ex_99-1.htm

Edison Electric Institute

October 31 - November 3, 2010

forward-looking statement…

During the course of this presentation, there will be forward-looking

statements within the meaning of the “safe harbor” provisions of the

Private Securities Litigation Reform Act of 1995. Forward-looking

statements often address our expected future business and financial
performance, and often contain words such as “expects,” “anticipates,”

“intends,” “plans,” “believes,” “seeks,” or “will.”

The information in this presentation is based upon our current

expectations as of the date hereof unless otherwise noted. Our actual

future business and financial performance may differ materially and

adversely from our expectations expressed in any forward-looking

statements. We undertake no obligation to revise or publicly update our
forward-looking statements or this presentation for any reason. Although

our expectations and beliefs are based on reasonable assumptions, actual

results may differ materially. The factors that may affect our results are

listed in certain of our press releases and disclosed in the Company’s

public filings with the SEC.

who we are…

Above data as of 9/30/10

(1) Book capitalization calculated as total debt, excluding capital leases, plus shareholders’
equity.

¾ 661,000 customers

» 399,000 electric

» 262,000 natural gas

¾ Approximately 123,000 square
miles of service territory in
Montana, South Dakota, and
Nebraska

» 32,000 miles of electric T&D lines

» 8,400 miles of natural gas T&D pipelines

» 18 Bcf natural gas storage

» 8 Bcf natural gas proven reserves

¾ Total generation (mostly base load coal)

» MT - 222 MW - regulated

» SD - 312 MW - regulated

¾ Total Assets: $2,899 MM

¾ Total Capitalization: $1,834 MM(1)

¾ Total Employees: 1,354

Located in states with relatively stable economies

with opportunity for system investment and grid expansion.

NorthWestern’s attributes…

¾ Solid operations

» Cost competitive

» Above-average reliability

» Award-winning customer service

¾ Low single A secured credit ratings with a strong balance sheet and

liquidity

» April 15, 2010 Fitch upgraded secured and unsecured ratings to A- and BBB+

respectively

¾ Positive earnings and ROE trend

» Delivery services rate cases for Montana electric and natural gas

» Mill Creek Generation Station anticipated into rates early 2011

¾ Strong cash flows

» NOLs and repair tax deduction provide an effective tax shield until likely 2014

» 94% pension funded status at end of 2009

¾ Competitive total shareholder return and dividend that has increased

every year since 2005

» Added to S&P 600 SmallCap Index on April 9, 2010

¾ Constructive regulatory environment

¾ Forbes.com listed as one of “100 Most Trustworthy Companies”

¾ Realistic investment opportunities

improving credit ratings…

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.

strong balance sheet and liquidity…

¾ Total Debt / Total capitalization of 55.8%(1)

¾ May 2010

» We refinanced existing $225 million, 5.875% Senior Secured Notes
due 2014 with 15-year First Mortgage Bonds due 2025. Bonds
priced April 15th at 5.01%.

¾ Total liquidity approximately $147 million

¾ Nearly all long-term debt matures after 2015

(1) Total Debt / Total capitalization as of 9/30/10

(2) Excludes outstanding 9/30/10 Revolver balance of $109 million maturing
in 2012.

reaffirming 2010 EPS guidance…

¾ The major assumptions include, but are not limited to, the
following expectations:

» Excludes approximately $.06/share for the 2010 estimated effect of the Montana rate
increase proposed by the Stipulation, which is pending approval by the MPSC;

» The release of the second quarter 2010 valuation allowance of approximately $.06/share
against certain state NOL carryforwards is excluded from the earnings outlook;

» The tax benefit associated with the IRS approval of a tax accounting method to deduct
repairs is included in the earnings outlook;

» Fully diluted average shares outstanding of 36.5 million; and

» Normal weather in the Company’s electric and natural gas service territories for the
remainder of 2010.

strong cash flows…

Earnings trend and NOLs provide strong cash flows to
fund future investment.

(1) Utility maintenance capex only, excludes investment project opportunities.

(2) 2009 Cash Flow from Operations adjusted to include pension funding in excess of expense and Ammondson settlement paid.

solid pension funding position…

Data source: SNL
Financial

As a result of the significant contribution of $93 million to our pension
plan and solid market returns in 2009, we are better positioned than
our peers at December 31, 2009

competitive total shareholder return…

Data source: SNL
Financial

Our 53% Total Shareholder Return (TSR) since emergence has

exceeded our peer average as well as major indices (11/2/04 - 10/27/10)

and growing dividend…

Goal for dividend payout ratio of 60% - 70%.
Current dividend yield about 5% with year-over-year dividend growth.

(1) 2010 estimated payout range assumes midpoint of $1.95 - $2.10
guidance range

constructive regulatory environment…

¾ Montana

» Rate case filed October 2009

♦ September 2010 - Stipulated settlement with Consumer Counsel for a $6.7 million rate increase,

subject to MPSC approval

♦ Hearing ended September 24th and we are awaiting a final decision from the MPSC during the

fourth quarter of 2010

♦ The remaining contested issues are decoupling and rate design.

» Mill Creek Generation Station filed with MPSC

♦ Under construction with $161.3 million capitalized CWIP as of September 30, 2010

♦ Filed for interim rates with desire to be effective with plant in-service (est. January 1, 2011)

» Colstrip Unit 4 placed into rate base starting January 2009

¾ South Dakota / Nebraska

» Expect to file natural gas rate cases during 2011 pending 2010 results

¾ FERC

» Encouraged Company to develop MSTI on a cost of service basis by requesting

appropriate tariff waivers for existing OATT

» Approved 230kV Renewable Collector Open Season

» Docket filed for Mill Creek on April 10, 2010 to establish rates as of January 1, 2011

♦ October 15, 2010, Order issued authorizing us to put our filed tariffs in place January 1, 2011,

subject to refund, and set the case for hearing.

near-term potential earnings drivers…

¾ In 2010 we anticipate

» Mill Creek AFUDC

♦ Approximately $9 million full year pre-tax contribution

» Modest recovery in volumes and economic activity in 2010

♦ High ratio of residential/commercial vs. industrial customers

● Electric: 69% Residential & Commercial, 31% Industrial

● Natural Gas: 99% Residential & Commercial, 1% Industrial

♦ Relatively healthy economy within our service territory

♦ Effective cost control

» Montana rate adjustment expected to take effect last quarter of 2010

¾ 2011 we anticipate:

» Full year effect of Montana rate adjustment

♦ Awaiting a decision from PSC on $6.7 million stipulation settlement

» Mill Creek in rate base

♦ Approximately $10 million annualized contribution to net income, or $3.7 million

incremental post-tax contribution compared to 2010

» Potential South Dakota and Nebraska natural gas partial year rate

adjustments

longer term investment opportunities…

¾ Distribution system enhancements

» Incremental rate based investment to enhance reliability and

capacity, improve rural service, and prepare the system for

potential smart grid applications (early stages)

¾ Energy supply

» Mill Creek Generation Station

» South Dakota peaking generation

» Wind projects and other renewable projects (early stages)

» Big Stone pollution control equipment (early stages)

» Natural gas reserves (early stages)

¾ Transmission projects

» Colstrip 500 kV upgrade

» 230 kV Renewable Collector System

» Mountain States Transmission Intertie (MSTI)

» Electric Transmission America (ETA) (early stages)

» Green Power Express (ITC) (early stages)

potential project summary…

Opportunity to increase and diversify earnings as
compared with our existing $1.6 billion rate base.

in summary…

¾ Solid operations

¾ Low single A secured credit ratings with a
strong balance sheet and liquidity

¾ Positive earnings and ROE trend

¾ Strong cash flows

¾ Competitive total shareholder return and
dividend that has increased every year
since 2005

¾ Constructive regulatory environment

¾ Forbes.com “100 Most Trustworthy
Companies”

¾ Realistic investment opportunities

Appendix

2009 to 2010 earnings bridge…

Appendix

The major assumptions include, but are not limited to, the following expectations:

» Excludes approximately $.06/share for the 2010 estimated effect of the Montana rate increase proposed by the
Stipulation, which is pending approval by the MPSC;

» The release of the second quarter 2010 valuation allowance of approximately $.06/share against certain state NOL
carryforwards is excluded from the earnings outlook;

» The tax benefit associated with the IRS approval of a tax accounting method to deduct repairs is included in the
earnings outlook;

» Fully diluted average shares outstanding of 36.5 million; and

» Normal weather in the Company’s electric and natural gas service territories for the remainder of 2010.

income statement…

Appendix

balance sheet…

Appendix

cash flow…

Appendix