, you should not regard the inclusion of any of our forward-looking statements in this Quarterly Report on Form 10-Q or other public communications as a representation by us that our plans and objectives will be achieved, and you should not place undue reliance on such forward-looking statements.

We undertake no obligation to publicly update or revise any forward-looking statements, whether as a result of new information, future events or otherwise. However, your attention is directed to any further disclosures made on related subjects in our subsequent reports filed with the Securities and Exchange Commission (SEC) on Forms 10-K, 10-Q and 8-K and Proxy Statements on Schedule 14A.

Unless the context requires otherwise, references to “we,” “us,” “our,” “NorthWestern Corporation,” “NorthWestern Energy,” and “NorthWestern” refer specifically to NorthWestern Corporation and its subsidiaries.

3

PART 1. FINANCIAL INFORMATION

ITEM 1. FINANCIAL STATEMENTS

NORTHWESTERN CORPORATION

CONDENSED CONSOLIDATED BALANCE SHEETS

(Unaudited)

(in thousands, except share data)

	March 31, 2013			December 31, 2012
ASSETS
Current Assets:
Cash and cash equivalents	$	6,884		$	9,822
Restricted cash	8,687			6,700
Accounts receivable, net	143,286			143,695
Inventories	38,848			54,161
Regulatory assets	25,569			40,301
Deferred income taxes	28,729			37,143
Other	13,375			11,306
Total current assets	265,378			303,128
Property, plant, and equipment, net	2,444,405			2,435,590
Goodwill	355,128			355,128
Regulatory assets	388,483			367,890
Other noncurrent assets	27,336			23,797
Total assets	$	3,480,730		$	3,485,533
LIABILITIES AND SHAREHOLDERS' EQUITY
Current Liabilities:
Current maturities of capital leases	$	1,638		$	1,612
Short-term borrowings	43,985			122,934
Accounts payable	67,250			83,746
Accrued expenses	213,446			192,548
Regulatory liabilities	49,717			48,425
Total current liabilities	376,036			449,265
Long-term capital leases	31,146			31,562
Long-term debt	1,055,079			1,055,074
Deferred income taxes	382,636			363,928
Noncurrent regulatory liabilities	279,784			276,618
Other noncurrent liabilities	380,439			375,054
Total liabilities	2,505,120			2,551,501
Commitments and Contingencies (Note 13)
Shareholders' Equity:
Common stock, par value $0.01; authorized 200,000,000 shares; issued and outstanding 41,407,918 and 37,805,238 shares, respectively; Preferred stock, par value $0.01; authorized 50,000,000 shares; none issued	414			408
Treasury stock at cost	(91,951		)	(90,702		)
Paid-in capital	868,441			849,218
Retained earnings	196,523			172,791
Accumulated other comprehensive income	2,183			2,317
Total shareholders' equity	975,610			934,032
Total liabilities and shareholders' equity	$	3,480,730		$	3,485,533

See Notes to Condensed Consolidated Financial Statements

4

NORTHWESTERN CORPORATION

CONDENSED CONSOLIDATED STATEMENTS OF INCOME

(Unaudited)

(in thousands, except per share amounts)

	Three Months Ended March 31,
	2013			2012
Revenues
Electric	$	210,092		207,055
Gas	102,518			101,746
Other	410			299
Total Revenues	313,020			309,100
Operating Expenses
Cost of sales	132,196			138,396
Operating, general and administrative	68,837			65,573
Property and other taxes	25,759			23,665
Depreciation	29,218			26,433
Total Operating Expenses	256,010			254,067
Operating Income	57,010			55,033
Interest Expense, net	(16,779		)	(15,962		)
Other Income	2,715			984
Income Before Income Taxes	42,946			40,055
Income Tax Expense	(5,044		)	(8,012		)
Net Income	$	37,902		$	32,043
Average Common Shares Outstanding	37,384			36,328
Basic Earnings per Average Common Share	$	1.01		$	0.88
Diluted Earnings per Average Common Share	$	1.01		$	0.88
Dividends Declared per Average Common Share	$	0.38		$	0.37

See Notes to Condensed Consolidated Financial Statements

5

NORTHWESTERN CORPORATION

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME

(Unaudited)

(in thousands, except per share amounts)

	Three Months Ended March 31,
	2013			2012
Net Income	$	37,902		$	32,043
Other comprehensive (loss) income, net of tax:
Reclassification of net gains on derivative instruments	(183		)	(183		)
Postretirement medical liability adjustment	—			205
Foreign currency translation	49			(47		)
Total Other Comprehensive Loss	(134		)	(25		)
Comprehensive Income	$	37,768		$	32,018

See Notes to Condensed Consolidated Financial Statements

6

NORTHWESTERN CORPORATION

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS

(Unaudited)

(in thousands)

	Three Months Ended March 31,
	2013			2012
OPERATING ACTIVITIES:
Net Income	$	37,902		$	32,043
Items not affecting cash:
Depreciation	29,218			26,433
Amortization of debt issue costs, discount and deferred hedge gain	64			90
Amortization of restricted stock	669			1,075
Equity portion of allowance for funds used during construction	(1,234		)	(930		)
Gain on disposition of assets	—			(56		)
Deferred income taxes	27,236			20,195
Changes in current assets and liabilities:
Restricted cash	(1,987		)	3,681
Accounts receivable	409			15,639
Inventories	15,313			17,856
Other current assets	(2,069		)	1,153
Accounts payable	(14,118		)	(16,099		)
Accrued expenses	24,025			19,812
Regulatory assets	12,598			6,718
Regulatory liabilities	1,292			(794		)
Other noncurrent assets	(23,489		)	(13,717		)
Other noncurrent liabilities	6,051			6,826
Cash provided by operating activities	111,880			119,925
INVESTING ACTIVITIES:
Property, plant, and equipment additions	(38,114		)	(47,107		)
Proceeds from sale of assets	—			80
Cash used in investing activities	(38,114		)	(47,027		)
FINANCING ACTIVITIES:
Treasury stock activity	(1,249		)	75
Proceeds from issuance of common stock, net	17,701			—
Dividends on common stock	(14,170		)	(13,358		)
Repayments on long-term debt	(37		)	(3,795		)
Repayments of short-term borrowings, net	(78,949		)	(53,956		)
Cash used in financing activities	(76,704		)	(71,034		)
(Decrease) Increase in Cash and Cash Equivalents	(2,938		)	1,864
Cash and Cash Equivalents, beginning of period	9,822			5,928
Cash and Cash Equivalents, end of period	$	6,884		$	7,792
Supplemental Cash Flow Information:
Cash paid (received) during the period for:
Income taxes	38			(335		)
Interest	11,826			8,806
Significant non-cash transactions:
Capital expenditures included in accounts payable and accrued expenses	6,810			5,823

See Notes to Condensed Consolidated Financial Statements

7

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(Reference is made to Notes to Financial Statements included in NorthWestern Corporation’s Annual Report)

(Unaudited)

(1) Nature of Operations and Basis of Consolidation

NorthWestern Corporation, doing business as NorthWestern Energy, provides electricity and natural gas to approximately 673,200 customers in Montana, South Dakota and Nebraska.

The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America (GAAP) requires management to make estimates and assumptions that may affect the reported amounts of assets, liabilities, revenues and expenses during the reporting period. Actual results could differ from those estimates. The unaudited Condensed Consolidated Financial Statements (Financial Statements) reflect all adjustments (which unless otherwise noted are normal and recurring in nature) that are, in the opinion of management, necessary to fairly present our financial position, results of operations and cash flows. The actual results for the interim periods are not necessarily indicative of the operating results to be expected for a full year or for other interim periods. Events occurring subsequent to March 31, 2013, have been evaluated as to their potential impact to the Financial Statements through the date of issuance.

The Financial Statements included herein have been prepared by NorthWestern, without audit, pursuant to the rules and regulations of the SEC. Certain information and footnote disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations; however, management believes that the condensed disclosures provided are adequate to make the information presented not misleading. Management recommends that these unaudited Financial Statements be read in conjunction with the audited financial statements and related footnotes included in our Annual Report on Form 10-K for the year ended December 31, 2012.

Variable Interest Entities

A reporting company is required to consolidate a variable interest entity (VIE) as its primary beneficiary, which means it has a controlling financial interest, when it has both the power to direct the activities of the VIE that most significantly impact the VIE's economic performance, and the obligation to absorb losses or the right to receive benefits from the VIE that could potentially be significant to the VIE. An entity is considered to be a VIE when its total equity investment at risk is not sufficient to permit the entity to finance its activities without additional subordinated financial support, or its equity investors, as a group, lack the characteristics of having a controlling financial interest. The determination of whether a company is required to consolidate an entity is based on, among other things, an entity’s purpose and design and a company’s ability to direct the activities of the entity that most significantly impact the entity’s economic performance.

Certain long-term purchase power and tolling contracts may be considered variable interests. We have various long-term purchase power contracts with other utilities and certain Qualifying Facility (QF) plants. We identified one QF contract that may constitute a VIE. We entered into a power purchase contract in 1984 with this 35 Megawatt (MW) coal-fired QF to purchase substantially all of the facility's capacity and electrical output over a substantial portion of its estimated useful life. We absorb a portion of the facility's variability through annual changes to the price we pay per Megawatt Hour (MWH) (energy payment). After making exhaustive efforts, we have been unable to obtain the information from the facility necessary to determine whether the facility is a VIE or whether we are the primary beneficiary of the facility. The contract with the facility contains no provision which legally obligates the facility to release this information. We have accounted for this QF contract as an executory contract. Based on the current contract terms with this QF, our estimated gross contractual payments aggregate approximately $302.9 million through 2024.

(2) New Accounting Standards

Accounting Standards Issued and Adopted

In February 2013, the Financial Accounting Standards Board issued guidance that requires disclosure of amounts reclassified out of accumulated other comprehensive income by component. Significant amounts are required to be presented by the respective line items of net income or should be cross-referenced to other disclosures. These disclosures may be presented on the income statement or in the notes to the financial statements. We adopted this standard during the first quarter of 2013 and have included the required disclosures in notes to the financial statements. The adoption of this standard did not have a material effect on our financial statement disclosures.

8

(3) Regulatory Matters

Dave Gates Generating Station at Mill Creek (DGGS)

As a result of a Federal Energy Regulatory Commission (FERC) Administrative Law Judge's (ALJ) initial nonbinding decision issued in September 2012, we have cumulative deferred revenue of approximately $18.5 million, which is subject to refund and recorded within current regulatory liabilities in the Condensed Consolidated Balance Sheets. The ALJ concluded we should allocate only a fraction of the costs we believe (based on past practice) should be allocated to FERC jurisdictional customers. Our brief in opposition to the ALJ's initial decision is pending before the FERC.

Although we have no assurance as to timing, the FERC is expected to consider the matter and issue a binding decision during 2013. The FERC is not obligated to follow any of the ALJ's findings and conclusions, and the FERC can accept or reject the initial decision in whole or in part. If the FERC upholds the ALJ's decision and a portion of the costs are effectively disallowed, we would be required to assess DGGS for impairment. If we disagree with a decision issued by the FERC, we may pursue full appellate rights through rehearing and appeal to a United States Circuit Court of Appeals, which could extend into 2015. We continue to bill FERC jurisdictional customers interim rates that have been in effect since January 1, 2011. These interim rates are subject to refund plus interest pending final resolution at FERC.

Montana Electric and Natural Gas Tracker Filings

Each year we submit electric and natural gas tracker filings for recovery of supply costs for the 12-month period ended

June 30 and for the projected supply costs for the next 12-month period. The Montana Public Service Commission (MPSC) reviews such filings and makes its cost recovery determination based on whether or not our electric and natural gas supply procurement activities were prudent.

We do not expect the MPSC to issue final orders related to our 2012 electric supply tracker filing, including our request for demand-side management (DSM) lost revenues, until at least the third quarter of 2013. As of March 31, 2013, we have deferred revenue of approximately $6.2 million related to DSM lost revenues, which is recorded within current regulatory liabilities in the Condensed Consolidated Balance Sheets.

Montana Natural Gas Production Assets

During the third quarter of 2012, we completed the purchase of natural gas production interests in northern Montana's Bear Paw Basin, including a 75% interest in two gas gathering systems (Bear Paw). We are collecting the cost of service for Bear Paw natural gas produced, including a return on our investment, through our natural gas supply tracker on an interim basis. We expect to file an application with the MPSC to place our Bear Paw assets in natural gas rate base during 2013 and this revenue is subject to refund until we receive MPSC approval of our application.

Montana Natural Gas Rate Filing

In September 2012, we filed a request with the MPSC for an annual natural gas delivery revenue increase of approximately $15.7 million. This request was based on a return on equity of 10.5%, a capital structure consisting of 52% debt and 48% equity and rate base of $309.5 million.

In April 2013, we reached a joint settlement with intervenors and received MPSC approval to increase our annual natural gas delivery rates by approximately $11.5 million, based on a return on equity of 9.8%.

9

Montana Avoided Cost Compliance Filing

Colstrip Energy Limited Partnership (CELP) is a QF with which we have a power purchase agreement (PPA) for approximately 306,600 MWH's annually through June 2024. Under the terms of the PPA with CELP, energy and capacity rates were fixed for the first fifteen years and beginning July 1, 2004, through the end of the contract, energy and capacity rates are to be determined each year pursuant to a formula, subject to annual review and approval by the MPSC. Until April 2013, the MPSC's most recent final order related to this compliance filing covered rates through June 30, 2006. We had been in litigation with CELP since 2007 over how to determine energy and capacity rates under the PPA. On November 1, 2012, an arbitration panel issued a final award in our favor. In April 2013, the MPSC issued a final order consistent with the arbitration panel's final award for the contract years July 1, 2006 through June 30, 2013.

(4) Income Taxes

Our effective tax rate was 11.7% for the three months ended March 31, 2013 as compared with 20.0% for the three months ended March 31, 2012. The following table reconciles our effective income tax rate to the federal statutory rate:

	Three Months Ended March 31,
	2013		2012
Federal statutory rate	35.0	%	35.0	%
Flow-through repairs deductions	(18.0	)	(13.9	)
Flow-through of state bonus depreciation deduction	(4.1	)	(3.4	)
Production tax credits	(2.7	)	—
State income tax and other, net	1.5		2.3
	11.7	%	20.0	%

The following table summarizes the significant differences in income tax expense based on the differences between our effective tax rate and the federal statutory rate (in thousands):

	Three Months Ended March 31,
	2013			2012
Income Before Income Taxes	$	42,946		$	40,055
Income tax calculated at 35% federal statutory rate	15,031			14,019
Permanent or flow through adjustments:
Flow-through repairs deductions	(7,710		)	(5,571		)
Flow-through of state bonus depreciation deduction	(1,756		)	(1,371		)
Production tax credits	(1,168		)	—
State income tax and other, net	647			935
	$	(9,987	)	$	(6,007	)
Income tax expense	$	5,044		$	8,012

Our effective tax rate differs from the federal statutory tax rate of 35% primarily due to the regulatory impact of flowing through the federal and state tax benefit of repairs deductions, state tax benefit of bonus depreciation deductions and production tax credits. The regulatory accounting treatment of these deductions requires immediate income recognition for temporary tax differences of this type, which is referred to as the flow-through method. When the flow-through method of accounting for temporary differences is reflected in regulated revenues, we record deferred income taxes and establish related regulatory assets and liabilities.

10

Uncertain Tax Positions

We have unrecognized tax benefits of approximately $113.8 million as of March 31, 2013, including approximately $79.7 million that, if recognized, would impact our effective tax rate. We do not anticipate that total unrecognized tax benefits will significantly change due to the settlement of audits or the expiration of statutes of limitation within the next twelve months.

The Internal Revenue Service (IRS) issued guidance during the third quarter of 2011 providing a safe harbor method for determining the tax treatment of repair costs related to electric transmission and distribution property. That guidance was updated in the third quarter of 2012 to allow companies additional time to adopt the safe harbor method. We are evaluating whether or not we want to elect the safe harbor method, which may result in a change in related repairs deductions and unrecognized tax benefits.

Our policy is to recognize interest and penalties related to uncertain tax positions in income tax expense. During the three months ended March 31, 2013, we have not recognized expense for interest or penalties, and do not have any amounts accrued at March 31, 2013 and December 31, 2012, respectively, for the payment of interest and penalties.

Our federal tax returns from 2000 forward remain subject to examination by the IRS.

(5) Goodwill

There were no changes in our goodwill during the three months ended March 31, 2013. Goodwill by segment is as follows for both March 31, 2013 and December 31, 2012 (in thousands):

Electric	$	241,100
Natural gas	114,028
	$	355,128

(6) Comprehensive (Loss) Income

The following tables display the components of Other Comprehensive (Loss) Income, after-tax, and the related tax effects (in thousands):

	March 31, 2013
	Three Months Ended
	Before-Tax Amount			Tax Benefit		Net-of-Tax Amount
Foreign currency translation adjustment	$	49		$	—	$	49
Reclassification of net gains on derivative instruments to net income	(297		)	114		(183		)
Other comprehensive loss	$	(248	)	$	114	$	(134	)

	March 31, 2012
	Three Months Ended
	Before-Tax Amount			Tax Benefit			Net-of-Tax Amount
Foreign currency translation adjustment	$	(47	)	$	—		$	(47	)
Reclassification of net gains on derivative instruments to net income	(297		)	114			(183		)
Pension and postretirement medical liability adjustment	$	333		$	(128	)	$	205
Other comprehensive loss	$	(11	)	$	(14	)	$	(25	)

11

Balances by classification included within accumulated other comprehensive income (AOCI) on the Condensed Consolidated Balance Sheets are as follows, net of tax (in thousands):

	March 31, 2013			December 31, 2012
Foreign currency translation	$	415		$	366
Derivative instruments designated as cash flow hedges	4,060			4,243
Pension and postretirement medical plans	(2,292		)	(2,292		)
Accumulated other comprehensive income	$	2,183		$	2,317

The following table displays the changes in AOCI by component are as follows, net of tax (in thousands):

		March 31, 2013
		Three Months Ended
	Affected Line Item in the Condensed Consolidated Statements Of Income	Gains on Derivative Instruments Designated as Cash Flow Hedges			Pension and Postretirement Medical Plans			Foreign Currency Translation		Total
Beginning balance		$	4,243		$	(2,292	)	$	366	$	2,317
Other comprehensive income before reclassifications		—			—			49		49
Amounts reclassified from accumulated other comprehensive income	Interest Expense	(183		)	—			—		(183		)
Net current-period other comprehensive (loss) income		(183		)	—			49		(134		)
Ending balance		$	4,060		$	(2,292	)	$	415	$	2,183

(7) Risk Management and Hedging Activities

Nature of Our Business and Associated Risks

We are exposed to certain risks related to the ongoing operations of our business, including the impact of market fluctuations in the price of electricity and natural gas commodities and changes in interest rates. We rely on market purchases to fulfill a large portion of our electric and natural gas supply requirements within the Montana market. Several factors influence price levels and volatility. These factors include, but are not limited to, seasonal changes in demand, weather conditions, available generating assets within regions, transportation availability and reliability within and between regions, fuel availability, market liquidity, and the nature and extent of current and potential federal and state regulations.

Objectives and Strategies for Using Derivatives

To manage our exposure to fluctuations in commodity prices we routinely enter into derivative contracts, such as fixed-price forward purchase and sales contracts. The objective of these transactions is to fix the price for a portion of anticipated energy purchases to supply our customers. These types of contracts are included in our electric and natural gas supply portfolios and are used to manage price volatility risk by taking advantage of fluctuations in market prices. While individual contracts may be above or below market value, the overall portfolio approach is intended to provide greater price stability for consumers. These commodity costs are included in our cost tracking mechanisms and are recoverable from customers subject to prudence reviews by the applicable state regulatory commissions. We do not maintain a trading portfolio, and our derivative transactions are only used for risk management purposes consistent with regulatory guidelines. In addition, in the past we have used and in the future we may use interest rate swaps to manage our interest rate exposures associated with new debt issuances or to manage our exposure to fluctuations in interest rates on variable rate debt.

12

Accounting for Derivative Instruments

We evaluate new and existing transactions and agreements to determine whether they are derivatives. The permitted accounting treatments include: normal purchase normal sale; cash flow hedge; fair value hedge; and mark-to-market. Mark-to-market accounting is the default accounting treatment for all derivatives unless they qualify, and we specifically designate them, for one of the other accounting treatments. Derivatives designated for any of the elective accounting treatments must meet specific, restrictive criteria both at the time of designation and on an ongoing basis. The changes in the fair value of recognized derivatives are recorded each period in current earnings or other comprehensive income, depending on whether a derivative is designated as part of a hedge transaction and the type of hedge transaction.

Normal Purchases and Normal Sales

We have applied the normal purchase and normal sale scope exception (NPNS) to most of our contracts involving the physical purchase and sale of gas and electricity at fixed prices in future periods. During our normal course of business, we enter into full-requirement energy contracts, power purchase agreements and physical capacity contracts, which qualify for NPNS. All of these contracts are accounted for using the accrual method of accounting; therefore, there were no amounts recorded in the Financial Statements at March 31, 2013 and December 31, 2012. Revenues and expenses from these contracts are reported on a gross basis in the appropriate revenue and expense categories as the commodities are received or delivered.

Mark-to-Market Accounting

Certain contracts for the purchase of natural gas associated with our gas utility operations do not qualify for NPNS. These are typically forward purchase contracts for natural gas where we lock in a fixed price, settle the contracts financially and do not take physical delivery of the natural gas. We use the mark-to-market method of accounting for these derivative contracts as we do not elect hedge accounting. Upon settlement of these contracts, associated proceeds or costs are refunded to or collected from our customers consistent with regulatory requirements; therefore, we record a regulatory asset or liability based on changes in market value.

The following table represents the fair value and location of derivative instruments subject to mark-to-market accounting (in thousands). For more information on the determination of fair value see Note 8.

Mark-to-Market Transactions	Balance Sheet Location	March 31, 2013		December 31, 2012
Natural gas net derivative liability	Accrued Expenses	$	3,294	$	5,428

The following table represents the net change in fair value for these derivatives (in thousands):

	Unrealized gain recognized in Regulatory Assets
	Three Months Ended
Derivatives Subject to Regulatory Deferral	March 31, 2013		March 31, 2012
Natural gas	$	2,134	$	1,256

Credit Risk

We are exposed to credit risk primarily through buying and selling electricity and natural gas to serve customers. Credit risk is the potential loss resulting from counterparty non-performance under an agreement. We manage credit risk with policies and procedures for, among other things, counterparty analysis and exposure measurement, monitoring and mitigation. We may request collateral or other security from our counterparties based on the assessment of creditworthiness and expected credit exposure. It is possible that volatility in commodity prices could cause us to have material credit risk exposures with one or more counterparties.

We enter into commodity master enabling agreements with our counterparties to mitigate credit exposure, as these agreements reduce the risk of default by allowing us or our counterparty the ability to make net payments. The agreements

13

generally are: (1) Western Systems Power Pool agreements – standardized power purchase and sales contracts in the electric industry; (2) International Swaps and Derivatives Association agreements – standardized financial gas and electric contracts; (3) North American Energy Standards Board agreements – standardized physical gas contracts; and (4) Edison Electric Institute Master Purchase and Sale Agreements – standardized power sales contracts in the electric industry.

Many of our forward purchase contracts contain provisions that require us to maintain an investment grade credit rating from each of the major credit rating agencies. If our credit rating were to fall below investment grade, the counterparties could require immediate payment or demand immediate and ongoing full overnight collateralization on contracts in net liability positions.

As of March 31, 2013, none of the forward purchase contracts that do not qualify for NPNS contain credit risk-related contingent features.

Interest Rate Swaps Designated as Cash Flow Hedges

We have previously used interest rate swaps designated as cash flow hedges to manage our interest rate exposures associated with new debt issuances. These swaps were designated as cash flow hedges with the effective portion of gains and losses, net of associated deferred income tax effects, recorded in AOCI. We reclassify these gains from AOCI into interest expense during the periods in which the hedged interest payments occur. The following table shows the effect of these derivative instruments on the Financial Statements (in thousands):

	Location of gain reclassified from AOCI to Income	Three Months Ended March 31, 2013 and 2012
Amount of gain reclassified from AOCI	Interest Expense	$	297

Approximately $6.6 million of the pre-tax gain on these cash flow hedges is remaining in AOCI as of March 31, 2013, and we expect to reclassify approximately $1.2 million from AOCI into interest expense during the next twelve months. These gains relate to swaps previously terminated, and we have no current interest rate swaps outstanding.

(8) Fair Value Measurements

Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date (i.e., an exit price). Measuring fair value requires the use of market data or assumptions that market participants would use in pricing the asset or liability, including assumptions about risk and the risks inherent in the inputs to the valuation technique. These inputs can be readily observable, corroborated by market data, or generally unobservable. Valuation techniques are required to maximize the use of observable inputs and minimize the use of unobservable inputs.

A fair value hierarchy that prioritizes the inputs used to measure fair value, and requires fair value measurements to be categorized based on the observability of those inputs has been established by the applicable accounting guidance. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 inputs) and the lowest priority to unobservable inputs (Level 3 inputs). The three levels of the fair value hierarchy are as follows:

• Level 1 – Unadjusted quoted prices available in active markets at the measurement date for identical assets or liabilities;

• Level 2 – Pricing inputs, other than quoted prices included within Level 1, which are either directly or indirectly observable as of the reporting date; and

• Level 3 – Significant inputs that are generally not observable from market activity.

We classify assets and liabilities within the fair value hierarchy based on the lowest level of input that is significant to the fair value measurement of each individual asset and liability taken as a whole. The table below sets forth by level within the fair value hierarchy the gross components of our assets and liabilities measured at fair value on a recurring basis. Normal purchases and sales transactions are not included in the fair values by source table as they are not recorded at fair value. There were no transfers between levels for the periods presented. See Note 7 for further discussion.

14

	Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)		Significant Other Observable Inputs (Level 2)			Significant Unobservable Inputs (Level 3)		Margin Cash Collateral Offset		Total Net Fair Value
	(in thousands)
March 31, 2013
Restricted cash	$	8,381	$	—		$	—	$	—	$	8,381
Rabbi trust investments	14,235		—			—		—		14,235
Derivative liability (1)	—		(3,294		)	—		—		(3,294		)
Total	$	22,616	$	(3,294	)	$	—	$	—	$	19,322
December 31, 2012
Restricted cash	$	6,392	$	—		$	—	$	—	$	6,392
Rabbi trust investments	10,522		—			—		—		10,522
Derivative liability (1)	—		(5,428		)	—		—		(5,428		)
Total	$	16,914	$	(5,428	)	$	—	$	—	$	11,486

_________________________

(1) The changes in the fair value of these derivatives are deferred as a regulatory asset or liability until the contracts are settled. Upon settlement, associated proceeds or costs are passed through the applicable cost tracking mechanism to customers.

We present our derivative assets and liabilities on a net basis in the Condensed Consolidated Balance Sheets. The table above disaggregates our net derivative assets and liabilities on a gross contract-by-contract basis as required and classifies each individual asset or liability within the appropriate level in the fair value hierarchy, regardless of whether a particular contract is eligible for netting against other contracts. These gross balances are intended solely to provide information on sources of inputs to fair value and do not represent our actual credit exposure or net economic exposure. Increases and decreases in the gross components presented in each of the levels in this table also do not indicate changes in the level of derivative activities. Rather, the primary factors affecting the gross amounts are commodity prices.

Restricted cash represents amounts held in money market mutual funds. Rabbi trust assets represent assets held for non-qualified deferred compensation plans, which consist of our common stock and actively traded mutual funds with quoted prices in active markets. Fair value for the commodity derivatives was determined using internal models based on quoted forward commodity prices. We consider nonperformance risk in our valuation of derivative instruments by analyzing the credit standing of our counterparties and considering any counterparty credit enhancements (e.g., collateral). The fair value measurement of liabilities also reflects the nonperformance risk of the reporting entity, as applicable. Therefore, we have factored the impact of our credit standing as well as any potential credit enhancements into the fair value measurement of both derivative assets and derivative liabilities. Consideration of our own credit risk did not have a material impact on our fair value measurements.

15

Financial Instruments

The estimated fair value of financial instruments is summarized as follows (in thousands):

	March 31, 2013				December 31, 2012
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Liabilities:
Long-term debt	$	1,055,079	$	1,225,056	$	1,055,074	$	1,229,233

Short-term borrowings consist of commercial paper and are not included in the table above as carrying value approximates fair value. The estimated fair value amounts have been determined using available market information and appropriate valuation methodologies; however, considerable judgment is required in interpreting market data to develop estimates of fair value. Accordingly, the estimates presented herein are not necessarily indicative of the amounts that we would realize in a current market exchange.

We determined fair value for long-term debt based on interest rates that are currently available to us for issuance of debt with similar terms and remaining maturities, except for publicly traded debt, for which fair value is based on market prices for the same or similar issues or upon the quoted market prices of U.S. treasury issues having a similar term to maturity, adjusted for our bond issuance rating and the present value of future cash flows. These are significant other observable inputs, or level 2 inputs, in the fair value hierarchy.

(9) Financing Activities

In April 2012, we entered into an Equity Distribution Agreement pursuant to which we may offer and sell shares of our common stock from time to time, having an aggregate gross sales price of up to $100 million. Since inception, 1,274,662 shares of our common stock at an average price of $36.80 per share have been issued, for net proceeds of $46.2 million. During the three months ended March 31, 2013, we sold 459,246 shares of our common stock at an average price of $38.98 per share. Proceeds received were approximately $17.7 million, which are net of sales commissions of approximately $0.2 million and other fees.

16

(10) Segment Information

Our reportable business segments are primarily engaged in the electric and natural gas business. The remainder of our operations are presented as other, which is not considered a business unit. Other primarily consists of the wind down of our captive insurance subsidiary and our unallocated corporate costs.

We evaluate the performance of these segments based on gross margin. The accounting policies of the operating segments are the same as the parent except that the parent allocates some of its operating expenses to the operating segments according to a methodology designed by management for internal reporting purposes and involves estimates and assumptions. Financial data for the business segments are as follows (in thousands):

Three Months Ended
March 31, 2013	Electric			Gas			Other			Eliminations		Total
Operating revenues	$	210,092		$	102,518		$	410		$	—	$	313,020
Cost of sales	83,095			49,101			—			—		132,196
Gross margin	126,997			53,417			410			—		180,824
Operating, general and administrative	45,718			19,895			3,224			—		68,837
Property and other taxes	19,152			6,604			3			—		25,759
Depreciation	23,611			5,599			8			—		29,218
Operating income (loss)	38,516			21,319			(2,825		)	—		57,010
Interest expense	(14,127		)	(2,426		)	(226		)	—		(16,779		)
Other income	2,011			677			27			—		2,715
Income tax (expense) benefit	(4,304		)	(1,772		)	1,032			—		(5,044		)
Net income (loss)	$	22,096		$	17,798		$	(1,992	)	$	—	$	37,902
Total assets	$	2,438,892		$	1,031,518		$	10,320		$	—	$	3,480,730
Capital expenditures	$	33,315		$	4,799		$	—		$	—	$	38,114

Three Months Ended
March 31, 2012	Electric			Gas			Other			Eliminations		Total
Operating revenues	$	207,055		$	101,746		$	299		$	—	$	309,100
Cost of sales	82,979			55,417			—			—		138,396
Gross margin	124,076			46,329			299			—		170,704
Operating, general and administrative	45,357			19,288			928			—		65,573
Property and other taxes	17,538			6,124			3			—		23,665
Depreciation	21,569			4,856			8			—		26,433
Operating income (loss)	39,612			16,061			(640		)	—		55,033
Interest expense	(13,667		)	(2,067		)	(228		)	—		(15,962		)
Other income	612			345			27			—		984
Income tax expense	(3,174		)	(3,590		)	(1,248		)	—		(8,012		)
Net income (loss)	$	23,383		$	10,749		$	(2,089	)	$	—	$	32,043
Total assets	$	2,266,842		$	938,335		$	12,194		$	—	$	3,217,371
Capital expenditures	$	24,856		$	22,251		$	—		$	—	$	47,107

17

(11) Earnings Per Share

Basic earnings per share is computed by dividing net income by the weighted average number of common shares outstanding for the period. Diluted earnings per share reflects the potential dilution of common stock equivalent shares that could occur if all unvested shares were to vest. Common stock equivalent shares are calculated using the treasury stock method, as applicable. The dilutive effect is computed by dividing net income by the weighted average number of common shares outstanding plus the effect of the outstanding unvested restricted stock and performance share awards.

Average shares used in computing the basic and diluted earnings per share are as follows:

	Three Months Ended
	March 31, 2013	March 31, 2012
Basic computation	37,384,429	36,328,360
Dilutive effect of
Restricted stock and performance share awards (1)	101,305	171,933
Diluted computation	37,485,734	36,500,293

_________________

(1)           Performance share awards are included in diluted weighted average number of shares outstanding based upon what would be issued if the end of the most recent reporting period was the end of the term of the award.

(12) Employee Benefit Plans

Net periodic benefit cost (income) for our pension and other postretirement plans consists of the following (in thousands):

	Pension Benefits						Other Postretirement Benefits
	Three Months Ended March 31,						Three Months Ended March 31,
	2013			2012			2013			2012
Components of Net Periodic Benefit Cost (Income)
Service cost	$	3,439		$	3,024		$	156		$	123
Interest cost	5,624			5,935			217			285
Expected return on plan assets	(8,125		)	(7,506		)	(254		)	(257		)
Amortization of prior service cost	62			62			(500		)	(500		)
Recognized actuarial loss	2,752			2,105			225			184
Net Periodic Benefit Cost (Income)	$	3,752		$	3,620		$	(156	)	$	(165	)

18

(13) Commitments and Contingencies

ENVIRONMENTAL LIABILITIES AND REGULATION

The operation of electric generating, transmission and distribution facilities, and gas gathering, transportation and distribution facilities, along with the development (involving site selection, environmental assessments, and permitting) and construction of these assets, are subject to extensive federal, state, and local environmental and land use laws and regulations. Our activities involve compliance with diverse laws and regulations that address emissions and impacts to the environment, including air and water, protection of natural resources, avian and wildlife. We monitor federal, state, and local environmental initiatives to determine potential impacts on our financial results. As new laws or regulations are implemented, our policy is to assess their applicability and implement the necessary modifications to our facilities or their operation to maintain ongoing compliance.

Our environmental exposure includes a number of components, including remediation expenses related to the cleanup of current or former properties, and costs to comply with changing environmental regulations related to our operations. At present, the majority of our environmental reserve relates to the remediation of former manufactured gas plant sites owned by us. We use a combination of site investigations and monitoring to formulate an estimate of environmental remediation costs for specific sites. Our monitoring procedures and development of actual remediation plans depend not only on site specific information but also on coordination with the different environmental regulatory agencies in our respective jurisdictions; therefore, while remediation exposure exists, it may be many years before costs become fixed and reliably determinable.

Our liability for environmental remediation obligations is estimated to range between $28.3 million to $36.4 million, primarily for manufactured gas plants discussed below. As of March 31, 2013, we have a reserve of approximately $31.3 million, which has not been discounted. Environmental costs are recorded when it is probable we are liable for the remediation and we can reasonably estimate the liability. Over time, as specific laws are implemented and we gain experience in operating under them, a portion of the costs related to such laws will become determinable, and we may seek authorization to recover such costs in rates or seek insurance reimbursement as applicable; therefore, although we cannot guarantee regulatory recovery, we do not expect these costs to have a material effect on our consolidated financial position or ongoing operations.

Manufactured Gas Plants - Approximately $24.6 million of our environmental reserve accrual is related to manufactured gas plants. A formerly operated manufactured gas plant located in Aberdeen, South Dakota, has been identified on the Federal Comprehensive Environmental Response, Compensation, and Liability Information System list as contaminated with coal tar residue. We are currently conducting remedial actions at the Aberdeen site pursuant to work plans approved by the South Dakota Department of Environment and Natural Resources (DENR). Our current reserve for remediation costs at this site is approximately $12.2 million, and we estimate that approximately $8.6 million of this amount will be incurred during the next five years.

We also own sites in North Platte, Kearney and Grand Island, Nebraska on which former manufactured gas facilities were located. During 2005, the Nebraska Department of Environmental Quality (NDEQ) conducted Phase II investigations of soil and groundwater at our Kearney and Grand Island sites. During 2006, the NDEQ released to us the Phase II Limited Subsurface Assessments performed by the NDEQ's environmental consulting firm for Kearney and Grand Island. In February 2011, NDEQ completed an Abbreviated Preliminary Assessment and Site Investigation Report for Grand Island, which recommended additional ground water testing. In April of 2012, we received a letter from NDEQ regarding a recently completed Vapor Intrusion Assessment Report and an invitation to join NDEQ's Voluntary Cleanup Program (VCP). We declined NDEQ's offer to join its VCP at this time and also committed to conducting a limited soil vapor investigation. We will work independently to fully characterize the nature and extent of impacts associated with the former manufactured gas plant. After the site has been fully characterized, we will discuss the possibility of joining NDEQ's VCP. Our reserve estimate includes assumptions for additional ground water testing. At present, we cannot determine with a reasonable degree of certainty the nature and timing of any risk-based remedial action at our Nebraska locations.

In addition, we own or have responsibility for sites in Butte, Missoula and Helena, Montana on which former manufactured gas plants were located. An investigation conducted at the Missoula site did not require remediation activities, but required preparation of a groundwater monitoring plan. The Butte and Helena sites were placed into the Montana Department of Environmental Quality (MDEQ) voluntary remediation program for cleanup due to excess regulated pollutants in the groundwater. Voluntary soil and coal tar removals were conducted in the past at the Butte and Helena locations in accordance with MDEQ requirements. We have conducted additional groundwater monitoring at the Butte and Missoula sites and, at this time, we believe natural attenuation should address the conditions at these sites; however, additional groundwater monitoring will be necessary. Monitoring of groundwater at the Helena site is ongoing and will be necessary for an extended

19

period of time. At this time, we cannot estimate with a reasonable degree of certainty the nature and timing of risk-based remedial action at the Helena site or if any additional actions beyond monitored natural attenuation will be required.

Global Climate Change - There are national and international efforts to adopt measures related to global climate change and the contribution of emissions of greenhouse gases (GHG) including, most significantly, carbon dioxide. These efforts include legislative proposals and Environmental Protection Agency (EPA) regulations at the federal level, actions at the state level, and private party litigation relating to GHG emissions. Coal-fired plants have come under particular scrutiny due to their level of GHG emissions. We have joint ownership interests in four electric generating plants, all of which are coal fired and operated by other companies. We have undivided interests in these facilities and are responsible for our proportionate share of the capital and operating costs while being entitled to our proportionate share of the power generated.

While numerous bills have been introduced that address climate change from different perspectives, including through direct regulation of GHG emissions, the establishment of cap and trade programs and the establishment of Federal renewable portfolio standards, Congress has not passed any federal climate change legislation and we cannot predict the timing or form of any potential legislation. In the absence of such legislation, the EPA is regulating GHG emissions under its existing authority pursuant to the Clean Air Act. For example, EPA regulations now require that major sources in the United States annually report information regarding, and obtain certain permits for, their GHG emissions.

In March 2012, the EPA proposed New Source Performance Standards that would limit carbon dioxide emissions from new electric generating units (EGUs). The proposed limits would not apply to existing or reconstructed EGUs. The proposed rule was part of an agreement to settle litigation brought by states, municipalities and environmental groups. The EPA accepted comments on the proposed standards through the end of June 2012. The EPA has not issued final standards.

On June 20, 2011, the U.S. Supreme Court issued a decision that bars state and private parties from bringing federal common law nuisance actions against electrical utility companies based on their alleged contribution to climate change. The Supreme Court's decision did not, however, address state law claims. This decision is expected to affect other pending federal climate change litigation. In addition, on June 26, 2012 a federal court issued a ruling affirming several of the EPA's greenhouse gas rules, which had been challenged by industry petitioners and certain states. Although we are not a party to any of these proceedings, additional litigation in federal and state courts over these issues is continuing.

Physical impacts of climate change may present potential risks for severe weather, such as floods and tornadoes, in the locations where we operate or have interests. Furthermore, requirements to reduce GHG emissions from stationary sources could cause us to incur material costs of compliance, increase our costs of procuring electricity in the marketplace or curtail the demand for fossil fuels such as oil and gas. In addition, we believe future legislation and regulations that affect GHG emissions from power plants are likely, although technology to efficiently capture, remove and/or sequester such emissions may not be available within a timeframe consistent with the implementation of such requirements. We cannot predict with any certainty whether these risks will have a material impact on our operations.

Coal Combustion Residuals (CCRs) - In June 2010, the EPA proposed two approaches to regulating the disposal and management of CCRs under the Resource Conservation and Recovery Act (RCRA). CCRs include fly ash, bottom ash and scrubber wastes. Under one approach, the EPA would regulate CCRs as a hazardous waste under Subtitle C of RCRA. This approach would have significant impacts on coal-fired plants, and would require plants to retrofit their operations to comply with hazardous waste requirements from the generation of CCRs and associated waste waters through transportation and disposal. This could also have a negative impact on the beneficial use of CCRs and the current markets associated with such use. The second approach would regulate CCRs as a solid waste under Subtitle D of RCRA. This approach would only affect disposal, most significantly any wet disposal, of CCRs. The EPA has not yet issued a final CCR rule; however, litigation has commenced to require it to do so. In addition, legislation was introduced in Congress to regulate coal ash. We cannot predict at this time the final requirements of any CCR regulations or legislation and what impact, if any, they would have on us, but the costs of complying with any such requirements could be significant.

Water Intakes - Section 316(b) of the Federal Clean Water Act requires that the location, design, construction and capacity of any cooling water intake structure reflect the “best available technology” for minimizing environmental impacts. Permits required for existing facilities are to be developed by the individual states using their best professional judgment until the EPA takes action to address several court decisions that rejected portions of previous rules and confirmed that the EPA has discretion to consider costs relative to benefits in developing cooling water intake structure regulations. In March 2011, the EPA proposed a rule to address impingement and entrainment of aquatic organisms at existing cooling water intake structures. The EPA is under a consent decree to issue a final rule by June 2013. When a final rule is issued and implemented, additional capital and/or increased operating costs may be incurred. The costs of complying with any such final water intake standards are not currently determinable, but could be significant.

20

Clean Air Act Rules and Associated Emission Control Equipment Expenditures

The EPA has proposed or issued a number of rules under different provisions of the Clean Air Act that could require the installation of emission control equipment at the generation plants where we have joint ownership.

The Clean Air Visibility Rule was issued by the EPA in June 2005, to address regional haze in national parks and wilderness areas across the United States. The Clean Air Visibility Rule requires the installation and operation of Best Available Retrofit Technology (BART) to achieve emissions reductions from designated sources (including certain electric generating units) that are deemed to cause or contribute to visibility impairment in such 'Class I' areas.

In December 2011, the EPA issued a final rule relating to Mercury and Air Toxics Standards (MATS), which was formerly the proposed Maximum Achievable Control Technology standards for hazardous air pollutant emissions from new and existing electric generating units. Among other things, these MATS standards set stringent emission limits for acid gases, mercury, and other hazardous air pollutants. Facilities that are subject to the MATS must come into compliance within three years after the effective date of the rule (or by 2015) unless a one year extension is granted on a case-by-case basis. On March 20, 2013, the EPA finalized updates to emission limits under the MATS for new power plants. Numerous challenges to the MATS standards have been filed with the EPA and in Federal court and we cannot predict the outcome of such challenges.

On July 7, 2011, the EPA finalized the Cross-State Air Pollution Rule (CSAPR) to reduce emissions from electric generating units that interfere with the ability of downwind states to achieve ambient air quality standards. Under CSAPR, significant reductions in emissions of nitrogen oxide (NOx) and sulfur dioxide (SO2) were to be required beginning in 2012. After having issued a stay of CSAPR earlier this year, however, a Federal court found that CSAPR violated federal law and ordered that it be vacated. The Clean Air Interstate Rule remains in effect until the EPA issues a valid replacement. The EPA and environmental groups have petitioned the Supreme Court to review the Federal court's ruling.

We have joint ownership in generation plants located in South Dakota, North Dakota, Iowa and Montana that are or may become subject to various regulations that have been issued or proposed under the Clean Air Act, as discussed below.

South Dakota. The South Dakota DENR determined that the Big Stone Plant, of which we have a 23.4% ownership, is subject to the BART requirements of the Regional Haze Rule. South Dakota DENR's State Implementation Plan (SIP) was approved by the EPA in May 2012. Under the SIP, the Big Stone plant must install and operate a new BART compliant air quality control system (AQCS) to reduce SO2, NOx and particulate emissions as expeditiously as practicable, but no later than five years after the EPA's approval of the SIP. The current project cost for the AQCS is estimated to be approximately $405 million (our share is 23.4%) and it is expected to be operational by 2016.

Our incremental capital expenditure projections include amounts related to our share of the BART technologies at Big Stone based on current estimates. We could, however, face additional capital or financing costs. We will seek to recover any such costs through the regulatory process. The South Dakota Public Utilities Commission has historically allowed timely recovery of the costs of environmental improvements; however, there is no precedent on a project of this size.

Based on the finalized MATS standards, it appears that Big Stone would meet the requirements by installing the AQCS system and using mercury control technology such as activated carbon injection. Mercury emissions monitoring equipment is already installed at Big Stone, but its operation has been put on hold pending additional regulatory direction. The equipment will need to be reevaluated for operability under the final rule.

North Dakota. The North Dakota Regional Haze SIP requires the Coyote generating facility, of which we have 10% ownership, to reduce its NOx emissions. Coyote must install control equipment to limit its NOx emissions to 0.5 pounds per million Btu as calculated on a 30-day rolling average basis, including periods of start-up and shutdown, beginning on July 1, 2018. The current estimate of the total cost of the project is approximately $6 million (our share is 10.0%).

Based on the finalized MATS standards, it appears that Coyote would meet the requirements by using mercury control technology such as activated carbon injection.

Iowa. The Neal 4 generating facility, of which we have an 8.7% ownership, is installing a scrubber, a baghouse, activated carbon and a selective non-catalytic reduction system to comply with national ambient air quality standards and MATS standards. Capital expenditures for such equipment are currently estimated to be approximately $270 million (our share is 8.7%). The plant began incurring such costs in 2011 and the project is expected to be complete in 2013.

21

Montana. Colstrip Unit 4, a coal fired generating facility in which we have a 30% interest, is currently controlling emissions of mercury under regulations issued by the State of Montana, which are more strict than the Federal MATS standard. The owners do not believe additional equipment will be necessary to meet the MATS standards for mercury, and anticipate meeting all other expected MATS emissions limitations required by the rule without additional costs except those costs related to increased monitoring frequency. These additional costs are not expected to be significant.

In September 2012, a final Federal Implementation Plan for Montana was published in the Federal Register to address regional haze. As finalized, Colstrip Unit 4 does not have to improve removal efficiency for pollutants that contribute to regional haze. The plan is reviewed every five years and Colstrip Unit 4 could be impacted during a subsequent review period.

See 'Legal Proceedings - Colstrip Litigation' below for discussion of Sierra Club litigation.

Other - We continue to manage equipment containing polychlorinated biphenyl (PCB) oil in accordance with the EPA's Toxic Substance Control Act regulations. We will continue to use certain PCB-contaminated equipment for its remaining useful life and will, thereafter, dispose of the equipment according to pertinent regulations that govern the use and disposal of such equipment.

We routinely engage the services of a third-party environmental consulting firm to assist in performing a comprehensive evaluation of our environmental reserve. Based upon information available at this time, we believe that the current environmental reserve properly reflects our remediation exposure for the sites currently and previously owned by us. The portion of our environmental reserve applicable to site remediation may be subject to change as a result of the following uncertainties:

• We may not know all sites for which we are alleged or will be found to be responsible for remediation; and

• Absent performance of certain testing at sites where we have been identified as responsible for remediation, we cannot estimate with a reasonable degree of certainty the total costs of remediation.

LEGAL PROCEEDINGS

Colstrip Litigation

On July 25, 2012, the Sierra Club and the Montana Environmental Information Center (MEIC) served on each of the individual owners of the Colstrip Steam Electric Station (CSES), including us and the owner or managing agent of the station, a notice of intent to sue for alleged violations of the federal Clean Air Act, 42 U.S.C. § 7401 et seq. Since serving the initial notice of intent to sue, the Sierra Club and MEIC have revised it three times.

On March 6, 2013, the Sierra Club and the MEIC (Plaintiffs) filed suit in the United States District Court for the District of Montana against the individual owners of the CSES, including us, and the operator or managing agent of the station. Plaintiffs' complaint, which includes 39 claims for relief, alleges violations of the Clean Air Act and seeks injunctive and declaratory relief, civil penalties, imposition of a beneficial environmental project, and recovery of their attorney fees. Plaintiffs have identified physical changes made at the CSES between 1992 and 2012, which they allege have increased emissions of SO2, NOx and particulate matter and were “major modifications” subject to permitting requirements under the Clean Air Act. They also have alleged violations of the requirements related to Part 70 Operating Permits, as well as provisions in the Montana State Implementation Plan regulating the opacity of emissions. We intend to vigorously defend this lawsuit. Due to the preliminary nature of the lawsuit, at this time, we cannot predict or determine the outcome of the lawsuit, nor is it reasonably possible to estimate the amount of loss, if any, that would be associated with an adverse decision.

Other Legal Proceedings

We are also subject to various other legal proceedings, governmental audits and claims that arise in the ordinary course of business. In the opinion of management, the amount of ultimate liability with respect to these other actions will not materially affect our financial position, results of operations, or cash flows.

22

ITEM 2. MANAGEMENT’S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS

OVERVIEW

NorthWestern Corporation, doing business as Northwestern Energy, provides electricity and natural gas to approximately 673,200 customers in Montana, South Dakota and Nebraska. For a discussion of NorthWestern’s business strategy, see Management’s Discussion and Analysis of Financial Condition and Results of Operations in our Annual Report on Form 10-K for the year ended December 31, 2012.

Significant items during the three months ended March 31, 2013 include:

• Improvement in net income of approximately $5.9 million as compared with the same period in 2012, due primarily to natural gas production and electric supply acquisitions;

• Received MPSC approval to increase rates effective April 1, 2013, in our natural gas distribution rate case; and

• Received proceeds of approximately $17.7 million after commissions and other fees from the sale of 459,246 common shares under our Equity Distribution Agreement.

Montana Natural Gas Production Assets

During the third quarter of 2012, we completed the purchase of natural gas production interests in northern Montana's Bear Paw Basin, including a 75% interest in two gas gathering systems (Bear Paw). During the three months ended March 31, 2013, the Bear Paw acquisition contributed approximately $2.6 million to gross margin. We are collecting the cost of service for Bear Paw natural gas produced, including a return on our investment, through our natural gas supply tracker on an interim basis. We expect to file an application with the MPSC to place our Bear Paw assets in natural gas rate base during 2013 and this revenue is subject to refund until we receive MPSC approval of our application.

Wind Generation

During the fourth quarter of 2012, we purchased and placed into service the 40 MW Spion Kop wind project in Judith Basin County in Montana for approximately $84 million. Beginning in December 2012, the cost of service of the electricity generated, including a return on our investment, has been included in electric supply rates. During the three months ended March 31, 2013, the acquisition of Spion Kop contributed approximately $1.6 million to gross margin and approximately $1.2 million in production tax credits (lower income tax expense).

Montana Natural Gas Rate Filing

In September 2012, we filed a request with the MPSC for a natural gas delivery revenue increase of approximately $15.7 million. This request was based on a return on equity of 10.5%, a capital structure consisting of 52% debt and 48% equity and rate base of $309.5 million.

In April 2013, we reached a joint settlement with intervenors and received MPSC approval to increase our annual natural gas delivery rates by approximately $11.5 million, based on a return on equity of 9.8%.

Dave Gates Generating Station at Mill Creek (DGGS)

As a result of a FERC Administrative Law Judge's (ALJ) initial nonbinding decision issued in September 2012, we have cumulative deferred revenue of approximately $18.5 million, which includes approximately $2.0 million deferred during the first quarter of 2013. These amounts are subject to refund and recorded within current regulatory liabilities in the Condensed Consolidated Balance Sheets. The ALJ concluded we should allocate only a fraction of the costs we believed (based on past practice) should be allocated to FERC jurisdictional customers. Our brief in opposition to the ALJ's initial decision is pending before the FERC.

Although we have no assurance as to timing, the FERC is expected to consider the matter and issue a binding decision during 2013. The FERC is not obligated to follow any of the ALJ's findings and conclusions, and the FERC can accept or reject the initial decision in whole or in part. If the FERC upholds the ALJ's decision and a portion of the costs are effectively disallowed, we would be required to assess DGGS for impairment. If we disagree with a decision issued by the FERC, we may pursue full appellate rights through rehearing and appeal to a United States Circuit Court of Appeals, which could extend into

23

2015. We continue to bill FERC jurisdictional customers interim rates that have been in effect since January 1, 2011. These interim rates are subject to refund plus interest pending final resolution at FERC.

STRATEGY UPDATE

Regulatory Matters

General rate cases are necessary to generate the revenues necessary to provide safe, reliable service, while contributing to earnings growth and achieving our financial objectives. We regularly review the need for electric and natural gas rate changes in each state in which we provide service. Our general rate cases are based on historic test years, with known and measurable adjustments. Based on our analysis of 2012 actual results, with anticipated known and measurable adjustments, we currently do not believe general rate cases are necessary during 2013 in any of our jurisdictions.

We had anticipated filing a general electric rate case in South Dakota based on a 2012 test year due to the supply investments discussed below. After evaluating our overall cost of service, we do not believe a general rate case will be necessary until at least 2014. When we do file an electric rate case in South Dakota, we expect to request a tariff mechanism (environmental rider) to recover future environmental related expenses and capital costs associated with Big Stone and Neal #4 electric generation units. Until such a rider is authorized, we are recording allowance for funds used during construction (AFUDC) on our capital investments before they are placed into service.

Supply Investments

During 2012, we began construction on the Aberdeen Generating Station, a 60 MW natural gas peaking facility located in Aberdeen, South Dakota, which we expect to achieve commercial operation during the second quarter of 2013. This facility is intended to provide peaking reserve margin necessary to comply with capacity reserve requirements. As of March 31, 2013, we have capitalized approximately $53.3 million associated with this project. We do not expect additional capital expenditures during 2013 to be significant.

The Big Stone and Neal #4 electric generation facilities are subject to additional emission reduction requirements. Neal #4 began incurring such costs in 2011 and work is expected to be completed by the end of 2013. Big Stone began incurring costs in 2013 with costs expected to be spread over three years. Based on updated cost estimates from the operator, our share of capital expenditures related to the Big Stone project has been reduced from approximately $115 million to approximately $95 million.

24

RESULTS OF OPERATIONS

Our consolidated results include the results of our reportable business segments, which are primarily engaged in the electric and natural gas business. The overall consolidated discussion is followed by a detailed discussion of gross margin by segment.

Non-GAAP Financial Measure

The following discussion includes financial information prepared in accordance with GAAP, as well as another financial measure, Gross Margin, that is considered a “non-GAAP financial measure.” Generally, a non-GAAP financial measure is a numerical measure of a company’s financial performance, financial position or cash flows that exclude (or include) amounts that are included in (or excluded from) the most directly comparable measure calculated and presented in accordance with GAAP. Gross Margin (Revenues less Cost of Sales) is a non-GAAP financial measure due to the exclusion of depreciation from the measure. The presentation of Gross Margin is intended to supplement investors’ understanding of our operating performance. Gross Margin is used by us to determine whether we are collecting the appropriate amount of energy costs from customers to allow recovery of operating costs. Our Gross Margin measure may not be comparable to other companies’ Gross Margin measure. Furthermore, this measure is not intended to replace operating income as determined in accordance with GAAP as an indicator of operating performance.

Factors Affecting Results of Operations

Our revenues may fluctuate substantially with changes in supply costs, which are generally collected in rates from customers. In addition, various regulatory agencies approve the prices for electric and natural gas utility service within their respective jurisdictions and regulate our ability to recover costs from customers.

Revenues are also impacted to a lesser extent by customer growth and usage, the latter of which is primarily affected by weather. Very cold winters increase demand for natural gas and to a lesser extent, electricity, while warmer than normal summers increase demand for electricity, especially among our residential and commercial customers. We measure this effect using degree-days, which is the difference between the average daily actual temperature and a baseline temperature of 65 degrees. Heating degree-days result when the average daily temperature is less than the baseline. Cooling degree-days result when the average daily temperature is greater than the baseline. The statistical weather information in our regulated segments represents a comparison of this data.

25

OVERALL CONSOLIDATED RESULTS

Three Months Ended March 31,2013 Compared with the Three Months Ended March 31,2012

	Three Months Ended March 31,
	2013		2012		Change		% Change
	(dollars in millions)
Operating Revenues
Electric	$	210.1	$	207.1	$	3.0	1.4	%
Natural Gas	102.5		101.7		0.8		0.8
Other	0.4		0.3		0.1		33.3
	$	313.0	$	309.1	$	3.9	1.3	%

	Three Months Ended March 31,
	2013		2012		Change			% Change
	(dollars in millions)
Cost of Sales
Electric	$	83.1	$	83.0	$	0.1		0.1	%
Natural Gas	49.1		55.4		(6.3		)	(11.4	)
	$	132.2	$	138.4	$	(6.2	)	(4.5	)%

	Three Months Ended March 31,
	2013		2012		Change		% Change
	(dollars in millions)
Gross Margin
Electric	$	127.0	$	124.1	$	2.9	2.3	%
Natural Gas	53.4		46.3		7.1		15.3
Other	0.4		0.3		0.1		33.3
	$	180.8	$	170.7	$	10.1	5.9	%

Primary components of the change in gross margin include the following:

	Gross Margin 2013 vs. 2012
	(in millions)
Natural gas production	$	3.6
Natural gas and electric retail volumes	2.6
Transmission capacity	2.5
Spion Kop	1.6
DSM lost revenues	0.9
Transportation and storage capacity	0.9
Montana property tax tracker	0.4
DGGS	(4.3		)
Other	1.9
Increase in Consolidated Gross Margin	$	10.1

26

Consolidated gross margin increased $10.1 million primarily due to the following:

• An increase in natural gas production margin, primarily due to the acquisition of the Bear Paw assets in the third quarter of 2012;

• An increase in natural gas and electric retail volumes due primarily to colder winter weather;

• An increase in transmission capacity revenues due to higher demand to transmit energy for others across our lines due to favorable wholesale market pricing conditions;

• The acquisition of the Spion Kop wind farm in the fourth quarter of 2012;

• An increase in DSM lost revenues recovered through our supply trackers related to efficiency measures implemented by customers;

• An increase in transportation and storage capacity revenues due to higher demand to transmit natural gas for others across our pipelines and higher demand to store natural gas for others as a result of lower average natural gas prices; and

• An increase in Montana property taxes included in a tracker.

These increases were partly offset by lower DGGS revenue in the first quarter 2013, as the same period in 2012 included recognition of approximately $2.7 million that we had deferred in prior periods pending outcome of allocation uncertainty in Montana. In addition, during the first quarter of 2013, our FERC related deferral increased by approximately $1.6 million as compared with 2012 due to the initial FERC ALJ nonbinding decision.

Demand-side management (DSM) lost revenues - Base rates, including impacts of past DSM activities, are reset in general rate case filings. As time passes between rate cases, more energy saving measures (primarily more efficient residential and commercial lighting) are implemented, causing an increase in DSM lost revenues. Historically, the MPSC had authorized us to include a calculation of lost revenues based on actual historic DSM program activity, but prohibited the inclusion of forecasted or estimated future lost revenue in the electric tracker. In its April 2012 order, the MPSC authorized us to include forecasted lost revenues in future tracker filings. We have not recognized the entire forecasted amount as we were required to provide the MPSC with a detailed independent study supporting our requested DSM lost revenues during the first quarter of 2013. The study is also subject to review and potential challenge by intervenors, such as the Montana Consumer Counsel. The MPSC could ultimately determine our requested amounts are too high and we may have to refund a portion of DSM lost revenues that we have recognized. As of March 31, 2013, we have deferred revenue of approximately $1.3 million related to DSM lost revenues collected in 2013, and $4.9 million collected during 2012. We do not expect the MPSC to issue a final order related to electric DSM lost revenues until at least the third quarter of 2013.

	Three Months Ended March 31,
	2013		2012		Change		% Change
	(dollars in millions)
Operating Expenses (excluding cost of sales)
Operating, general and administrative	$	68.8	$	65.6	$	3.2	4.9	%
Property and other taxes	25.8		23.7		2.1		8.9
Depreciation	29.2		26.4		2.8		10.6
	$	123.8	$	115.7	$	8.1	7.0	%

27

Consolidated operating, general and administrative expenses were $68.8 million for the three months ended March 31, 2013, as compared with $65.6 million for the three months ended March 31, 2012. Primary components of the change include the following:

	Operating, General & Administrative Expenses
	2013 vs. 2012
	(in millions)
Distribution System Infrastructure Project (DSIP) expenses	$	2.6
Non-employee directors deferred compensation	1.4
Natural gas production	0.9
Insurance expense	0.7
Plant operator costs	0.5
Pension and employee benefits	(4.2		)
Other	1.3
Increase in Operating, General & Administrative Expenses	$	3.2

The increase in operating, general and administrative expenses of $3.2 million was primarily due to the following:

• Incremental operating and maintenance costs related to the phase-in of DSIP during 2012 and 2011 were deferred in accordance with the MPSC's approval of an accounting order. Incremental DSIP costs for 2013 forward are being expensed as incurred and the amounts previously deferred are being amortized over five years. During the first quarter of 2013 we amortized approximately $0.8 million and incurred incremental DSIP expenses of approximately $1.8 million;

• Non-employee directors deferred compensation increased primarily due to changes in our stock price. Directors may defer their board fees into deferred shares held in a rabbi trust. Compensation expense changes with the market value of our stock; however, this change in value is offset in other income due to the change in value of trust assets with no impact on net income;

• Higher natural gas production costs due to the Bear Paw acquisition;

• Increased insurance expense primarily due to general liability matters; and

• Higher plant operator costs primarily due to the Spion Kop acquisition.

These increases were partly offset by decreased pension expense, offset in part by increased medical expenses. Our Montana pension costs are included in expense on a pay as you go (cash funding) basis. We received a pension accounting order from the MPSC in 2008, which based our Montana pension expense on an average of our funding requirements for calendar years 2005 through 2012 in order to smooth the impact of increased cash funding. We expect our 2013 Montana pension expense to be approximately $20.0 million lower than 2012 on an annualized basis due to the expiration of this order and our current cash funding estimate.

Property and other taxes was $25.8 million for the three months ended March 31, 2013, as compared with $23.7 million in the same period of 2012. This increase was primarily due to higher estimated property valuations in Montana and plant additions. We estimate property taxes throughout each year and update to the actual expense when we receive our Montana property tax bills in November.

Depreciation expense was $29.2 million for the three months ended March 31, 2013, as compared with $26.4 million in the same period of 2012. This increase was primarily due to plant additions.

Consolidated operating income for the three months ended March 31, 2013 was $57.0 million, as compared with $55.0 million in the same period of 2012. This increase was due to the increase in gross margin partly offset by higher operating expenses as discussed above.

Consolidated interest expense for the three months ended March 31, 2013 was $16.8 million, as compared with $16.0 million in the same period of 2012. This increase was primarily due to higher debt outstanding partially offset by higher capitalization of AFUDC.

28

Consolidated other income for the three months ended March 31, 2013, was $2.7 million, as compared with $1.0 million in the same period of 2012. This increase was primarily due to a $1.4 million gain on deferred shares held in trust for non-employee directors deferred compensation discussed above and higher capitalization of AFUDC.

Consolidated income tax expense for the three months ended March 31, 2013 was $5.0 million, as compared with $8.0 million in the same period of 2012. Our effective tax rate was 11.7% for the three months ended March 31, 2013 as compared with 20.0% for the three months ended March 31, 2012. The following table summarizes the significant differences in income tax expense based on the differences between our effective tax rate and the federal statutory rate (in millions):

	Three Months Ended March 31,
	2013			2012
Income Before Income Taxes	$	42.9		$	40.1
Income tax calculated at 35% federal statutory rate	15.0			14.0
Permanent or flow through adjustments:
Flow-through repairs deductions	(7.7		)	(5.6		)
Production tax credits	(1.2		)	—
Flow-through of state bonus depreciation deduction	(1.8		)	(1.4		)
State income tax and other, net	0.7			1.0
	(10.0		)	(6.0		)
Income tax expense	$	5.0		$	8.0

Our effective tax rate differs from the federal statutory tax rate of 35% primarily due to the regulatory impact of flowing through federal and state tax benefits of repairs deductions, state tax benefit of bonus depreciation deductions and production tax credits. The regulatory accounting treatment of these deductions requires immediate income recognition for temporary tax differences of this type, which is referred to as the flow-through method. When the flow-through method of accounting for temporary differences is reflected in regulated revenues, we record deferred income taxes and establish related regulatory assets and liabilities.

Consolidated net income for the three months ended March 31, 2013 was $37.9 million as compared with $32.0 million for the same period in 2012. This increase was primarily due to higher operating income, higher other income, and lower income tax expense offset in part by higher interest expense as discussed above.

29

ELECTRIC SEGMENT

We have various classifications of electric revenues, defined as follows:

• Retail: Sales of electricity to residential, commercial and industrial customers.

• Regulatory amortization: Primarily represents timing differences for electric supply costs and property taxes between when we incur these costs and when we recover these costs in rates from our customers, which has a minimal impact on gross margin.

• Transmission: Reflects transmission revenues regulated by the FERC.

• Ancillary Services: FERC jurisdictional services that ensure reliability and support the transmission of electricity from generation sites to customer loads. Such services include regulation service, reserves and voltage support.

• Wholesale: Sales of electricity to electric cooperatives, municipalities and other electric utilities, the prices for which are based on prevailing market prices.

• Other: Miscellaneous electric revenues.

Three Months Ended March 31,2013 Compared with the Three Months Ended March 31,2012

	Results
	2013			2012			Change			% Change
	(dollars in millions)
Retail revenues	$	200.0		$	192.0		$	8.0		4.2	%
Regulatory amortization	(5.9		)	(0.5		)	(5.4		)	1,080.0
Total retail revenues	194.1			191.5			2.6			1.4
Transmission	13.6			11.1			2.5			22.5
Ancillary services	0.4			2.2			(1.8		)	(81.8	)
Wholesale	0.5			0.9			(0.4		)	(44.4	)
Other	1.5			1.4			0.1			7.1
Total Revenues	210.1			207.1			3.0			1.4
Total Cost of Sales	83.1			83.0			0.1			0.1
Gross Margin	$	127.0		$	124.1		$	2.9		2.3	%

	Revenues				Megawatt Hours (MWH)		Avg. Customer Counts
	2013		2012		2013	2012	2013	2012
	(in thousands)
Retail Electric
Montana	$	76,006	$	72,137	681	671	276,601	274,164
South Dakota	13,824		12,986		178	160	49,175	48,840
Residential	89,830		85,123		859	831	325,776	323,004
Montana	77,772		75,696		780	794	62,638	62,010
South Dakota	17,344		16,916		245	235	12,060	11,954
Commercial	95,116		92,612		1,025	1,029	74,698	73,964
Industrial	10,401		9,637		748	730	74	73
Other	4,660		4,581		23	23	4,509	4,511
Total Retail Electric	$	200,007	$	191,953	2,655	2,613	405,057	401,552
Total Wholesale Electric	$	507	$	869	23	53	—	—

30

	Degree Days			2013 as compared with:
Heating Degree-Days	2013	2012	Historic Average	2012	Historic Average
Montana	3,223	3,039	3,283	6% colder	2% warmer
South Dakota	4,217	3,417	4,054	23% colder	4% colder

The following summarizes the components of the changes in electric gross margin for the three months ended March 31, 2013 and 2012:

	Gross Margin 2013 vs. 2012
	(in millions)
Transmission capacity	$	2.5
Spion Kop	1.6
DSM lost revenues	0.9
Retail volumes	0.8
DGGS	(4.3		)
Other	1.4
Increase in Gross Margin	$	2.9

This increase in gross margin was primarily due to the following:

• An increase in transmission capacity revenues due to higher demand driven by improved wholesale market pricing conditions;

• The acquisition of the Spion Kop wind farm in the fourth quarter of 2012;

• An increase in DSM lost revenues recovered through our supply trackers related to efficiency measures implemented by customers; and

• An increase in volumes due primarily to colder winter weather.

These increases were partly offset by lower ancillary services revenue from DGGS in the first quarter of 2013.

Demand for transmission capacity can fluctuate substantially from year to year based on hydro, weather and market conditions in Montana and states to the South and West. Improved wholesale market pricing during the first quarter of 2013 resulted in increased demand to transmit electricity from Montana over our lines.

Retail volumes increased primarily due to colder winter weather and customer growth. Wholesale volumes decreased from lower plant utilization in 2013 due to market conditions and lower plant availability in 2013 related to unscheduled maintenance.

31

NATURAL GAS SEGMENT

We have various classifications of natural gas revenues, defined as follows:

• Retail: Sales of natural gas to residential, commercial and industrial customers.

• Regulatory amortization: Primarily represents timing differences for natural gas supply costs and property taxes between when we incur these costs and when we recover these costs in rates from our customers, which has a minimal impact on gross margin.

• Wholesale: Primarily represents transportation and storage for others.

Three Months Ended March 31,2013 Compared with the Three Months Ended March 31,2012

	Results
	2013			2012			Change			% Change
	(dollars in millions)
Retail revenues	$	101.7		$	95.6		$	6.1		6.4	%
Regulatory amortization	(10.4		)	(3.2		)	(7.2		)	225.0
Total retail revenues	91.3			92.4			(1.1		)	(1.2	)
Wholesale and other	11.2			9.3			1.9			20.4
Total Revenues	102.5			101.7			0.8			0.8
Total Cost of Sales	49.1			55.4			(6.3		)	(11.4	)
Gross Margin	$	53.4		$	46.3		$	7.1		15.3	%

	Revenues				Dekatherms (Dkt)		Customer Counts
	2013		2012		2013	2012	2013	2012
	(in thousands)
Retail Gas
Montana	$	42,864	$	41,839	5,161	4,983	161,070	159,886
South Dakota	11,879		10,363		1,512	1,256	38,461	38,098
Nebraska	10,913		9,421		1,276	1,141	37,028	36,918
Residential	65,656		61,623		7,949	7,380	236,559	234,902
Montana	21,540		21,050		2,621	2,524	22,534	22,427
South Dakota	7,818		6,653		1,271	1,051	6,083	6,001
Nebraska	5,777		5,415		871	829	4,655	4,639
Commercial	35,135		33,118		4,763	4,404	33,272	33,067
Industrial	460		443		57	54	266	277
Other	416		395		58	53	158	150
Total Retail Gas	$	101,667	$	95,579	12,827	11,891	270,255	268,396

	Degree Days			2013 as compared with:
Heating Degree-Days	2013	2012	Historic Average	2012	Historic Average
Montana	3,223	3,039	3,283	6% colder	2% warmer
South Dakota	4,217	3,417	4,054	23% colder	4% colder
Nebraska	3,355	2,949	3,365	14% colder	remained flat

32

The following summarizes the components of the changes in natural gas gross margin for the three months ended March 31, 2013 and 2012:

	Gross Margin 2013 vs. 2012
	(in millions)
Natural gas production	$	3.6
Retail volumes	1.8
Transportation and storage capacity	0.9
Montana property tax tracker	0.3
Other	0.5
Increase in Gross Margin	$	7.1

This increase in gross margin and volumes was primarily due to:

• An increase in natural gas production margin primarily due to the acquisition of the Bear Paw assets in the third quarter of 2012;

• Higher retail volumes driven by colder weather;

• An increase in transportation and storage capacity revenues due to higher demand to transmit natural gas for others across our pipelines and higher demand to store natural gas for others as a result of lower average natural gas prices; and

• An increase in Montana property taxes included in a tracker, which fluctuate depending upon volumes and estimated property tax expense.

Average natural gas supply prices decreased in 2013 resulting in lower retail revenues and cost of sales as compared with 2012, with no impact to gross margin.

Retail volumes increased primarily due to colder winter weather and customer growth.

33

LIQUIDITY AND CAPITAL RESOURCES

Short-term liquidity is provided by internal cash flows, the sale of commercial paper and use of our revolving credit facility. We utilize our short-term borrowings and/or revolver availability to manage our cash flows due to the seasonality of our business, and utilize any cash on hand in excess of current operating requirements to invest in our business and reduce borrowings. Short-term borrowings may also be used to temporarily fund utility capital requirements. As of March 31, 2013, our total net liquidity was approximately $260.4 million, including $6.9 million of cash and $253.5 million of revolving credit facility availability. Revolving credit facility availability was $287.5 millionas of April 19, 2013.

The following table presents additional information about short term borrowings during the three months ended March 31, 2013 (in millions):

Amount outstanding	$	44.0
Daily average amount outstanding	$	71.7
Maximum amount outstanding	$	122.9

Sources and Uses of Funds

We require liquidity to support and grow our business, and use our liquidity for working capital needs, capital expenditures, investments in or acquisitions of assets, and to repay debt. We believe our cash flows from operations and existing borrowing capacity should be sufficient to fund our operations, service existing debt, pay dividends, and fund capital expenditures (excluding strategic growth opportunities). The amount of capital expenditures and dividends are subject to certain factors including the use of existing cash, cash equivalents and the receipt of cash from operations. In addition, a material change in operations or available financing could impact our current liquidity and ability to fund capital resource requirements, and we may defer a portion of our planned capital expenditures as necessary.

We issue debt securities to refinance retiring maturities, reduce short-term debt, fund construction programs and for other general corporate purposes. To fund our strategic growth opportunities we intend to utilize available cash flow, debt capacity that would allow us to maintain investment grade ratings, and based on current plans, issue equity over the next two years. In February 2012, we filed a shelf registration statement with the SEC that can be used for the issuance of debt or equity securities. In April 2012, we entered into an Equity Distribution Agreement with UBS pursuant to which we may offer and sell shares of our common stock from time to time, having an aggregate gross sales price of up to $100 million. During the three months ended March 31, 2013, we sold 459,246 shares of our common stock at an average price of $38.98 per share. Proceeds received were approximately $17.7 million, which are net of sales commissions paid to UBS of approximately $0.2 million and other fees. Since inception, we have issued 1,274,662 shares at an average price of $36.80, for net proceeds of approximately $46.2 million. Proceeds were used primarily to repay commercial paper borrowings.

We plan to maintain a 50 - 55% debt to total capital ratio excluding capital leases, and expect to continue targeting a long-term dividend payout ratio of 60 - 70% of net income; however, there can be no assurance that we will be able to meet these targets.

Factors Impacting our Liquidity

Supply Costs - Our operations are subject to seasonal fluctuations in cash flow. During the heating season, which is primarily from November through March, cash receipts from natural gas and electric sales typically exceed cash requirements. During the summer months, cash on hand, together with the seasonal increase in cash flows and utilization of our existing revolver, are used to purchase natural gas to place in storage, perform maintenance and make capital improvements.

The effect of this seasonality on our liquidity is also impacted by changes in the market prices of our electric and natural gas supply, which is recovered through various monthly cost tracking mechanisms. These energy supply tracking mechanisms are designed to provide stable and timely recovery of supply costs on a monthly basis during the July to June annual tracking period, with an adjustment in the following annual tracking period to correct for any under or over collection in our monthly trackers. Due to the lag between our purchases of electric and natural gas commodities and revenue receipt from customers, cyclical over and under collection situations arise consistent with the seasonal fluctuations discussed above; therefore we usually under collect in the fall and winter and over collect in the spring. Fluctuations in recoveries under our cost tracking mechanisms can have a significant effect on cash flows from operations and make year-to-year comparisons difficult.

34

As of March 31, 2013, we are over collected on our current Montana natural gas and electric trackers by approximately $1.3 million, as compared with an under collection of $10.4 million as of December 31, 2012, and an under collection of $4.9 million as of March 31, 2012.

Dodd-Frank– The Dodd-Frank Wall Street Reform and Consumer Protection Act includes a provision that requires certain over-the-counter derivative transactions to be executed through an exchange or centrally cleared. Such clearing requirements would result in a significant change from our current practice of bilateral transactions and negotiated credit terms. In July 2012, the Commodity Futures Trading Commission (CFTC) issued a final rule providing for an exemption to such clearing requirements. In December 2012 the CFTC specified the types of transactions that trigger the mandatory clearing obligation. We do not believe the financial reform legislation will have a material impact on us. We do not engage in any derivative transactions that would require mandatory clearing. In addition, even if we did, we believe we wouldqualify under the end user exemption. Finally, while the legislation also includes provisions under which the CFTC may impose collateral and margin requirements for transactions and require swap dealers and major swap participants to have credit support arrangements with their end user counterparties, we do not believe these costs will affect us materially.

Credit Ratings

In general, less favorable credit ratings make debt financing more costly and more difficult to obtain on terms that are favorable to us and impact our trade credit availability. Fitch Ratings (Fitch), Moody's Investors Service (Moody’s) and Standard and Poor’s Ratings Service (S&P) are independent credit-rating agencies that rate our debt securities. These ratings indicate the agencies’ assessment of our ability to pay interest and principal when due on our debt. As of April 19, 2013, our current ratings with these agencies are as follows:

	Senior Secured Rating	Senior Unsecured Rating	Commercial Paper	Outlook
Fitch	A-	BBB+	F2	Positive
Moody’s	A2	Baa1	Prime-2	Stable
S&P	A-	BBB	A-2	Stable

A security rating is not a recommendation to buy, sell or hold securities. Such rating may be subject to revision or withdrawal at any time by the credit rating agency and each rating should be evaluated independently of any other rating.

35

Cash Flows

The following table summarizes our consolidated cash flows (in millions):

	Three Months Ended March 31,
	2013			2012
Operating Activities
Net income	$	37.9		$	32.0
Non-cash adjustments to net income	56.0			46.8
Changes in working capital	35.5			48.0
Other	(17.5		)	(6.9		)
	111.9			119.9
Investing Activities
Property, plant and equipment additions	(38.1		)	(47.1		)
Other	—			0.1
	(38.1		)	(47.0		)
Financing Activities
Proceeds from issuance of common stock, net	17.7			—
Repayments of long-term debt, net	—			(3.7		)
Repayments of short-term borrowings, net	(78.9		)	(54.0		)
Dividends on common stock	(14.2		)	(13.4		)
Other	(1.3		)	0.1
	(76.7		)	(71.0		)
Net (Decrease) Increase in Cash and Cash Equivalents	$	(2.9	)	$	1.9
Cash and Cash Equivalents, beginning of period	$	9.8		$	5.9
Cash and Cash Equivalents, end of period	$	6.9		$	7.8

Cash Provided by Operating Activities

As of March 31, 2013, cash and cash equivalents were $6.9 million as compared with $9.8 million at December 31, 2012 and $7.8 million at March 31, 2012. Cash provided by operating activities totaled $111.9 million for the three months ended March 31, 2013 as compared with $119.9 million during the three months ended March 31, 2012. This decrease in operating cash flows is due largely to higher trade receivables resulting from colder winter weather partially offset by improvements in the collection of our supply costs.

Cash Used in Investing Activities

Cash used in investing activities decreased by approximately $8.9 million as compared with the first three months of 2012. Plant additions during 2013 include maintenance additions of approximately $20.3 million, supply related capital expenditures of approximately $11.3 million, primarily related to the 60 MW peaking facility in South Dakota, and DSIP capital expenditures of approximately $6.5 million. Plant additions during the first quarter of 2012 include supply related capital expenditures of approximately $17.6 million, primarily related to the 60 MW peaking facility in South Dakota, and DSIP capital expenditures of approximately $2.9 million.

Cash Used in Financing Activities

Cash used in financing activities totaled approximately $76.7 million during the three months ended March 31, 2013 as compared with approximately $71.0 million during the three months ended March 31, 2012. During the three months ended March 31, 2013, net cash used in financing activities consisted of net repayments of commercial paper of $78.9 million and the payment of dividends of $14.2 million offset in part by proceeds received from the issuance of common stock pursuant to our equity distribution agreement of $17.7 million. During the three months ended March 31, 2012, net cash used in financing

36

activities consisted of net repayments of commercial paper of $54.0 million, the repayment of long-term debt of $3.7 million and the payment of dividends of $13.4 million.

Contractual Obligations and Other Commitments

We have a variety of contractual obligations and other commitments that require payment of cash at certain specified periods. The following table summarizes our contractual cash obligations and commitments as of March 31, 2013. See our Annual Report on Form 10-K for the year ended December 31, 2012 for additional discussion.

	Total		2013		2014		2015		2016		2017		Thereafter
	(in thousands)
Long-term debt	$	1,055,079	$	—	$	—	$	—	$	150,000	$	—	$	905,079
Capital leases	32,784		1,221		1,668		1,733		1,837		1,979		24,346
Short-term borrowings	43,985		43,985		—		—		—		—		—
Future minimum operating lease payments	4,914		1,359		1,306		913		633		479		224
Estimated pension and other postretirement obligations (1)	67,340		12,957		13,673		13,633		13,583		13,494		N/A
Qualifying facilities liability (2)	1,130,538		48,167		67,283		69,606		71,598		73,622		800,262
Supply and capacity contracts (3)	1,501,976		227,528		198,275		117,536		117,258		103,616		737,763
Contractual interest payments on debt (4)	615,500		45,394		57,092		57,092		56,986		47,820		351,116
Total Commitments (5)	$	4,452,116	$	380,611	$	339,297	$	260,513	$	411,895	$	241,010	$	2,818,790

_________________________

(1) We estimate cash obligations related to our pension and other postretirement benefit programs for five years, as it is not practicable to estimate thereafter. These estimates reflect our expected cash contributions, which may be in excess of minimum funding requirements.

(2) Certain QFs require us to purchase minimum amounts of energy at prices ranging from $71 to $136 per MWH through 2029. Our estimated gross contractual obligation related to these QFs is approximately $1.1 billion. A portion of the costs incurred to purchase this energy is recoverable through rates authorized by the MPSC, totaling approximately $0.9 billion.

(3) We have entered into various purchase commitments, largely purchased power, coal and natural gas supply and natural gas transportation contracts. These commitments range from one to 25 years.

(4) For our variable rate short-term borrowings outstanding, we have assumed an average interest rate of 0.48% through maturity.

(5) Potential tax payments related to uncertain tax positions are not practicable to estimate and have been excluded from this table.

37

CRITICAL ACCOUNTING POLICIES AND ESTIMATES

Management’s discussion and analysis of financial condition and results of operations is based on our condensed consolidated financial statements, which have been prepared in accordance with GAAP. The preparation of these financial statements requires us to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses, and related disclosure of contingent assets and liabilities. We base our estimates on historical experience and other assumptions that are believed to be proper and reasonable under the circumstances.

As of March 31, 2013, there have been no significant changes with regard to the critical accounting policies disclosed in Management’s Discussion and Analysis of Financial Condition and Results of Operations in our Annual Report on Form 10-K for the year ended December 31, 2012. The policies disclosed included the accounting for the following: goodwill and long-lived assets, qualifying facilities liability, revenue recognition, regulatory assets and liabilities, pension and postretirement benefit plans, and income taxes. We continually evaluate the appropriateness of our estimates and assumptions. Actual results could differ from those estimates.

38

ITEM 3. QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK

We are exposed to market risks, including, but not limited to, interest rates, energy commodity price volatility, and credit exposure. Management has established comprehensive risk management policies and procedures to manage these market risks.

Interest Rate Risk

Interest rate risks include exposure to adverse interest rate movements for outstanding variable rate debt and for future anticipated financings. We manage our interest rate risk by issuing primarily fixed-rate long-term debt with varying maturities, refinancing certain debt and, at times, hedging the interest rate on anticipated borrowings. All of our debt has fixed interest rates, with the exception of our revolving credit facility. The revolving credit facility bears interest at the lower of prime or available rates tied to the LIBOR plus a credit spread, ranging from 0.88% to 1.75% over LIBOR. To more cost effectively meet short-term cash requirements, we established a program where we may issue commercial paper; which is supported by our revolving credit facility. Since commercial paper terms are short-term, we are subject to interest rate risk. As of March 31, 2013, we had approximately $44.0 million of commercial paper outstanding and no borrowings on our revolving credit facility. A 1% increase in interest rates would increase our annual interest expense by approximately $0.4 million.

Commodity Price Risk

We are exposed to commodity price risk due to our reliance on market purchases to fulfill a large portion of our electric and natural gas supply requirements within the Montana market. We also participate in the wholesale electric market to balance our supply of power from our own generating resources, primarily in South Dakota. Several factors influence price levels and volatility. These factors include, but are not limited to, seasonal changes in demand, weather conditions, available generating assets within regions, transportation availability and reliability within and between regions, fuel availability, market liquidity, and the nature and extent of current and potential federal and state regulations.

As part of our overall strategy for fulfilling our electric and natural gas supply requirements, we employ the use of market purchases, including forward purchase and sales contracts. These types of contracts are included in our supply portfolios and in some instances, are used to manage price volatility risk by taking advantage of seasonal fluctuations in market prices. These contracts are part of an overall portfolio approach intended to provide price stability for consumers. As a regulated utility, our exposure to market risk caused by changes in commodity prices is substantially mitigated because these commodity costs are included in our cost tracking mechanisms and are recoverable from customers subject to prudence reviews by applicable state regulatory commissions.

Counterparty Credit Risk

We are exposed to counterparty credit risk related to the ability of our counterparties to meet their contractual payment obligations, and the potential non-performance of counterparties to deliver contracted commodities or services at the contracted price. We are also exposed to counterparty credit risk related to providing transmission service to our customers under our Open Access Transmission Tariff and under gas transportation agreements. We have risk management policies in place to limit our transactions to high quality counterparties. We monitor closely the status of our counterparties and take action, as appropriate, to further manage this risk. This includes, but is not limited to, requiring letters of credit or prepayment terms. There can be no assurance, however, that the management tools we employ will eliminate the risk of loss.

39

ITEM 4. CONTROLS AND PROCEDURES

Evaluation of Disclosure Controls and Procedures

We have established disclosure controls and procedures designed to ensure that information required to be disclosed in the reports we file or submit under the Securities Exchange Act of 1934 is recorded, processed, summarized and reported, within the time periods specified in the SEC’s rules and forms and accumulated and reported to management, including the principal executive officer and principal financial officer to allow timely decisions regarding required disclosure.

We conducted an evaluation, under the supervision and with the participation of our principal executive officer and principal financial officer of our disclosure controls and procedures (as defined in Rules 13a-15(e) and 15d-15(e) under the Securities Exchange Act of 1934). Based on this evaluation, our principal executive officer and principal financial officer have concluded that, as of the end of the period covered by this report, our disclosure controls and procedures are effective.

Changes in Internal Control Over Financial Reporting

There have been no changes in our internal control over financial reporting during the most recent fiscal quarter that have materially affected, or are reasonably likely to materially affect, our internal control over financial reporting.

40

PART II. OTHER INFORMATION

ITEM 1. LEGAL PROCEEDINGS

See Note 13, Commitments and Contingencies, to the Financial Statements for information about legal proceedings.

ITEM 1A. RISK FACTORS

You should carefully consider the risk factors described below, as well as all other information available to you, before making an investment in our common stock or other securities.

We are subject to potential unfavorable government and regulatory outcomes, including extensive and changing laws

and regulations that affect our industry and our operations, which could have a material adverse effect on our liquidity and results of operations.

The profitability of our operations is dependent on our ability to recover the costs of providing energy and utility services to our customers and earn a return on our capital investment in our utility operations. We provide service at rates approved by one or more regulatory commissions. These rates are generally regulated based on an analysis of our costs incurred in a historical test year. In addition, each regulatory commission sets rates based in part upon their acceptance of an allocated share of total utility costs. When commissions adopt different methods to calculate inter-jurisdictional cost allocations, some costs may not be recovered. Thus, the rates we are allowed to charge may or may not match our costs at any given time. While rate regulation is premised on providing a reasonable opportunity to earn a reasonable rate of return on invested capital, there can be no assurance that the applicable regulatory commission will judge all of our costs to have been prudently incurred or that the regulatory process in which rates are determined will always result in rates that will produce full recovery of such costs.

For example, in our regulatory filings related to DGGS, we proposed an allocation of approximately 80% of costs to retail customers subject to the MPSC's jurisdiction and approximately 20% allocated to wholesale customers subject to FERC's jurisdiction. In March 2012, the MPSC's final order approved using our proposed cost allocation methodology, but requires us to complete a study of the relative contribution of retail and wholesale customers to regulation capacity needs. The results of this study may be used in determining future cost allocations between retail and wholesale customers. However, there is no assurance that both the MPSC and FERC will agree on the results of this study, which could result in an inability to fully recover our costs.

In September 2012, we received a non-binding initial decision from a FERC ALJ concluding that we should only recover approximately 4.4% of the revenue requirement from FERC jurisdictional customers. Although we are asking the FERC to reject this decision, there is significant uncertainty related to the FERC's ultimate treatment of our cost allocation methodology, which could result in an inability to fully recover our costs.

We are subject to various rules and regulations of the FERC covering our electric and natural gas business. We must also comply with established reliability standards and requirements, which apply to the North American Electric Reliability Corporation (NERC) functions for which we have registered in both the Midwest Reliability Organization for our South Dakota operations and the Western Electricity Coordination Council for our Montana operations. The FERC, NERC, or a regional reliability organization may assess penalties against any responsible entity that violates their rules, regulations or standards. Violations may be discovered through various means, including self-certification, self-reporting, compliance investigations, periodic data submissions, exception reporting, and complaints. Penalties for the most severe violations can reach as high as $1 million per violation, per day. If a serious reliability incident or other incidence of noncompliance did occur, it could have a material adverse effect on our operating and financial results.

In addition, changes in laws and regulations may have a detrimental effect on our business. In July 2010, the Dodd-Frank Wall Street Reform and Consumer Protection Act was signed into law, which is intended to improve the regulation of financial markets. Certain provisions of the Act relating to derivatives could result in increased capital and/or collateral requirements. Despite certain exemptions in the law, concern remains that counterparties not qualifying for the exemption will pass along the increased cost and margin requirements through higher prices and reductions in unsecured credit limits.

41

We are subject to extensive environmental laws and regulations and potential environmental liabilities, which could result in significant costs and additional liabilities.

We are subject to extensive laws and regulations imposed by federal, state, and local government authorities in the ordinary course of operations with regard to the environment, including environmental laws and regulations relating to air and water quality, protection of natural resources and wildlife, solid waste disposal, coal ash and other environmental considerations. We believe that we are in compliance with environmental regulatory requirements; however, possible future developments, such as more stringent environmental laws and regulations, and the timing of future enforcement proceedings that may be taken by environmental authorities, could affect our costs and the manner in which we conduct our business and could require us to make substantial additional capital expenditures or abandon certain projects.

There are national and international efforts to adopt measures related to global climate change and the contribution of emissions of green house gases (GHGs) including, most significantly, carbon dioxide. These efforts include legislative proposals and agency regulations at the federal level, actions at the state level, as well as litigation relating to GHG emissions. Increased pressure for carbon dioxide emissions reduction also is coming from investor organizations. If legislation or regulations are passed at the federal or state levels imposing mandatory reductions of carbon dioxide and other GHGs on generation facilities, the cost to us of such reductions could be significant.

Many of these environmental laws and regulations provide for substantial civil and criminal fines for noncompliance which, if imposed, could result in material costs or liabilities. In addition, there is a risk of environmental damages claims from private parties or government entities. We may be required to make significant expenditures in connection with the investigation and remediation of alleged or actual spills, personal injury or property damage claims, and the repair, upgrade or expansion of our facilities to meet future requirements and obligations under environmental laws.

To the extent that costs exceed our estimated environmental liabilities and/or we are not successful recovering a material portion of remediation costs in our rates, our results of operations and financial position could be adversely affected.

Our owned and jointly owned electric generating facilities are subject to operational risks that could result in unscheduled plant outages, unanticipated operation and maintenance expenses and increased power purchase costs.

Operation of electric generating facilities involves risks, which can adversely affect energy output and efficiency levels. Operational risks include facility shutdowns due to breakdown or failure of equipment or processes, labor disputes, operator error, catastrophic events such as fires, explosions, floods, and intentional acts of destruction or other similar occurrences affecting the electric generating facilities; and operational changes necessitated by environmental legislation, litigation or regulation. The loss of a major electric generating facility would require us to find other sources of supply or ancillary services, if available, and expose us to higher purchased power costs.

In addition, most of our generating capacity is coal-fired. We rely on a limited number of suppliers of coal for our electric generation, making us vulnerable to increased prices for fuel as existing contracts expire or in the event of unanticipated interruptions in fuel supply. We are a captive rail shipper of the Burlington Northern Santa Fe Railway for shipments of coal to the Big Stone Plant (our largest source of generation in South Dakota), making us vulnerable to railroad capacity and operational issues and/or increased prices for coal transportation from a sole supplier.

Our revenues, results of operations and financial condition are impacted by customer growth and usage in our service territories and may fluctuate with current economic conditions or response to price increases. We are also impacted by market conditions outside of our service territories related to demand for transmission capacity and wholesale electric pricing.

 Our revenues, results of operations and financial condition are impacted by customer growth and usage, which can be impacted by population growth as well as by economic factors. Our customers may voluntarily reduce their consumption of electricity and natural gas from us in response to increases in prices, decreases in their disposable income, individual energy conservation efforts or the use of distributed generation for electricity.

Demand for our Montana transmission capacity fluctuates with regional demand, fuel prices and weather related conditions. The levels of wholesale sales depend on the wholesale market price, transmission availability and the availability of generation for wholesale sales, among other factors. Declines in wholesale market price, availability of generation, transmission constraints in the wholesale markets, or low wholesale demand could reduce wholesale sales. These events could adversely affect our results of operations, financial position and cash flows.

42

Our natural gas distribution services involve numerous activities that may result in accidents and other operating risks and costs.

Inherent in our natural gas distribution services are a variety of hazards and operating risks, such as leaks, explosions and mechanical problems. These risks could cause a loss of human life, significant damage to property, environmental pollution, impairment of our operations, and substantial financial losses to us. In accordance with customary industry practice, we maintain insurance against some, but not all, of these risks and losses. The occurrence of any of these events not fully covered by insurance could have a material adverse effect on our financial position and results of operations. For our distribution lines located near populated areas, including residential areas, commercial business centers, industrial sites and other public gathering areas, the level of damages resulting from these risks potentially is greater.

To the extent our incurred supply costs are deemed imprudent by the applicable state regulatory commissions, we would not recover some of our costs, which could adversely impact our results of operations and liquidity.

Our wholesale costs for electricity and natural gas are recovered through various pass-through cost tracking mechanisms in each of the states we serve. The rates are established based upon projected market prices or contractual obligations. As these variables change, we adjust our rates through our monthly trackers. To the extent our energy supply costs are deemed imprudent by the applicable state regulatory commissions, we would not recover some of our costs, which could adversely impact our results of operations.

We currently procure a large portion of our natural gas supply and our Montana electric supply pursuant to contracts with third-party suppliers. In light of this reliance on third-party suppliers, we are exposed to certain risks in the event a third-party supplier is unable to satisfy its contractual obligation. If this occurred, then we might be required to purchase gas and/or electricity supply requirements in the energy markets, which may not be on favorable terms, if at all. If prices were higher in the energy markets, it could result in a temporary material under recovery that would reduce our liquidity.

Our plans for future expansion through capital improvements to current assets, new electric generation or natural gas reserves, and transmission grid expansion involve substantial risks. Failure to adequately execute and manage significant construction plans, as well as the risk of recovering such costs, could materially impact our results of operations and liquidity.

The age of our existing assets may result in them being more costly to maintain and susceptible to outages in spite of diligent efforts by us to properly maintain these assets through inspection, scheduled maintenance and capital investment. The failure of such assets could result in a reduction in revenue and / or increased expenses which may not be fully recoverable from customers.

We are planning significant investment in capital improvements and additions to modernize existing infrastructure, generation investments, transmission capacity expansion and acquisition of natural gas reserves. The completion of generation and natural gas investments and transmission projects are subject to many construction and development risks, including, but not limited to, risks related to financing, regulatory recovery, escalating costs of materials and labor, meeting construction budgets and schedules, and environmental compliance. In addition, these capital projects may require a significant amount of capital expenditures. We cannot provide certainty that adequate external financing will be available to support such projects. Additionally, borrowings incurred to finance construction may adversely impact our leverage, which could increase our cost of capital.

Poor investment performance of plan assets of our defined benefit pension and post-retirement benefit plans, in addition to other factors impacting these costs, could unfavorably impact our results of operations and liquidity.

Our costs for providing defined benefit retirement and postretirement benefit plans are dependent upon a number of factors. Assumptions related to future costs, return on investments and interest rates have a significant impact on our funding requirements related to these plans. These estimates and assumptions may change based on economic conditions, actual stock market performance and changes in governmental regulations. Without sustained growth in the plan assets over time and depending upon interest rate changes as well as other factors noted above, the costs of such plans reflected in our results of operations and financial position and cash funding obligations may change significantly from projections.

43

Our obligation to include a minimum annual quantity of power in our Montana electric supply portfolio at an agreed upon price per MWH could expose us to material commodity price risk if certain QFs under contract with us do not perform during a time of high commodity prices, as we are required to make up the difference. In addition, we are subject to price escalation risk with one of our largest QF contracts.

As part of a stipulation in 2002 with the MPSC and other parties, we agreed to include a minimum annual quantity of power in our Montana electric supply portfolio at an agreed upon price per MWH through June 2029. The annual minimum energy requirement is achievable under normal QF operations, including normal periods of planned and forced outages. However, to the extent the supplied QF power for any year does not reach the minimum quantity set forth in the settlement, we are obligated to purchase the difference from other sources. The anticipated source for any QF shortfall is the wholesale market, which would subject us to commodity price risk if the cost of replacement power is higher than contracted QF rates.

In addition, we are subject to price escalation risk with one of our largest QF contracts due to variable contract terms. In estimating our QF liability, we have estimated an annual escalation rate of 3% over the remaining term of the contract (through June 2024). To the extent the annual escalation rate exceeds 3%, our results of operations, cash flows and financial position could be adversely affected.

Weather and weather patterns, including normal seasonal and quarterly fluctuations of weather, as well as extreme weather events that might be associated with climate change, could adversely affect our results of operations and liquidity.

Our electric and natural gas utility business is seasonal, and weather patterns can have a material impact on our financial performance. Demand for electricity and natural gas is often greater in the summer and winter months associated with cooling and heating. Because natural gas is heavily used for residential and commercial heating, the demand for this product depends heavily upon weather patterns throughout our market areas, and a significant amount of natural gas revenues are recognized in the first and fourth quarters related to the heating season. Accordingly, our operations have historically generated less revenues and income when weather conditions are milder in the winter and cooler in the summer. In the event that we experience unusually mild winters or cool summers in the future, our results of operations and financial position could be adversely affected. In addition, exceptionally hot summer weather or unusually cold winter weather could add significantly to working capital needs to fund higher than normal supply purchases to meet customer demand for electricity and natural gas.

There is also a concern that the physical risks of climate change could include changes in weather conditions, such as an increase in changes in precipitation and extreme weather events. Climate change and the costs that may be associated with its impacts have the potential to affect our business in many ways, including increasing the cost incurred in providing electricity and natural gas, impacting the demand for and consumption of electricity and natural gas (due to change in both costs and weather patterns), and affecting the economic health of the regions in which we operate. Extreme weather conditions creating high energy demand on our own and/or other systems may raise market prices as we buy short-term energy to serve our own system. Severe weather impacts our service territories, primarily through thunderstorms, tornadoes and snow or ice storms. To the extent the frequency of extreme weather events increase, this could increase our cost of providing service. Changes in precipitation resulting in droughts or water shortages could adversely affect our ability to provide electricity to customers, as well as increase the price they pay for energy. In addition, extreme weather may exacerbate the risks to physical infrastructure. We may not recover all costs related to mitigating these physical and financial risks.

Our business is dependent on our ability to successfully access capital markets on favorable terms. Limits on our access to capital may adversely impact our ability to execute our business plan or pursue improvements that we would otherwise rely on for future growth.

Our cash requirements are driven by the capital-intensive nature of our business. Access to the capital and credit markets, at a reasonable cost, is necessary for us to fund our operations, including capital requirements. We rely on a revolving credit facility and commercial paper market for short-term liquidity needs due to the seasonality of our business, and on capital markets to raise capital for growth projects that are not otherwise provided by operating cash flows. Instability in the financial markets may increase the cost of capital, limit our ability to draw on our revolving credit facility, access the commercial paper market and/or raise capital. If we are unable to obtain the liquidity needed to meet our business requirements on favorable terms, we may defer growth projects and/or capital expenditures.

44

We must meet certain credit quality standards. If we are unable to maintain investment grade credit ratings, our liquidity, access to capital and operations could be materially adversely affected.

A downgrade of our credit ratings to less than investment grade could adversely affect our liquidity. Certain of our credit agreements and other credit arrangements with counterparties require us to provide collateral in the form of letters of credit or cash to support our obligations if we fall below investment grade. Also, a downgrade below investment grade could hinder our ability to raise capital on favorable terms, including through the commercial paper markets. Higher interest rates on short-term borrowings with variable interest rates or on incremental commercial paper issuances could also have an adverse effect on our results of operations.

Threats of terrorism and catastrophic events that could result from terrorism, cyber attacks, or individuals and/or groups attempting to disrupt our business, or the businesses of third parties, may affect our operations

in unpredictable ways and could adversely affect our liquidity and results of operations.

We are subject to the potentially adverse operating and financial effects of terrorist acts and threats, as well as cyber attacks and other disruptive activities of individuals or groups. Our generation, transmission and distribution facilities, information technology systems and other infrastructure facilities and systems could be direct targets of, or indirectly affected by, such activities. Any significant interruption of these systems could prevent us from fulfilling our critical business functions, and sensitive, confidential and other data could be compromised.

Terrorist acts, cyber attacks (such as hacking and viruses) or other similar events could harm our business by limiting our ability to generate, purchase or transmit power and by delaying the development and construction of new generating facilities and capital improvements to existing facilities. These events, and governmental actions in response, could result in a material decrease in revenues and significant additional costs to repair and insure assets, and could adversely affect our operations by contributing to disruption of supplies and markets for natural gas, oil and other fuels. These events could also impair our ability to raise capital by contributing to financial instability and lower economic activity.

45

ITEM 6.                      EXHIBITS

(a)Exhibits

Exhibit 10.1—Form of NorthWestern Corporation Long-Term Performance Incentive Restricted Stock Award Agreement (incorporated by reference to Exhibit 99.1 of NorthWestern Corporation's Current Report on Form 8-K, dated February 13, 2013, Commission File No. 1-10499).

Exhibit 31.1—Certification of chief executive officer.

Exhibit 31.2—Certification of chief financial officer.

Exhibit 32.1—Certification of chief executive officer pursuant to Section 906 of the Sarbanes-Oxley Act of 2002.

Exhibit 32.2—Certification of chief financial officer pursuant to Section 906 of the Sarbanes-Oxley Act of 2002.

Exhibit 101.INS—XBRL Instance Document

Exhibit 101.SCH—XBRL Taxonomy Extension Schema Document

Exhibit 101.CAL—XBRL Taxonomy Extension Calculation Linkbase Document

Exhibit 101.DEF—XBRL Taxonomy Extension Definition Linkbase Document

Exhibit 101.LAB—XBRL Taxonomy Label Linkbase Document

Exhibit 101.PRE—XBRL Taxonomy Extension Presentation Linkbase Document

46

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.

			NorthWestern Corporation
Date:	April 25, 2013	By:	/s/ BRIAN B. BIRD
			Brian B. Bird
			Chief Financial Officer
			Duly Authorized Officer and Principal Financial Officer

47

EXHIBIT INDEX

Exhibit Number	Description
10.1	Form of NorthWestern Corporation Long-Term Performance Incentive Restricted Stock Award Agreement (incorporated by reference to Exhibit 99.1 of NorthWestern Corporation's Current Report on Form 8-K, dated February 13, 2013, Commission File No. 1-10499).
*31.1	Certification of chief executive officer.
*31.2	Certification of chief financial officer.
*32.1	Certification of chief executive officer pursuant to Section 906 of the Sarbanes-Oxley Act of 2002.
*32.2	Certification of chief financial officer pursuant to Section 906 of the Sarbanes-Oxley Act of 2002.
*101.INS	XBRL Instance Document
*101.SCH	XBRL Taxonomy Extension Schema Document
*101.CAL	XBRL Taxonomy Extension Calculation Linkbase Document
*101.DEF	XBRL Taxonomy Extension Definition Linkbase Document
*101.LAB	XBRL Taxonomy Label Linkbase Document
*101.PRE	XBRL Taxonomy Extension Presentation Linkbase Document

_________________________

* Filed herewith

48

EX-31.1

EXHIBIT 31.1

CERTIFICATION

I, Robert C. Rowe, certify that:

1. I have reviewed this report on Form 10-Q of NorthWestern Corporation;

2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3. Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4. The registrant’s other certifying officer(s) and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

a) Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

b) Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

c) Evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

d) Disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

5. The registrant’s other certifying officer(s) and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant’s auditors and the audit committee of the registrant’s board of directors (or persons performing the equivalent functions):

a) All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize and report financial information; and

b) Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting.

April 25, 2013

/s/ ROBERT C. ROWE

Robert C. Rowe

President and Chief Executive Officer

EX-31.2

EXHIBIT 31.2

CERTIFICATION

I, Brian B. Bird, certify that:

1. I have reviewed this report on Form 10-Q of NorthWestern Corporation;

2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3. Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4. The registrant’s other certifying officer(s) and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

a) Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

b) Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

c) Evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

d) Disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

5. The registrant’s other certifying officer(s) and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant’s auditors and the audit committee of the registrant’s board of directors (or persons performing the equivalent functions):

a) All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize and report financial information; and

b) Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting.

April 25, 2013

/s/ BRIAN B. BIRD

Brian B. Bird

Vice President and Chief Financial Officer

EX-32.1

EXHIBIT 32.1

CERTIFICATION OF PRINCIPAL EXECUTIVE OFFICER PURSUANT TO 18 U.S.C. SECTION 1350,

AS ADOPTED PURSUANT TO SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the Quarterly Report of NorthWestern Corporation (the “Company”) on Form 10-Q for the period ended March 31, 2013, as filed with the Securities and Exchange Commission on the date hereof (the “Report”), I, Robert C. Rowe, President and Chief Executive Officer of the Company, certify, pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that to my knowledge:

1) The Report fully complies with the requirements of Sections 13(a) or 15(d) of the Securities Exchange Act of 1934; and

2) The information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company.

April 25, 2013	/s/ ROBERT C. ROWE
	Robert C. Rowe
	President and Chief Executive Officer

EX-32.2

Exhibit 32.2

CERTIFICATION OF CHIEF FINANCIAL OFFICER PURSUANT TO 18 U.S.C. SECTION 1350,

AS ADOPTED PURSUANT TO SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the Quarterly Report of NorthWestern Corporation (the “Company”) on Form 10-Q for the period ended March 31, 2013, as filed with the Securities and Exchange Commission on the date hereof (the “Report”), I, Brian B. Bird, Vice President and Chief Financial Officer of the Company, certify, pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that to my knowledge:

1) The Report fully complies with the requirements of Sections 13(a) or 15(d) of the Securities Exchange Act of 1934; and

2) The information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company.

April 25, 2013	/s/ BRIAN B. BIRD
	Brian B. Bird
	Vice President and Chief Financial Officer

XML

Financing Activities (Details) (Equity Distribution Agreement [Member], USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		12 Months Ended
	Mar. 31, 2013	Jun. 30, 2012	Mar. 31, 2013
Common Stock [Member]
Debt Instrument [Line Items]
Common stock, aggregate gross sales price		$ 100
Stock issued inception to date, shares issued			1,274,662
Common stock average share price since inception			$ 36.80
Proceeds received from new issues, inception to date			46.2
Stock issued during period, shares, new issues	459,246
Common stock average share price during the period	$ 38.98
Proceeds received from new issues during the period	17.7
Additional Paid-in Capital [Member]
Debt Instrument [Line Items]
Sales commissons and fees	$ 0.2

XML

Goodwill (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Dec. 31, 2012
Goodwill [Line Items]
Change in goodwill	$ 0
Goodwill	355,128	355,128
Electric [Member]
Goodwill [Line Items]
Goodwill	241,100	241,100
Natural gas [Member]
Goodwill [Line Items]
Goodwill	$ 114,028	$ 114,028

XML

Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2013

Fair Value Disclosures [Abstract]

Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]

The table below sets forth by level within the fair value hierarchy the gross components of our assets and liabilities measured at fair value on a recurring basis. Normal purchases and sales transactions are not included in the fair values by source table as they are not recorded at fair value. There were no transfers between levels for the periods presented. See Note 7 for further discussion.

	Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)		Significant Other Observable Inputs (Level 2)			Significant Unobservable Inputs (Level 3)		Margin Cash Collateral Offset		Total Net Fair Value
	(in thousands)
March 31, 2013
Restricted cash	$	8,381	$	—		$	—	$	—	$	8,381
Rabbi trust investments	14,235		—			—		—		14,235
Derivative liability (1)	—		(3,294		)	—		—		(3,294		)
Total	$	22,616	$	(3,294	)	$	—	$	—	$	19,322
December 31, 2012
Restricted cash	$	6,392	$	—		$	—	$	—	$	6,392
Rabbi trust investments	10,522		—			—		—		10,522
Derivative liability (1)	—		(5,428		)	—		—		(5,428		)
Total	$	16,914	$	(5,428	)	$	—	$	—	$	11,486

_________________________

(1) The changes in the fair value of these derivatives are deferred as a regulatory asset or liability until the contracts are settled. Upon settlement, associated proceeds or costs are passed through the applicable cost tracking mechanism to customers.

Fair Value Financial Instruments [Table Text Block]

The estimated fair value of financial instruments is summarized as follows (in thousands):

	March 31, 2013				December 31, 2012
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Liabilities:
Long-term debt	$	1,055,079	$	1,225,056	$	1,055,074	$	1,229,233

XML

Employee Benefit Plans Net Periodic Benefit Cost (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Pension Benefits [Member]
Components of Net Periodic Benefit Cost (Income) [Abstract]
Service cost	$ 3,439	$ 3,024
Interest cost	5,624	5,935
Expected return on plan assets	(8,125)	(7,506)
Amortization of prior service cost	62	62
Recognized actuarial loss	2,752	2,105
Net Periodic Benefit Cost (Income)	3,752	3,620
Other Postretirement Benefits [Member]
Components of Net Periodic Benefit Cost (Income) [Abstract]
Service cost	156	123
Interest cost	217	285
Expected return on plan assets	(254)	(257)
Amortization of prior service cost	(500)	(500)
Recognized actuarial loss	225	184
Net Periodic Benefit Cost (Income)	$ (156)	$ (165)

XML

Fair Value Recurring Basis (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013		Dec. 31, 2012
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value, assets, level 1 to level 2 transfers, amount	$ 0		$ 0
Fair value, assets, level 2 to level 1 transfers, amount	0		0
Fair value, liabilities, level 1 to level 2 transfers, amount	0		0
Fair value, liabilities, level 2 to level 1 transfers, amount	0		0
Fair Value, Measurements, Recurring [Member] | Total Net Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Restricted cash	8,381		6,392
Rabbi trust investments	14,235		10,522
Derivative liability (1)	(3,294)	[1]	(5,428)	[1]
Total	19,322		11,486
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Restricted cash	8,381		6,392
Rabbi trust investments	14,235		10,522
Derivative liability (1)	0	[1]	0
Total	22,616		16,914
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs(Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Restricted cash	0		0
Rabbi trust investments	0		0
Derivative liability (1)	(3,294)	[1]	(5,428)
Total	(3,294)		(5,428)
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs(Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Restricted cash	0		0
Rabbi trust investments	0		0
Derivative liability (1)	0	[1]	0
Total	0		0
Fair Value, Measurements, Recurring [Member] | Margin Cash Collateral Offset [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Restricted cash	0		0
Rabbi trust investments	0		0
Derivative liability (1)	0	[1]	0
Total	$ 0		$ 0

[1] The changes in the fair value of these derivatives are deferred as a regulatory asset or liability until the contracts are settled. Upon settlement, associated proceeds or costs are passed through the applicable cost tracking mechanism to customers.

XML

Regulatory Matters

3 Months Ended

Mar. 31, 2013

Regulated Operations [Abstract]

Public Utilities Disclosure [Text Block]

Regulatory Matters

Dave Gates Generating Station at Mill Creek (DGGS)

As a result of a Federal Energy Regulatory Commission (FERC) Administrative Law Judge's (ALJ) initial nonbinding decision issued in September 2012, we have cumulative deferred revenue of approximately $18.5 million, which is subject to refund and recorded within current regulatory liabilities in the Condensed Consolidated Balance Sheets. The ALJ concluded we should allocate only a fraction of the costs we believe (based on past practice) should be allocated to FERC jurisdictional customers. Our brief in opposition to the ALJ's initial decision is pending before the FERC.

Although we have no assurance as to timing, the FERC is expected to consider the matter and issue a binding decision during 2013. The FERC is not obligated to follow any of the ALJ's findings and conclusions, and the FERC can accept or reject the initial decision in whole or in part. If the FERC upholds the ALJ's decision and a portion of the costs are effectively disallowed, we would be required to assess DGGS for impairment. If we disagree with a decision issued by the FERC, we may pursue full appellate rights through rehearing and appeal to a United States Circuit Court of Appeals, which could extend into 2015. We continue to bill FERC jurisdictional customers interim rates that have been in effect since January 1, 2011. These interim rates are subject to refund plus interest pending final resolution at FERC.

Montana Electric and Natural Gas Tracker Filings

Each year we submit electric and natural gas tracker filings for recovery of supply costs for the 12-month period ended

June 30 and for the projected supply costs for the next 12-month period. The Montana Public Service Commission (MPSC) reviews such filings and makes its cost recovery determination based on whether or not our electric and natural gas supply procurement activities were prudent.

We do not expect the MPSC to issue final orders related to our 2012 electric supply tracker filing, including our request for demand-side management (DSM) lost revenues, until at least the third quarter of 2013. As of March 31, 2013, we have deferred revenue of approximately $6.2 million related to DSM lost revenues, which is recorded within current regulatory liabilities in the Condensed Consolidated Balance Sheets.

Montana Natural Gas Production Assets

During the third quarter of 2012, we completed the purchase of natural gas production interests in northern Montana's Bear Paw Basin, including a 75% interest in two gas gathering systems (Bear Paw). We are collecting the cost of service for Bear Paw natural gas produced, including a return on our investment, through our natural gas supply tracker on an interim basis. We expect to file an application with the MPSC to place our Bear Paw assets in natural gas rate base during 2013 and this revenue is subject to refund until we receive MPSC approval of our application.

Montana Natural Gas Rate Filing

In September 2012, we filed a request with the MPSC for an annual natural gas delivery revenue increase of approximately $15.7 million. This request was based on a return on equity of 10.5%, a capital structure consisting of 52% debt and 48% equity and rate base of $309.5 million.

In April 2013, we reached a joint settlement with intervenors and received MPSC approval to increase our annual natural gas delivery rates by approximately $11.5 million, based on a return on equity of 9.8%.

Montana Avoided Cost Compliance Filing

Colstrip Energy Limited Partnership (CELP) is a QF with which we have a power purchase agreement (PPA) for approximately 306,600 MWH's annually through June 2024. Under the terms of the PPA with CELP, energy and capacity rates were fixed for the first fifteen years and beginning July 1, 2004, through the end of the contract, energy and capacity rates are to be determined each year pursuant to a formula, subject to annual review and approval by the MPSC. Until April 2013, the MPSC's most recent final order related to this compliance filing covered rates through June 30, 2006. We had been in litigation with CELP since 2007 over how to determine energy and capacity rates under the PPA. On November 1, 2012, an arbitration panel issued a final award in our favor. In April 2013, the MPSC issued a final order consistent with the arbitration panel's final award for the contract years July 1, 2006 through June 30, 2013.

XML

Commitments and Contingencies Environmental (Details) (USD $) In Millions, unless otherwise specified			3 Months Ended				3 Months Ended
	Mar. 31, 2013	Mar. 31, 2013 Manufactured Gas Plants [Member]	Mar. 31, 2013 Manufactured Gas Plants [Member] Aberdeen South Dakota Site [Member]	Mar. 31, 2013 Clean Air Act Rules and Associated Emission Control Equipment Expenditures [Member] Big Stone Generating Facility [Member] Jointly Owned Electricity Generation Plant [Member]	Feb. 23, 2010 Clean Air Act Rules and Associated Emission Control Equipment Expenditures [Member] Coyote Generating Facility [Member]	Mar. 31, 2013 Clean Air Act Rules and Associated Emission Control Equipment Expenditures [Member] Coyote Generating Facility [Member] Jointly Owned Electricity Generation Plant [Member]	Mar. 31, 2013 Clean Air Act Rules and Associated Emission Control Equipment Expenditures [Member] Neal 4 Generating Facility [Member] Jointly Owned Electricity Generation Plant [Member]	Mar. 31, 2013 Clean Air Act Rules and Associated Emission Control Equipment Expenditures [Member] Colstrip Unit 4 [Member] Jointly Owned Electricity Generation Plant [Member]
Environmental remediation obligation, minimum	$ 28.3
Environmental remediation obligation, maximum	36.4
Accrual for environmental loss contingencies	31.3	24.6	12.2
Environmental remediation obligation next 5 years			8.6
Jointly owned utility plant ownership percentage				23.40%		10.00%	8.70%	30.00%
NOx emissions per million Btu as calculated on a 30 day rolling average basis					0.5
Estimated capital expenditures for environmental obligations				$ 405		$ 6	$ 270
Site contingency, time frame of disbursements							scheduled to commence in 2011 and be spread over the next three years.
Number of years for environmental remediation obligation to be incurred			5 years

XML

Nature of Operations and Basis of Consolidation (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013 watts customers
Number of customers	673,200
Number of megawatts of qualifying facility	35
Estimated aggregate gross contractual payments for qualifying facilities through 2024	$ 302.9

XML

Employee Benefit Plans (Tables)

3 Months Ended

Mar. 31, 2013

Compensation and Retirement Disclosure [Abstract]

Schedule of Defined Benefit Plans Disclosures [Table Text Block]

Net periodic benefit cost (income) for our pension and other postretirement plans consists of the following (in thousands):

	Pension Benefits						Other Postretirement Benefits
	Three Months Ended March 31,						Three Months Ended March 31,
	2013			2012			2013			2012
Components of Net Periodic Benefit Cost (Income)
Service cost	$	3,439		$	3,024		$	156		$	123
Interest cost	5,624			5,935			217			285
Expected return on plan assets	(8,125		)	(7,506		)	(254		)	(257		)
Amortization of prior service cost	62			62			(500		)	(500		)
Recognized actuarial loss	2,752			2,105			225			184
Net Periodic Benefit Cost (Income)	$	3,752		$	3,620		$	(156	)	$	(165	)

XML

Regulatory Matters (Details) (USD $) In Millions, unless otherwise specified		3 Months Ended		12 Months Ended
	Mar. 31, 2013 Demand-side management (DSM) lost revenues [Member] Revenue Subject to Refund [Member]	Jun. 30, 2013 Montana Natural Gas Rate Filing [Member]	Sep. 30, 2012 Montana Natural Gas Rate Filing [Member]	Dec. 31, 2012 Expires June 2024 [Member] Colstrip Energy Limited Partnership Rate Dispute [Member] watts	Mar. 31, 2013 Cumulative deferred revenue [Member] Dave Gates Generating Station [Member] Revenue Subject to Refund [Member]	Sep. 30, 2012 Bear Paw Basin [Member] Montana Natural Gas Production Assets [Member]
Customer refund liability, current	$ 6.2				$ 18.5
Megawatts of capacity				306,600
Proportionate ownership share in gas gathering systems						75.00%
Capital structure percentage of debt			52.00%
Capitalized structure percentage of equity			48.00%
Natural gas distribution requested increase			15.7
Requested return on equity for rate base			10.50%
Public utilities, base rate, natural gas distribution			309.5
Public utilities natural gas distribution stipulated increase		$ 11.5
Public utilities, stipulated return on equity for base rate		9.80%

XML

Income Taxes (Details) (USD $)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Income Tax Contingency [Line Items]
Effective income tax rate	11.70%	20.00%
Federal statutory rate	35.00%	35.00%
Unrecognized tax benefits	$ 113,800,000
Unrecognized tax benefits, income tax penalties and interest expense	0
Unrecognized tax benefits, income tax penalties and interest accrued	0		0
Unrecognized tax benefits that would impact effective tax rate	$ 79,700,000
Internal Revenue Service (IRS) [Member]
Income Tax Contingency [Line Items]
Effective income tax rate	11.70%	20.00%
Federal statutory rate	35.00%
Earliest year subject to examination	2000

XML

New Accounting Standards

3 Months Ended

Mar. 31, 2013

New Accounting Pronouncement or Change in Accounting Principle, Current Period Disclosures [Abstract]

New Accounting Pronouncements [Text Block]

New Accounting Standards

Accounting Standards Issued and Adopted

In February 2013, the Financial Accounting Standards Board issued guidance that requires disclosure of amounts reclassified out of accumulated other comprehensive income by component. Significant amounts are required to be presented by the respective line items of net income or should be cross-referenced to other disclosures. These disclosures may be presented on the income statement or in the notes to the financial statements. We adopted this standard during the first quarter of 2013 and have included the required disclosures in notes to the financial statements. The adoption of this standard did not have a material effect on our financial statement disclosures.

XML

Income Taxes Effective Tax Rate Reconciliation (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Effective tax rate reconciliation
Federal statutory rate	35.00%	35.00%
Flow-through repairs deductions	(18.00%)	(13.90%)
Flow-through of state bonus depreciaton deduction	(4.10%)	(3.40%)
Production tax credits	(2.70%)	0.00%
State income tax and other, net	1.50%	2.30%
Effective income tax rate	11.70%	20.00%
Significant differences from federal statutory rate
Income Before Income Taxes	$ 42,946	$ 40,055
Income tax calculated at 35% federal statutory rate	15,031	14,019
Permanent or flow through adjustments:
Flow-through repairs deductions	(7,710)	(5,571)
Flow-through of state bonus depreciation deduction	(1,756)	(1,371)
Production tax credits	(1,168)	0
State income tax and other, net	647	935
Total permanent or flow-through adjustments	(9,987)	(6,007)
Income tax expense	$ 5,044	$ 8,012

XML

Segment Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Segment Reporting Information [Line Items]
Operating revenues	$ 313,020	$ 309,100
Cost of sales	132,196	138,396
Gross margin	180,824	170,704
Operating, general and administrative	68,837	65,573
Property and other taxes	25,759	23,665
Depreciation	29,218	26,433
Operating income (loss)	57,010	55,033
Interest expense	(16,779)	(15,962)
Other income	2,715	984
Income tax (expense) benefit	(5,044)	(8,012)
Net Income (Loss)	37,902	32,043
Total assets	3,480,730	3,217,371	3,485,533
Capital expenditures	38,114	47,107
Electric [Member]
Segment Reporting Information [Line Items]
Operating revenues	210,092	207,055
Cost of sales	83,095	82,979
Gross margin	126,997	124,076
Operating, general and administrative	45,718	45,357
Property and other taxes	19,152	17,538
Depreciation	23,611	21,569
Operating income (loss)	38,516	39,612
Interest expense	(14,127)	(13,667)
Other income	2,011	612
Income tax (expense) benefit	(4,304)	(3,174)
Net Income (Loss)	22,096	23,383
Total assets	2,438,892	2,266,842
Capital expenditures	33,315	24,856
Natural Gas [Member]
Segment Reporting Information [Line Items]
Operating revenues	102,518	101,746
Cost of sales	49,101	55,417
Gross margin	53,417	46,329
Operating, general and administrative	19,895	19,288
Property and other taxes	6,604	6,124
Depreciation	5,599	4,856
Operating income (loss)	21,319	16,061
Interest expense	(2,426)	(2,067)
Other income	677	345
Income tax (expense) benefit	(1,772)	(3,590)
Net Income (Loss)	17,798	10,749
Total assets	1,031,518	938,335
Capital expenditures	4,799	22,251
All Other Segments [Member]
Segment Reporting Information [Line Items]
Operating revenues	410	299
Cost of sales	0	0
Gross margin	410	299
Operating, general and administrative	3,224	928
Property and other taxes	3	3
Depreciation	8	8
Operating income (loss)	(2,825)	(640)
Interest expense	(226)	(228)
Other income	27	27
Income tax (expense) benefit	1,032	(1,248)
Net Income (Loss)	(1,992)	(2,089)
Total assets	10,320	12,194
Capital expenditures	0	0
Intersegment Elimination [Member]
Segment Reporting Information [Line Items]
Operating revenues	0	0
Cost of sales	0	0
Gross margin	0	0
Operating, general and administrative	0	0
Property and other taxes	0	0
Depreciation	0	0
Operating income (loss)	0	0
Interest expense	0	0
Other income	0	0
Income tax (expense) benefit	0	0
Net Income (Loss)	0	0
Total assets	0	0
Capital expenditures	$ 0	$ 0

XML

CONDENSED CONSOLIDATED BALANCE SHEET (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Current Assets:
Cash and cash equivalents	$ 6,884	$ 9,822
Restricted cash	8,687	6,700
Accounts receivable, net	143,286	143,695
Inventories	38,848	54,161
Regulatory assets	25,569	40,301
Deferred income taxes	28,729	37,143
Other	13,375	11,306
Total current assets	265,378	303,128
Property, plant, and equipment, net	2,444,405	2,435,590
Goodwill	355,128	355,128
Regulatory assets	388,483	367,890
Other noncurrent assets	27,336	23,797
Total assets	3,480,730	3,485,533
Current Liabilities:
Current maturities of capital leases	1,638	1,612
Short-term borrowings	43,985	122,934
Accounts payable	67,250	83,746
Accrued expenses	213,446	192,548
Regulatory liabilities	49,717	48,425
Total current liabilities	376,036	449,265
Long-term capital leases	31,146	31,562
Long-term debt	1,055,079	1,055,074
Deferred income taxes	382,636	363,928
Noncurrent regulatory liabilities	279,784	276,618
Other noncurrent liabilities	380,439	375,054
Total liabilities	2,505,120	2,551,501
Commitments and Contingencies (Note 13)
Shareholders' Equity:
Common stock, par value $0.01; authorized 200,000,000 shares; issued and outstanding 41,407,918 and 37,805,238 respectively; Preferred stock, par value $0.01; authorized 50,000,000 shares; none issued	414	408
Treasury stock at cost	(91,951)	(90,702)
Paid-in capital	868,441	849,218
Retained earnings	196,523	172,791
Accumulated other comprehensive income	2,183	2,317
Total shareholders' equity	975,610	934,032
Total liabilities and shareholders' equity	$ 3,480,730	$ 3,485,533

XML

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
OPERATING ACTIVITIES:
Net Income	$ 37,902	$ 32,043
Items not affecting cash:
Depreciation	29,218	26,433
Amortization of debt issue costs, discount and deferred hedge gain	64	90
Amortization of restricted stock	669	1,075
Equity portion of allowance for funds used during construction	(1,234)	(930)
Gain on disposition of assets	0	(56)
Deferred income taxes	27,236	20,195
Changes in current assets and liabilities:
Restricted cash	(1,987)	3,681
Accounts receivable	409	15,639
Inventories	15,313	17,856
Other current assets	(2,069)	1,153
Accounts payable	(14,118)	(16,099)
Accrued expenses	24,025	19,812
Regulatory assets	12,598	6,718
Regulatory liabilities	1,292	(794)
Other noncurrent assets	(23,489)	(13,717)
Other noncurrent liabilities	6,051	6,826
Cash provided by operating activities	111,880	119,925
INVESTING ACTIVITIES:
Property, plant, and equipment additions	(38,114)	(47,107)
Proceeds from sale of assets	0	80
Cash used in investing activities	(38,114)	(47,027)
FINANCING ACTIVITIES:
Treasury stock activity	(1,249)	75
Proceeds from issuance of common stock, net	17,701	0
Dividends on common stock	(14,170)	(13,358)
Repayments on long-term debt	(37)	(3,795)
Repayments of short-term borrowings, net	(78,949)	(53,956)
Cash used in financing activities	(76,704)	(71,034)
(Decrease) Increase in Cash and Cash Equivalents	(2,938)	1,864
Cash and Cash Equivalents, beginning of period	9,822	5,928
Cash and Cash Equivalents, end of period	6,884	7,792
Cash paid (received) during the period for:
Income taxes	38	(335)
Interest	11,826	8,806
Significant non-cash transactions:
Capital expenditures included in accounts payable and accrued expenses	$ 6,810	$ 5,823

XML

Comprehensive Income (Loss) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Other Comprehensive Income (Loss), before Tax [Abstract]
Foreign currency translation adjustment	$ 49	$ (47)
Reclassification of net gains on derivative instruments to net income	(297)	(297)
Pension and postretirement medical liability adjustment		333
Other comprehensive loss	(248)	(11)
Other Comprehensive Income (Loss), Tax [Abstract]
Foreign currency translation adjustment	0	0
Reclassification of net gains on derivative instruments to net income	114	114
Pension and postretirement medical liability adjustment		(128)
Other comprehensive loss	114	(14)
Other comprehensive (loss) income, net of tax:
Foreign currency translation adjustment	49	(47)
Amounts reclassified from accumulated other comprehensive income	(183)	(183)
Pension and postretirement medical liability adjustment	0	205
Other Comprehensive (Loss) Income	(134)	(25)
Accumulated Other Comprehensive Income [Abstract]
Foreign currency translation	415		366
Derivative instruments designated as cash flow hedges	4,060		4,243
Pension and postretirement medical plans	(2,292)		(2,292)
Accumulated other comprehensive income	$ 2,183		$ 2,317

XML

Goodwill (Tables)

3 Months Ended

Mar. 31, 2013

Goodwill [Abstract]

Schedule of Goodwill [Table Text Block]

Goodwill by segment is as follows for both March 31, 2013 and December 31, 2012 (in thousands):

Electric	$	241,100
Natural gas	114,028
	$	355,128

XML

Risk Management and Hedging Activities (Details) (USD $)			3 Months Ended				3 Months Ended
	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2013 Commodity Contract [Member] Forward Contracts [Member]	Mar. 31, 2012 Commodity Contract [Member] Forward Contracts [Member]	Mar. 31, 2013 Commodity Contract [Member] Forward Contracts [Member] Not Designated as Hedging Instrument [Member] Accrued Liabilities [Member]	Dec. 31, 2012 Commodity Contract [Member] Forward Contracts [Member] Not Designated as Hedging Instrument [Member] Accrued Liabilities [Member]	Mar. 31, 2013 Interest Rate Swap [Member]	Mar. 31, 2013 Interest Rate Swap [Member] Interest Expense [Member]	Mar. 31, 2012 Interest Rate Swap [Member] Interest Expense [Member]
Derivative [Line Items]
Natural gas net derivative liability					$ 3,294,000	$ 5,428,000
Natural gas derivative, unrealized gain recognized in regulatory assets			2,134,000	1,256,000
Amount of gain reclassified from AOCI								297,000	297,000
Pre-tax gain on cash flow hedges remaining in AOCI							6,600,000
Pre-tax gain on cash flow hedge to be reclassified within twelve months from AOCI to interest expense							1,200,000
Interest rate swaps outstanding	0
Physical purchase and sale of gas and electricity at fixed prices	0	0
Credit risk-related contingent features for forward purchase contracts not qualifying for NPNS			$ 0

XML

Risk Management and Hedging Activities (Tables)

3 Months Ended

Mar. 31, 2013

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Schedule of Derivative Instruments [Table Text Block]

The following table represents the fair value and location of derivative instruments subject to mark-to-market accounting (in thousands). For more information on the determination of fair value see Note 8.

Mark-to-Market Transactions	Balance Sheet Location	March 31, 2013		December 31, 2012
Natural gas net derivative liability	Accrued Expenses	$	3,294	$	5,428

Schedule of Derivative Instruments in Statement of Financial Position, Fair Value [Table Text Block]

The following table represents the net change in fair value for these derivatives (in thousands):

	Unrealized gain recognized in Regulatory Assets
	Three Months Ended
Derivatives Subject to Regulatory Deferral	March 31, 2013		March 31, 2012
Natural gas	$	2,134	$	1,256

Schedule of Cash Flow Hedges Included in Accumulated Other Comprehensive Income (Loss) [Table Text Block]

The following table shows the effect of these derivative instruments on the Financial Statements (in thousands):

	Location of gain reclassified from AOCI to Income	Three Months Ended March 31, 2013 and 2012
Amount of gain reclassified from AOCI	Interest Expense	$	297

XML

Nature of Operations and Basis of Consolidation

3 Months Ended

Mar. 31, 2013

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Organization, Consolidation and Presentation of Financial Statements Disclosure and Significant Accounting Policies [Text Block]

Nature of Operations and Basis of Consolidation

NorthWestern Corporation, doing business as NorthWestern Energy, provides electricity and natural gas to approximately 673,200 customers in Montana, South Dakota and Nebraska.

The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America (GAAP) requires management to make estimates and assumptions that may affect the reported amounts of assets, liabilities, revenues and expenses during the reporting period. Actual results could differ from those estimates. The unaudited Condensed Consolidated Financial Statements (Financial Statements) reflect all adjustments (which unless otherwise noted are normal and recurring in nature) that are, in the opinion of management, necessary to fairly present our financial position, results of operations and cash flows. The actual results for the interim periods are not necessarily indicative of the operating results to be expected for a full year or for other interim periods. Events occurring subsequent to March 31, 2013, have been evaluated as to their potential impact to the Financial Statements through the date of issuance.

The Financial Statements included herein have been prepared by NorthWestern, without audit, pursuant to the rules and regulations of the SEC. Certain information and footnote disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations; however, management believes that the condensed disclosures provided are adequate to make the information presented not misleading. Management recommends that these unaudited Financial Statements be read in conjunction with the audited financial statements and related footnotes included in our Annual Report on Form 10-K for the year ended December 31, 2012.

Variable Interest Entities

A reporting company is required to consolidate a variable interest entity (VIE) as its primary beneficiary, which means it has a controlling financial interest, when it has both the power to direct the activities of the VIE that most significantly impact the VIE's economic performance, and the obligation to absorb losses or the right to receive benefits from the VIE that could potentially be significant to the VIE. An entity is considered to be a VIE when its total equity investment at risk is not sufficient to permit the entity to finance its activities without additional subordinated financial support, or its equity investors, as a group, lack the characteristics of having a controlling financial interest. The determination of whether a company is required to consolidate an entity is based on, among other things, an entity’s purpose and design and a company’s ability to direct the activities of the entity that most significantly impact the entity’s economic performance.

Certain long-term purchase power and tolling contracts may be considered variable interests. We have various long-term purchase power contracts with other utilities and certain Qualifying Facility (QF) plants. We identified one QF contract that may constitute a VIE. We entered into a power purchase contract in 1984 with this 35 Megawatt (MW) coal-fired QF to purchase substantially all of the facility's capacity and electrical output over a substantial portion of its estimated useful life. We absorb a portion of the facility's variability through annual changes to the price we pay per Megawatt Hour (MWH) (energy payment). After making exhaustive efforts, we have been unable to obtain the information from the facility necessary to determine whether the facility is a VIE or whether we are the primary beneficiary of the facility. The contract with the facility contains no provision which legally obligates the facility to release this information. We have accounted for this QF contract as an executory contract. Based on the current contract terms with this QF, our estimated gross contractual payments aggregate approximately $302.9 million through 2024.

XML

CONDENSED CONSOLIDATED BALANCE SHEET PARENTHETICAL (USD $)	Mar. 31, 2013
Common Stock, Par or Stated Value Per Share	$ 0.01
Common Stock, Shares Authorized	200,000,000
Common Stock, Shares, Issued	41,407,918
Common Stock, Shares, Outstanding	37,805,238
Preferred Stock, Par or Stated Value Per Share	$ 0.01
Preferred Stock, Shares Authorized	50,000,000
Preferred Stock, Shares Issued	0
Preferred Stock, Shares Outstanding	0

XML

Earnings Per Share

3 Months Ended

Mar. 31, 2013

Earnings Per Share [Abstract]

Earnings Per Share [Text Block]

Earnings Per Share

Basic earnings per share is computed by dividing net income by the weighted average number of common shares outstanding for the period. Diluted earnings per share reflects the potential dilution of common stock equivalent shares that could occur if all unvested shares were to vest. Common stock equivalent shares are calculated using the treasury stock method, as applicable. The dilutive effect is computed by dividing net income by the weighted average number of common shares outstanding plus the effect of the outstanding unvested restricted stock and performance share awards.

Average shares used in computing the basic and diluted earnings per share are as follows:

	Three Months Ended
	March 31, 2013	March 31, 2012
Basic computation	37,384,429	36,328,360
Dilutive effect of
Restricted stock and performance share awards (1)	101,305	171,933
Diluted computation	37,485,734	36,500,293

_________________

(1)           Performance share awards are included in diluted weighted average number of shares outstanding based upon what would be issued if the end of the most recent reporting period was the end of the term of the award.

XML

Document and Document Entity Information	3 Months Ended
	Mar. 31, 2013	Apr. 19, 2013
Entity Information [Line Items]
Entity Registrant Name	NORTHWESTERN CORPORATION
Entity Central Index Key	0000073088
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Mar. 31, 2013
Document Fiscal Year Focus	2013
Document Fiscal Period Focus	Q1
Amendment Flag	false
Entity Common Stock, Shares Outstanding		37,884,938
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes

XML

Employee Benefit Plans

3 Months Ended

Mar. 31, 2013

Compensation and Retirement Disclosure [Abstract]

Pension and Other Postretirement Benefits Disclosure [Text Block]

Employee Benefit Plans

Net periodic benefit cost (income) for our pension and other postretirement plans consists of the following (in thousands):

	Pension Benefits						Other Postretirement Benefits
	Three Months Ended March 31,						Three Months Ended March 31,
	2013			2012			2013			2012
Components of Net Periodic Benefit Cost (Income)
Service cost	$	3,439		$	3,024		$	156		$	123
Interest cost	5,624			5,935			217			285
Expected return on plan assets	(8,125		)	(7,506		)	(254		)	(257		)
Amortization of prior service cost	62			62			(500		)	(500		)
Recognized actuarial loss	2,752			2,105			225			184
Net Periodic Benefit Cost (Income)	$	3,752		$	3,620		$	(156	)	$	(165	)

XML

CONDENSED CONSOLIDATED STATEMENTS OF INCOME (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Revenues
Electric	$ 210,092	$ 207,055
Gas	102,518	101,746
Other	410	299
Total Revenues	313,020	309,100
Operating Expenses
Cost of sales	132,196	138,396
Operating, general and administrative	68,837	65,573
Property and other taxes	25,759	23,665
Depreciation	29,218	26,433
Total Operating Expenses	256,010	254,067
Operating Income	57,010	55,033
Interest Expense, net	(16,779)	(15,962)
Other Income	2,715	984
Income Before Income Taxes	42,946	40,055
Income Tax Expense	(5,044)	(8,012)
Net Income (Loss)	$ 37,902	$ 32,043
Average Common Shares Outstanding	37,384,429	36,328,360
Basic Earnings per Average Common Share	$ 1.01	$ 0.88
Diluted Earnings per Average Common Share	$ 1.01	$ 0.88
Dividends Declared per Average Common Share	$ 0.38	$ 0.37

XML

Comprehensive Income (Loss)

3 Months Ended

Mar. 31, 2013

Statement of Other Comprehensive Income [Abstract]

Comprehensive Income (Loss) Note [Text Block]

Comprehensive (Loss) Income

The following tables display the components of Other Comprehensive (Loss) Income, after-tax, and the related tax effects (in thousands):

	March 31, 2013
	Three Months Ended
	Before-Tax Amount			Tax Benefit		Net-of-Tax Amount
Foreign currency translation adjustment	$	49		$	—	$	49
Reclassification of net gains on derivative instruments to net income	(297		)	114		(183		)
Other comprehensive loss	$	(248	)	$	114	$	(134	)

	March 31, 2012
	Three Months Ended
	Before-Tax Amount			Tax Benefit			Net-of-Tax Amount
Foreign currency translation adjustment	$	(47	)	$	—		$	(47	)
Reclassification of net gains on derivative instruments to net income	(297		)	114			(183		)
Pension and postretirement medical liability adjustment	$	333		$	(128	)	$	205
Other comprehensive loss	$	(11	)	$	(14	)	$	(25	)

Balances by classification included within accumulated other comprehensive income (AOCI) on the Condensed Consolidated Balance Sheets are as follows, net of tax (in thousands):

	March 31, 2013			December 31, 2012
Foreign currency translation	$	415		$	366
Derivative instruments designated as cash flow hedges	4,060			4,243
Pension and postretirement medical plans	(2,292		)	(2,292		)
Accumulated other comprehensive income	$	2,183		$	2,317

The following table displays the changes in AOCI by component are as follows, net of tax (in thousands):

		March 31, 2013
		Three Months Ended
	Affected Line Item in the Condensed Consolidated Statements Of Income	Gains on Derivative Instruments Designated as Cash Flow Hedges			Pension and Postretirement Medical Plans			Foreign Currency Translation		Total
Beginning balance		$	4,243		$	(2,292	)	$	366	$	2,317
Other comprehensive income before reclassifications		—			—			49		49
Amounts reclassified from accumulated other comprehensive income	Interest Expense	(183		)	—			—		(183		)
Net current-period other comprehensive (loss) income		(183		)	—			49		(134		)
Ending balance		$	4,060		$	(2,292	)	$	415	$	2,183

XML

Goodwill

3 Months Ended

Mar. 31, 2013

Goodwill [Abstract]

Goodwill Disclosure [Text Block]

Goodwill

There were no changes in our goodwill during the three months ended March 31, 2013. Goodwill by segment is as follows for both March 31, 2013 and December 31, 2012 (in thousands):

Electric	$	241,100
Natural gas	114,028
	$	355,128

XML

Comprehensive Income (Loss) (Tables)

3 Months Ended

Mar. 31, 2013

Statement of Other Comprehensive Income [Abstract]

Schedule of Comprehensive Income (Loss) [Table Text Block]

The following tables display the components of Other Comprehensive (Loss) Income, after-tax, and the related tax effects (in thousands):

	March 31, 2013
	Three Months Ended
	Before-Tax Amount			Tax Benefit		Net-of-Tax Amount
Foreign currency translation adjustment	$	49		$	—	$	49
Reclassification of net gains on derivative instruments to net income	(297		)	114		(183		)
Other comprehensive loss	$	(248	)	$	114	$	(134	)

	March 31, 2012
	Three Months Ended
	Before-Tax Amount			Tax Benefit			Net-of-Tax Amount
Foreign currency translation adjustment	$	(47	)	$	—		$	(47	)
Reclassification of net gains on derivative instruments to net income	(297		)	114			(183		)
Pension and postretirement medical liability adjustment	$	333		$	(128	)	$	205
Other comprehensive loss	$	(11	)	$	(14	)	$	(25	)

Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block]

Balances by classification included within accumulated other comprehensive income (AOCI) on the Condensed Consolidated Balance Sheets are as follows, net of tax (in thousands):

	March 31, 2013			December 31, 2012
Foreign currency translation	$	415		$	366
Derivative instruments designated as cash flow hedges	4,060			4,243
Pension and postretirement medical plans	(2,292		)	(2,292		)
Accumulated other comprehensive income	$	2,183		$	2,317

Accumulated Other Comprehensive Income [Table Text Block]

The following table displays the changes in AOCI by component are as follows, net of tax (in thousands):

		March 31, 2013
		Three Months Ended
	Affected Line Item in the Condensed Consolidated Statements Of Income	Gains on Derivative Instruments Designated as Cash Flow Hedges			Pension and Postretirement Medical Plans			Foreign Currency Translation		Total
Beginning balance		$	4,243		$	(2,292	)	$	366	$	2,317
Other comprehensive income before reclassifications		—			—			49		49
Amounts reclassified from accumulated other comprehensive income	Interest Expense	(183		)	—			—		(183		)
Net current-period other comprehensive (loss) income		(183		)	—			49		(134		)
Ending balance		$	4,060		$	(2,292	)	$	415	$	2,183

XML

Commitments and Contingencies

3 Months Ended

Mar. 31, 2013

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies Disclosure [Text Block]

Commitments and Contingencies

ENVIRONMENTAL LIABILITIES AND REGULATION

The operation of electric generating, transmission and distribution facilities, and gas gathering, transportation and distribution facilities, along with the development (involving site selection, environmental assessments, and permitting) and construction of these assets, are subject to extensive federal, state, and local environmental and land use laws and regulations. Our activities involve compliance with diverse laws and regulations that address emissions and impacts to the environment, including air and water, protection of natural resources, avian and wildlife. We monitor federal, state, and local environmental initiatives to determine potential impacts on our financial results. As new laws or regulations are implemented, our policy is to assess their applicability and implement the necessary modifications to our facilities or their operation to maintain ongoing compliance.

Our environmental exposure includes a number of components, including remediation expenses related to the cleanup of current or former properties, and costs to comply with changing environmental regulations related to our operations. At present, the majority of our environmental reserve relates to the remediation of former manufactured gas plant sites owned by us. We use a combination of site investigations and monitoring to formulate an estimate of environmental remediation costs for specific sites. Our monitoring procedures and development of actual remediation plans depend not only on site specific information but also on coordination with the different environmental regulatory agencies in our respective jurisdictions; therefore, while remediation exposure exists, it may be many years before costs become fixed and reliably determinable.

Our liability for environmental remediation obligations is estimated to range between $28.3 million to $36.4 million, primarily for manufactured gas plants discussed below. As of March 31, 2013, we have a reserve of approximately $31.3 million, which has not been discounted. Environmental costs are recorded when it is probable we are liable for the remediation and we can reasonably estimate the liability. Over time, as specific laws are implemented and we gain experience in operating under them, a portion of the costs related to such laws will become determinable, and we may seek authorization to recover such costs in rates or seek insurance reimbursement as applicable; therefore, although we cannot guarantee regulatory recovery, we do not expect these costs to have a material effect on our consolidated financial position or ongoing operations.

Manufactured Gas Plants - Approximately $24.6 million of our environmental reserve accrual is related to manufactured gas plants. A formerly operated manufactured gas plant located in Aberdeen, South Dakota, has been identified on the Federal Comprehensive Environmental Response, Compensation, and Liability Information System list as contaminated with coal tar residue. We are currently conducting remedial actions at the Aberdeen site pursuant to work plans approved by the South Dakota Department of Environment and Natural Resources (DENR). Our current reserve for remediation costs at this site is approximately $12.2 million, and we estimate that approximately $8.6 million of this amount will be incurred during the next five years.

We also own sites in North Platte, Kearney and Grand Island, Nebraska on which former manufactured gas facilities were located. During 2005, the Nebraska Department of Environmental Quality (NDEQ) conducted Phase II investigations of soil and groundwater at our Kearney and Grand Island sites. During 2006, the NDEQ released to us the Phase II Limited Subsurface Assessments performed by the NDEQ's environmental consulting firm for Kearney and Grand Island. In February 2011, NDEQ completed an Abbreviated Preliminary Assessment and Site Investigation Report for Grand Island, which recommended additional ground water testing. In April of 2012, we received a letter from NDEQ regarding a recently completed Vapor Intrusion Assessment Report and an invitation to join NDEQ's Voluntary Cleanup Program (VCP). We declined NDEQ's offer to join its VCP at this time and also committed to conducting a limited soil vapor investigation. We will work independently to fully characterize the nature and extent of impacts associated with the former manufactured gas plant. After the site has been fully characterized, we will discuss the possibility of joining NDEQ's VCP. Our reserve estimate includes assumptions for additional ground water testing. At present, we cannot determine with a reasonable degree of certainty the nature and timing of any risk-based remedial action at our Nebraska locations.

In addition, we own or have responsibility for sites in Butte, Missoula and Helena, Montana on which former manufactured gas plants were located. An investigation conducted at the Missoula site did not require remediation activities, but required preparation of a groundwater monitoring plan. The Butte and Helena sites were placed into the Montana Department of Environmental Quality (MDEQ) voluntary remediation program for cleanup due to excess regulated pollutants in the groundwater. Voluntary soil and coal tar removals were conducted in the past at the Butte and Helena locations in accordance with MDEQ requirements. We have conducted additional groundwater monitoring at the Butte and Missoula sites and, at this time, we believe natural attenuation should address the conditions at these sites; however, additional groundwater monitoring will be necessary. Monitoring of groundwater at the Helena site is ongoing and will be necessary for an extended period of time. At this time, we cannot estimate with a reasonable degree of certainty the nature and timing of risk-based remedial action at the Helena site or if any additional actions beyond monitored natural attenuation will be required.

Global Climate Change - There are national and international efforts to adopt measures related to global climate change and the contribution of emissions of greenhouse gases (GHG) including, most significantly, carbon dioxide. These efforts include legislative proposals and Environmental Protection Agency (EPA) regulations at the federal level, actions at the state level, and private party litigation relating to GHG emissions. Coal-fired plants have come under particular scrutiny due to their level of GHG emissions. We have joint ownership interests in four electric generating plants, all of which are coal fired and operated by other companies. We have undivided interests in these facilities and are responsible for our proportionate share of the capital and operating costs while being entitled to our proportionate share of the power generated.

While numerous bills have been introduced that address climate change from different perspectives, including through direct regulation of GHG emissions, the establishment of cap and trade programs and the establishment of Federal renewable portfolio standards, Congress has not passed any federal climate change legislation and we cannot predict the timing or form of any potential legislation. In the absence of such legislation, the EPA is regulating GHG emissions under its existing authority pursuant to the Clean Air Act. For example, EPA regulations now require that major sources in the United States annually report information regarding, and obtain certain permits for, their GHG emissions.

In March 2012, the EPA proposed New Source Performance Standards that would limit carbon dioxide emissions from new electric generating units (EGUs). The proposed limits would not apply to existing or reconstructed EGUs. The proposed rule was part of an agreement to settle litigation brought by states, municipalities and environmental groups. The EPA accepted comments on the proposed standards through the end of June 2012. The EPA has not issued final standards.

On June 20, 2011, the U.S. Supreme Court issued a decision that bars state and private parties from bringing federal common law nuisance actions against electrical utility companies based on their alleged contribution to climate change. The Supreme Court's decision did not, however, address state law claims. This decision is expected to affect other pending federal climate change litigation. In addition, on June 26, 2012 a federal court issued a ruling affirming several of the EPA's greenhouse gas rules, which had been challenged by industry petitioners and certain states. Although we are not a party to any of these proceedings, additional litigation in federal and state courts over these issues is continuing.

Physical impacts of climate change may present potential risks for severe weather, such as floods and tornadoes, in the locations where we operate or have interests. Furthermore, requirements to reduce GHG emissions from stationary sources could cause us to incur material costs of compliance, increase our costs of procuring electricity in the marketplace or curtail the demand for fossil fuels such as oil and gas. In addition, we believe future legislation and regulations that affect GHG emissions from power plants are likely, although technology to efficiently capture, remove and/or sequester such emissions may not be available within a timeframe consistent with the implementation of such requirements. We cannot predict with any certainty whether these risks will have a material impact on our operations.

Coal Combustion Residuals (CCRs) - In June 2010, the EPA proposed two approaches to regulating the disposal and management of CCRs under the Resource Conservation and Recovery Act (RCRA). CCRs include fly ash, bottom ash and scrubber wastes. Under one approach, the EPA would regulate CCRs as a hazardous waste under Subtitle C of RCRA. This approach would have significant impacts on coal-fired plants, and would require plants to retrofit their operations to comply with hazardous waste requirements from the generation of CCRs and associated waste waters through transportation and disposal. This could also have a negative impact on the beneficial use of CCRs and the current markets associated with such use. The second approach would regulate CCRs as a solid waste under Subtitle D of RCRA. This approach would only affect disposal, most significantly any wet disposal, of CCRs. The EPA has not yet issued a final CCR rule; however, litigation has commenced to require it to do so. In addition, legislation was introduced in Congress to regulate coal ash. We cannot predict at this time the final requirements of any CCR regulations or legislation and what impact, if any, they would have on us, but the costs of complying with any such requirements could be significant.

Water Intakes - Section 316(b) of the Federal Clean Water Act requires that the location, design, construction and capacity of any cooling water intake structure reflect the “best available technology” for minimizing environmental impacts. Permits required for existing facilities are to be developed by the individual states using their best professional judgment until the EPA takes action to address several court decisions that rejected portions of previous rules and confirmed that the EPA has discretion to consider costs relative to benefits in developing cooling water intake structure regulations. In March 2011, the EPA proposed a rule to address impingement and entrainment of aquatic organisms at existing cooling water intake structures. The EPA is under a consent decree to issue a final rule by June 2013. When a final rule is issued and implemented, additional capital and/or increased operating costs may be incurred. The costs of complying with any such final water intake standards are not currently determinable, but could be significant.

Clean Air Act Rules and Associated Emission Control Equipment Expenditures

The EPA has proposed or issued a number of rules under different provisions of the Clean Air Act that could require the installation of emission control equipment at the generation plants where we have joint ownership.

The Clean Air Visibility Rule was issued by the EPA in June 2005, to address regional haze in national parks and wilderness areas across the United States. The Clean Air Visibility Rule requires the installation and operation of Best Available Retrofit Technology (BART) to achieve emissions reductions from designated sources (including certain electric generating units) that are deemed to cause or contribute to visibility impairment in such 'Class I' areas.

In December 2011, the EPA issued a final rule relating to Mercury and Air Toxics Standards (MATS), which was formerly the proposed Maximum Achievable Control Technology standards for hazardous air pollutant emissions from new and existing electric generating units. Among other things, these MATS standards set stringent emission limits for acid gases, mercury, and other hazardous air pollutants. Facilities that are subject to the MATS must come into compliance within three years after the effective date of the rule (or by 2015) unless a one year extension is granted on a case-by-case basis. On March 20, 2013, the EPA finalized updates to emission limits under the MATS for new power plants. Numerous challenges to the MATS standards have been filed with the EPA and in Federal court and we cannot predict the outcome of such challenges.

On July 7, 2011, the EPA finalized the Cross-State Air Pollution Rule (CSAPR) to reduce emissions from electric generating units that interfere with the ability of downwind states to achieve ambient air quality standards. Under CSAPR, significant reductions in emissions of nitrogen oxide (NOx) and sulfur dioxide (SO2) were to be required beginning in 2012. After having issued a stay of CSAPR earlier this year, however, a Federal court found that CSAPR violated federal law and ordered that it be vacated. The Clean Air Interstate Rule remains in effect until the EPA issues a valid replacement. The EPA and environmental groups have petitioned the Supreme Court to review the Federal court's ruling.

We have joint ownership in generation plants located in South Dakota, North Dakota, Iowa and Montana that are or may become subject to various regulations that have been issued or proposed under the Clean Air Act, as discussed below.

South Dakota. The South Dakota DENR determined that the Big Stone Plant, of which we have a 23.4% ownership, is subject to the BART requirements of the Regional Haze Rule. South Dakota DENR's State Implementation Plan (SIP) was approved by the EPA in May 2012. Under the SIP, the Big Stone plant must install and operate a new BART compliant air quality control system (AQCS) to reduce SO2, NOx and particulate emissions as expeditiously as practicable, but no later than five years after the EPA's approval of the SIP. The current project cost for the AQCS is estimated to be approximately $405 million (our share is 23.4%) and it is expected to be operational by 2016.

Our incremental capital expenditure projections include amounts related to our share of the BART technologies at Big Stone based on current estimates. We could, however, face additional capital or financing costs. We will seek to recover any such costs through the regulatory process. The South Dakota Public Utilities Commission has historically allowed timely recovery of the costs of environmental improvements; however, there is no precedent on a project of this size.

Based on the finalized MATS standards, it appears that Big Stone would meet the requirements by installing the AQCS system and using mercury control technology such as activated carbon injection. Mercury emissions monitoring equipment is already installed at Big Stone, but its operation has been put on hold pending additional regulatory direction. The equipment will need to be reevaluated for operability under the final rule.

North Dakota. The North Dakota Regional Haze SIP requires the Coyote generating facility, of which we have 10% ownership, to reduce its NOx emissions. Coyote must install control equipment to limit its NOx emissions to 0.5 pounds per million Btu as calculated on a 30-day rolling average basis, including periods of start-up and shutdown, beginning on July 1, 2018. The current estimate of the total cost of the project is approximately $6 million (our share is 10.0%).

Based on the finalized MATS standards, it appears that Coyote would meet the requirements by using mercury control technology such as activated carbon injection.

Iowa. The Neal 4 generating facility, of which we have an 8.7% ownership, is installing a scrubber, a baghouse, activated carbon and a selective non-catalytic reduction system to comply with national ambient air quality standards and MATS standards. Capital expenditures for such equipment are currently estimated to be approximately $270 million (our share is 8.7%). The plant began incurring such costs in 2011 and the project is expected to be complete in 2013.

Montana. Colstrip Unit 4, a coal fired generating facility in which we have a 30% interest, is currently controlling emissions of mercury under regulations issued by the State of Montana, which are more strict than the Federal MATS standard. The owners do not believe additional equipment will be necessary to meet the MATS standards for mercury, and anticipate meeting all other expected MATS emissions limitations required by the rule without additional costs except those costs related to increased monitoring frequency. These additional costs are not expected to be significant.

In September 2012, a final Federal Implementation Plan for Montana was published in the Federal Register to address regional haze. As finalized, Colstrip Unit 4 does not have to improve removal efficiency for pollutants that contribute to regional haze. The plan is reviewed every five years and Colstrip Unit 4 could be impacted during a subsequent review period.

See 'Legal Proceedings - Colstrip Litigation' below for discussion of Sierra Club litigation.

Other - We continue to manage equipment containing polychlorinated biphenyl (PCB) oil in accordance with the EPA's Toxic Substance Control Act regulations. We will continue to use certain PCB-contaminated equipment for its remaining useful life and will, thereafter, dispose of the equipment according to pertinent regulations that govern the use and disposal of such equipment.

We routinely engage the services of a third-party environmental consulting firm to assist in performing a comprehensive evaluation of our environmental reserve. Based upon information available at this time, we believe that the current environmental reserve properly reflects our remediation exposure for the sites currently and previously owned by us. The portion of our environmental reserve applicable to site remediation may be subject to change as a result of the following uncertainties:

• We may not know all sites for which we are alleged or will be found to be responsible for remediation; and

• Absent performance of certain testing at sites where we have been identified as responsible for remediation, we cannot estimate with a reasonable degree of certainty the total costs of remediation.

LEGAL PROCEEDINGS

Colstrip Litigation

On July 25, 2012, the Sierra Club and the Montana Environmental Information Center (MEIC) served on each of the individual owners of the Colstrip Steam Electric Station (CSES), including us and the owner or managing agent of the station, a notice of intent to sue for alleged violations of the federal Clean Air Act, 42 U.S.C. § 7401 et seq. Since serving the initial notice of intent to sue, the Sierra Club and MEIC have revised it three times.

On March 6, 2013, the Sierra Club and the MEIC (Plaintiffs) filed suit in the United States District Court for the District of Montana against the individual owners of the CSES, including us, and the operator or managing agent of the station. Plaintiffs' complaint, which includes 39 claims for relief, alleges violations of the Clean Air Act and seeks injunctive and declaratory relief, civil penalties, imposition of a beneficial environmental project, and recovery of their attorney fees. Plaintiffs have identified physical changes made at the CSES between 1992 and 2012, which they allege have increased emissions of SO2, NOx and particulate matter and were “major modifications” subject to permitting requirements under the Clean Air Act. They also have alleged violations of the requirements related to Part 70 Operating Permits, as well as provisions in the Montana State Implementation Plan regulating the opacity of emissions. We intend to vigorously defend this lawsuit. Due to the preliminary nature of the lawsuit, at this time, we cannot predict or determine the outcome of the lawsuit, nor is it reasonably possible to estimate the amount of loss, if any, that would be associated with an adverse decision.

Other Legal Proceedings

We are also subject to various other legal proceedings, governmental audits and claims that arise in the ordinary course of business. In the opinion of management, the amount of ultimate liability with respect to these other actions will not materially affect our financial position, results of operations, or cash flows.

XML

Financing Activities

3 Months Ended

Mar. 31, 2013

Financing Activities [Abstract]

Debt Disclosure [Text Block]

Financing Activities

In April 2012, we entered into an Equity Distribution Agreement pursuant to which we may offer and sell shares of our common stock from time to time, having an aggregate gross sales price of up to $100 million. Since inception, 1,274,662 shares of our common stock at an average price of $36.80 per share have been issued, for net proceeds of $46.2 million. During the three months ended March 31, 2013, we sold 459,246 shares of our common stock at an average price of $38.98 per share. Proceeds received were approximately $17.7 million, which are net of sales commissions of approximately $0.2 million and other fees.

XML

Risk Management and Hedging Activities

3 Months Ended

Mar. 31, 2013

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Derivative Instruments and Hedging Activities Disclosure [Text Block]

Risk Management and Hedging Activities

Nature of Our Business and Associated Risks

We are exposed to certain risks related to the ongoing operations of our business, including the impact of market fluctuations in the price of electricity and natural gas commodities and changes in interest rates. We rely on market purchases to fulfill a large portion of our electric and natural gas supply requirements within the Montana market. Several factors influence price levels and volatility. These factors include, but are not limited to, seasonal changes in demand, weather conditions, available generating assets within regions, transportation availability and reliability within and between regions, fuel availability, market liquidity, and the nature and extent of current and potential federal and state regulations.

Objectives and Strategies for Using Derivatives

To manage our exposure to fluctuations in commodity prices we routinely enter into derivative contracts, such as fixed-price forward purchase and sales contracts. The objective of these transactions is to fix the price for a portion of anticipated energy purchases to supply our customers. These types of contracts are included in our electric and natural gas supply portfolios and are used to manage price volatility risk by taking advantage of fluctuations in market prices. While individual contracts may be above or below market value, the overall portfolio approach is intended to provide greater price stability for consumers. These commodity costs are included in our cost tracking mechanisms and are recoverable from customers subject to prudence reviews by the applicable state regulatory commissions. We do not maintain a trading portfolio, and our derivative transactions are only used for risk management purposes consistent with regulatory guidelines. In addition, in the past we have used and in the future we may use interest rate swaps to manage our interest rate exposures associated with new debt issuances or to manage our exposure to fluctuations in interest rates on variable rate debt.

Accounting for Derivative Instruments

We evaluate new and existing transactions and agreements to determine whether they are derivatives. The permitted accounting treatments include: normal purchase normal sale; cash flow hedge; fair value hedge; and mark-to-market. Mark-to-market accounting is the default accounting treatment for all derivatives unless they qualify, and we specifically designate them, for one of the other accounting treatments. Derivatives designated for any of the elective accounting treatments must meet specific, restrictive criteria both at the time of designation and on an ongoing basis. The changes in the fair value of recognized derivatives are recorded each period in current earnings or other comprehensive income, depending on whether a derivative is designated as part of a hedge transaction and the type of hedge transaction.

Normal Purchases and Normal Sales

We have applied the normal purchase and normal sale scope exception (NPNS) to most of our contracts involving the physical purchase and sale of gas and electricity at fixed prices in future periods. During our normal course of business, we enter into full-requirement energy contracts, power purchase agreements and physical capacity contracts, which qualify for NPNS. All of these contracts are accounted for using the accrual method of accounting; therefore, there were no amounts recorded in the Financial Statements at March 31, 2013 and December 31, 2012. Revenues and expenses from these contracts are reported on a gross basis in the appropriate revenue and expense categories as the commodities are received or delivered.

Mark-to-Market Accounting

Certain contracts for the purchase of natural gas associated with our gas utility operations do not qualify for NPNS. These are typically forward purchase contracts for natural gas where we lock in a fixed price, settle the contracts financially and do not take physical delivery of the natural gas. We use the mark-to-market method of accounting for these derivative contracts as we do not elect hedge accounting. Upon settlement of these contracts, associated proceeds or costs are refunded to or collected from our customers consistent with regulatory requirements; therefore, we record a regulatory asset or liability based on changes in market value.

The following table represents the fair value and location of derivative instruments subject to mark-to-market accounting (in thousands). For more information on the determination of fair value see Note 8.

Mark-to-Market Transactions	Balance Sheet Location	March 31, 2013		December 31, 2012
Natural gas net derivative liability	Accrued Expenses	$	3,294	$	5,428

The following table represents the net change in fair value for these derivatives (in thousands):

	Unrealized gain recognized in Regulatory Assets
	Three Months Ended
Derivatives Subject to Regulatory Deferral	March 31, 2013		March 31, 2012
Natural gas	$	2,134	$	1,256

Credit Risk

We are exposed to credit risk primarily through buying and selling electricity and natural gas to serve customers. Credit risk is the potential loss resulting from counterparty non-performance under an agreement. We manage credit risk with policies and procedures for, among other things, counterparty analysis and exposure measurement, monitoring and mitigation. We may request collateral or other security from our counterparties based on the assessment of creditworthiness and expected credit exposure. It is possible that volatility in commodity prices could cause us to have material credit risk exposures with one or more counterparties.

We enter into commodity master enabling agreements with our counterparties to mitigate credit exposure, as these agreements reduce the risk of default by allowing us or our counterparty the ability to make net payments. The agreements generally are: (1) Western Systems Power Pool agreements – standardized power purchase and sales contracts in the electric industry; (2) International Swaps and Derivatives Association agreements – standardized financial gas and electric contracts; (3) North American Energy Standards Board agreements – standardized physical gas contracts; and (4) Edison Electric Institute Master Purchase and Sale Agreements – standardized power sales contracts in the electric industry.

Many of our forward purchase contracts contain provisions that require us to maintain an investment grade credit rating from each of the major credit rating agencies. If our credit rating were to fall below investment grade, the counterparties could require immediate payment or demand immediate and ongoing full overnight collateralization on contracts in net liability positions.

As of March 31, 2013, none of the forward purchase contracts that do not qualify for NPNS contain credit risk-related contingent features.

Interest Rate Swaps Designated as Cash Flow Hedges

We have previously used interest rate swaps designated as cash flow hedges to manage our interest rate exposures associated with new debt issuances. These swaps were designated as cash flow hedges with the effective portion of gains and losses, net of associated deferred income tax effects, recorded in AOCI. We reclassify these gains from AOCI into interest expense during the periods in which the hedged interest payments occur. The following table shows the effect of these derivative instruments on the Financial Statements (in thousands):

	Location of gain reclassified from AOCI to Income	Three Months Ended March 31, 2013 and 2012
Amount of gain reclassified from AOCI	Interest Expense	$	297

Approximately $6.6 million of the pre-tax gain on these cash flow hedges is remaining in AOCI as of March 31, 2013, and we expect to reclassify approximately $1.2 million from AOCI into interest expense during the next twelve months. These gains relate to swaps previously terminated, and we have no current interest rate swaps outstanding.

XML

Fair Value Measurements

3 Months Ended

Mar. 31, 2013

Fair Value Disclosures [Abstract]

Fair Value Disclosures [Text Block]

Fair Value Measurements

Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date (i.e., an exit price). Measuring fair value requires the use of market data or assumptions that market participants would use in pricing the asset or liability, including assumptions about risk and the risks inherent in the inputs to the valuation technique. These inputs can be readily observable, corroborated by market data, or generally unobservable. Valuation techniques are required to maximize the use of observable inputs and minimize the use of unobservable inputs.

A fair value hierarchy that prioritizes the inputs used to measure fair value, and requires fair value measurements to be categorized based on the observability of those inputs has been established by the applicable accounting guidance. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 inputs) and the lowest priority to unobservable inputs (Level 3 inputs). The three levels of the fair value hierarchy are as follows:

• Level 1 – Unadjusted quoted prices available in active markets at the measurement date for identical assets or liabilities;

• Level 2 – Pricing inputs, other than quoted prices included within Level 1, which are either directly or indirectly observable as of the reporting date; and

• Level 3 – Significant inputs that are generally not observable from market activity.

We classify assets and liabilities within the fair value hierarchy based on the lowest level of input that is significant to the fair value measurement of each individual asset and liability taken as a whole. The table below sets forth by level within the fair value hierarchy the gross components of our assets and liabilities measured at fair value on a recurring basis. Normal purchases and sales transactions are not included in the fair values by source table as they are not recorded at fair value. There were no transfers between levels for the periods presented. See Note 7 for further discussion.

	Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)		Significant Other Observable Inputs (Level 2)			Significant Unobservable Inputs (Level 3)		Margin Cash Collateral Offset		Total Net Fair Value
	(in thousands)
March 31, 2013
Restricted cash	$	8,381	$	—		$	—	$	—	$	8,381
Rabbi trust investments	14,235		—			—		—		14,235
Derivative liability (1)	—		(3,294		)	—		—		(3,294		)
Total	$	22,616	$	(3,294	)	$	—	$	—	$	19,322
December 31, 2012
Restricted cash	$	6,392	$	—		$	—	$	—	$	6,392
Rabbi trust investments	10,522		—			—		—		10,522
Derivative liability (1)	—		(5,428		)	—		—		(5,428		)
Total	$	16,914	$	(5,428	)	$	—	$	—	$	11,486

_________________________

(1) The changes in the fair value of these derivatives are deferred as a regulatory asset or liability until the contracts are settled. Upon settlement, associated proceeds or costs are passed through the applicable cost tracking mechanism to customers.

We present our derivative assets and liabilities on a net basis in the Condensed Consolidated Balance Sheets. The table above disaggregates our net derivative assets and liabilities on a gross contract-by-contract basis as required and classifies each individual asset or liability within the appropriate level in the fair value hierarchy, regardless of whether a particular contract is eligible for netting against other contracts. These gross balances are intended solely to provide information on sources of inputs to fair value and do not represent our actual credit exposure or net economic exposure. Increases and decreases in the gross components presented in each of the levels in this table also do not indicate changes in the level of derivative activities. Rather, the primary factors affecting the gross amounts are commodity prices.

Restricted cash represents amounts held in money market mutual funds. Rabbi trust assets represent assets held for non-qualified deferred compensation plans, which consist of our common stock and actively traded mutual funds with quoted prices in active markets. Fair value for the commodity derivatives was determined using internal models based on quoted forward commodity prices. We consider nonperformance risk in our valuation of derivative instruments by analyzing the credit standing of our counterparties and considering any counterparty credit enhancements (e.g., collateral). The fair value measurement of liabilities also reflects the nonperformance risk of the reporting entity, as applicable. Therefore, we have factored the impact of our credit standing as well as any potential credit enhancements into the fair value measurement of both derivative assets and derivative liabilities. Consideration of our own credit risk did not have a material impact on our fair value measurements.

Financial Instruments

The estimated fair value of financial instruments is summarized as follows (in thousands):

	March 31, 2013				December 31, 2012
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Liabilities:
Long-term debt	$	1,055,079	$	1,225,056	$	1,055,074	$	1,229,233

Short-term borrowings consist of commercial paper and are not included in the table above as carrying value approximates fair value. The estimated fair value amounts have been determined using available market information and appropriate valuation methodologies; however, considerable judgment is required in interpreting market data to develop estimates of fair value. Accordingly, the estimates presented herein are not necessarily indicative of the amounts that we would realize in a current market exchange.

We determined fair value for long-term debt based on interest rates that are currently available to us for issuance of debt with similar terms and remaining maturities, except for publicly traded debt, for which fair value is based on market prices for the same or similar issues or upon the quoted market prices of U.S. treasury issues having a similar term to maturity, adjusted for our bond issuance rating and the present value of future cash flows. These are significant other observable inputs, or level 2 inputs, in the fair value hierarchy.

XML

Segment Information

3 Months Ended

Mar. 31, 2013

Segment Reporting [Abstract]

Segment Reporting Disclosure [Text Block]

Segment Information

Our reportable business segments are primarily engaged in the electric and natural gas business. The remainder of our operations are presented as other, which is not considered a business unit. Other primarily consists of the wind down of our captive insurance subsidiary and our unallocated corporate costs.

We evaluate the performance of these segments based on gross margin. The accounting policies of the operating segments are the same as the parent except that the parent allocates some of its operating expenses to the operating segments according to a methodology designed by management for internal reporting purposes and involves estimates and assumptions. Financial data for the business segments are as follows (in thousands):

Three Months Ended
March 31, 2013	Electric			Gas			Other			Eliminations		Total
Operating revenues	$	210,092		$	102,518		$	410		$	—	$	313,020
Cost of sales	83,095			49,101			—			—		132,196
Gross margin	126,997			53,417			410			—		180,824
Operating, general and administrative	45,718			19,895			3,224			—		68,837
Property and other taxes	19,152			6,604			3			—		25,759
Depreciation	23,611			5,599			8			—		29,218
Operating income (loss)	38,516			21,319			(2,825		)	—		57,010
Interest expense	(14,127		)	(2,426		)	(226		)	—		(16,779		)
Other income	2,011			677			27			—		2,715
Income tax (expense) benefit	(4,304		)	(1,772		)	1,032			—		(5,044		)
Net income (loss)	$	22,096		$	17,798		$	(1,992	)	$	—	$	37,902
Total assets	$	2,438,892		$	1,031,518		$	10,320		$	—	$	3,480,730
Capital expenditures	$	33,315		$	4,799		$	—		$	—	$	38,114

Three Months Ended
March 31, 2012	Electric			Gas			Other			Eliminations		Total
Operating revenues	$	207,055		$	101,746		$	299		$	—	$	309,100
Cost of sales	82,979			55,417			—			—		138,396
Gross margin	124,076			46,329			299			—		170,704
Operating, general and administrative	45,357			19,288			928			—		65,573
Property and other taxes	17,538			6,124			3			—		23,665
Depreciation	21,569			4,856			8			—		26,433
Operating income (loss)	39,612			16,061			(640		)	—		55,033
Interest expense	(13,667		)	(2,067		)	(228		)	—		(15,962		)
Other income	612			345			27			—		984
Income tax expense	(3,174		)	(3,590		)	(1,248		)	—		(8,012		)
Net income (loss)	$	23,383		$	10,749		$	(2,089	)	$	—	$	32,043
Total assets	$	2,266,842		$	938,335		$	12,194		$	—	$	3,217,371
Capital expenditures	$	24,856		$	22,251		$	—		$	—	$	47,107

XML

Accumulated Other Comprehensive Income by Component (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Accumulated Other Comprehensive Income [Line Items]
Beginning balance, accumulated other comprehensive income	$ 2,317
Other comprehensive income before reclassifications	49	(47)
Amounts reclassified from accumulated other comprehensive income	(183)	(183)
Other Comprehensive (Loss) Income	(134)	(25)
Ending balance, accumulated other comprehensive income	2,183
Gains on Derivative Instruments Designated as Cash Flow Hedges
Accumulated Other Comprehensive Income [Line Items]
Beginning balance, accumulated other comprehensive income	4,243
Other comprehensive income before reclassifications	0
Amounts reclassified from accumulated other comprehensive income	(183)
Other Comprehensive (Loss) Income	(183)
Ending balance, accumulated other comprehensive income	4,060
Pension and Postretirement Medical Plans
Accumulated Other Comprehensive Income [Line Items]
Beginning balance, accumulated other comprehensive income	(2,292)
Other comprehensive income before reclassifications	0
Amounts reclassified from accumulated other comprehensive income	0
Other Comprehensive (Loss) Income	0
Ending balance, accumulated other comprehensive income	(2,292)
Foreign Currency Translation
Accumulated Other Comprehensive Income [Line Items]
Beginning balance, accumulated other comprehensive income	366
Other comprehensive income before reclassifications	49
Amounts reclassified from accumulated other comprehensive income	0
Other Comprehensive (Loss) Income	49
Ending balance, accumulated other comprehensive income	$ 415

XML

Income Taxes (Tables)

3 Months Ended

Mar. 31, 2013

Income Tax Disclosure [Abstract]

Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]

The following table reconciles our effective income tax rate to the federal statutory rate:

	Three Months Ended March 31,
	2013		2012
Federal statutory rate	35.0	%	35.0	%
Flow-through repairs deductions	(18.0	)	(13.9	)
Flow-through of state bonus depreciation deduction	(4.1	)	(3.4	)
Production tax credits	(2.7	)	—
State income tax and other, net	1.5		2.3
	11.7	%	20.0	%

The following table summarizes the significant differences in income tax expense based on the differences between our effective tax rate and the federal statutory rate (in thousands):

	Three Months Ended March 31,
	2013			2012
Income Before Income Taxes	$	42,946		$	40,055
Income tax calculated at 35% federal statutory rate	15,031			14,019
Permanent or flow through adjustments:
Flow-through repairs deductions	(7,710		)	(5,571		)
Flow-through of state bonus depreciation deduction	(1,756		)	(1,371		)
Production tax credits	(1,168		)	—
State income tax and other, net	647			935
	$	(9,987	)	$	(6,007	)
Income tax expense	$	5,044		$	8,012

XML

Segment Information (Tables)

3 Months Ended

Mar. 31, 2013

Segment Reporting [Abstract]

Schedule of Segment Reporting Information, by Segment [Table Text Block]

Financial data for the business segments are as follows (in thousands):

Three Months Ended
March 31, 2013	Electric			Gas			Other			Eliminations		Total
Operating revenues	$	210,092		$	102,518		$	410		$	—	$	313,020
Cost of sales	83,095			49,101			—			—		132,196
Gross margin	126,997			53,417			410			—		180,824
Operating, general and administrative	45,718			19,895			3,224			—		68,837
Property and other taxes	19,152			6,604			3			—		25,759
Depreciation	23,611			5,599			8			—		29,218
Operating income (loss)	38,516			21,319			(2,825		)	—		57,010
Interest expense	(14,127		)	(2,426		)	(226		)	—		(16,779		)
Other income	2,011			677			27			—		2,715
Income tax (expense) benefit	(4,304		)	(1,772		)	1,032			—		(5,044		)
Net income (loss)	$	22,096		$	17,798		$	(1,992	)	$	—	$	37,902
Total assets	$	2,438,892		$	1,031,518		$	10,320		$	—	$	3,480,730
Capital expenditures	$	33,315		$	4,799		$	—		$	—	$	38,114

Three Months Ended
March 31, 2012	Electric			Gas			Other			Eliminations		Total
Operating revenues	$	207,055		$	101,746		$	299		$	—	$	309,100
Cost of sales	82,979			55,417			—			—		138,396
Gross margin	124,076			46,329			299			—		170,704
Operating, general and administrative	45,357			19,288			928			—		65,573
Property and other taxes	17,538			6,124			3			—		23,665
Depreciation	21,569			4,856			8			—		26,433
Operating income (loss)	39,612			16,061			(640		)	—		55,033
Interest expense	(13,667		)	(2,067		)	(228		)	—		(15,962		)
Other income	612			345			27			—		984
Income tax expense	(3,174		)	(3,590		)	(1,248		)	—		(8,012		)
Net income (loss)	$	23,383		$	10,749		$	(2,089	)	$	—	$	32,043
Total assets	$	2,266,842		$	938,335		$	12,194		$	—	$	3,217,371
Capital expenditures	$	24,856		$	22,251		$	—		$	—	$	47,107

XML

Earnings Per Share (Details)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Basic computation	37,384,429	36,328,360
Dilutive effect of Restricted stock and performance share awards (1)	101,305	171,933
Diluted computation	37,485,734	36,500,293

XML

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Net Income	$ 37,902	$ 32,043
Other comprehensive (loss) income, net of tax:
Reclassification of net gains on derivative instruments	(183)	(183)
Postretirement medical liability adjustment	0	205
Foreign currency translation adjustment	49	(47)
Total Other Comprehensive Loss	(134)	(25)
Comprehensive Income	$ 37,768	$ 32,018

XML

Income Taxes

3 Months Ended

Mar. 31, 2013

Income Tax Disclosure [Abstract]

Income Tax Disclosure [Text Block]

Income Taxes

Our effective tax rate was 11.7% for the three months ended March 31, 2013 as compared with 20.0% for the three months ended March 31, 2012. The following table reconciles our effective income tax rate to the federal statutory rate:

	Three Months Ended March 31,
	2013		2012
Federal statutory rate	35.0	%	35.0	%
Flow-through repairs deductions	(18.0	)	(13.9	)
Flow-through of state bonus depreciation deduction	(4.1	)	(3.4	)
Production tax credits	(2.7	)	—
State income tax and other, net	1.5		2.3
	11.7	%	20.0	%

The following table summarizes the significant differences in income tax expense based on the differences between our effective tax rate and the federal statutory rate (in thousands):

	Three Months Ended March 31,
	2013			2012
Income Before Income Taxes	$	42,946		$	40,055
Income tax calculated at 35% federal statutory rate	15,031			14,019
Permanent or flow through adjustments:
Flow-through repairs deductions	(7,710		)	(5,571		)
Flow-through of state bonus depreciation deduction	(1,756		)	(1,371		)
Production tax credits	(1,168		)	—
State income tax and other, net	647			935
	$	(9,987	)	$	(6,007	)
Income tax expense	$	5,044		$	8,012

Our effective tax rate differs from the federal statutory tax rate of 35% primarily due to the regulatory impact of flowing through the federal and state tax benefit of repairs deductions, state tax benefit of bonus depreciation deductions and production tax credits. The regulatory accounting treatment of these deductions requires immediate income recognition for temporary tax differences of this type, which is referred to as the flow-through method. When the flow-through method of accounting for temporary differences is reflected in regulated revenues, we record deferred income taxes and establish related regulatory assets and liabilities.

Uncertain Tax Positions

We have unrecognized tax benefits of approximately $113.8 million as of March 31, 2013, including approximately $79.7 million that, if recognized, would impact our effective tax rate. We do not anticipate that total unrecognized tax benefits will significantly change due to the settlement of audits or the expiration of statutes of limitation within the next twelve months.

The Internal Revenue Service (IRS) issued guidance during the third quarter of 2011 providing a safe harbor method for determining the tax treatment of repair costs related to electric transmission and distribution property. That guidance was updated in the third quarter of 2012 to allow companies additional time to adopt the safe harbor method. We are evaluating whether or not we want to elect the safe harbor method, which may result in a change in related repairs deductions and unrecognized tax benefits.

Our policy is to recognize interest and penalties related to uncertain tax positions in income tax expense. During the three months ended March 31, 2013, we have not recognized expense for interest or penalties, and do not have any amounts accrued at March 31, 2013 and December 31, 2012, respectively, for the payment of interest and penalties.

Our federal tax returns from 2000 forward remain subject to examination by the IRS.

XML

Earnings Per Share (Tables)

3 Months Ended

Mar. 31, 2013

Earnings Per Share [Abstract]

Schedule of Weighted Average Number of Shares [Table Text Block]

Average shares used in computing the basic and diluted earnings per share are as follows:

	Three Months Ended
	March 31, 2013	March 31, 2012
Basic computation	37,384,429	36,328,360
Dilutive effect of
Restricted stock and performance share awards (1)	101,305	171,933
Diluted computation	37,485,734	36,500,293

_________________

(1)           Performance share awards are included in diluted weighted average number of shares outstanding based upon what would be issued if the end of the most recent reporting period was the end of the term of the award.

XML

Fair Value Measurements Fair Value Finanical Insruments (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt (including current portion), carrying value	$ 1,055,079	$ 1,055,074
Long-term debt (including current portion), fair value	$ 1,225,056	$ 1,229,233

XML

Nature of Operations and Basis of Consolidation (Policies)

3 Months Ended

Mar. 31, 2013

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Consolidation, Variable Interest Entity [Policy Text Block]

Variable Interest Entities

A reporting company is required to consolidate a variable interest entity (VIE) as its primary beneficiary, which means it has a controlling financial interest, when it has both the power to direct the activities of the VIE that most significantly impact the VIE's economic performance, and the obligation to absorb losses or the right to receive benefits from the VIE that could potentially be significant to the VIE. An entity is considered to be a VIE when its total equity investment at risk is not sufficient to permit the entity to finance its activities without additional subordinated financial support, or its equity investors, as a group, lack the characteristics of having a controlling financial interest. The determination of whether a company is required to consolidate an entity is based on, among other things, an entity’s purpose and design and a company’s ability to direct the activities of the entity that most significantly impact the entity’s economic performance.

Certain long-term purchase power and tolling contracts may be considered variable interests. We have various long-term purchase power contracts with other utilities and certain Qualifying Facility (QF) plants. We identified one QF contract that may constitute a VIE. We entered into a power purchase contract in 1984 with this 35 Megawatt (MW) coal-fired QF to purchase substantially all of the facility's capacity and electrical output over a substantial portion of its estimated useful life. We absorb a portion of the facility's variability through annual changes to the price we pay per Megawatt Hour (MWH) (energy payment). After making exhaustive efforts, we have been unable to obtain the information from the facility necessary to determine whether the facility is a VIE or whether we are the primary beneficiary of the facility. The contract with the facility contains no provision which legally obligates the facility to release this information. We have accounted for this QF contract as an executory contract. Based on the current contract terms with this QF, our estimated gross contractual payments aggregate approximately $302.9 million through 2024.