10-Q

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-Q

(Mark One)

☒    Quarterly Report pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934

For the quarterly period ended June 30, 2023 or

☐    Transition Report pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934

Commission File Number 0-53713 

OTTER TAIL CORPORATION

(Exact name of registrant as specified in its charter) 

Minnesota (State or other jurisdiction of incorporation or organization)	27-0383995 (I.R.S. Employer Identification No.)
215 South Cascade Street, Box 496, Fergus Falls, Minnesota (Address of principal executive offices)	56538-0496 (Zip Code)

Registrant's telephone number, including area code: 866-410-8780

Securities registered pursuant to Section 12(b) of the Act: 

Title of each class	Trading Symbol(s)	Name of each exchange on which registered
Common Shares, par value $5.00 per share	OTTR	The Nasdaq Stock Market LLC

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  ☑    No  ☐ 

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T during the preceding 12 months (or for such shorter period that the registrant was required to submit such files). Yes  ☑     No  ☐ 

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,” “smaller reporting company” and “emerging growth company” in Rule 12b-2 of the Exchange Act. (Check one): 

Large Accelerated Filer ☑	Accelerated Filer ☐
Non-Accelerated Filer ☐	Smaller Reporting Company ☐	Emerging Growth Company ☐

 

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act  ☐ 

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

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

41,710,521 Common Shares ($5 par value) as of July 28, 2023. 

TABLE OF CONTENTS

	Description	Page
	Definitions	2
	Forward Looking Information	2
PART I
ITEM 1.	Financial Statements:
	Consolidated Balance Sheets	3
	Consolidated Statements of Income	4
	Consolidated Statements of Comprehensive Income	5
	Consolidated Statements of Shareholders’ Equity	6
	Consolidated Statements of Cash Flows	7
	Condensed Notes to Consolidated Financial Statements	8
ITEM 2.	Management’s Discussion and Analysis of Financial Condition and Results of Operations	20
ITEM 3.	Quantitative and Qualitative Disclosures About Market Risk	30
ITEM 4.	Controls and Procedures	30
PART II
ITEM 1.	Legal Proceedings	30
ITEM 1A.	Risk Factors	30
ITEM 5.	Other Information	30
ITEM 6.	Exhibits	31
Signatures		32

1

DEFINITIONS

The following abbreviations or acronyms are used in the text.

AMDT	Advanced Meter and Distribution Technology	MISO	Midcontinent Independent System Operator, Inc.
ARP	Alternative Revenue Program	MPUC	Minnesota Public Utilities Commission
BTD	BTD Manufacturing, Inc.	NDDEQ	North Dakota Department of Environmental Quality
CCS	Carbon Capture and Sequestration	OTC	Otter Tail Corporation
CIP	Conservation Improvement Program	OTP	Otter Tail Power Company
EGU	Electric Generating Units	PIR	Phase-In Rider
EITE	Energy Intensive, Trade Exposed Rider	PSLRA	Private Securities Litigation Reform Act of 1995
EPA	Environmental Protection Agency	PTC	Production Tax Credits
ESSRP	Executive Survivor and Supplemental Retirement Plan	PVC	Polyvinyl chloride
EUIC	Electric Utility Infrastructure Cost Recovery Rider	RHR	Regional Haze Rule
FERC	Federal Energy Regulatory Commission	ROE	Return on equity
GCR	Generation Cost Recovery Rider	RRR	Renewable Resource Rider
GHG	Greenhouse Gas	SEC	Securities and Exchange Commission
ISO	Independent System Operator	T.O. Plastics	T.O. Plastics, Inc.
kwh	kilowatt-hour	TCR	Transmission Cost Recovery Rider
Merricourt	Merricourt Wind Energy Center

FORWARD-LOOKING INFORMATION

This Quarterly Report on Form 10-Q contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995 (the "PSLRA"). When used in this Form 10-Q and in future filings by Otter Tail Corporation (the "Company") with the Securities and Exchange Commission (SEC), in the Company’s press releases and in oral statements, words such as “anticipate,” “believe,” “could,” “estimate,” “expect,” "future," "goal," “intend,” "likely," “may,” “outlook,” “plan,” “possible,” “potential,” "probable," "projected," “should,” "target," “will,” “would” or similar expressions are intended to identify forward-looking statements within the meaning of the PSLRA. Such statements are based on current expectations and assumptions and entail various risks and uncertainties that could cause actual results to differ materially from those expressed in such forward-looking statements. The Company’s risks and uncertainties include, among other things, uncertainty of future investments and capital expenditures, rate base levels and rate base growth, long-term investment risk, seasonal weather patterns and extreme weather events, counterparty credit risk, future business volumes with key customers, reductions in our credit ratings, our ability to access capital markets on favorable terms, assumptions and costs relating to funding our employee benefit plans, our subsidiaries’ ability to make dividend payments, cyber security threats or data breaches, the impact of government legislation and regulation including foreign trade policy and environmental, health and safety laws and regulations, the impact of climate change including compliance with legislative and regulatory changes to address climate change, operational and economic risks associated with our electric generating and manufacturing facilities, risks associated with energy markets, the availability and pricing of resource materials, inflation cost pressures, attracting and maintaining a qualified and stable workforce, expectations regarding regulatory proceedings, and changing macroeconomic and industry conditions. These and other risks and uncertainties are more fully described in our filings with the SEC, including our most recently filed Annual Report on Form 10-K. Forward-looking statements speak only as of the date they are made, and we expressly disclaim any obligation to update any forward-looking information.

PART I. FINANCIAL INFORMATION

ITEM 1. FINANCIAL STATEMENTS

2

OTTER TAIL CORPORATION

CONSOLIDATED BALANCE SHEETS (unaudited)

(in thousands, except share data)	June 30, 2023		December 31, 2022
Assets
Current Assets
Cash and Cash Equivalents	$	150,578	$	118,996
Receivables, net of allowance for credit losses	194,951		144,393
Inventories	144,441		145,952
Regulatory Assets	19,058		24,999
Other Current Assets	15,084		18,412
Total Current Assets	524,112		452,752
Noncurrent Assets
Investments	59,882		54,845
Property, Plant and Equipment, net of accumulated depreciation	2,316,246		2,212,717
Regulatory Assets	96,128		94,655
Intangible Assets, net of accumulated amortization	7,393		7,943
Goodwill	37,572		37,572
Other Noncurrent Assets	52,653		41,177
Total Noncurrent Assets	2,569,874		2,448,909
Total Assets	$	3,093,986	$	2,901,661
Liabilities and Shareholders' Equity
Current Liabilities
Short-Term Debt	$	50,197	$	8,204
Accounts Payable	104,661		104,400
Accrued Salaries and Wages	26,029		32,327
Accrued Taxes	31,900		19,340
Regulatory Liabilities	41,743		17,300
Other Current Liabilities	46,032		56,065
Total Current Liabilities	300,562		237,636
Noncurrent Liabilities
Pension Benefit Liability	33,198		33,210
Other Postretirement Benefits Liability	47,364		46,977
Regulatory Liabilities	245,935		244,497
Deferred Income Taxes	231,910		221,302
Deferred Tax Credits	15,544		15,916
Other Noncurrent Liabilities	67,093		60,985
Total Noncurrent Liabilities	641,044		622,887
Commitments and Contingencies (Note 9)
Capitalization
Long-Term Debt	823,941		823,821
Shareholders' Equity
Common Shares: 50,000,000 shares authorized, $5 par value; 41,710,521 and 41,631,113 outstanding at June 30, 2023 and December 31, 2022	208,553		208,156
Additional Paid-In Capital	425,867		423,034
Retained Earnings	693,138		585,212
Accumulated Other Comprehensive Income	881		915
Total Shareholders' Equity	1,328,439		1,217,317
Total Capitalization	2,152,380		2,041,138
Total Liabilities and Shareholders' Equity	$	3,093,986	$	2,901,661

See accompanying notes to consolidated financial statements.

3

OTTER TAIL CORPORATION

CONSOLIDATED STATEMENTS OF INCOME (unaudited)

	Three Months Ended June 30,				Six Months Ended June 30,
(in thousands, except per-share amounts)	2023		2022		2023		2022
Operating Revenues
Electric	$	113,763	$	130,949	$	265,671	$	261,365
Product Sales	223,953		269,091		411,126		513,579
Total Operating Revenues	337,716		400,040		676,797		774,944
Operating Expenses
Electric Production Fuel	14,833		14,714		26,326		29,567
Electric Purchased Power	5,212		24,162		47,037		44,691
Electric Operating and Maintenance Expenses	45,522		42,379		91,070		86,659
Cost of Products Sold (excluding depreciation)	120,658		152,466		233,027		304,225
Other Nonelectric Expenses	16,870		17,252		35,568		34,457
Depreciation and Amortization	24,232		23,566		48,089		47,113
Electric Property Taxes	4,336		4,435		8,957		8,866
Total Operating Expenses	231,663		278,974		490,074		555,578
Operating Income	106,053		121,066		186,723		219,366
Other Income and (Expense)
Interest Expense	(9,696)		(8,991)		(19,111)		(17,939)
Nonservice Components of Postretirement Benefits	2,421		751		4,833		772
Other Income (Expense), net	3,253		(889)		5,370		(629)
Income Before Income Taxes	102,031		111,937		177,815		201,570
Income Tax Expense	20,062		26,000		33,365		43,630
Net Income	$	81,969	$	85,937	$	144,450	$	157,940
Weighted-Average Common Shares Outstanding:
Basic	41,678		41,597		41,655		41,573
Diluted	42,053		41,944		42,035		41,907
Earnings Per Share:
Basic	$	1.97	$	2.07	$	3.47	$	3.80
Diluted	$	1.95	$	2.05	$	3.44	$	3.77

See accompanying notes to consolidated financial statements.

4

OTTER TAIL CORPORATION

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (unaudited)

	Three Months Ended June 30,				Six Months Ended June 30,
(in thousands)	2023		2022		2023		2022
Net Income	$	81,969	$	85,937	$	144,450	$	157,940
Other Comprehensive Income (Loss):
Unrealized Gain (Loss) on Available-for-Sale Securities, net of tax (expense) benefit of $16, $20, $(5) and $81	(61)		(74)		19		(305)
Pension and Other Postretirement Benefits, net of tax benefit (expense) of $9, $(37), $19 and $29	(27)		106		(53)		(84)
Total Other Comprehensive Income (Loss)	(88)		32		(34)		(389)
Total Comprehensive Income	$81,881		$85,969		$144,416		$157,551

See accompanying notes to consolidated financial statements.

5

OTTER TAIL CORPORATION

CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (unaudited)

(in thousands, except common shares outstanding)	Common Shares Outstanding	Par Value, Common Shares		Additional Paid-In Capital		Retained Earnings		Accumulated Other Comprehensive Income (Loss)		Total Shareholders' Equity
Balance, March 31, 2023	41,684,526	$	208,423	$	424,948	$	629,437	$	969	$	1,263,777
Stock Issued Under Share-Based Compensation Plans, net of shares withheld for employee taxes	25,995	130		(130)		—		—		—
Stock Issued Under Stock Purchase Plan, net of expenses	—	—		(167)		—		—		(167)
Net Income	—	—		—		81,969		—		81,969
Other Comprehensive Loss	—	—		—		—		(88)		(88)
Stock Compensation Expense	—	—		1,216		—		—		1,216
Common Dividends ($0.4375 per share)	—	—		—		(18,268)		—		(18,268)
Balance, June 30, 2023	41,710,521	$	208,553	$	425,867	$	693,138	$	881	$	1,328,439
Balance, March 31, 2022	41,605,884	$	208,029	$	421,449	$	424,605	$	(6,945)	$	1,047,138
Stock Issued Under Share-Based Compensation Plans, net of shares withheld for employee taxes	24,915	125		(105)		—		—		20
Net Income	—	—		—		85,937		—		85,937
Other Comprehensive Income	—	—		—		—		32		32
Stock Compensation Expense	—	—		607		—		—		607
Common Dividends ($0.4125 per share)	—	—		—		(17,191)		—		(17,191)
Balance, June 30, 2022	41,630,799	$	208,154	$	421,951	$	493,351	$	(6,913)	$	1,116,543
Balance, December 31, 2022	41,631,113	$	208,156	$	423,034	$	585,212	$	915	$	1,217,317
Stock Issued Under Share-Based Compensation Plans, net of shares withheld for employee taxes	79,408	397		(3,485)		—		—		(3,088)
Stock Issued Under Stock Purchase Plan, net of expenses	—	—		(166)		—		—		(166)
Net Income	—	—		—		144,450		—		144,450
Other Comprehensive Loss	—	—		—		—		(34)		(34)
Stock Compensation Expense	—	—		6,484		—		—		6,484
Common Dividends ($0.875 per share)	—	—		—		(36,524)		—		(36,524)
Balance, June 30, 2023	41,710,521	$	208,553	$	425,867	$	693,138	$	881	$	1,328,439
Balance, December 31, 2021	41,551,524	$	207,758	$	419,760	$	369,783	$	(6,524)	$	990,777
Stock Issued Under Share-Based Compensation Plans, net of shares withheld for employee taxes	79,275	396		(3,320)		—		—		(2,924)
Net Income	—	—		—		157,940		—		157,940
Other Comprehensive Loss	—	—		—		—		(389)		(389)
Stock Compensation Expense	—	—		5,511		—		—		5,511
Common Dividends ($0.825 per share)	—	—		—		(34,372)		—		(34,372)
Balance, June 30, 2022	41,630,799	$	208,154	$	421,951	$	493,351	$	(6,913)	$	1,116,543

See accompanying notes to consolidated financial statements.

6

OTTER TAIL CORPORATION

CONSOLIDATED STATEMENTS OF CASH FLOWS (unaudited)

	Six Months Ended June 30,
(in thousands)	2023		2022
Operating Activities
Net Income	$	144,450	$	157,940
Adjustments to Reconcile Net Income to Net Cash Provided by Operating Activities:
Depreciation and Amortization	48,089		47,113
Deferred Tax Credits	(372)		(373)
Deferred Income Taxes	8,708		25,160
Discretionary Contribution to Pension Plan	—		(20,000)
Investment (Gains) Losses	(4,295)		4,440
Stock Compensation Expense	6,484		5,511
Other, Net	161		(164)
Changes in Operating Assets and Liabilities:
Receivables	(50,558)		(50,885)
Inventories	2,396		2,889
Regulatory Assets	7,320		5,604
Other Assets	3,561		3,240
Accounts Payable	1,037		1,933
Accrued and Other Liabilities	(4,271)		(3,394)
Regulatory Liabilities	27,169		(3,859)
Pension and Other Postretirement Benefits	(5,382)		475
Net Cash Provided by Operating Activities	184,497		175,630
Investing Activities
Capital Expenditures	(151,516)		(70,791)
Proceeds from Disposal of Noncurrent Assets	2,970		2,840
Cash Used for Investments and Other Assets	(5,079)		(5,944)
Net Cash Used in Investing Activities	(153,625)		(73,895)
Financing Activities
Net Borrowings (Repayments) of Short-Term Debt	41,993		(91,163)
Proceeds from Issuance of Long-Term Debt	—		90,000
Dividends Paid	(36,524)		(34,372)
Payments for Shares Withheld for Employee Tax Obligations	(3,088)		(2,942)
Other, net	(1,671)		(2,806)
Net Cash Provided by (Used in) Financing Activities	710		(41,283)
Net Change in Cash and Cash Equivalents	31,582		60,452
Cash and Cash Equivalents at Beginning of Period	118,996		1,537
Cash and Cash Equivalents at End of Period	$	150,578	$	61,989
Supplemental Disclosure of Noncash Investing Activities
Accrued Property, Plant and Equipment Additions	$	13,149	$	11,116

See accompanying notes to consolidated financial statements

7

OTTER TAIL CORPORATION

CONDENSED NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (unaudited)

1. Summary of Significant Accounting Policies

Overview

Otter Tail Corporation (OTC) and its subsidiaries (collectively, the "Company", "us", "our" or "we") form a diverse, multi-platform business consisting of a vertically integrated, regulated utility with generation, transmission and distribution facilities complemented by manufacturing businesses providing metal fabrication for custom machine parts and metal components, manufacturing of extruded and thermoformed plastic products, and manufacturing of polyvinyl chloride (PVC) pipe products. We classify our business into three segments: Electric, Manufacturing and Plastics.

Basis of Presentation

The unaudited consolidated financial statements included herein have been prepared pursuant to the rules and regulations of the SEC for interim reporting. Accordingly, they do not include all the information and footnotes required by generally accepted accounting principles. In the opinion of management, we have included all adjustments, including normal recurring accruals, necessary for a fair presentation of the consolidated financial statements for the periods presented. The consolidated financial statements and condensed notes thereto should be read in conjunction with the consolidated financial statements and notes included in our Annual Report on Form 10-K for the fiscal year ended December 31, 2022.

Because of the seasonality of our businesses and other factors, the earnings for the three and six months ended June 30, 2023 should not be taken as an indication of earnings for all or any part of the balance of the current year or as an indication of earnings for future years.

Use of Estimates

We use estimates based on the best information available in recording transactions and balances resulting from business operations. As better information becomes available or actual amounts are known, the recorded estimates are revised. Consequently, operating results can be affected by revisions to prior accounting estimates.

Reclassifications

Certain reclassifications of amounts previously reported have been made to the accompanying consolidated statements of cash flows to maintain consistency and comparability between periods presented. Other, net operating cash flows previously reported for the six months ended June 30, 2022, included $4.4 million of investment losses, which are presented separately in the current period, and excluded $0.6 million of allowance for equity funds used during construction, which were previously presented separately. The reclassifications had no impact on previously reported net cash provided by operating activities, net cash used in investing activities, net cash (used in) provided by financing activities, or cash and cash equivalents.

Concentration of Deposits and Investments

The Company has financial instruments that potentially subject us to a concentration risk, including cash and cash equivalents held in deposit and money market accounts with various financial institutions. These deposits are guaranteed by the Federal Deposit Insurance Corporation up to an insurance limit of $250,000. Currently, our cash and cash equivalents significantly exceed federally insured levels.

2. Segment Information

We classify our business into three segments, Electric, Manufacturing, and Plastics consistent with our business strategy, organizational structure and our internal reporting and review processes used by our chief operating decision maker to make decisions regarding allocation of resources, to assess operating performance and to make strategic decisions.

Certain assets and costs are not allocated to our operating segments. Corporate operating costs include items such as corporate staff and overhead costs, the results of our captive insurance company and other items excluded from the measurement of operating segment performance. Corporate assets consist primarily of cash and cash equivalents, prepaid expenses, investments and fixed assets. Corporate is not an operating segment, rather it is added to operating segment totals to reconcile to consolidated amounts.

8

Information for each segment and our unallocated corporate costs for the three and six months ended June 30, 2023 and 2022 are as follows:

	Three Months Ended June 30,				Six Months Ended June 30,
(in thousands)	2023		2022		2023		2022
Operating Revenue
Electric	$	113,763	$	130,949	$	265,671	$	261,365
Manufacturing	102,475		103,196		209,257		208,154
Plastics	121,478		165,895		201,869		305,425
Total	$	337,716	$	400,040	$	676,797	$	774,944
Net Income (Loss)
Electric	$	19,634	$	18,858	$	42,854	$	38,091
Manufacturing	5,969		7,555		12,831		11,639
Plastics	55,392		63,959		89,078		114,806
Corporate	974		(4,435)		(313)		(6,596)
Total	$	81,969	$	85,937	$	144,450	$	157,940

The following provides the identifiable assets by segment and corporate assets as of June 30, 2023 and December 31, 2022:

(in thousands)	June 30, 2023		December 31, 2022
Identifiable Assets
Electric	$	2,446,293	$	2,351,961
Manufacturing	260,050		245,869
Plastics	177,470		126,318
Corporate	210,173		177,513
Total	$	3,093,986	$	2,901,661

3. Revenue

Presented below are our operating revenues to external customers, in total and by amounts arising from contracts with customers and alternative revenue program (ARP) arrangements, disaggregated by revenue source and segment for the three and six months ended June 30, 2023 and 2022:

	Three Months Ended June 30,				Six Months Ended June 30,
(in thousands)	2023		2022		2023		2022
Operating Revenues
Electric Segment
Retail: Residential	$	26,974	$	33,011	$	70,951	$	73,743
Retail: Commercial and Industrial	64,989		78,521		155,474		149,527
Retail: Other	1,752		2,071		3,743		3,972
Total Retail	93,715		113,603		230,168		227,242
Transmission	14,829		11,697		26,936		24,254
Wholesale	2,670		3,537		4,508		6,000
Other	2,549		2,112		4,059		3,869
Total Electric Segment	113,763		130,949		265,671		261,365
Manufacturing Segment
Metal Parts and Tooling	89,396		88,296		179,463		177,869
Plastic Products and Tooling	10,068		11,416		24,211		23,860
Scrap Metal Sales	3,011		3,484		5,583		6,425
Total Manufacturing Segment	102,475		103,196		209,257		208,154
Plastics Segment
PVC Pipe	121,478		165,895		201,869		305,425
Total Operating Revenue	337,716		400,040		676,797		774,944
Less: Non-contract Revenues Included Above
Electric Segment - ARP Revenues	(334)		(4,928)		(1,545)		(7,388)
Total Operating Revenues from Contracts with Customers	$	338,050	$	404,968	$	678,342	$	782,332

9

4. Select Balance Sheet Information

Receivables and Allowance for Credit Losses

Receivables as of June 30, 2023 and December 31, 2022 are as follows:

(in thousands)	June 30, 2023		December 31, 2022
Receivables
Trade	$	166,267	$	112,126
Other	11,183		9,983
Unbilled Receivables	19,715		23,932
Total Receivables	197,165		146,041
Less: Allowance for Credit Losses	2,214		1,648
Receivables, net of allowance for credit losses	$	194,951	$	144,393

The following is a summary of activity in the allowance for credit losses for the six months ended June 30, 2023 and 2022:

(in thousands)	2023		2022
Beginning Balance, January 1	$	1,648	$	1,836
Additions Charged to Expense	1,001		382
Reductions for Amounts Written Off, Net of Recoveries	(435)		(461)
Ending Balance, June 30	$	2,214	$	1,757

Inventories

Inventories consist of the following as of June 30, 2023 and December 31, 2022:

(in thousands)	June 30, 2023		December 31, 2022
Raw Material, Fuel and Supplies	$	73,314	$	70,374
Work in Process	29,326		31,766
Finished Goods	41,801		43,812
Total Inventories	$	144,441	$	145,952

Investments

The following is a summary of our investments as of June 30, 2023 and December 31, 2022:

(in thousands)	June 30, 2023		December 31, 2022
Corporate-Owned Life Insurance Policies	$	39,352	$	38,991
Corporate and Government Debt Securities	8,926		8,761
Money Market Funds	4,069		1,560
Mutual Funds	7,505		5,503
Other Investments	30		30
Total Investments	$	59,882	$	54,845

The amount of unrealized gains and losses on debt securities as of June 30, 2023 and December 31, 2022 was not material and no unrealized losses were deemed to be other-than-temporary. In addition, the amount of unrealized gains and losses on marketable equity securities still held as of June 30, 2023 and December 31, 2022 was not material.

10

Property, Plant and Equipment

Major classes of property, plant and equipment as of June 30, 2023 and December 31, 2022 include:

(in thousands)	June 30, 2023		December 31, 2022
Electric Plant
Electric Plant in Service	$	2,933,603	$	2,844,379
Construction Work in Progress	141,249		113,932
Total Gross Electric Plant	3,074,852		2,958,311
Less Accumulated Depreciation and Amortization	888,374		859,988
Net Electric Plant	2,186,478		2,098,323
Nonelectric Property, Plant and Equipment
Nonelectric Property, Plant and Equipment in Service	297,908		293,928
Construction Work in Progress	34,147		15,170
Total Gross Nonelectric Property, Plant and Equipment	332,055		309,098
Less Accumulated Depreciation and Amortization	202,287		194,704
Net Nonelectric Property, Plant and Equipment	129,768		114,394
Net Property, Plant and Equipment	$	2,316,246	$	2,212,717

On January 3, 2023, we purchased the Ashtabula III wind farm, located in eastern North Dakota, which consists of 39 wind turbines and the related infrastructure, adding 62.4 megawatts of nameplate capacity to our owned generation assets. The total purchase price of the acquisition was $50.6 million. In addition to the acquired assets, we also recognized a $3.3 million asset retirement obligation liability associated with the wind farm and became party to the land easement agreements with the landowners of the wind farm.

5. Regulatory Matters

Regulatory Assets and Liabilities

The following presents our current and long-term regulatory assets and liabilities as of June 30, 2023 and December 31, 2022 and the period we expect to recover or refund such amounts:

	Period of	June 30, 2023				December 31, 2022
(in thousands)	Recovery/Refund	Current		Long-Term		Current		Long-Term
Regulatory Assets
Pension and Other Postretirement Benefit Plans1	Various	$	—	$	90,602	$	—	$	88,354
Alternative Revenue Program Riders2	Up to 2 years	6,563		79		5,679		2,508
Asset Retirement Obligations1	Asset lives	—		2,327		—		1,467
Deferred Income Taxes	Asset lives	—		847		—		—
ISO Cost Recovery Trackers1	Up to 2 years	288		207		575		314
Unrecovered Project Costs1	Up to 4 years	349		1,048		320		990
Deferred Rate Case Expenses1	Up to 3 years	377		566		377		754
Fuel Clause Adjustments1	Up to 1 year	9,935		—		10,893		—
Derivative Instruments1	Up to 2 years	1,521		207		7,130		—
Other1	Various	25		245		25		268
Total Regulatory Assets		$	19,058	$	96,128	$	24,999	$	94,655
Regulatory Liabilities
Deferred Income Taxes	Asset lives	$	—	$	129,567	$	—	$	131,480
Plant Removal Obligations	Asset lives	8,474		106,393		8,509		105,733
Fuel Clause Adjustments	Up to 1 year	22,358		—		365		—
Alternative Revenue Program Riders	Up to 1 year	4,560		—		2,504		—
North Dakota PTC Refunds	Asset lives	—		9,512		—		7,136
Pension and Other Postretirement Benefit Plans	Up to 1 year	5,589		—		5,589		—
Other	Various	762		463		333		148
Total Regulatory Liabilities		$	41,743	$	245,935	$	17,300	$	244,497
1Costs subject to recovery without a rate of return.
2Amount eligible for recovery includes an incentive or rate of return.

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6. Short-Term and Long-Term Borrowings

The following is a summary of our outstanding short- and long-term borrowings by borrower, OTC or Otter Tail Power Company (OTP), as of June 30, 2023 and December 31, 2022:

Short-Term Debt

The following is a summary of our lines of credit as of June 30, 2023 and December 31, 2022:

			June 30, 2023						December 31, 2022
(in thousands)	Borrowing Limit		Amount Outstanding		Letters of Credit		Amount Available		Amount Available
OTC Credit Agreement	$	170,000	$	—	$	—	$	170,000	$	170,000
OTP Credit Agreement	170,000		50,197		9,573		110,230		152,223
Total	$	340,000	$	50,197	$	9,573	$	280,230	$	322,223

Long-Term Debt

The following is a summary of outstanding long-term debt by borrower as of June 30, 2023 and December 31, 2022: 

					(in thousands)
Borrower		Debt Instrument	Rate	Maturity	June 30, 2023		December 31, 2022
OTC		Guaranteed Senior Notes	3.55%	12/15/26	$	80,000	$	80,000
OTP		Series 2007C Senior Unsecured Notes	6.37%	08/02/27	42,000		42,000
OTP		Series 2013A Senior Unsecured Notes	4.68%	02/27/29	60,000		60,000
OTP		Series 2019A Senior Unsecured Notes	3.07%	10/10/29	10,000		10,000
OTP		Series 2020A Senior Unsecured Notes	3.22%	02/25/30	10,000		10,000
OTP		Series 2020B Senior Unsecured Notes	3.22%	08/20/30	40,000		40,000
OTP		Series 2021A Senior Unsecured Notes	2.74%	11/29/31	40,000		40,000
OTP		Series 2007D Senior Unsecured Notes	6.47%	08/20/37	50,000		50,000
OTP		Series 2019B Senior Unsecured Notes	3.52%	10/10/39	26,000		26,000
OTP		Series 2020C Senior Unsecured Notes	3.62%	02/25/40	10,000		10,000
OTP		Series 2013B Senior Unsecured Notes	5.47%	02/27/44	90,000		90,000
OTP		Series 2018A Senior Unsecured Notes	4.07%	02/07/48	100,000		100,000
OTP		Series 2019C Senior Unsecured Notes	3.82%	10/10/49	64,000		64,000
OTP		Series 2020D Senior Unsecured Notes	3.92%	02/25/50	15,000		15,000
OTP		Series 2021B Senior Unsecured Notes	3.69%	11/29/51	100,000		100,000
OTP		Series 2022A Senior Unsecured Notes	3.77%	05/20/52	90,000		90,000
Total					$	827,000	$	827,000
Less:	Unamortized Long-Term Debt Issuance Costs				3,059		3,179
Total Long-Term Debt, Net of Unamortized Debt Issuance Costs					$	823,941	$	823,821

Financial Covenants

Certain of OTC's and OTP's short- and long-term debt agreements require the borrower, whether OTC or OTP, to maintain certain financial covenants, including a maximum debt to total capitalization ratio of 0.60 to 1.00, a minimum interest and dividend coverage ratio of 1.50 to 1.00, and a maximum level of priority indebtedness. As of June 30, 2023, OTC and OTP were in compliance with these financial covenants.

7. Employee Postretirement Benefits

Pension Plan and Other Postretirement Benefits

The Company sponsors a noncontributory funded pension plan (the "Pension Plan"), an unfunded, nonqualified Executive Survivor and Supplemental Retirement Plan (the "ESSRP"), both accounted for as defined benefit pension plans, and a postretirement healthcare plan accounted for as an other postretirement benefit plan.

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The following table includes the components of net periodic benefit cost (income) related to our defined benefit pension plans and other postretirement benefits for the three and six months ended June 30, 2023 and 2022:

	Three Months Ended June 30,
	Pension Benefits (Pension Plan)				Pension Benefits (ESSRP)				Postretirement Benefits
(in thousands)	2023		2022		2023		2022		2023		2022
Service Cost	$	924	$	1,644	$	18	$	49	$	153	$	334
Interest Cost	4,109		3,086		473		336		669		511
Expected Return on Assets	(6,478)		(5,921)		—		—		—		—
Amortization of Prior Service Cost	—		—		—		—		(1,434)		(1,434)
Amortization of Net Actuarial Loss	—		1,967		—		142		—		766
Net Periodic Benefit Cost (Income)	$	(1,445)	$	776	$	491	$	527	$	(612)	$	177
	Six Months Ended June 30,
	Pension Benefits (Pension Plan)				Pension Benefits (ESSRP)				Postretirement Benefits
(in thousands)	2023		2022		2023		2022		2023		2022
Service Cost	$	1,849	$	3,288	$	36	$	98	$	306	$	669
Interest Cost	8,218		6,172		945		671		1,338		1,021
Expected Return on Assets	(12,957)		(11,842)		—		—		—		—
Amortization of Prior Service Cost	—		—		—		—		(2,867)		(2,867)
Amortization of Net Actuarial Loss	—		3,933		—		284		—		1,532
Net Periodic Benefit Cost (Income)	$	(2,890)	$	1,551	$	981	$	1,053	$	(1,223)	$	355

The following table includes the impact of regulation on the recognition of periodic benefit cost (income) arising from pension and other postretirement benefits for the three and six months ended June 30, 2023 and 2022:

	Three Months Ended June 30,				Six Months Ended June 30,
(in thousands)	2023		2022		2023		2022
Net Periodic Benefit Cost (Income)	$	(1,566)	$	1,480	$	(3,132)	$	2,959
Net Amount Amortized (Deferred) Due to the Effect of Regulation	240		(204)		490		324
Net Periodic Benefit Cost (Income) Recognized	$	(1,326)	$	1,276	$	(2,642)	$	3,283

We had no minimum funding requirements for our Pension Plan or any other postretirement benefit plans as of December 31, 2022. We did not make any contributions to our Pension Plan during the six months ended June 30, 2023. We made a discretionary contribution to our Pension Plan of $20.0 million during the six months ended June 30, 2022.

8. Income Taxes

The reconciliation of the statutory federal income tax rate to our effective tax rate for each of the three and six months ended June 30, 2023 and 2022 is as follows:

	Three Months Ended June 30,								Six Months Ended June 30,
	2023				2022				2023				2022
Income Taxes at Federal Statutory Rate	$	21,426	21.0	%	$	23,507	21.0	%	$	37,341	21.0	%	$	42,330	21.0	%
Increases (Decreases) in Tax from:
State Taxes on Income, Net of Federal Tax	5,104		5.0		5,596		5.0		8,893		5.0		10,078		5.0
Production Tax Credits (PTCs)	(4,574)		(4.5)		(4,719)		(4.2)		(9,229)		(5.2)		(8,686)		(4.3)
Amortization of Excess Deferred Income Taxes	(622)		(0.6)		99		—		(1,420)		(0.8)		(1,078)		(0.5)
North Dakota Wind Tax Credit Amortization, Net of Federal Tax	(146)		(0.1)		(155)		(0.1)		(310)		(0.2)		(355)		(0.2)
Corporate-Owned Life Insurance	(460)		(0.5)		965		0.8		(878)		(0.5)		1,142		0.6
Other, Net	(666)		(0.6)		707		0.7		(1,032)		(0.5)		199		—
Income Tax Expense / Effective Tax Rate	$	20,062	19.7	%	$	26,000	23.2	%	$	33,365	18.8	%	$	43,630	21.6	%

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9. Commitments and Contingencies

Commitments

Land Easements. Since 2013, OTP had purchased the wind-generated electricity from the Ashtabula III wind farm pursuant to a power purchase agreement. That agreement granted us the option to purchase the wind farm and on January 3, 2023, we completed the purchase for $50.6 million. In connection with the purchase, we assumed 51 land easements, not classified as leases, which require annual payments. As of June 30, 2023, the remaining payments to be made under the easements total $4.1 million and the remaining terms of the agreements extend into 2034.

Contingencies

FERC Return on Equity (ROE). In November 2013 and February 2015, customers filed complaints with the Federal Energy Regulatory Commission (FERC) seeking to reduce the return on equity component of the transmission rates that Midcontinent Independent System Operator, Inc. (MISO) transmission owners, including OTP, may collect under the MISO tariff rate. FERC's most recent order, issued on November 19, 2020, adopted a revised ROE methodology and set the base ROE at 10.02% (10.52% with an adder) effective for the fifteen-month period from November 2013 to February 2015 and on a prospective basis beginning in September 2016. The order also dismissed any complaints covering the period from February 2015 to May 2016. On August 9, 2022, the U.S. Court of Appeals for the District of Columbia Circuit vacated the FERC order citing a lack of reasoned explanation by FERC in its adoption of its revised ROE methodology as outlined in its November 2020 order. The U.S. Court of Appeals remanded the matter to FERC to reopen the proceedings.

Significant uncertainty exists as to how FERC will proceed upon remand and there is no prescribed timeline under which FERC must act. We have deferred recognition and recorded a refund liability of $2.7 million as of June 30, 2023. This refund liability reflects our best estimate of amounts previously collected from customers under the MISO tariff rate that may be required to be refunded to customers once all regulatory and judicial proceedings are complete and a final ROE is established for the periods outlined above.

Regional Haze Rule (RHR). The RHR was adopted in an effort to improve visibility in national parks and wilderness areas. The RHR requires states, in coordination with the Environmental Protection Agency (EPA) and other governmental agencies, to develop and implement plans to achieve natural visibility conditions. The second RHR implementation period covers the years 2018-2028. States are required to submit a state implementation plan to assess reasonable progress with the RHR and determine what additional emission reductions are appropriate, if any.

Coyote Station, OTP's jointly owned coal-fired power plant in North Dakota, is subject to assessment in the second implementation period under the North Dakota state implementation plan. The North Dakota Department of Environmental Quality (NDDEQ) submitted its state implementation plan to the EPA for approval in August, 2022. In its plan, the NDDEQ concluded it is not reasonable to require additional emission controls during this planning period. The EPA has previously expressed disagreement with the NDDEQ's recommendation to forgo additional emission controls and has indicated that such a plan is not likely to be accepted.

We cannot predict with certainty the impact the state implementation plan may have on our business until the plan has been approved or otherwise acted on by the EPA. However, significant emission control investments could be required and the recovery of such costs from customers would require regulatory approval. Alternatively, investments in emission control equipment may prove to be uneconomic and result in the early retirement of or the sale of our interest in Coyote Station, subject to regulatory approval. We cannot estimate the ultimate financial effects such a retirement or sale may have on our consolidated operating results, financial position or cash flows, but such amounts could be material and the recovery of such costs in rates would be subject to regulatory approval.

Self-Funding of Transmission Upgrades. The FERC has granted transmission owners within MISO the unilateral authority to determine the funding mechanism for interconnection transmission upgrades that are necessary to accommodate new generation facilities connecting to the electrical grid. Under existing FERC orders, transmission owners can unilaterally determine whether the generator pays the transmission owner in advance for the transmission upgrade or, alternatively, the transmission owner can elect to fund the upgrade and recover over time from the generator the cost of and a return on the upgrade investment (a self-funding). FERC’s orders granting transmission owners this unilateral funding authority has been judicially contested on the basis that transmission owners may be motivated to discriminate among generators in making funding determinations. In the most recent judicial proceedings, the petitioners argued to the U.S. Court of Appeals for the District of Columbia that FERC did not comply with a previous judicial order to fully develop a record regarding the risk of discrimination and the financial risk absorbed by transmission owners for generator-funded upgrades. On December 2, 2022, the Court of Appeals ruled in favor of the petitioners remanding the matter to FERC, instructing the agency to adequately explain the basis of its orders. The Court of Appeals decision did not vacate transmission owners’ unilateral funding authority.

OTP, as a transmission owner in MISO, has exercised its authority and elected to self-fund previous transmission upgrades necessary to accommodate new system generation. Under such an election, OTP is recovering the cost of the transmission upgrade and a return on that investment from the generator over a contractual period of time. Should FERC, on remand from the Court of Appeals, eliminate transmission owners’ unilateral funding authority, on either a prospective or retrospective basis, our financial results would be impacted. We cannot at this time reasonably predict the outcome of this matter given the uncertainty as to how and when FERC may respond to the judicial remand.

Other Contingencies. We are party to litigation and regulatory matters arising in the normal course of business. We regularly analyze relevant information and, as necessary, estimate and record accrued liabilities for legal, regulatory enforcement and other matters in which a loss is probable of occurring and can be reasonably estimated. We believe the effect on our consolidated operating results, financial position and cash flows, if any, for the disposition of all matters pending as of June 30, 2023, other than those discussed above, will not be material.

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10. Stockholders' Equity

Registration Statements

On May 3, 2021, we filed a shelf registration statement with the SEC under which we may offer for sale, from time to time, either separately or together in any combination, equity, debt or other securities described in the shelf registration statement. No new debt or equity has been issued pursuant to the registration statement. The registration statement expires in May 2024.

On May 3, 2021, we filed a second registration statement with the SEC for the issuance of up to 1,500,000 common shares under an Automatic Dividend Reinvestment and Share Purchase Plan, which provides shareholders, retail customers of OTP and other interested investors methods of purchasing our common shares, by reinvesting their dividends or making optional cash investments. Shares purchased under the plan may be newly issued common shares or common shares purchased on the open market. During the six months ended June 30, 2023, we issued 56,311 shares under this plan. We repurchased a sufficient number of shares on the open market to satisfy issuance under the plan; accordingly, no proceeds from the issuance were received. As of June 30, 2023, there were 1,194,682 shares available for purchase or issuance under the plan. The registration statement expires in May 2024.

Dividend Restrictions

OTC is a holding company with no significant operations of its own. The primary source of funds for payments of dividends to OTC's shareholders is from dividends paid or distributions made by OTC's subsidiaries. As a result of certain statutory limitations or regulatory or financing agreements, the amount of distributions allowed to be made by OTC's subsidiaries or the amount of dividends paid by OTC could be restricted. Both the OTC Credit Agreement and OTP Credit Agreement contain restrictions on the payment of cash dividends upon a default or event of default, including failure to maintain certain financial covenants. As of June 30, 2023, we were in compliance with these financial covenants.

Under the Federal Power Act, a public utility may not pay dividends from any funds properly included in a capital account. What constitutes “funds properly included in a capital account” is undefined in the Federal Power Act or the related regulations; however, the FERC has consistently interpreted the provision to allow dividends to be paid as long as i) the source of the dividends is clearly disclosed, ii) the dividend is not excessive and iii) there is no self-dealing on the part of corporate officials.

The Minnesota Public Utilities Commission (MPUC) indirectly limits the amount of dividends OTP can pay to OTC by requiring an equity-to-total-capitalization ratio between 47.5% and 58.0% based on OTP’s capital structure petition effective by order of the MPUC on November 8, 2022. As of June 30, 2023, OTP’s equity-to-total-capitalization ratio, including short-term debt, was 53.8% and its net assets restricted from distribution totaled approximately $778.6 million. Under the MPUC order, total capitalization for OTP cannot exceed $1.8 billion.

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11. Accumulated Other Comprehensive Income (Loss)

The following presents the changes in accumulated other comprehensive loss for the three and six months ended June 30, 2023 and 2022:

	Three Months Ended June 30,
	2023								2022
(in thousands)	Pension and Other Postretirement Benefits			Net Unrealized Gains (Losses) on Available-for-Sale Securities			Total		Pension and Other Postretirement Benefits			Net Unrealized Gains (Losses) on Available-for-Sale Securities			Total
Balance, Beginning of Period	$	1,308		$	(339)		$	969	$	(6,727)		$	(218)		$	(6,945)
Other Comprehensive Loss Before Reclassifications, net of tax	—			(62)			(62)		—			(75)			(75)
Amounts Reclassified from Accumulated Other Comprehensive Income (Loss)	(27)		(1)	1		(2)	(26)		106		(1)	1		(2)	107
Total Other Comprehensive Income (Loss)	(27)			(61)			(88)		106			(74)			32
Balance, End of Period	$	1,281		$	(400)		$	881	$	(6,621)		$	(292)		$	(6,913)
	Six Months Ended June 30,
	2023								2022
(in thousands)	Pension and Other Postretirement Benefits			Net Unrealized Gains (Losses) on Available-for-Sale Securities			Total		Pension and Other Postretirement Benefits			Net Unrealized Gains (Losses) on Available-for-Sale Securities			Total
Balance, Beginning of Period	$	1,334		$	(419)		$	915	$	(6,537)		$	13		$	(6,524)
Other Comprehensive Income (Loss) Before Reclassifications, net of tax	—			18			18		—			(306)			(306)
Amounts Reclassified from Accumulated Other Comprehensive Income (Loss)	(53)		(1)	1		(2)	(52)		(84)		(1)	1		(2)	(83)
Total Other Comprehensive Income (Loss)	(53)			19			(34)		(84)			(305)			(389)
Balance, End of Period	$	1,281		$	(400)		$	881	$	(6,621)		$	(292)		$	(6,913)
(1) Included in the computation of net periodic pension and other postretirement benefit costs. See Note 7.
(2) Included in other income (expense), net on the accompanying consolidated statements of income.

12. Share-Based Payments

Stock Compensation Expense

Stock-based compensation expense arising from our employee stock purchase plan and share-based compensation plans recognized within operating expenses in the consolidated statements of income amounted to $1.2 million and $0.6 million for the three months ended June 30, 2023 and 2022, respectively, and $6.5 million and $5.5 million for the six months ended June 30, 2023 and 2022, respectively.

Restricted Stock Awards. We grant restricted stock awards to members of our Board of Directors and restricted stock units to certain key employees. The awards vest, depending on award type and recipient, either ratably over periods of three or four years or cliff vest after four years. Vesting is accelerated in certain circumstances, including on retirement.

The following is a summary of stock award activity for the six months ended June 30, 2023:

	Shares	Weighted-Average Grant-Date Fair Value
Nonvested, January 1, 2023	141,551	$	49.83
Granted	55,205	68.03
Vested	(45,493)	50.02
Forfeited	(1,300)	50.00
Nonvested, June 30, 2023	149,963	$	56.47

The fair value of vested awards was $3.1 million and $3.0 million during the six months ended June 30, 2023 and 2022.

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Stock Performance Awards. Stock performance awards are granted to executive officers and certain other key employees. The awards vest at the end of a three-year performance period. The number of common shares awarded, if any, at the end of the performance period ranges from zero to 150% of the target amount based on two performance measures: i) total shareholder return relative to a peer group and ii) return on equity. Vesting of the awards is accelerated in certain circumstances, including on retirement. The number of common shares awarded on an accelerated vesting is based either on actual performance at the end of the performance period or the number of common shares earned at target.

The grant date fair value of stock performance awards granted during the six months ended June 30, 2023 and 2022 was determined using a Monte Carlo fair value simulation model incorporating the following assumptions:

	2023		2022
Risk-free interest rate	4.15	%	1.52	%
Expected term (in years)	3		3
Expected volatility	34.00	%	32.00	%
Dividend yield	2.50	%	2.90	%

The risk-free interest rate was derived from yields on U.S. government bonds of a similar term. The expected term of the award is equal to the three-year performance period. Expected volatility was estimated based on actual historical volatility of our common stock. Dividend yield was estimated based on historical and future yield estimates.

The following is a summary of stock performance award activity for the six months ended June 30, 2023 (share amounts reflect awards at target):

	Shares	Weighted-Average Grant-Date Fair Value
Nonvested, January 1, 2023	189,800	$	45.95
Granted	59,400	61.97
Vested	(55,000)	47.79
Forfeited	—	—
Nonvested, June 30, 2023	194,200	$	50.33

The fair value of vested awards was $5.3 million and $5.1 million during the six months ended June 30, 2023 and 2022, respectively.

13. Earnings Per Share

The numerator used in the calculation of both basic and diluted earnings per common share is net income. The denominator used in the calculation of basic earnings per common share is the weighted-average number of common shares outstanding during the period. The denominator used in the calculation of diluted earnings per common share is derived by adjusting basic shares outstanding for the dilutive effect of potential common shares outstanding, which consist of time and performance-based stock awards and employee stock purchase plan shares.

The following includes the computation of the denominator for basic and diluted weighted-average shares outstanding for the three and six months ended June 30, 2023 and 2022:

	Three Months Ended June 30,		Six Months Ended June 30,
(in thousands)	2023	2022	2023	2022
Weighted-Average Common Shares Outstanding – Basic	41,678	41,597	41,655	41,573
Effect of Dilutive Securities:
Stock Performance Awards	281	259	281	239
Restricted Stock Awards	92	85	97	94
Employee Stock Purchase Plan Shares and Other	2	3	2	1
Dilutive Effect of Potential Common Shares	375	347	380	334
Weighted-Average Common Shares Outstanding – Diluted	42,053	41,944	42,035	41,907

The number of shares excluded from diluted weighted-average common shares outstanding because such shares were anti-dilutive was not material for the three and six months ended June 30, 2023 and 2022.

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14. Derivative Instruments

OTP enters into derivative instruments to manage its exposure to future market energy price variability and reduce volatility in prices for our retail customers. These derivative instruments are not designated as qualifying hedging transactions but provide for an economic hedge against future market energy price variability. The instruments are recorded at fair value on the consolidated balance sheets. In accordance with rate-making and cost recovery processes, we recognize a regulatory asset or liability to defer losses or gains from derivative activity until settlement of the associated derivative instrument.

As of June 30, 2023, OTP had multiple outstanding pay-fixed, receive-variable swap agreements with an aggregate notional amount of 195,400 megawatt-hours of electricity, with various settlement dates extending to December 31, 2024. As of June 30, 2023, the fair value of these derivative instruments was $1.7 million, of which $1.5 million is included in other current liabilities and $0.2 million is included in other noncurrent liabilities, on the consolidated balance sheets. As of December 31, 2022, the fair value of these types of derivative contracts was $7.1 million, which is included in other current liabilities. There were no contracts which matured during the three months ended June 30, 2023 or 2022. During the six months ended June 30, 2023 and 2022, contracts matured and were settled in an aggregate amount of a $16.0 million loss and a $2.8 million gain, respectively. Gains and losses recognized on the settlement of derivative instruments are recorded in electric purchased power in the consolidated statements of income. Such settlement gains and losses are returned to or recovered from our electric customers through fuel recovery mechanisms in each state.

15. Fair Value Measurements

The following tables present our assets and liabilities measured at fair value on a recurring basis as of June 30, 2023 and December 31, 2022 classified by the input method used to measure fair value:

(in thousands)	Level 1		Level 2		Level 3
June 30, 2023
Assets:
Investments:
Money Market Funds	$	4,069	$	—	$	—
Mutual Funds	7,505		—		—
Corporate Debt Securities	—		1,456		—
Government-Backed and Government-Sponsored Enterprises’ Debt Securities	—		7,470		—
Total Assets	$	11,574	$	8,926	$	—
Liabilities:
Derivative Instruments	$	—	$	1,728	$	—
Total Liabilities	$	—	$	1,728	$	—
December 31, 2022
Assets:
Investments:
Money Market Funds	$	1,560	$	—	$	—
Mutual Funds	5,503		—		—
Corporate Debt Securities	—		1,434		—
Government-Backed and Government-Sponsored Enterprises’ Debt Securities	—		7,327		—
Total Assets	$	7,063	$	8,761	$	—
Liabilities:
Derivative Instruments	—		7,130		—
Total Liabilities	$	—	$	7,130	$	—

Level 1 fair value measurements are based on quoted prices (unadjusted) in active markets for identical assets or liabilities that we have the ability to access at the measurement date.

The level 2 fair value measurements for government-backed and government-sponsored enterprises and corporate debt securities are determined based on valuations provided by a third-party pricing service which utilizes industry accepted valuation models and observable market inputs to determine valuation. Some valuations or model inputs used by the pricing service may be based on broker quotes.

The level 2 fair value measurements for derivative instruments are determined by using inputs such as forward electric commodity prices, adjusted for location differences. These inputs are observable in the marketplace throughout the full term of the instrument, can be derived from observable data, or are supported by observable levels at which transactions are executed in the marketplace.

In addition to assets recorded at fair value on a recurring basis, we also hold financial instruments that are not recorded at fair value in the consolidated balance sheets but for which disclosure of the fair value of these financial instruments is provided.

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The following reflects the carrying value and estimated fair value of these assets and liabilities as of June 30, 2023 and December 31, 2022:

	June 30, 2023				December 31, 2022
(in thousands)	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Assets:
Cash and Cash Equivalents	$	150,578	$	150,578	$	118,996	$	118,996
Total	150,578		150,578		118,996		118,996
Liabilities:
Short-Term Debt	50,197		50,197		8,204		8,204
Long-Term Debt	823,941		698,831		823,821		681,615
Total	$	874,138	$	749,028	$	832,025	$	689,819

The following methods and assumptions were used to estimate the fair value of each class of financial instruments for which it is practicable to estimate that value:

Cash Equivalents: The carrying amount approximates fair value because of the short-term maturity of those instruments.

Short-Term Debt: The carrying amount approximates fair value because the debt obligations are short-term and the balances outstanding are subject to variable rates of interest which reset frequently, a Level 2 fair value input.

Long-Term Debt: The fair value of long-term debt is estimated based on current market indications for borrowings of similar maturities, a Level 2 fair value input.

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

You should read the following discussion and analysis of our financial condition and results of operations together with our interim financial statements and the related notes appearing under Item 1 of this Quarterly Report on Form 10-Q, and our annual financial statements and the related notes along with the discussion and analysis of our financial condition and results of operations contained in our Annual Report on Form 10-K for the year ended December 31, 2022.

Otter Tail Corporation and its subsidiaries form a diverse group of businesses with operations classified into three segments: Electric, Manufacturing and Plastics. Our Electric segment business is a vertically integrated, regulated utility with generation, transmission and distribution facilities to serve our customers in western Minnesota, eastern North Dakota and northeastern South Dakota. Our Manufacturing segment provides metal fabrication for custom machine parts and metal components and manufactures extruded and thermoformed plastic products. Our Plastics segment manufactures PVC pipe for use in, among other applications, municipal and rural water, wastewater and water reclamation projects.

PVC PIPE SUPPLY AND DEMAND CONDITIONS

Extraordinary supply and demand conditions in the PVC industry beginning in 2021 have led to a significant expansion in operating margins and elevated earnings in our Plastics segment. Periodic disruptions in the supply of resin, the primary material input used in the manufacturing of PVC pipe, coupled with robust demand for resin, led to a significant increase in the cost of resin over the last two years. Low industry volumes of PVC pipe and robust end market demand for the product led to a rapid and significant increase in sales prices for PVC pipe, significantly outpacing the increase in resin input costs, leading to widening margins within our Plastics segment.

Demand for PVC pipe began to soften in the second half of 2022 and softening demand continued through the first half of 2023 as distributors and contractors have reduced purchase volumes in response to uncertain and competitive market conditions. Resin prices have declined over this time frame but sales prices for PVC pipe remain elevated, continuing to produce expanded operating margins.

These unique market dynamics impacting our Plastics segment resulted in a significant increase in earnings in 2022 compared to prior periods. We currently expect earnings of our Plastics segment to remain elevated in 2023 compared to pre-2021 levels, but as the industry supply and demand conditions normalize, we expect segment earnings to normalize in the last half of 2024.

STEEL PRICING

Volatility in the price of steel, a key material input to our Manufacturing segment, significantly impacted our operating results in the last two years. Steel prices were elevated at the beginning of 2022 but began to steadily decline at the end of the second quarter and returned to near historical levels by the end of the year. Elevated steel prices led to increased sales prices in 2022 for our products at BTD Manufacturing, Inc. (BTD), our metal fabrication business within our Manufacturing segment, as we passed along material cost increases to our customers. Steel prices in the first half of 2023 had significantly declined from the same period in the previous year, impacting our comparative operating results.

The marketplace dynamics impacting both our Manufacturing and Plastics segments are fluid and subject to change and may impact our operating results prospectively.

RESULTS OF OPERATIONS – QUARTER TO DATE

Provided below is a summary and discussion of our operating results on a consolidated basis followed by a discussion of the operating results of each of our segments: Electric, Manufacturing and Plastics. In addition to the segment results, we provide an overview of our Corporate costs. Our Corporate costs do not constitute a reportable segment, but rather consist of unallocated general corporate expenses, such as corporate staff and overhead costs, the results of our captive insurance company and other items excluded from the measurement of segment performance. Corporate costs are added to operating segment totals to reconcile to totals on our consolidated statements of income.

CONSOLIDATED RESULTS    

The following table summarizes consolidated operating results for the three months ended June 30, 2023 and 2022:

(in thousands)	2023		2022		$ change		% change
Operating Revenues	$	337,716	$	400,040	$	(62,324)	(15.6)	%
Operating Expenses	231,663		278,974		(47,311)		(17.0)
Operating Income	106,053		121,066		(15,013)		(12.4)
Interest Expense	(9,696)		(8,991)		(705)		7.8
Nonservice Components of Postretirement Benefits	2,421		751		1,670		222.4
Other Income (Expense)	3,253		(889)		4,142		(465.9)
Income Before Income Taxes	102,031		111,937		(9,906)		(8.8)
Income Tax Expense	20,062		26,000		(5,938)		(22.8)
Net Income	$	81,969	$	85,937	$	(3,968)	(4.6)	%

Operating Revenues decreased $62.3 million primarily due to decreased sales volumes within our Plastics segment, decreased fuel recovery revenues in our Electric segment and decreased steel prices in our Manufacturing segment. These decreases were partially offset by increased transmission services revenue, increased rider revenue, and higher commercial and industrial sales in our Electric segment and increased sales volumes in our Manufacturing segment. In our Plastics segment, PVC pipe sale volumes decreased as customer demand softened from the same

20

period a year ago amid changing market conditions. Decreased sales prices in our Manufacturing segment were primarily due to decreased steel prices, which are passed through to customers. In our Electric segment, decreased fuel recovery revenues were driven by lower purchased power costs and volumes. See our segment disclosures below for additional discussion of items impacting operating revenues.

Operating Expenses decreased $47.3 million primarily due to lower sales volumes in our Plastics segment, lower purchased power costs in our Electric segment and lower material costs in our Manufacturing segment, as discussed above. See our segment disclosures below for additional discussion of items impacting operating expenses.

Interest Expense increased $0.7 million due to increased interest rates on our short-term variable rate debt and a higher level of average borrowings.

Nonservice Components of Postretirement Benefits improved by $1.7 million, having a positive impact on net income, primarily due to a change in actuarial assumptions used to measure our pension benefit and postretirement benefit obligations, including an increase in the discount rate applied and an increase in the expected return on assets assumption.

Other Income increased $4.1 million primarily due to gains on our corporate-owned life insurance policies during the second quarter of 2023 compared to investment losses in the previous year and investment income earned on our short-term cash equivalent investments.

Income Tax Expense decreased $5.9 million primarily due to decreased income before income taxes. Our effective tax rate was 19.7% in the second quarter of 2023 and 23.2% in the second quarter of 2022. The decrease in our effective tax rate was primarily due to non-taxable gains on our corporate-owned life insurance policy investments. See Note 8 to our consolidated financial statements included in this Quarterly Report on Form 10-Q for additional information regarding factors impacting our effective tax rate in 2023 and 2022.

ELECTRIC SEGMENT RESULTS

The following table summarizes Electric segment operating results for the three months ended June 30, 2023 and 2022:

(in thousands)	2023		2022		$ change		% change
Retail Revenues	$	93,715	$	113,603	$	(19,888)	(17.5)	%
Transmission Services Revenues	14,829		11,697		3,132		26.8
Wholesale Revenues	2,670		3,537		(867)		(24.5)
Other Electric Revenues	2,549		2,112		437		20.7
Total Operating Revenues	113,763		130,949		(17,186)		(13.1)
Production Fuel	14,833		14,714		119		0.8
Purchased Power	5,212		24,162		(18,950)		(78.4)
Operating and Maintenance Expenses	45,522		42,379		3,143		7.4
Depreciation and Amortization	18,672		18,390		282		1.5
Property Taxes	4,336		4,435		(99)		(2.2)
Operating Income	$	25,188	$	26,869	$	(1,681)	(6.3)	%
	2023		2022		change		% change
Electric kilowatt-hour (kwh) Sales (in thousands)
Retail kwh Sales	1,345,830		1,286,419		59,411		4.6	%
Wholesale kwh Sales – Company Generation	87,032		56,514		30,518		54.0
Heating Degree Days	639		716		(77)		(10.8)
Cooling Degree Days	254		154		100		64.9

The operating results of our Electric segment are impacted by fluctuations in weather conditions and the resulting demand for electricity for heating and cooling. The following table shows heating degree days and cooling degree days as a percent of normal for the three months ended June 30, 2023 and 2022.

	2023		2022
Heating Degree Days	120.6	%	135.1	%
Cooling Degree Days	215.3	%	129.4	%

The following table summarizes the estimated effect on diluted earnings per share of the difference in retail kwh sales under actual weather conditions and expected retail kwh sales under normal weather conditions in 2023 and 2022, and between years.

	2023 vs Normal		2023 vs 2022		2022 vs Normal
Effect on Diluted Earnings Per Share	$	0.04	$	0.01	$	0.03

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Retail Revenues decreased $19.9 million primarily due to a $19.2 million decrease in fuel recovery revenues, due to decreased purchased power costs and volumes, as described below. Also, our Minnesota rate case was finalized in the second quarter of 2022, which included a determination of the final interim rate refund and resulted in an additional $4.1 million of retail revenue in the second quarter of 2022. These decreases, were partially offset by:

•A $1.6 million increase in retail revenues from increased sales volumes to commercial and industrial customers.

•A $2.1 million increase in renewable resource rider revenue, including recovery of costs related to our Hoot Lake Solar project and the Ashtabula III wind farm.

Transmission Services Revenue increased $3.1 million primarily due to increased sales volumes compared to same period in the prior year.

Purchased Power costs to serve retail customers decreased $19.0 million due to a 72% decrease in the price of purchased power per kwh, primarily due to decreased market energy costs, and a 23% decrease in the volume of purchased power, primarily due to the planned outage at Coyote Station in the second quarter of 2022, which resulted in higher purchase volumes last year, as well as the acquisition of the Ashtabula III wind farm in the current year. Prior to the acquisition of Ashtabula III, OTP purchased the wind generated electricity from the facility under the terms of a power purchase agreement.

Operating and Maintenance Expenses increased $3.1 million primarily due to increased labor costs, increased maintenance and transmission service activities at our wind farm facilities, including the incremental costs associated with the Ashtabula III facility that was purchased during the year, maintenance expenses related to an outage at Big Stone Plant, increased vegetative management expenses, and increased MISO tariff expenses. These increases were partially offset by decreased maintenance and other expenses related to Coyote Station, as the second quarter of 2022 includes costs associated with a planned outage at Coyote Station.

MANUFACTURING SEGMENT RESULTS

The following table summarizes Manufacturing segment operating results for the three months ended June 30, 2023 and 2022:

(in thousands)	2023		2022		$ change		% change
Operating Revenues	$	102,475	$	103,196	$	(721)	(0.7)	%
Cost of Products Sold (excluding depreciation)	79,154		78,515		639		0.8
Other Operating Expenses	10,470		9,890		580		5.9
Depreciation and Amortization	4,531		4,091		440		10.8
Operating Income	$	8,320	$	10,700	$	(2,380)	(22.2)	%

Operating Revenues decreased $0.7 million primarily due to decreased steel prices, which impacted revenues at BTD Manufacturing, as well as decreased sales volumes at T.O. Plastics. Steel prices declined compared to the second quarter of 2022, resulting in a 15% decrease in material costs, which are passed through to customers. The impact of decreased steel prices was offset by a 14% increase in sales volumes, driven by strong customer and end market demand in the construction, agriculture, and energy markets, as well as sales price increases which were implemented in response to labor and non-steel material cost inflation. Lower scrap metal prices also impacted operating revenues as scrap metal revenues decreased $0.5 million from the previous year. Operating revenues at T.O. Plastics decreased primarily due to decreased sales volumes of horticulture products in response to changing market conditions as order and delivery lead times began to normalize.

Cost of Products Sold increased $0.6 million primarily due to increased sales volumes, as described above, largely offset by decreased material costs, as well as unfavorable cost absorption at BTD. Increased labor costs and lower productivity contributed to unfavorable cost absorption and lower profit margins. The increase in labor costs and the lower level of productivity during the quarter resulted from increased incentives and overtime wages combined with increased staffing levels to meet higher business volumes and the time required for new employees to achieve peak productivity.

Other Operating Expenses increased $0.6 million primarily due to increased salaries, benefits, and other compensation costs.

PLASTICS SEGMENT RESULTS

The following table summarizes Plastics segment operating results for the three months ended June 30, 2023 and 2022:

(in thousands)	2023		2022		$ change		% change
Operating Revenues	$	121,478	$	165,895	$	(44,417)	(26.8)	%
Cost of Products Sold (excluding depreciation)	41,504		73,951		(32,447)		(43.9)
Other Operating Expenses	3,936		4,340		(404)		(9.3)
Depreciation and Amortization	1,003		1,043		(40)		(3.8)
Operating Income	$	75,035	$	86,561	$	(11,526)	(13.3)	%

Operating Revenues decreased $44.4 million primarily due to a 26% decrease in sales volumes compared to the same period last year. Sales volume decreases in the second quarter were driven by general end market softness and distributors continuing to manage inventory levels. Sales prices declined 1% from the second quarter of 2022 but remained elevated compared to pre-2021 levels.

22

Cost of Products Sold decreased $32.4 million due to decreased sales volumes, as described above, and decreased PVC resin costs. PVC resin and other input material costs decreased 37% compared to the same period in the previous year as the unique supply and demand conditions, which caused significant increases in resin costs, have subsided and resin costs have stabilized.

CORPORATE COSTS

The following table summarizes Corporate operating results for the three months ended June 30, 2023 and 2022:

(in thousands)	2023		2022		$ change		% change
Other Operating Expenses	$	2,464	$	3,022	$	(558)	(18.5)	%
Depreciation and Amortization	26		42		(16)		(38.1)
Operating Loss	$	2,490	$	3,064	$	(574)	(18.7)	%

Other Operating Expenses decreased $0.6 million primarily due to decreased employee benefit expenses related to decreases in our employee health insurance claim costs.

RESULTS OF OPERATIONS – YEAR TO DATE

CONSOLIDATED RESULTS

The following table summarizes consolidated operating results for the six months ended June 30, 2023 and 2022:

(in thousands)	2023		2022		$ change		% change
Operating Revenues	$	676,797	$	774,944	$	(98,147)	(12.7)	%
Operating Expenses	490,074		555,578		(65,504)		(11.8)
Operating Income	186,723		219,366		(32,643)		(14.9)
Interest Expense	(19,111)		(17,939)		(1,172)		6.5
Nonservice Components of Postretirement Benefits	4,833		772		4,061		526.0
Other Income (Expense)	5,370		(629)		5,999		(953.7)
Income Before Income Taxes	177,815		201,570		(23,755)		(11.8)
Income Tax Expense	33,365		43,630		(10,265)		(23.5)
Net Income	$	144,450	$	157,940	$	(13,490)	(8.5)	%

Operating Revenues decreased $98.1 million primarily due to lower sales volumes within our Plastics segment and decreased steel prices in our Manufacturing segment. These decreases were partially offset by increased sales volumes, due to strong customer demand, in our Manufacturing segment and increased retail and transmission services revenues, due to increased sales volumes and rider revenues, within our Electric segment. See our segment disclosures below for additional discussion of items impacting operating revenues.

Operating Expenses decreased $65.5 million primarily due to lower sales volumes within our Plastics segment, as discussed above. In addition to lower sales volumes, operating expenses in our Plastics segment also decreased due to decreased PVC resin and other input costs. Decreased operating expenses in our Manufacturing segment primarily due to lower material costs at BTD, driven by lower steel prices, were largely offset by higher sales volumes and increases in other operating expenses. Operating expenses in our Electric segment increased primarily due to higher labor costs, maintenance expenses related to an outage at Big Stone Plant, increased maintenance expenses associated with our wind generation assets, and increased vegetative management expenses. See our segment disclosures below for additional discussion of items impacting operating expenses.

Interest Expense increased $1.2 million due to increased interest rates on our short-term variable rate debt, partially offset by a lower level of average borrowings.

Nonservice Components of Postretirement Benefits improved by $4.1 million, having a positive impact on net income, primarily due to a change in actuarial assumptions used to measure our pension benefit and postretirement benefit obligations, including an increase in the discount rate applied and an increase in the expected return on assets assumption.

Other Income increased $6.0 million primarily due to gains on our corporate-owned life insurance policies during the second quarter of 2023 compared to investment losses in the same period of the previous year and investment income earned on our short-term cash equivalent investments.

Income Tax Expense decreased $10.3 million primarily due to decreased income before income taxes. Our effective tax rate was 18.8% for the six months ended June 30, 2023 and 21.6% for the same period in the previous year. The decrease in our effective tax rate was driven by non-taxable gains on our corporate-owned life insurance policy investments and an increase in production tax credits from our wind generation assets in the current period. See Note 8 to our consolidated financial statements included in the report on Form 10-Q for additional information regarding factors impacting our effective tax rate.

23

ELECTRIC SEGMENT RESULTS

The following table summarizes Electric segment operating results for the six months ended June 30, 2023 and 2022:

(in thousands)	2023		2022		$ change		% change
Retail Revenues	$	230,168	$	227,242	$	2,926	1.3	%
Transmission Services Revenues	26,936		24,254		2,682		11.1
Wholesale Revenues	4,508		6,000		(1,492)		(24.9)
Other Electric Revenues	4,059		3,869		190		4.9
Total Operating Revenues	265,671		261,365		4,306		1.6
Production Fuel	26,326		29,567		(3,241)		(11.0)
Purchased Power	47,037		44,691		2,346		5.2
Operating and Maintenance Expenses	91,070		86,659		4,411		5.1
Depreciation and Amortization	36,997		36,772		225		0.6
Property Taxes	8,957		8,866		91		1.0
Operating Income	$	55,284	$	54,810	$	474	0.9	%
	2023		2022		change		% change
Electric kilowatt-hour (kwh) Sales (in thousands)
Retail kwh Sales	2,981,076		2,801,716		179,360		6.4	%
Wholesale kwh Sales – Company Generation	148,886		122,701		26,185		21.3
Heating Degree Days	4,371		4,537		(166)		(3.7)
Cooling Degree Days	254		154		100		64.9

The operating results of our Electric segment are impacted by fluctuations in weather conditions and the resulting demand for electricity for heating and cooling. The following table shows heating and cooling degree days as a percent of normal for the six months ended June 30, 2023 and 2022.

	2023		2022
Heating Degree Days	109.9	%	114.9	%
Cooling Degree Days	215.3	%	129.4	%

The following table summarizes the estimated effect on diluted earnings per share of the difference in retail kwh sales under actual weather conditions and expected retail kwh sales under normal weather conditions in 2023 and 2022, and between years.

	2023 vs Normal		2023 vs 2022		2022 vs Normal
Effect on Diluted Earnings Per Share	$	0.07	$	—	$	0.07

Retail Revenues increased $2.9 million primarily due to the following:

•A $4.3 million increase in retail revenues from increased sales volumes from commercial and industrial customers, including the impact of a new commercial customer load in North Dakota that came online during the first quarter of 2022.

•A $3.4 million increase in renewable resource rider revenue, including recovery of costs related to our Hoot Lake Solar project and the Ashtabula III wind farm.

These increases were partially offset by a decrease in fuel recovery revenues, primarily due to decreased fuel and market energy costs, as described below. Also, our Minnesota rate case was finalized in the second quarter of 2022, which included a determination of the final interim rate refund and resulted in an additional $4.1 million of retail revenue in 2022.

Production Fuel costs decreased $3.2 million primarily due to a 10% decrease in fuel cost per kwh resulting from decreases in natural gas prices.

Purchased Power costs to serve retail customers increased $2.3 million due to a 13% increase in the volume of purchased power due to increased customer demand and favorable market energy prices, partially offset by a 7% decrease in the price of purchased power per kwh, resulting from decreased natural gas and market energy prices.

Operating and Maintenance Expense increased $4.4 million, primarily due to increased labor costs, maintenance expenses related to an outage at Big Stone Plant, increased maintenance and transmission service activities at our wind farm facilities, including the incremental costs associated with the Ashtabula III facility that was purchased during the year, increased vegetative management expenses, higher insurance expenses, and increased MISO tariff expenses. These increases were partially offset by decreased maintenance and other expenses related to Coyote Station, as the second quarter of 2022 included costs associated with a planned outage at the facility.

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MANUFACTURING SEGMENT RESULTS

The following table summarizes Manufacturing segment operating results for the six months ended June 30, 2023 and 2022:

(in thousands)	2023		2022		$ change		% change
Operating Revenues	$	209,257	$	208,154	$	1,103	0.5	%
Cost of Products Sold (excluding depreciation)	161,381		164,676		(3,295)		(2.0)
Other Operating Expenses	21,047		18,736		2,311		12.3
Depreciation and Amortization	9,000		8,105		895		11.0
Operating Income	$	17,829	$	16,637	$	1,192	7.2	%

Operating Revenues increased $1.1 million primarily due to a 17% increase in sales volumes at BTD, as well as sales price increases which were implemented in response to labor and non-steel material cost inflation. Increased sales volumes and pricing were largely offset by a 18% decrease in material costs, which are passed through to customers, as a result of lower steel prices. Increased sales prices at T.O. Plastics, partially offset by a decrease in sales volumes of horticulture products, also contributed to the increase in operating revenues.

Cost of Products Sold decreased $3.3 million primarily due to lower material costs at BTD, as discussed above, largely offset by increased sales volumes and unfavorable cost absorption. Unfavorable cost absorption was primarily due to increased labor costs and lower productivity. The increase in labor costs and the lower level of productivity during the current year resulted from increased incentives and overtime wages combined with increased staffing levels to meet higher production volumes, and the time required for new employees to achieve peak productivity. Decreased sales volumes at T.O. Plastics, as discussed above, also contributed to the decrease in cost of products sold.

Other Operating Expenses increased $2.3 million due to variable costs associated with increased business activity and financial performance during the period.

PLASTICS SEGMENT RESULTS

The following table summarizes Plastics segment operating results for the six months ended June 30, 2023 and 2022:

(in thousands)	2023		2022		$ change		% change
Operating Revenues	$	201,869	$	305,425	$	(103,556)	(33.9)	%
Cost of Products Sold (excluding depreciation)	71,646		139,549		(67,903)		(48.7)
Other Operating Expenses	7,465		8,304		(839)		(10.1)
Depreciation and Amortization	2,040		2,150		(110)		(5.1)
Operating Income	$	120,718	$	155,422	$	(34,704)	(22.3)	%

Operating Revenues decreased $103.6 million, primarily due to a 36% decrease in sales volumes compared to the same period last year, partially offset by a 3% increase in sales price per pound of PVC pipe sold. Sales volume decreases continue to be attributable to distributor customer inventory management as distributors continue to closely manage their inventory levels and make strategic purchasing decisions amid uncertain and competitive market conditions.

Cost of Products Sold decreased $67.9 million due to decreased sales volumes, as discussed above, as well as a 30% decrease in PVC resin and other input costs.

CORPORATE COSTS

The following table summarizes Corporate operating results for the six months ended June 30, 2023 and 2022:

(in thousands)	2023		2022		$ change		% change
Other Operating Expenses	$	7,056	$	7,417	$	(361)	(4.9)	%
Depreciation and Amortization	52		86		(34)		(39.5)
Operating Loss	$	7,108	$	7,503	$	(395)	(5.3)	%

Other Operating Expenses decreased $0.4 million primarily due to decreased employee benefit expenses related to decreases in our employee health insurance claim costs.

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REGULATORY MATTERS

The following provides a summary of rate rider filings and other regulatory filings that have or are expected to have a material impact on our operating results, financial position or cash flows.

RATE RIDERS

The following table includes a summary of pending and recently concluded rate rider proceedings:

Recovery			Filing	Amount		Effective
Mechanism	Jurisdiction	Status	Date	(in millions)		Date	Description
RRR - 2022	MN	Approved	11/01/22	$	17.5	07/01/23	Recovery of Hoot Lake Solar costs, Ashtabula III costs, and true up for PTCs from Merricourt.
CIP - 2022	MN	Approved	04/01/22	10.8		10/01/22	Recovery of energy conservation improvement costs as well as a demand side management financial incentive.
CIP - 2023	MN	Approved	04/03/23	9.7		10/01/23	Recovery of energy conservation improvement costs as well as a demand side management financial incentive.
TCR - 2021	MN	Approved	11/23/21	7.2		08/01/22	Recovery of transmission project costs.
RRR - 2021	MN	Approved	12/06/21	7.0		08/01/22	Recovery of Hoot Lake Solar and Ashtabula III costs.
EITE - 2023	MN	Approved	04/14/23	2.2		01/01/24	Biennial update to Energy-Intensive, Trade-Exposed rider.
EUIC - 2023	MN	Requested	03/20/23	1.3		07/01/23	Recovery of advanced metering infrastructure, outage management and demand response system projects.
RRR - 2023	ND	Approved	12/30/22	12.2		05/01/23	Recovery of Merricourt, Ashtabula III and other costs.
RRR - 2022	ND	Approved	01/05/22	7.8		04/01/22	Recovery of Merricourt costs, Ashtabula III costs, and deferred taxes and production tax credits.
TCR - 2022	ND	Approved	09/15/22	7.5		01/01/23	Recovery of transmission project costs.
TCR - 2021	ND	Approved	09/15/21	6.1		01/01/22	Recovery of transmission project costs.
GCR - 2022	ND	Approved	03/01/22	3.3		07/01/22	Annual update to generation cost recovery rider.
AMDT - 2022	ND	Approved	07/08/22	3.1		01/01/23	Recovery of advanced metering infrastructure, outage management system and demand response projects.
GCR - 2023	ND	Approved	03/03/23	2.2		07/01/23	Recovery of Astoria Station, net of anticipated savings associated with the retirement of Hoot Lake Plant.
PIR - 2022	SD	Approved	06/01/22	3.0		09/01/22	Recovery of Ashtabula III, Merricourt, Astoria Station, Advanced Grid Infrastructure project costs, and impact of load growth credits.
TCR - 2022	SD	Approved	11/01/22	3.0		03/01/23	Recovery of transmission project costs.
PIR - 2023	SD	Requested	06/01/23	2.6		09/01/23	Recovery of Ashtabula III, Merricourt, Astoria Station, Advanced Grid Infrastructure project costs, and impact of load growth credits.
TCR - 2021	SD	Approved	10/29/21	2.2		03/01/22	Recovery of transmission project costs.

INTEGRATED RESOURCE PLAN

On March 31, 2023, OTP submitted a supplemental resource plan filing to the MPUC, the NDPSC, and the South Dakota Public Utilities Commission. The supplemental filing updates OTP’s original 2022 Integrated Resource Plan (2022 IRP), which was filed on September 1, 2021. In the supplemental filing, OTP outlined its updated plan for meeting customers’ anticipated capacity and energy needs while maintaining system reliability and low electric service rates, in light of several changes that have occurred since the original filing, including significant winter and spring reserve planning margins adopted by MISO, tax credits made available for renewable energy projects under the Inflation Reduction Act, the enactment of the Clean Energy Bill in Minnesota, and recent volatility in energy and capacity markets.

The major requests in OTP's supplemental filing include:

•the addition of on-site liquefied natural gas fuel storage at our Astoria Station natural gas plant in 2026;

•the addition of approximately 200 megawatts of solar generation in 2027-2028;

•undertaking the initial steps necessary to add approximately 200 megawatts of wind generation in 2029; and

•a withdrawal from our 35 percent ownership interest in Coyote Station, a jointly-owned coal-fired generation plant, in the event we are required to make a major, non-routine capital investment in the plant.

Consistent with the original 2022 IRP, the supplemental filing proposes to, subject to regulatory approval, create a regulatory asset to recover costs related to any future withdrawal from Coyote Station. Should such a withdrawal occur, we anticipate the regulatory asset would include the net

26

book value of the plant on the withdrawal date, anticipated decommissioning costs, and any costs incurred if the existing lignite sales agreement, under which Coyote Station acquires all of its lignite coal, must be terminated. As part of an economic analysis included in the filing, OTP developed an estimate of the reasonably foreseeable costs of withdrawing from Coyote Station, which was determined to be $68.5 million, assuming a withdrawal at the end of 2028. These costs may differ from actual results due to the uncertainty and timing of future events which could result in a withdrawal from Coyote Station.

ENVIRONMENTAL REGULATION

Climate Change and Greenhouse Gas Regulation

In May 2023, the EPA proposed new regulations under Section 111 of the Clean Air Act to regulate greenhouse gas (GHG) emissions from existing and new fossil fuel-based electric generating units (EGU). The proposal provides requirements for different types of fossil fuel-based EGUs with various compliance dates.

For existing coal-fired steam generating units that were in operation before January 8, 2014 and that plan to operate past December 31, 2039, the proposal would (subject to certain exceptions) set emissions standards that reflect the use of carbon capture and sequestration (CCS) with 90% capture of carbon dioxide emissions beginning in 2030.

For existing coal-fired steam generating units that are scheduled to be retired between January 1, 2032 and December 31, 2039, the proposed rule would, in general, set emissions standards that reflect the use of co-firing 40% natural gas with coal beginning in 2030.

For existing coal-fired steam generating units that will either (a) retire by January 1, 2032, or (b) retire between 2032 and December 21, 2034 and will operate at a 20% annual capacity factor limit in the meantime, the proposed rule would simply require routine maintenance and no increase in emission rate.

The proposal also includes emission standards for existing large (greater than 300 mega-watt), frequently-used (those that operate at a capacity factor over 50%) natural gas combustion turbines, including the use of CCS or co-firing with low-GHG hydrogen. Under the proposed rule, each state must submit a plan to the EPA to implement standards that are at least as stringent as the EPA’s emission guidelines. The EPA is proposing to require states to submit their plans within 24 months of the effective date of the regulation.

We continue to review and evaluate the proposal and its impact, if adopted as proposed, on our EGUs and the potential impact to our operating results, financial condition and liquidity. Coyote Station and Big Stone Plant, our two co-owned coal-fired power plants, would be within the scope of the proposed regulations. We do not believe our combustion turbines would be within the scope of the regulation given their size and operating frequency.

LIQUIDITY

LIQUIDITY OVERVIEW

We believe our financial condition is strong and our cash and cash equivalents, other liquid assets, operating cash flows, existing lines of credit, access to capital markets and borrowing ability, because of investment-grade credit ratings, when taken together, provide us ample liquidity to conduct our business operations, fund our short-term and long-term capital expenditure plans and satisfy our obligations as they become due. Our liquidity, including our operating cash flows and access to capital markets, could be impacted by macroeconomic factors outside of our control, including higher interest rates and debt capital costs and diminished credit availability. In addition, our liquidity could be impacted by non-compliance with certain financial covenants under our various debt instruments. As of June 30, 2023, we were in compliance with all financial covenants (see the Financial Covenants section under Capital Resources below).

The following table presents the status of our lines of credit as of June 30, 2023 and December 31, 2022:

			2023						2022
(in thousands)	Borrowing Limit		Amount Outstanding		Letters of Credit		Amount Available		Amount Available
OTC Credit Agreement	$	170,000	$	—	$	—	$	170,000	$	170,000
OTP Credit Agreement	170,000		50,197		9,573		110,230		152,223
Total	$	340,000	$	50,197	$	9,573	$	280,230	$	322,223

We have an internal risk tolerance metric to maintain a minimum of $50 million of liquidity under the OTC Credit Agreement. Should additional liquidity be needed, this agreement includes an accordion feature allowing us to increase the amount available to $290 million, subject to certain terms and conditions. The OTP Credit Agreement also includes an accordion feature allowing OTP to increase that facility to $250 million, subject to certain terms and conditions.

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CASH FLOWS

The following is a discussion of our cash flows for the six months ended June 30, 2023 and 2022:

(in thousands)	2023		2022
Net Cash Provided by Operating Activities	$	184,497	$	175,630

Net Cash Provided by Operating Activities increased $8.9 million for the six months ended June 30, 2023 compared to the six months ended June 30, 2022, primarily due to the absence of a pension plan contribution in 2023 due to the plan's funded status, whereas a $20.0 million discretionary contribution was made in February 2022, as well as increases to certain regulatory liabilities for fuel cost recovery due to increased customer collections that will be returned to customers in future periods. Increases to operating cash flows were partially offset by lower earnings and higher working capital.

(in thousands)	2023		2022
Net Cash Used in Investing Activities	$	153,625	$	73,895

Net Cash Used in Investing Activities increased $79.7 million for the six months ended June 30, 2023 compared to the six months ended June 30, 2022. The increase in cash used in investing activities was primarily due to a higher amount of Electric segment capital investment compared to last year, including the purchase of the Ashtabula III wind farm for $50.6 million in January 2023. Capital expenditures in our Manufacturing and Plastics segments increased $14.0 million as a result of investments in additional equipment and a facility expansion project at our Plastics segment facility in Phoenix, Arizona.

(in thousands)	2023		2022
Net Cash Provided by (Used in) Financing Activities	$	710	$	(41,283)

Net Cash Provided by (Used in) Financing Activities increased $42.0 million for the six months ended June 30, 2023 compared to the six months ended June 30, 2022. Financing activities for the six months ended June 30, 2023 included net proceeds from short-term borrowings of $42.0 million under the OTP credit agreement, which were primarily used to fund the acquisition of Ashtabula III and other capital investments, and dividend payments of $36.5 million. Financing activities for the six months ended June 30, 2022 included net repayments of short-term borrowings of $91.2 million, the issuance of $90.0 million of long-term debt, and dividend payments of $34.4 million.

CAPITAL REQUIREMENTS

CAPITAL EXPENDITURES

We have a capital expenditure program for expanding, upgrading and improving our plants and operating equipment. Typical uses of cash for capital expenditures are investments in electric generation facilities and environmental upgrades, transmission and distribution lines, manufacturing facilities and upgrades, equipment used in the manufacturing process, and computer hardware and information systems. Our capital expenditure program is subject to review and regulatory approval and is revised in light of changes in demands for energy, technology, environmental laws, tax laws, regulatory changes, business expansion opportunities, the costs of labor, materials and equipment, and our financial condition.

The following provides a summary of actual capital expenditures for the year ended December 31, 2022, anticipated annual capital expenditures for the current year ending December 31, 2023, and the subsequent four years, along with electric utility average rate base and annual rate base growth:

(in millions)	2022			2023(1)			2024			2025			2026			2027			Total 2023 - 2027
Electric Segment
Renewables and Natural Gas Generation				$	88		$	119		$	88		$	85		$	49		$	429
Technology and Infrastructure				33			30			6			5			1			75
Distribution Plant Replacements				33			37			38			38			43			189
Transmission (includes replacements)				34			36			46			87			78			281
Other				26			25			30			24			23			128
Total Electric Segment	$	148		$	214		$	247		$	208		$	239		$	194		$	1,102
Manufacturing and Plastics Segments	23			48			53			29			25			24			179
Total Capital Expenditures	$	171		$	262		$	300		$	237		$	264		$	218		$	1,281
Total Electric Utility Average Rate Base	$	1,624		$	1,748		$	1,851		$	1,990		$	2,111		$	2,230
Annual Rate Base Growth	3.1		%	7.6		%	5.9		%	7.5		%	6.1		%	5.6		%
(1) Includes actual results for the six months ended June 30, 2023, and anticipated capital expenditures for the remaining six months of 2023.

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CONTRACTUAL OBLIGATIONS

Our contractual obligations primarily include principal and interest payments due under our outstanding debt obligations, commitments to acquire coal, energy and capacity commitments, payments to meet our postretirement benefit obligations, and payment obligations under land easements and leasing arrangements.

Our contractual obligations as of December 31, 2022 are included in Item 7, Management's Discussion and Analysis of Financial Condition and Results of Operations, of our Annual Report on Form 10-K for the year ended December 31, 2022. Except for the obligations arising from new land easements assumed in connection with the purchase of Ashtabula III, there were no material changes in our contractual obligations outside of the ordinary course of business during the six months ended June 30, 2023.

In connection with the purchase of the Ashtabula III wind farm in January 2023, we assumed 51 land easements not classified as leases, which require annual payments. As of June 30, 2023, the remaining payments to be made under the easements were $4.1 million and the remaining terms of the agreements extend into 2034.

COMMON STOCK DIVIDENDS

We paid dividends to our common stockholders totaling $36.5 million, or $0.875 per share, in the first six months of 2023. The determination of the amount of future cash dividends to be paid will depend on, among other things, our financial condition, our actual or expected level of earnings and cash flows from operations, the level of our capital expenditures and our future business prospects. As a result of certain statutory limitations or regulatory or financing agreements, the amount of dividends we are allowed to pay could be restricted. See Note 10 to our consolidated financial statements included in this Quarterly Report on Form 10-Q for additional information. The decision to declare dividends is reviewed quarterly by our Board of Directors.

CAPITAL RESOURCES

Financial flexibility is provided by operating cash flows, unused lines of credit and access to capital markets, and is aided by strong financial coverages and investment grade credit ratings. Debt financing will be required in the five-year period from 2023 through 2028 to refinance maturing debt and to finance our capital investments. Our financing plans are subject to change and are impacted by our planned level of capital investments, and decisions to reduce borrowings under our lines of credit, to refund or retire early any of our outstanding debt, to complete acquisitions, or to use capital for other corporate purposes.

REGISTRATION STATEMENTS

On May 3, 2021, we filed a shelf registration statement with the SEC under which we may offer for sale, from time to time, either separately or together in any combination, equity, debt or other securities described in the shelf registration statement. No new debt or equity has been issued pursuant to the registration statement. The registration statement expires in May 2024.

On May 3, 2021, we filed a second registration statement with the SEC for the issuance of up to 1,500,000 common shares under an Automatic Dividend Reinvestment and Share Purchase Plan, which provides shareholders, retail customers of OTP and other interested investors methods of purchasing our common shares by reinvesting their dividends or making optional cash investments. Shares purchased under the plan may be newly issued common shares or common shares purchased on the open market. As of June 30, 2023, there were 1,194,682 shares available for purchase or issuance under the plan. The registration statement expires in May 2024.

SHORT-TERM DEBT

OTC and OTP are each party to a credit agreement (the OTC Credit Agreement and the OTP Credit Agreement, respectively) which each provide for unsecured revolving lines of credit. The following is a summary of key provisions and borrowing information as of, and for the six months ended, June 30, 2023:

(in thousands, except interest rates)	OTC Credit Agreement			OTP Credit Agreement
Borrowing Limit	$	170,000		$	170,000
Borrowing Limit if Accordion Exercised1	290,000			250,000
Amount Restricted Due to Outstanding Letters of Credit as of June 30, 2023	—			9,573
Amount Outstanding as of June 30, 2023	—			50,197
Average Amount Outstanding During the Six Months Ended June 30, 2023	—			48,846
Maximum Amount Outstanding During the Six Months Ended June 30, 2023	—			61,006
Interest Rate as of June 30, 2023	6.64		%	6.48		%
Maturity Date	October 29, 2027			October 29, 2027
1Each facility includes an accordion featuring allowing the borrower to increase the borrowing limit if certain terms and conditions are met.

LONG-TERM DEBT

As of June 30, 2023, we had $827.0 million of principal outstanding under long-term debt arrangements. These instruments generally provide for unsecured borrowings at fixed rates of interest with maturities ranging from 2026 to 2052. Note 6 to our consolidated financial statements included in this Quarterly Report on Form 10-Q includes additional information regarding these short-term and long-term debt instruments.

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Financial Covenants

Certain of our short- and long-term debt agreements require OTC and OTP to maintain certain financial covenants. As of June 30, 2023, we were in compliance with these financial covenants as further described below:

OTC, under its financial covenants, may not permit its ratio of interest-bearing debt to total capitalization to exceed 0.60 to 1.00, may not permit its interest and dividend coverage ratio to be less than 1.50 to 1.00, and may not permit its priority indebtedness to exceed 10 percent of its total capitalization. As of June 30, 2023, OTC's interest-bearing debt to total capitalization was 0.40 to 1.00, OTC's interest and dividend coverage ratio was 10.18 to 1.00, and OTC had no priority indebtedness outstanding.

OTP, under its financial covenants, may not permit its ratio of interest-bearing debt to total capitalization to exceed 0.60 to 1.00, may not permit its interest and dividend coverage ratio to be less than 1.50 to 1.00, and may not permit its priority indebtedness to exceed 20 percent of its total capitalization. As of June 30, 2023, OTP's interest-bearing debt to total capitalization was 0.46 to 1.00, OTP's interest and dividend coverage ratio was 3.65 to 1.00, and OTP had no priority indebtedness outstanding.

CRITICAL ACCOUNTING POLICIES INVOLVING SIGNIFICANT ESTIMATES

The discussion and analysis of our results of operations are based on financial statements prepared in accordance with generally accepted accounting principles in the United States of America. Certain of our accounting policies require management to make estimates and judgments that affect the reported amounts of assets, liabilities, revenues and expenses, and related disclosures of contingent assets and liabilities in the preparation of our consolidated financial statements. We have disclosed in our Annual Report on Form 10-K for the year ended December 31, 2022 the critical accounting policies that affect our most significant estimates and assumptions used in preparing our consolidated financial statements. There have been no material changes to our critical accounting policies and estimates from those disclosed in the most recent Annual Report on Form 10-K.

ITEM 3. QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK

There have been no material changes in our market risk from those disclosed in Item 7A, Quantitative and Qualitative Disclosures About Market Risk, in our Annual Report on Form 10-K for the year ended December 31, 2022.

ITEM 4. CONTROLS AND PROCEDURES

Evaluation of Disclosure Controls and Procedures. Under the supervision and with the participation of the Company’s management, including the Chief Executive Officer and the Chief Financial Officer, we evaluated the effectiveness of the design and operation of our disclosure controls and procedures (as defined in Rule 13a-15(e) under the Securities Exchange Act of 1934 (the Exchange Act)) as of June 30, 2023, the end of the period covered by this report. Based on that evaluation, the Chief Executive Officer and Chief Financial Officer concluded that our disclosure controls and procedures were effective as of June 30, 2023.

Changes in Internal Control over Financial Reporting. There were no changes in our internal control over financial reporting (as defined in Rules 13a-15(f) under the Exchange Act) during the quarter ended June 30, 2023 that have materially affected, or are reasonably likely to materially affect, our internal control over financial reporting.

PART II. OTHER INFORMATION

ITEM 1. LEGAL PROCEEDINGS

We are the subject of various legal and regulatory proceedings in the ordinary course of our business. Such matters are subject to many uncertainties and to outcomes that are not predictable with assurance. We record a liability in our consolidated financial statements for costs related to claims, including future legal costs, settlements and judgments, where we have assessed that a loss is probable, and an amount can be reasonably estimated. Material proceedings are described under Note 9, Commitments and Contingencies, to the consolidated financial statements, and in Management's Discussion and Analysis of Financial Condition and Results of Operations, Regulatory Matters.

ITEM 1A. RISK FACTORS

There have been no material changes from the risk factors disclosed in Item 1A, Risk Factors, of our Annual Report on Form 10-K for the year ended December 31, 2022.

ITEM 5. OTHER INFORMATION

Securities Trading Plans of Directors and Executive Officers. During the three months ended June 30, 2023, none of our directors or executive officers adopted, amended, or terminated any contract, instruction or written plan for the purchase or sale of our securities that was intended to satisfy the affirmative defense conditions of Rule 10b5-1(c) or any “non-Rule 10b5-1 trading arrangement.”

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ITEM 6. EXHIBITS

The following Exhibits are filed as part of, or incorporated by reference into, this report.

No.	Description
10.1	—2023 Stock Incentive Plan (incorporated by reference to Exhibit 10.1 to the Form 8-K filed by Otter Tail Corporation on April 19, 2023)
10.2	—Form of 2023 Restricted Stock Award Agreement for Directors (incorporated by reference to Exhibit 10.2 to the Form 8-K filed by Otter Tail Corporation on April 19, 2023)
10.3	—Executive Annual Incentive Plan (incorporated by reference to Exhibit 10.3 to the Form 8-K filed by Otter Tail Corporation on April 19, 2023)
31.1	—Certification of Chief Executive Officer Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002
31.2	—Certification of Chief Financial Officer Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002
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.SCH	—Inline XBRL Taxonomy Extension Schema Document
101.CAL	—Inline XBRL Taxonomy Extension Calculation Linkbase Document
101.LAB	—Inline XBRL Taxonomy Extension Label Linkbase Document
101.PRE	—Inline XBRL Taxonomy Extension Presentation Linkbase Document
101.DEF	—Inline XBRL Taxonomy Extension Definition Linkbase Document
104	—Cover Page Interactive Data File (formatted as Inline XBRL and contained in Exhibit 101)

31

SIGNATURES

Pursuant to the requirements of Section 13 or 15(d) 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.

OTTER TAIL CORPORATION
By:	/s/ Kevin G. Moug
	Kevin G. Moug Chief Financial Officer and Senior Vice President (duly authorized officer and principal financial officer)
	Dated: August 2, 2023

32

EX-31.1

Exhibit 31.1

CERTIFICATION PURSUANT TO

SECTION 302 OF THE SARBANES-OXLEY ACT OF 2002

I, Charles S. MacFarlane, certify that:

1.I have reviewed this Quarterly Report on Form 10-Q of Otter Tail 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 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 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.

Date: August 2, 2023

/s/ Charles S. MacFarlane

Charles S. MacFarlane

President and Chief Executive Officer

EX-31.2

Exhibit 31.2

CERTIFICATION PURSUANT TO

SECTION 302 OF THE SARBANES-OXLEY ACT OF 2002

I, Kevin G. Moug, certify that:

1.I have reviewed this Quarterly Report on Form 10-Q of Otter Tail 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 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 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.

Date: August 2, 2023

/s/ Kevin G. Moug

Kevin G. Moug

Chief Financial Officer and Senior Vice President

EX-32.1

Exhibit 32.1

CERTIFICATION PURSUANT TO

SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the Quarterly Report of Otter Tail Corporation (the “Company”) on Form 10-Q for the period ended June 30, 2023 as filed with the Securities and Exchange Commission on the date hereof (the “Report”), I, Charles S. MacFarlane, 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:

1.The Report fully complies with the requirements of Section 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.

/s/ Charles S. MacFarlane

Charles S. MacFarlane

President and Chief Executive Officer

August 2, 2023

EX-32.2

Exhibit 32.2

CERTIFICATION PURSUANT TO

SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the Quarterly Report of Otter Tail Corporation (the “Company”) on Form 10-Q for the period ended June 30, 2023 as filed with the Securities and Exchange Commission on the date hereof (the “Report”), I, Kevin G. Moug, 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:

1.The Report fully complies with the requirements of Section 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.

/s/ Kevin G. Moug

Kevin G. Moug

Chief Financial Officer and Senior Vice President

August 2, 2023

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Cover - shares	6 Months Ended
	Jun. 30, 2023	Jul. 28, 2023
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2023
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Entity File Number	0-53713
Entity Registrant Name	OTTER TAIL CORPORATION
Entity Incorporation, State or Country Code	MN
Entity Tax Identification Number	27-0383995
Entity Address, Address Line One	215 South Cascade Street
Entity Address, Address Line Two	Box 496
Entity Address, City or Town	Fergus Falls
Entity Address, State or Province	MN
Entity Address, Postal Zip Code	56538-0496
City Area Code	866
Local Phone Number	410-8780
Title of 12(b) Security	Common Shares, par value $5.00 per share
Trading Symbol	OTTR
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
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Entity Small Business	false
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CONSOLIDATED BALANCE SHEETS (unaudited) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Current Assets
Cash and Cash Equivalents	$ 150,578	$ 118,996
Receivables, net of allowance for credit losses	194,951	144,393
Inventories	144,441	145,952
Regulatory Assets	19,058	24,999
Other Current Assets	15,084	18,412
Total Current Assets	524,112	452,752
Noncurrent Assets
Investments	59,882	54,845
Property, Plant and Equipment, net of accumulated depreciation	2,316,246	2,212,717
Regulatory Assets	96,128	94,655
Intangible Assets, net of accumulated amortization	7,393	7,943
Goodwill	37,572	37,572
Other Noncurrent Assets	52,653	41,177
Total Noncurrent Assets	2,569,874	2,448,909
Total Assets	3,093,986	2,901,661
Current Liabilities
Short-Term Debt	50,197	8,204
Accounts Payable	104,661	104,400
Accrued Salaries and Wages	26,029	32,327
Accrued Taxes	31,900	19,340
Regulatory Liabilities	41,743	17,300
Other Current Liabilities	46,032	56,065
Total Current Liabilities	300,562	237,636
Noncurrent Liabilities
Pension Benefit Liability	33,198	33,210
Other Postretirement Benefits Liability	47,364	46,977
Regulatory Liabilities	245,935	244,497
Deferred Income Taxes	231,910	221,302
Deferred Tax Credits	15,544	15,916
Other Noncurrent Liabilities	67,093	60,985
Total Noncurrent Liabilities	641,044	622,887
Commitments and Contingencies (Note 9)
Capitalization
Long-Term Debt	823,941	823,821
Shareholders' Equity
Common Shares: 50,000,000 shares authorized, $5 par value; 41,710,521 and 41,631,113 outstanding at June 30, 2023 and December 31, 2022	208,553	208,156
Additional Paid-In Capital	425,867	423,034
Retained Earnings	693,138	585,212
Accumulated Other Comprehensive Income	881	915
Total Shareholders' Equity	1,328,439	1,217,317
Total Capitalization	2,152,380	2,041,138
Total Liabilities and Shareholders' Equity	$ 3,093,986	$ 2,901,661

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CONSOLIDATED BALANCE SHEETS (unaudited) (Parentheticals) - $ / shares	Jun. 30, 2023	Dec. 31, 2022
Shareholders' Equity
Common stock, shares authorized (in shares)	50,000,000	50,000,000
Common stock, par value (in dollars per share)	$ 5	$ 5
Common stock, shares outstanding (in shares)	41,710,521	41,631,113

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CONSOLIDATED STATEMENTS OF INCOME (unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Operating Revenues
Total Operating Revenues	$ 337,716	$ 400,040	$ 676,797	$ 774,944
Operating Expenses
Electric Production Fuel	14,833	14,714	26,326	29,567
Electric Purchased Power	5,212	24,162	47,037	44,691
Electric Operating and Maintenance Expenses	45,522	42,379	91,070	86,659
Cost of Products Sold (excluding depreciation)	120,658	152,466	233,027	304,225
Other Nonelectric Expenses	16,870	17,252	35,568	34,457
Depreciation and Amortization	24,232	23,566	48,089	47,113
Electric Property Taxes	4,336	4,435	8,957	8,866
Total Operating Expenses	231,663	278,974	490,074	555,578
Operating Income	106,053	121,066	186,723	219,366
Other Income and (Expense)
Interest Expense	(9,696)	(8,991)	(19,111)	(17,939)
Nonservice Components of Postretirement Benefits	2,421	751	4,833	772
Other Income (Expense), net	3,253	(889)	5,370	(629)
Income Before Income Taxes	102,031	111,937	177,815	201,570
Income Tax Expense	20,062	26,000	33,365	43,630
Net Income	$ 81,969	$ 85,937	$ 144,450	$ 157,940
Weighted-Average Common Shares Outstanding:
Basic (in shares)	41,678	41,597	41,655	41,573
Diluted (in shares)	42,053	41,944	42,035	41,907
Earnings Per Share:
Basic (in dollars per share)	$ 1.97	$ 2.07	$ 3.47	$ 3.80
Diluted (in dollars per share)	$ 1.95	$ 2.05	$ 3.44	$ 3.77
Electric
Operating Revenues
Total Operating Revenues	$ 113,763	$ 130,949	$ 265,671	$ 261,365
Product Sales
Operating Revenues
Total Operating Revenues	$ 223,953	$ 269,091	$ 411,126	$ 513,579

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CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Statement of Comprehensive Income [Abstract]
Net Income	$ 81,969	$ 85,937	$ 144,450	$ 157,940
Other Comprehensive Income (Loss):
Unrealized Gain (Loss) on Available-for-Sale Securities, net of tax (expense) benefit of $16, $20, $(5) and $81	(61)	(74)	19	(305)
Pension and Other Postretirement Benefits, net of tax benefit (expense) of $9, $(37), $19 and $29	(27)	106	(53)	(84)
Total Other Comprehensive Income (Loss)	(88)	32	(34)	(389)
Total Comprehensive Income	$ 81,881	$ 85,969	$ 144,416	$ 157,551

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CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (unaudited) (Parentheticals) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Statement of Comprehensive Income [Abstract]
Unrealized Gain (Loss) on Available-for-Sale Securities, tax (expense) benefit	$ 16	$ 20	$ (5)	$ 81
Pension and Other Postretirement Benefit Plan, tax benefit (expense)	$ 9	$ (37)	$ 19	$ 29

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CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (unaudited) - USD ($) $ in Thousands	Total	Common Shares	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Beginning balance (in shares) at Dec. 31, 2021		41,551,524
Beginning balance at Dec. 31, 2021	$ 990,777	$ 207,758	$ 419,760	$ 369,783	$ (6,524)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock Issued Under Share-Based Compensation Plans, net of shares withheld for employee taxes (in shares)		79,275
Stock Issued Under Share-Based Compensation Plans, net of shares withheld for employee taxes	(2,924)	$ 396	(3,320)
Net Income	157,940			157,940
Other Comprehensive Income (Loss)	(389)				(389)
Stock Compensation Expense	5,511		5,511
Common Dividends	(34,372)			(34,372)
Ending balance (in shares) at Jun. 30, 2022		41,630,799
Ending balance at Jun. 30, 2022	1,116,543	$ 208,154	421,951	493,351	(6,913)
Beginning balance (in shares) at Mar. 31, 2022		41,605,884
Beginning balance at Mar. 31, 2022	1,047,138	$ 208,029	421,449	424,605	(6,945)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock Issued Under Share-Based Compensation Plans, net of shares withheld for employee taxes (in shares)		24,915
Stock Issued Under Share-Based Compensation Plans, net of shares withheld for employee taxes	20	$ 125	(105)
Net Income	85,937			85,937
Other Comprehensive Income (Loss)	32				32
Stock Compensation Expense	607		607
Common Dividends	(17,191)			(17,191)
Ending balance (in shares) at Jun. 30, 2022		41,630,799
Ending balance at Jun. 30, 2022	$ 1,116,543	$ 208,154	421,951	493,351	(6,913)
Beginning balance (in shares) at Dec. 31, 2022	41,631,113	41,631,113
Beginning balance at Dec. 31, 2022	$ 1,217,317	$ 208,156	423,034	585,212	915
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock Issued Under Share-Based Compensation Plans, net of shares withheld for employee taxes (in shares)		79,408
Stock Issued Under Share-Based Compensation Plans, net of shares withheld for employee taxes	(3,088)	$ 397	(3,485)
Stock Issued Under Stock Purchase Plan, net of expenses	(166)		(166)
Net Income	144,450			144,450
Other Comprehensive Income (Loss)	(34)				(34)
Stock Compensation Expense	6,484		6,484
Common Dividends	$ (36,524)			(36,524)
Ending balance (in shares) at Jun. 30, 2023	41,710,521	41,710,521
Ending balance at Jun. 30, 2023	$ 1,328,439	$ 208,553	425,867	693,138	881
Beginning balance (in shares) at Mar. 31, 2023		41,684,526
Beginning balance at Mar. 31, 2023	1,263,777	$ 208,423	424,948	629,437	969
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock Issued Under Share-Based Compensation Plans, net of shares withheld for employee taxes (in shares)		25,995
Stock Issued Under Share-Based Compensation Plans, net of shares withheld for employee taxes	0	$ 130	(130)
Stock Issued Under Stock Purchase Plan, net of expenses	(167)		(167)
Net Income	81,969			81,969
Other Comprehensive Income (Loss)	(88)				(88)
Stock Compensation Expense	1,216		1,216
Common Dividends	$ (18,268)			(18,268)
Ending balance (in shares) at Jun. 30, 2023	41,710,521	41,710,521
Ending balance at Jun. 30, 2023	$ 1,328,439	$ 208,553	$ 425,867	$ 693,138	$ 881

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CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (unaudited) (Parentheticals) - $ / shares	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Statement of Stockholders' Equity [Abstract]
Common Dividends (in dollars per share)	$ 0.4375	$ 0.4125	$ 0.875	$ 0.825

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CONSOLIDATED STATEMENTS OF CASH FLOWS (unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022
Operating Activities
Net Income	$ 144,450	$ 157,940
Adjustments to Reconcile Net Income to Net Cash Provided by Operating Activities:
Depreciation and Amortization	48,089	47,113
Deferred Tax Credits	(372)	(373)
Deferred Income Taxes	8,708	25,160
Discretionary Contribution to Pension Plan	0	(20,000)
Investment (Gains) Losses	(4,295)	4,440
Stock Compensation Expense	6,484	5,511
Other, Net	161	(164)
Changes in Operating Assets and Liabilities:
Receivables	(50,558)	(50,885)
Inventories	2,396	2,889
Regulatory Assets	7,320	5,604
Other Assets	3,561	3,240
Accounts Payable	1,037	1,933
Accrued and Other Liabilities	(4,271)	(3,394)
Regulatory Liabilities	27,169	(3,859)
Pension and Other Postretirement Benefits	(5,382)	475
Net Cash Provided by Operating Activities	184,497	175,630
Investing Activities
Capital Expenditures	(151,516)	(70,791)
Proceeds from Disposal of Noncurrent Assets	2,970	2,840
Cash Used for Investments and Other Assets	(5,079)	(5,944)
Net Cash Used in Investing Activities	(153,625)	(73,895)
Financing Activities
Net Borrowings (Repayments) of Short-Term Debt	41,993	(91,163)
Proceeds from Issuance of Long-Term Debt	0	90,000
Dividends Paid	(36,524)	(34,372)
Payments for Shares Withheld for Employee Tax Obligations	(3,088)	(2,942)
Other, net	(1,671)	(2,806)
Net Cash Provided by (Used in) Financing Activities	710	(41,283)
Net Change in Cash and Cash Equivalents	31,582	60,452
Cash and Cash Equivalents at Beginning of Period	118,996	1,537
Cash and Cash Equivalents at End of Period	150,578	61,989
Supplemental Disclosure of Noncash Investing Activities
Accrued Property, Plant and Equipment Additions	$ 13,149	$ 11,116

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Summary of Significant Accounting Policies

6 Months Ended

Jun. 30, 2023

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

Summary of Significant Accounting Policies

Overview

Otter Tail Corporation (OTC) and its subsidiaries (collectively, the "Company", "us", "our" or "we") form a diverse, multi-platform business consisting of a vertically integrated, regulated utility with generation, transmission and distribution facilities complemented by manufacturing businesses providing metal fabrication for custom machine parts and metal components, manufacturing of extruded and thermoformed plastic products, and manufacturing of polyvinyl chloride (PVC) pipe products. We classify our business into three segments: Electric, Manufacturing and Plastics.

Basis of Presentation

The unaudited consolidated financial statements included herein have been prepared pursuant to the rules and regulations of the SEC for interim reporting. Accordingly, they do not include all the information and footnotes required by generally accepted accounting principles. In the opinion of management, we have included all adjustments, including normal recurring accruals, necessary for a fair presentation of the consolidated financial statements for the periods presented. The consolidated financial statements and condensed notes thereto should be read in conjunction with the consolidated financial statements and notes included in our Annual Report on Form 10-K for the fiscal year ended December 31, 2022.

Because of the seasonality of our businesses and other factors, the earnings for the three and six months ended June 30, 2023 should not be taken as an indication of earnings for all or any part of the balance of the current year or as an indication of earnings for future years.

Use of Estimates

We use estimates based on the best information available in recording transactions and balances resulting from business operations. As better information becomes available or actual amounts are known, the recorded estimates are revised. Consequently, operating results can be affected by revisions to prior accounting estimates.

Reclassifications

Certain reclassifications of amounts previously reported have been made to the accompanying consolidated statements of cash flows to maintain consistency and comparability between periods presented. Other, net operating cash flows previously reported for the six months ended June 30, 2022, included $4.4 million of investment losses, which are presented separately in the current period, and excluded $0.6 million of allowance for equity funds used during construction, which were previously presented separately. The reclassifications had no impact on previously reported net cash provided by operating activities, net cash used in investing activities, net cash (used in) provided by financing activities, or cash and cash equivalents.

Concentration of Deposits and Investments

The Company has financial instruments that potentially subject us to a concentration risk, including cash and cash equivalents held in deposit and money market accounts with various financial institutions. These deposits are guaranteed by the Federal Deposit Insurance Corporation up to an insurance limit of $250,000. Currently, our cash and cash equivalents significantly exceed federally insured levels.

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Segment Information

6 Months Ended

Jun. 30, 2023

Segment Reporting [Abstract]

Segment Information

Segment Information

We classify our business into three segments, Electric, Manufacturing, and Plastics consistent with our business strategy, organizational structure and our internal reporting and review processes used by our chief operating decision maker to make decisions regarding allocation of resources, to assess operating performance and to make strategic decisions.

Certain assets and costs are not allocated to our operating segments. Corporate operating costs include items such as corporate staff and overhead costs, the results of our captive insurance company and other items excluded from the measurement of operating segment performance. Corporate assets consist primarily of cash and cash equivalents, prepaid expenses, investments and fixed assets. Corporate is not an operating segment, rather it is added to operating segment totals to reconcile to consolidated amounts.

Information for each segment and our unallocated corporate costs for the three and six months ended June 30, 2023 and 2022 are as follows:

	Three Months Ended June 30,				Six Months Ended June 30,
(in thousands)	2023		2022		2023		2022
Operating Revenue
Electric	$	113,763	$	130,949	$	265,671	$	261,365
Manufacturing	102,475		103,196		209,257		208,154
Plastics	121,478		165,895		201,869		305,425
Total	$	337,716	$	400,040	$	676,797	$	774,944
Net Income (Loss)
Electric	$	19,634	$	18,858	$	42,854	$	38,091
Manufacturing	5,969		7,555		12,831		11,639
Plastics	55,392		63,959		89,078		114,806
Corporate	974		(4,435)		(313)		(6,596)
Total	$	81,969	$	85,937	$	144,450	$	157,940

The following provides the identifiable assets by segment and corporate assets as of June 30, 2023 and December 31, 2022:

(in thousands)	June 30, 2023		December 31, 2022
Identifiable Assets
Electric	$	2,446,293	$	2,351,961
Manufacturing	260,050		245,869
Plastics	177,470		126,318
Corporate	210,173		177,513
Total	$	3,093,986	$	2,901,661

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Revenue

6 Months Ended

Jun. 30, 2023

Revenue from Contract with Customer [Abstract]

Revenue

Revenue

Presented below are our operating revenues to external customers, in total and by amounts arising from contracts with customers and alternative revenue program (ARP) arrangements, disaggregated by revenue source and segment for the three and six months ended June 30, 2023 and 2022:

	Three Months Ended June 30,				Six Months Ended June 30,
(in thousands)	2023		2022		2023		2022
Operating Revenues
Electric Segment
Retail: Residential	$	26,974	$	33,011	$	70,951	$	73,743
Retail: Commercial and Industrial	64,989		78,521		155,474		149,527
Retail: Other	1,752		2,071		3,743		3,972
Total Retail	93,715		113,603		230,168		227,242
Transmission	14,829		11,697		26,936		24,254
Wholesale	2,670		3,537		4,508		6,000
Other	2,549		2,112		4,059		3,869
Total Electric Segment	113,763		130,949		265,671		261,365
Manufacturing Segment
Metal Parts and Tooling	89,396		88,296		179,463		177,869
Plastic Products and Tooling	10,068		11,416		24,211		23,860
Scrap Metal Sales	3,011		3,484		5,583		6,425
Total Manufacturing Segment	102,475		103,196		209,257		208,154
Plastics Segment
PVC Pipe	121,478		165,895		201,869		305,425
Total Operating Revenue	337,716		400,040		676,797		774,944
Less: Non-contract Revenues Included Above
Electric Segment - ARP Revenues	(334)		(4,928)		(1,545)		(7,388)
Total Operating Revenues from Contracts with Customers	$	338,050	$	404,968	$	678,342	$	782,332

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Select Balance Sheet Information

6 Months Ended

Jun. 30, 2023

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Select Balance Sheet Information

Select Balance Sheet Information

Receivables and Allowance for Credit Losses

Receivables as of June 30, 2023 and December 31, 2022 are as follows:

(in thousands)	June 30, 2023		December 31, 2022
Receivables
Trade	$	166,267	$	112,126
Other	11,183		9,983
Unbilled Receivables	19,715		23,932
Total Receivables	197,165		146,041
Less: Allowance for Credit Losses	2,214		1,648
Receivables, net of allowance for credit losses	$	194,951	$	144,393

The following is a summary of activity in the allowance for credit losses for the six months ended June 30, 2023 and 2022:

(in thousands)	2023		2022
Beginning Balance, January 1	$	1,648	$	1,836
Additions Charged to Expense	1,001		382
Reductions for Amounts Written Off, Net of Recoveries	(435)		(461)
Ending Balance, June 30	$	2,214	$	1,757

Inventories

Inventories consist of the following as of June 30, 2023 and December 31, 2022:

(in thousands)	June 30, 2023		December 31, 2022
Raw Material, Fuel and Supplies	$	73,314	$	70,374
Work in Process	29,326		31,766
Finished Goods	41,801		43,812
Total Inventories	$	144,441	$	145,952

Investments

The following is a summary of our investments as of June 30, 2023 and December 31, 2022:

(in thousands)	June 30, 2023		December 31, 2022
Corporate-Owned Life Insurance Policies	$	39,352	$	38,991
Corporate and Government Debt Securities	8,926		8,761
Money Market Funds	4,069		1,560
Mutual Funds	7,505		5,503
Other Investments	30		30
Total Investments	$	59,882	$	54,845

The amount of unrealized gains and losses on debt securities as of June 30, 2023 and December 31, 2022 was not material and no unrealized losses were deemed to be other-than-temporary. In addition, the amount of unrealized gains and losses on marketable equity securities still held as of June 30, 2023 and December 31, 2022 was not material.

Property, Plant and Equipment

Major classes of property, plant and equipment as of June 30, 2023 and December 31, 2022 include:

(in thousands)	June 30, 2023		December 31, 2022
Electric Plant
Electric Plant in Service	$	2,933,603	$	2,844,379
Construction Work in Progress	141,249		113,932
Total Gross Electric Plant	3,074,852		2,958,311
Less Accumulated Depreciation and Amortization	888,374		859,988
Net Electric Plant	2,186,478		2,098,323
Nonelectric Property, Plant and Equipment
Nonelectric Property, Plant and Equipment in Service	297,908		293,928
Construction Work in Progress	34,147		15,170
Total Gross Nonelectric Property, Plant and Equipment	332,055		309,098
Less Accumulated Depreciation and Amortization	202,287		194,704
Net Nonelectric Property, Plant and Equipment	129,768		114,394
Net Property, Plant and Equipment	$	2,316,246	$	2,212,717

On January 3, 2023, we purchased the Ashtabula III wind farm, located in eastern North Dakota, which consists of 39 wind turbines and the related infrastructure, adding 62.4 megawatts of nameplate capacity to our owned generation assets. The total purchase price of the acquisition was $50.6 million. In addition to the acquired assets, we also recognized a $3.3 million asset retirement obligation liability associated with the wind farm and became party to the land easement agreements with the landowners of the wind farm.

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Regulatory Matters

6 Months Ended

Jun. 30, 2023

Regulatory Assets and Liabilities Disclosure [Abstract]

Regulatory Matters

Regulatory Matters

Regulatory Assets and Liabilities

The following presents our current and long-term regulatory assets and liabilities as of June 30, 2023 and December 31, 2022 and the period we expect to recover or refund such amounts:

	Period of	June 30, 2023				December 31, 2022
(in thousands)	Recovery/Refund	Current		Long-Term		Current		Long-Term
Regulatory Assets
Pension and Other Postretirement Benefit Plans1	Various	$	—	$	90,602	$	—	$	88,354
Alternative Revenue Program Riders2	Up to 2 years	6,563		79		5,679		2,508
Asset Retirement Obligations1	Asset lives	—		2,327		—		1,467
Deferred Income Taxes	Asset lives	—		847		—		—
ISO Cost Recovery Trackers1	Up to 2 years	288		207		575		314
Unrecovered Project Costs1	Up to 4 years	349		1,048		320		990
Deferred Rate Case Expenses1	Up to 3 years	377		566		377		754
Fuel Clause Adjustments1	Up to 1 year	9,935		—		10,893		—
Derivative Instruments1	Up to 2 years	1,521		207		7,130		—
Other1	Various	25		245		25		268
Total Regulatory Assets		$	19,058	$	96,128	$	24,999	$	94,655
Regulatory Liabilities
Deferred Income Taxes	Asset lives	$	—	$	129,567	$	—	$	131,480
Plant Removal Obligations	Asset lives	8,474		106,393		8,509		105,733
Fuel Clause Adjustments	Up to 1 year	22,358		—		365		—
Alternative Revenue Program Riders	Up to 1 year	4,560		—		2,504		—
North Dakota PTC Refunds	Asset lives	—		9,512		—		7,136
Pension and Other Postretirement Benefit Plans	Up to 1 year	5,589		—		5,589		—
Other	Various	762		463		333		148
Total Regulatory Liabilities		$	41,743	$	245,935	$	17,300	$	244,497
1Costs subject to recovery without a rate of return.
2Amount eligible for recovery includes an incentive or rate of return.

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Short-Term and Long-Term Borrowings

6 Months Ended

Jun. 30, 2023

Debt Disclosure [Abstract]

Short-Term and Long-Term Borrowings

Short-Term and Long-Term Borrowings

The following is a summary of our outstanding short- and long-term borrowings by borrower, OTC or Otter Tail Power Company (OTP), as of June 30, 2023 and December 31, 2022:

Short-Term Debt

The following is a summary of our lines of credit as of June 30, 2023 and December 31, 2022:

			June 30, 2023						December 31, 2022
(in thousands)	Borrowing Limit		Amount Outstanding		Letters of Credit		Amount Available		Amount Available
OTC Credit Agreement	$	170,000	$	—	$	—	$	170,000	$	170,000
OTP Credit Agreement	170,000		50,197		9,573		110,230		152,223
Total	$	340,000	$	50,197	$	9,573	$	280,230	$	322,223

Long-Term Debt

The following is a summary of outstanding long-term debt by borrower as of June 30, 2023 and December 31, 2022: 

					(in thousands)
Borrower		Debt Instrument	Rate	Maturity	June 30, 2023		December 31, 2022
OTC		Guaranteed Senior Notes	3.55%	12/15/26	$	80,000	$	80,000
OTP		Series 2007C Senior Unsecured Notes	6.37%	08/02/27	42,000		42,000
OTP		Series 2013A Senior Unsecured Notes	4.68%	02/27/29	60,000		60,000
OTP		Series 2019A Senior Unsecured Notes	3.07%	10/10/29	10,000		10,000
OTP		Series 2020A Senior Unsecured Notes	3.22%	02/25/30	10,000		10,000
OTP		Series 2020B Senior Unsecured Notes	3.22%	08/20/30	40,000		40,000
OTP		Series 2021A Senior Unsecured Notes	2.74%	11/29/31	40,000		40,000
OTP		Series 2007D Senior Unsecured Notes	6.47%	08/20/37	50,000		50,000
OTP		Series 2019B Senior Unsecured Notes	3.52%	10/10/39	26,000		26,000
OTP		Series 2020C Senior Unsecured Notes	3.62%	02/25/40	10,000		10,000
OTP		Series 2013B Senior Unsecured Notes	5.47%	02/27/44	90,000		90,000
OTP		Series 2018A Senior Unsecured Notes	4.07%	02/07/48	100,000		100,000
OTP		Series 2019C Senior Unsecured Notes	3.82%	10/10/49	64,000		64,000
OTP		Series 2020D Senior Unsecured Notes	3.92%	02/25/50	15,000		15,000
OTP		Series 2021B Senior Unsecured Notes	3.69%	11/29/51	100,000		100,000
OTP		Series 2022A Senior Unsecured Notes	3.77%	05/20/52	90,000		90,000
Total					$	827,000	$	827,000
Less:	Unamortized Long-Term Debt Issuance Costs				3,059		3,179
Total Long-Term Debt, Net of Unamortized Debt Issuance Costs					$	823,941	$	823,821

Financial Covenants

Certain of OTC's and OTP's short- and long-term debt agreements require the borrower, whether OTC or OTP, to maintain certain financial covenants, including a maximum debt to total capitalization ratio of 0.60 to 1.00, a minimum interest and dividend coverage ratio of 1.50 to 1.00, and a maximum level of priority indebtedness. As of June 30, 2023, OTC and OTP were in compliance with these financial covenants.

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Employee Postretirement Benefits

6 Months Ended

Jun. 30, 2023

Retirement Benefits [Abstract]

Employee Postretirement Benefits

Employee Postretirement Benefits

Pension Plan and Other Postretirement Benefits

The Company sponsors a noncontributory funded pension plan (the "Pension Plan"), an unfunded, nonqualified Executive Survivor and Supplemental Retirement Plan (the "ESSRP"), both accounted for as defined benefit pension plans, and a postretirement healthcare plan accounted for as an other postretirement benefit plan.

The following table includes the components of net periodic benefit cost (income) related to our defined benefit pension plans and other postretirement benefits for the three and six months ended June 30, 2023 and 2022:

	Three Months Ended June 30,
	Pension Benefits (Pension Plan)				Pension Benefits (ESSRP)				Postretirement Benefits
(in thousands)	2023		2022		2023		2022		2023		2022
Service Cost	$	924	$	1,644	$	18	$	49	$	153	$	334
Interest Cost	4,109		3,086		473		336		669		511
Expected Return on Assets	(6,478)		(5,921)		—		—		—		—
Amortization of Prior Service Cost	—		—		—		—		(1,434)		(1,434)
Amortization of Net Actuarial Loss	—		1,967		—		142		—		766
Net Periodic Benefit Cost (Income)	$	(1,445)	$	776	$	491	$	527	$	(612)	$	177
	Six Months Ended June 30,
	Pension Benefits (Pension Plan)				Pension Benefits (ESSRP)				Postretirement Benefits
(in thousands)	2023		2022		2023		2022		2023		2022
Service Cost	$	1,849	$	3,288	$	36	$	98	$	306	$	669
Interest Cost	8,218		6,172		945		671		1,338		1,021
Expected Return on Assets	(12,957)		(11,842)		—		—		—		—
Amortization of Prior Service Cost	—		—		—		—		(2,867)		(2,867)
Amortization of Net Actuarial Loss	—		3,933		—		284		—		1,532
Net Periodic Benefit Cost (Income)	$	(2,890)	$	1,551	$	981	$	1,053	$	(1,223)	$	355

The following table includes the impact of regulation on the recognition of periodic benefit cost (income) arising from pension and other postretirement benefits for the three and six months ended June 30, 2023 and 2022:

	Three Months Ended June 30,				Six Months Ended June 30,
(in thousands)	2023		2022		2023		2022
Net Periodic Benefit Cost (Income)	$	(1,566)	$	1,480	$	(3,132)	$	2,959
Net Amount Amortized (Deferred) Due to the Effect of Regulation	240		(204)		490		324
Net Periodic Benefit Cost (Income) Recognized	$	(1,326)	$	1,276	$	(2,642)	$	3,283

We had no minimum funding requirements for our Pension Plan or any other postretirement benefit plans as of December 31, 2022. We did not make any contributions to our Pension Plan during the six months ended June 30, 2023. We made a discretionary contribution to our Pension Plan of $20.0 million during the six months ended June 30, 2022.

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Income Taxes

6 Months Ended

Jun. 30, 2023

Income Tax Disclosure [Abstract]

Income Taxes

Income TaxesThe reconciliation of the statutory federal income tax rate to our effective tax rate for each of the three and six months ended June 30, 2023 and 2022 is as follows:

	Three Months Ended June 30,								Six Months Ended June 30,
	2023				2022				2023				2022
Income Taxes at Federal Statutory Rate	$	21,426	21.0	%	$	23,507	21.0	%	$	37,341	21.0	%	$	42,330	21.0	%
Increases (Decreases) in Tax from:
State Taxes on Income, Net of Federal Tax	5,104		5.0		5,596		5.0		8,893		5.0		10,078		5.0
Production Tax Credits (PTCs)	(4,574)		(4.5)		(4,719)		(4.2)		(9,229)		(5.2)		(8,686)		(4.3)
Amortization of Excess Deferred Income Taxes	(622)		(0.6)		99		—		(1,420)		(0.8)		(1,078)		(0.5)
North Dakota Wind Tax Credit Amortization, Net of Federal Tax	(146)		(0.1)		(155)		(0.1)		(310)		(0.2)		(355)		(0.2)
Corporate-Owned Life Insurance	(460)		(0.5)		965		0.8		(878)		(0.5)		1,142		0.6
Other, Net	(666)		(0.6)		707		0.7		(1,032)		(0.5)		199		—
Income Tax Expense / Effective Tax Rate	$	20,062	19.7	%	$	26,000	23.2	%	$	33,365	18.8	%	$	43,630	21.6	%

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Commitments and Contingencies

6 Months Ended

Jun. 30, 2023

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

Commitments and Contingencies

Commitments

Land Easements. Since 2013, OTP had purchased the wind-generated electricity from the Ashtabula III wind farm pursuant to a power purchase agreement. That agreement granted us the option to purchase the wind farm and on January 3, 2023, we completed the purchase for $50.6 million. In connection with the purchase, we assumed 51 land easements, not classified as leases, which require annual payments. As of June 30, 2023, the remaining payments to be made under the easements total $4.1 million and the remaining terms of the agreements extend into 2034.

Contingencies

FERC Return on Equity (ROE). In November 2013 and February 2015, customers filed complaints with the Federal Energy Regulatory Commission (FERC) seeking to reduce the return on equity component of the transmission rates that Midcontinent Independent System Operator, Inc. (MISO) transmission owners, including OTP, may collect under the MISO tariff rate. FERC's most recent order, issued on November 19, 2020, adopted a revised ROE methodology and set the base ROE at 10.02% (10.52% with an adder) effective for the fifteen-month period from November 2013 to February 2015 and on a prospective basis beginning in September 2016. The order also dismissed any complaints covering the period from February 2015 to May 2016. On August 9, 2022, the U.S. Court of Appeals for the District of Columbia Circuit vacated the FERC order citing a lack of reasoned explanation by FERC in its adoption of its revised ROE methodology as outlined in its November 2020 order. The U.S. Court of Appeals remanded the matter to FERC to reopen the proceedings.

Significant uncertainty exists as to how FERC will proceed upon remand and there is no prescribed timeline under which FERC must act. We have deferred recognition and recorded a refund liability of $2.7 million as of June 30, 2023. This refund liability reflects our best estimate of amounts previously collected from customers under the MISO tariff rate that may be required to be refunded to customers once all regulatory and judicial proceedings are complete and a final ROE is established for the periods outlined above.

Regional Haze Rule (RHR). The RHR was adopted in an effort to improve visibility in national parks and wilderness areas. The RHR requires states, in coordination with the Environmental Protection Agency (EPA) and other governmental agencies, to develop and implement plans to achieve natural visibility conditions. The second RHR implementation period covers the years 2018-2028. States are required to submit a state implementation plan to assess reasonable progress with the RHR and determine what additional emission reductions are appropriate, if any.

Coyote Station, OTP's jointly owned coal-fired power plant in North Dakota, is subject to assessment in the second implementation period under the North Dakota state implementation plan. The North Dakota Department of Environmental Quality (NDDEQ) submitted its state implementation plan to the EPA for approval in August, 2022. In its plan, the NDDEQ concluded it is not reasonable to require additional emission controls during this planning period. The EPA has previously expressed disagreement with the NDDEQ's recommendation to forgo additional emission controls and has indicated that such a plan is not likely to be accepted.

We cannot predict with certainty the impact the state implementation plan may have on our business until the plan has been approved or otherwise acted on by the EPA. However, significant emission control investments could be required and the recovery of such costs from customers would require regulatory approval. Alternatively, investments in emission control equipment may prove to be uneconomic and result in the early retirement of or the sale of our interest in Coyote Station, subject to regulatory approval. We cannot estimate the ultimate financial effects such a retirement or sale may have on our consolidated operating results, financial position or cash flows, but such amounts could be material and the recovery of such costs in rates would be subject to regulatory approval.

Self-Funding of Transmission Upgrades. The FERC has granted transmission owners within MISO the unilateral authority to determine the funding mechanism for interconnection transmission upgrades that are necessary to accommodate new generation facilities connecting to the electrical grid. Under existing FERC orders, transmission owners can unilaterally determine whether the generator pays the transmission owner in advance for the transmission upgrade or, alternatively, the transmission owner can elect to fund the upgrade and recover over time from the generator the cost of and a return on the upgrade investment (a self-funding). FERC’s orders granting transmission owners this unilateral funding authority has been judicially contested on the basis that transmission owners may be motivated to discriminate among generators in making funding determinations. In the most recent judicial proceedings, the petitioners argued to the U.S. Court of Appeals for the District of Columbia that FERC did not comply with a previous judicial order to fully develop a record regarding the risk of discrimination and the financial risk absorbed by transmission owners for generator-funded upgrades. On December 2, 2022, the Court of Appeals ruled in favor of the petitioners remanding the matter to FERC, instructing the agency to adequately explain the basis of its orders. The Court of Appeals decision did not vacate transmission owners’ unilateral funding authority.

OTP, as a transmission owner in MISO, has exercised its authority and elected to self-fund previous transmission upgrades necessary to accommodate new system generation. Under such an election, OTP is recovering the cost of the transmission upgrade and a return on that investment from the generator over a contractual period of time. Should FERC, on remand from the Court of Appeals, eliminate transmission owners’ unilateral funding authority, on either a prospective or retrospective basis, our financial results would be impacted. We cannot at this time reasonably predict the outcome of this matter given the uncertainty as to how and when FERC may respond to the judicial remand.

Other Contingencies. We are party to litigation and regulatory matters arising in the normal course of business. We regularly analyze relevant information and, as necessary, estimate and record accrued liabilities for legal, regulatory enforcement and other matters in which a loss is probable of occurring and can be reasonably estimated. We believe the effect on our consolidated operating results, financial position and cash flows, if any, for the disposition of all matters pending as of June 30, 2023, other than those discussed above, will not be material.

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Stockholders' Equity

6 Months Ended

Jun. 30, 2023

Equity [Abstract]

Stockholders' Equity

Stockholders' Equity

Registration Statements

On May 3, 2021, we filed a shelf registration statement with the SEC under which we may offer for sale, from time to time, either separately or together in any combination, equity, debt or other securities described in the shelf registration statement. No new debt or equity has been issued pursuant to the registration statement. The registration statement expires in May 2024.

On May 3, 2021, we filed a second registration statement with the SEC for the issuance of up to 1,500,000 common shares under an Automatic Dividend Reinvestment and Share Purchase Plan, which provides shareholders, retail customers of OTP and other interested investors methods of purchasing our common shares, by reinvesting their dividends or making optional cash investments. Shares purchased under the plan may be newly issued common shares or common shares purchased on the open market. During the six months ended June 30, 2023, we issued 56,311 shares under this plan. We repurchased a sufficient number of shares on the open market to satisfy issuance under the plan; accordingly, no proceeds from the issuance were received. As of June 30, 2023, there were 1,194,682 shares available for purchase or issuance under the plan. The registration statement expires in May 2024.

Dividend Restrictions

OTC is a holding company with no significant operations of its own. The primary source of funds for payments of dividends to OTC's shareholders is from dividends paid or distributions made by OTC's subsidiaries. As a result of certain statutory limitations or regulatory or financing agreements, the amount of distributions allowed to be made by OTC's subsidiaries or the amount of dividends paid by OTC could be restricted. Both the OTC Credit Agreement and OTP Credit Agreement contain restrictions on the payment of cash dividends upon a default or event of default, including failure to maintain certain financial covenants. As of June 30, 2023, we were in compliance with these financial covenants.

Under the Federal Power Act, a public utility may not pay dividends from any funds properly included in a capital account. What constitutes “funds properly included in a capital account” is undefined in the Federal Power Act or the related regulations; however, the FERC has consistently interpreted the provision to allow dividends to be paid as long as i) the source of the dividends is clearly disclosed, ii) the dividend is not excessive and iii) there is no self-dealing on the part of corporate officials.

The Minnesota Public Utilities Commission (MPUC) indirectly limits the amount of dividends OTP can pay to OTC by requiring an equity-to-total-capitalization ratio between 47.5% and 58.0% based on OTP’s capital structure petition effective by order of the MPUC on November 8, 2022. As of June 30, 2023, OTP’s equity-to-total-capitalization ratio, including short-term debt, was 53.8% and its net assets restricted from distribution totaled approximately $778.6 million. Under the MPUC order, total capitalization for OTP cannot exceed $1.8 billion.

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Accumulated Other Comprehensive Income (Loss)

6 Months Ended

Jun. 30, 2023

Equity [Abstract]

Accumulated Other Comprehensive Income (Loss)

Accumulated Other Comprehensive Income (Loss)The following presents the changes in accumulated other comprehensive loss for the three and six months ended June 30, 2023 and 2022:

	Three Months Ended June 30,
	2023								2022
(in thousands)	Pension and Other Postretirement Benefits			Net Unrealized Gains (Losses) on Available-for-Sale Securities			Total		Pension and Other Postretirement Benefits			Net Unrealized Gains (Losses) on Available-for-Sale Securities			Total
Balance, Beginning of Period	$	1,308		$	(339)		$	969	$	(6,727)		$	(218)		$	(6,945)
Other Comprehensive Loss Before Reclassifications, net of tax	—			(62)			(62)		—			(75)			(75)
Amounts Reclassified from Accumulated Other Comprehensive Income (Loss)	(27)		(1)	1		(2)	(26)		106		(1)	1		(2)	107
Total Other Comprehensive Income (Loss)	(27)			(61)			(88)		106			(74)			32
Balance, End of Period	$	1,281		$	(400)		$	881	$	(6,621)		$	(292)		$	(6,913)
	Six Months Ended June 30,
	2023								2022
(in thousands)	Pension and Other Postretirement Benefits			Net Unrealized Gains (Losses) on Available-for-Sale Securities			Total		Pension and Other Postretirement Benefits			Net Unrealized Gains (Losses) on Available-for-Sale Securities			Total
Balance, Beginning of Period	$	1,334		$	(419)		$	915	$	(6,537)		$	13		$	(6,524)
Other Comprehensive Income (Loss) Before Reclassifications, net of tax	—			18			18		—			(306)			(306)
Amounts Reclassified from Accumulated Other Comprehensive Income (Loss)	(53)		(1)	1		(2)	(52)		(84)		(1)	1		(2)	(83)
Total Other Comprehensive Income (Loss)	(53)			19			(34)		(84)			(305)			(389)
Balance, End of Period	$	1,281		$	(400)		$	881	$	(6,621)		$	(292)		$	(6,913)
(1) Included in the computation of net periodic pension and other postretirement benefit costs. See Note 7.
(2) Included in other income (expense), net on the accompanying consolidated statements of income.

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Share-Based Payments

6 Months Ended

Jun. 30, 2023

Share-Based Payment Arrangement [Abstract]

Share-Based Payments

Share-Based Payments

Stock Compensation Expense

Stock-based compensation expense arising from our employee stock purchase plan and share-based compensation plans recognized within operating expenses in the consolidated statements of income amounted to $1.2 million and $0.6 million for the three months ended June 30, 2023 and 2022, respectively, and $6.5 million and $5.5 million for the six months ended June 30, 2023 and 2022, respectively.

Restricted Stock Awards. We grant restricted stock awards to members of our Board of Directors and restricted stock units to certain key employees. The awards vest, depending on award type and recipient, either ratably over periods of three or four years or cliff vest after four years. Vesting is accelerated in certain circumstances, including on retirement.

The following is a summary of stock award activity for the six months ended June 30, 2023:

	Shares	Weighted-Average Grant-Date Fair Value
Nonvested, January 1, 2023	141,551	$	49.83
Granted	55,205	68.03
Vested	(45,493)	50.02
Forfeited	(1,300)	50.00
Nonvested, June 30, 2023	149,963	$	56.47

The fair value of vested awards was $3.1 million and $3.0 million during the six months ended June 30, 2023 and 2022.

Stock Performance Awards. Stock performance awards are granted to executive officers and certain other key employees. The awards vest at the end of a three-year performance period. The number of common shares awarded, if any, at the end of the performance period ranges from zero to 150% of the target amount based on two performance measures: i) total shareholder return relative to a peer group and ii) return on equity. Vesting of the awards is accelerated in certain circumstances, including on retirement. The number of common shares awarded on an accelerated vesting is based either on actual performance at the end of the performance period or the number of common shares earned at target.

The grant date fair value of stock performance awards granted during the six months ended June 30, 2023 and 2022 was determined using a Monte Carlo fair value simulation model incorporating the following assumptions:

	2023		2022
Risk-free interest rate	4.15	%	1.52	%
Expected term (in years)	3		3
Expected volatility	34.00	%	32.00	%
Dividend yield	2.50	%	2.90	%

The risk-free interest rate was derived from yields on U.S. government bonds of a similar term. The expected term of the award is equal to the three-year performance period. Expected volatility was estimated based on actual historical volatility of our common stock. Dividend yield was estimated based on historical and future yield estimates.

The following is a summary of stock performance award activity for the six months ended June 30, 2023 (share amounts reflect awards at target):

	Shares	Weighted-Average Grant-Date Fair Value
Nonvested, January 1, 2023	189,800	$	45.95
Granted	59,400	61.97
Vested	(55,000)	47.79
Forfeited	—	—
Nonvested, June 30, 2023	194,200	$	50.33

The fair value of vested awards was $5.3 million and $5.1 million during the six months ended June 30, 2023 and 2022, respectively.

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Earnings Per Share

6 Months Ended

Jun. 30, 2023

Earnings Per Share [Abstract]

Earnings Per Share

Earnings Per Share

The numerator used in the calculation of both basic and diluted earnings per common share is net income. The denominator used in the calculation of basic earnings per common share is the weighted-average number of common shares outstanding during the period. The denominator used in the calculation of diluted earnings per common share is derived by adjusting basic shares outstanding for the dilutive effect of potential common shares outstanding, which consist of time and performance-based stock awards and employee stock purchase plan shares.

The following includes the computation of the denominator for basic and diluted weighted-average shares outstanding for the three and six months ended June 30, 2023 and 2022:

	Three Months Ended June 30,		Six Months Ended June 30,
(in thousands)	2023	2022	2023	2022
Weighted-Average Common Shares Outstanding – Basic	41,678	41,597	41,655	41,573
Effect of Dilutive Securities:
Stock Performance Awards	281	259	281	239
Restricted Stock Awards	92	85	97	94
Employee Stock Purchase Plan Shares and Other	2	3	2	1
Dilutive Effect of Potential Common Shares	375	347	380	334
Weighted-Average Common Shares Outstanding – Diluted	42,053	41,944	42,035	41,907

The number of shares excluded from diluted weighted-average common shares outstanding because such shares were anti-dilutive was not material for the three and six months ended June 30, 2023 and 2022.

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Derivative Instruments	6 Months Ended
	Jun. 30, 2023
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments	Derivative InstrumentsOTP enters into derivative instruments to manage its exposure to future market energy price variability and reduce volatility in prices for our retail customers. These derivative instruments are not designated as qualifying hedging transactions but provide for an economic hedge against future market energy price variability. The instruments are recorded at fair value on the consolidated balance sheets. In accordance with rate-making and cost recovery processes, we recognize a regulatory asset or liability to defer losses or gains from derivative activity until settlement of the associated derivative instrument. As of June 30, 2023, OTP had multiple outstanding pay-fixed, receive-variable swap agreements with an aggregate notional amount of 195,400 megawatt-hours of electricity, with various settlement dates extending to December 31, 2024. As of June 30, 2023, the fair value of these derivative instruments was $1.7 million, of which $1.5 million is included in other current liabilities and $0.2 million is included in other noncurrent liabilities, on the consolidated balance sheets. As of December 31, 2022, the fair value of these types of derivative contracts was $7.1 million, which is included in other current liabilities. There were no contracts which matured during the three months ended June 30, 2023 or 2022. During the six months ended June 30, 2023 and 2022, contracts matured and were settled in an aggregate amount of a $16.0 million loss and a $2.8 million gain, respectively. Gains and losses recognized on the settlement of derivative instruments are recorded in electric purchased power in the consolidated statements of income. Such settlement gains and losses are returned to or recovered from our electric customers through fuel recovery mechanisms in each state.

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Fair Value Measurements

6 Months Ended

Jun. 30, 2023

Fair Value Disclosures [Abstract]

Fair Value Measurements

Fair Value Measurements

The following tables present our assets and liabilities measured at fair value on a recurring basis as of June 30, 2023 and December 31, 2022 classified by the input method used to measure fair value:

(in thousands)	Level 1		Level 2		Level 3
June 30, 2023
Assets:
Investments:
Money Market Funds	$	4,069	$	—	$	—
Mutual Funds	7,505		—		—
Corporate Debt Securities	—		1,456		—
Government-Backed and Government-Sponsored Enterprises’ Debt Securities	—		7,470		—
Total Assets	$	11,574	$	8,926	$	—
Liabilities:
Derivative Instruments	$	—	$	1,728	$	—
Total Liabilities	$	—	$	1,728	$	—
December 31, 2022
Assets:
Investments:
Money Market Funds	$	1,560	$	—	$	—
Mutual Funds	5,503		—		—
Corporate Debt Securities	—		1,434		—
Government-Backed and Government-Sponsored Enterprises’ Debt Securities	—		7,327		—
Total Assets	$	7,063	$	8,761	$	—
Liabilities:
Derivative Instruments	—		7,130		—
Total Liabilities	$	—	$	7,130	$	—

Level 1 fair value measurements are based on quoted prices (unadjusted) in active markets for identical assets or liabilities that we have the ability to access at the measurement date.

The level 2 fair value measurements for government-backed and government-sponsored enterprises and corporate debt securities are determined based on valuations provided by a third-party pricing service which utilizes industry accepted valuation models and observable market inputs to determine valuation. Some valuations or model inputs used by the pricing service may be based on broker quotes.

The level 2 fair value measurements for derivative instruments are determined by using inputs such as forward electric commodity prices, adjusted for location differences. These inputs are observable in the marketplace throughout the full term of the instrument, can be derived from observable data, or are supported by observable levels at which transactions are executed in the marketplace.

In addition to assets recorded at fair value on a recurring basis, we also hold financial instruments that are not recorded at fair value in the consolidated balance sheets but for which disclosure of the fair value of these financial instruments is provided.

The following reflects the carrying value and estimated fair value of these assets and liabilities as of June 30, 2023 and December 31, 2022:

	June 30, 2023				December 31, 2022
(in thousands)	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Assets:
Cash and Cash Equivalents	$	150,578	$	150,578	$	118,996	$	118,996
Total	150,578		150,578		118,996		118,996
Liabilities:
Short-Term Debt	50,197		50,197		8,204		8,204
Long-Term Debt	823,941		698,831		823,821		681,615
Total	$	874,138	$	749,028	$	832,025	$	689,819

The following methods and assumptions were used to estimate the fair value of each class of financial instruments for which it is practicable to estimate that value:

Cash Equivalents: The carrying amount approximates fair value because of the short-term maturity of those instruments.

Short-Term Debt: The carrying amount approximates fair value because the debt obligations are short-term and the balances outstanding are subject to variable rates of interest which reset frequently, a Level 2 fair value input.

Long-Term Debt: The fair value of long-term debt is estimated based on current market indications for borrowings of similar maturities, a Level 2 fair value input.

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Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Pay vs Performance Disclosure
Net Income	$ 81,969	$ 85,937	$ 144,450	$ 157,940

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Insider Trading Arrangements	3 Months Ended
	Jun. 30, 2023
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

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Summary of Significant Accounting Policies (Policies)

6 Months Ended

Jun. 30, 2023

Accounting Policies [Abstract]

Basis of Presentation

Basis of Presentation

The unaudited consolidated financial statements included herein have been prepared pursuant to the rules and regulations of the SEC for interim reporting. Accordingly, they do not include all the information and footnotes required by generally accepted accounting principles. In the opinion of management, we have included all adjustments, including normal recurring accruals, necessary for a fair presentation of the consolidated financial statements for the periods presented. The consolidated financial statements and condensed notes thereto should be read in conjunction with the consolidated financial statements and notes included in our Annual Report on Form 10-K for the fiscal year ended December 31, 2022.

Because of the seasonality of our businesses and other factors, the earnings for the three and six months ended June 30, 2023 should not be taken as an indication of earnings for all or any part of the balance of the current year or as an indication of earnings for future years.

Use of Estimates

Use of Estimates

We use estimates based on the best information available in recording transactions and balances resulting from business operations. As better information becomes available or actual amounts are known, the recorded estimates are revised. Consequently, operating results can be affected by revisions to prior accounting estimates.

Reclassifications

Reclassifications

Certain reclassifications of amounts previously reported have been made to the accompanying consolidated statements of cash flows to maintain consistency and comparability between periods presented. Other, net operating cash flows previously reported for the six months ended June 30, 2022, included $4.4 million of investment losses, which are presented separately in the current period, and excluded $0.6 million of allowance for equity funds used during construction, which were previously presented separately. The reclassifications had no impact on previously reported net cash provided by operating activities, net cash used in investing activities, net cash (used in) provided by financing activities, or cash and cash equivalents.

Concentration of Deposits and Investments

Concentration of Deposits and Investments

The Company has financial instruments that potentially subject us to a concentration risk, including cash and cash equivalents held in deposit and money market accounts with various financial institutions. These deposits are guaranteed by the Federal Deposit Insurance Corporation up to an insurance limit of $250,000. Currently, our cash and cash equivalents significantly exceed federally insured levels.

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Segment Information (Tables)

6 Months Ended

Jun. 30, 2023

Segment Reporting [Abstract]

Schedule of Segment Reporting Information, by Segment

Information for each segment and our unallocated corporate costs for the three and six months ended June 30, 2023 and 2022 are as follows:

	Three Months Ended June 30,				Six Months Ended June 30,
(in thousands)	2023		2022		2023		2022
Operating Revenue
Electric	$	113,763	$	130,949	$	265,671	$	261,365
Manufacturing	102,475		103,196		209,257		208,154
Plastics	121,478		165,895		201,869		305,425
Total	$	337,716	$	400,040	$	676,797	$	774,944
Net Income (Loss)
Electric	$	19,634	$	18,858	$	42,854	$	38,091
Manufacturing	5,969		7,555		12,831		11,639
Plastics	55,392		63,959		89,078		114,806
Corporate	974		(4,435)		(313)		(6,596)
Total	$	81,969	$	85,937	$	144,450	$	157,940

The following provides the identifiable assets by segment and corporate assets as of June 30, 2023 and December 31, 2022:

(in thousands)	June 30, 2023		December 31, 2022
Identifiable Assets
Electric	$	2,446,293	$	2,351,961
Manufacturing	260,050		245,869
Plastics	177,470		126,318
Corporate	210,173		177,513
Total	$	3,093,986	$	2,901,661

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Revenue (Tables)

6 Months Ended

Jun. 30, 2023

Revenue from Contract with Customer [Abstract]

Schedule of Disaggregation of Revenue

Presented below are our operating revenues to external customers, in total and by amounts arising from contracts with customers and alternative revenue program (ARP) arrangements, disaggregated by revenue source and segment for the three and six months ended June 30, 2023 and 2022:

	Three Months Ended June 30,				Six Months Ended June 30,
(in thousands)	2023		2022		2023		2022
Operating Revenues
Electric Segment
Retail: Residential	$	26,974	$	33,011	$	70,951	$	73,743
Retail: Commercial and Industrial	64,989		78,521		155,474		149,527
Retail: Other	1,752		2,071		3,743		3,972
Total Retail	93,715		113,603		230,168		227,242
Transmission	14,829		11,697		26,936		24,254
Wholesale	2,670		3,537		4,508		6,000
Other	2,549		2,112		4,059		3,869
Total Electric Segment	113,763		130,949		265,671		261,365
Manufacturing Segment
Metal Parts and Tooling	89,396		88,296		179,463		177,869
Plastic Products and Tooling	10,068		11,416		24,211		23,860
Scrap Metal Sales	3,011		3,484		5,583		6,425
Total Manufacturing Segment	102,475		103,196		209,257		208,154
Plastics Segment
PVC Pipe	121,478		165,895		201,869		305,425
Total Operating Revenue	337,716		400,040		676,797		774,944
Less: Non-contract Revenues Included Above
Electric Segment - ARP Revenues	(334)		(4,928)		(1,545)		(7,388)
Total Operating Revenues from Contracts with Customers	$	338,050	$	404,968	$	678,342	$	782,332

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Select Balance Sheet Information (Tables)

6 Months Ended

Jun. 30, 2023

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Schedule of Receivables

Receivables as of June 30, 2023 and December 31, 2022 are as follows:

(in thousands)	June 30, 2023		December 31, 2022
Receivables
Trade	$	166,267	$	112,126
Other	11,183		9,983
Unbilled Receivables	19,715		23,932
Total Receivables	197,165		146,041
Less: Allowance for Credit Losses	2,214		1,648
Receivables, net of allowance for credit losses	$	194,951	$	144,393

Schedule of Activity in Allowance for Credit Losses

The following is a summary of activity in the allowance for credit losses for the six months ended June 30, 2023 and 2022:

(in thousands)	2023		2022
Beginning Balance, January 1	$	1,648	$	1,836
Additions Charged to Expense	1,001		382
Reductions for Amounts Written Off, Net of Recoveries	(435)		(461)
Ending Balance, June 30	$	2,214	$	1,757

Schedule of Inventories

Inventories consist of the following as of June 30, 2023 and December 31, 2022:

(in thousands)	June 30, 2023		December 31, 2022
Raw Material, Fuel and Supplies	$	73,314	$	70,374
Work in Process	29,326		31,766
Finished Goods	41,801		43,812
Total Inventories	$	144,441	$	145,952

Schedule of Investments

The following is a summary of our investments as of June 30, 2023 and December 31, 2022:

(in thousands)	June 30, 2023		December 31, 2022
Corporate-Owned Life Insurance Policies	$	39,352	$	38,991
Corporate and Government Debt Securities	8,926		8,761
Money Market Funds	4,069		1,560
Mutual Funds	7,505		5,503
Other Investments	30		30
Total Investments	$	59,882	$	54,845

Schedule of Property, Plant and Equipment

Major classes of property, plant and equipment as of June 30, 2023 and December 31, 2022 include:

(in thousands)	June 30, 2023		December 31, 2022
Electric Plant
Electric Plant in Service	$	2,933,603	$	2,844,379
Construction Work in Progress	141,249		113,932
Total Gross Electric Plant	3,074,852		2,958,311
Less Accumulated Depreciation and Amortization	888,374		859,988
Net Electric Plant	2,186,478		2,098,323
Nonelectric Property, Plant and Equipment
Nonelectric Property, Plant and Equipment in Service	297,908		293,928
Construction Work in Progress	34,147		15,170
Total Gross Nonelectric Property, Plant and Equipment	332,055		309,098
Less Accumulated Depreciation and Amortization	202,287		194,704
Net Nonelectric Property, Plant and Equipment	129,768		114,394
Net Property, Plant and Equipment	$	2,316,246	$	2,212,717

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Regulatory Matters (Tables)

6 Months Ended

Jun. 30, 2023

Regulatory Assets and Liabilities Disclosure [Abstract]

Schedule of Regulatory Assets and Liabilities

The following presents our current and long-term regulatory assets and liabilities as of June 30, 2023 and December 31, 2022 and the period we expect to recover or refund such amounts:

	Period of	June 30, 2023				December 31, 2022
(in thousands)	Recovery/Refund	Current		Long-Term		Current		Long-Term
Regulatory Assets
Pension and Other Postretirement Benefit Plans1	Various	$	—	$	90,602	$	—	$	88,354
Alternative Revenue Program Riders2	Up to 2 years	6,563		79		5,679		2,508
Asset Retirement Obligations1	Asset lives	—		2,327		—		1,467
Deferred Income Taxes	Asset lives	—		847		—		—
ISO Cost Recovery Trackers1	Up to 2 years	288		207		575		314
Unrecovered Project Costs1	Up to 4 years	349		1,048		320		990
Deferred Rate Case Expenses1	Up to 3 years	377		566		377		754
Fuel Clause Adjustments1	Up to 1 year	9,935		—		10,893		—
Derivative Instruments1	Up to 2 years	1,521		207		7,130		—
Other1	Various	25		245		25		268
Total Regulatory Assets		$	19,058	$	96,128	$	24,999	$	94,655
Regulatory Liabilities
Deferred Income Taxes	Asset lives	$	—	$	129,567	$	—	$	131,480
Plant Removal Obligations	Asset lives	8,474		106,393		8,509		105,733
Fuel Clause Adjustments	Up to 1 year	22,358		—		365		—
Alternative Revenue Program Riders	Up to 1 year	4,560		—		2,504		—
North Dakota PTC Refunds	Asset lives	—		9,512		—		7,136
Pension and Other Postretirement Benefit Plans	Up to 1 year	5,589		—		5,589		—
Other	Various	762		463		333		148
Total Regulatory Liabilities		$	41,743	$	245,935	$	17,300	$	244,497
1Costs subject to recovery without a rate of return.
2Amount eligible for recovery includes an incentive or rate of return.

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Short-Term and Long-Term Borrowings (Tables)

6 Months Ended

Jun. 30, 2023

Debt Disclosure [Abstract]

Schedule of Line of Credit Facilities

The following is a summary of our lines of credit as of June 30, 2023 and December 31, 2022:

			June 30, 2023						December 31, 2022
(in thousands)	Borrowing Limit		Amount Outstanding		Letters of Credit		Amount Available		Amount Available
OTC Credit Agreement	$	170,000	$	—	$	—	$	170,000	$	170,000
OTP Credit Agreement	170,000		50,197		9,573		110,230		152,223
Total	$	340,000	$	50,197	$	9,573	$	280,230	$	322,223

Schedule of Debt

The following is a summary of outstanding long-term debt by borrower as of June 30, 2023 and December 31, 2022: 

					(in thousands)
Borrower		Debt Instrument	Rate	Maturity	June 30, 2023		December 31, 2022
OTC		Guaranteed Senior Notes	3.55%	12/15/26	$	80,000	$	80,000
OTP		Series 2007C Senior Unsecured Notes	6.37%	08/02/27	42,000		42,000
OTP		Series 2013A Senior Unsecured Notes	4.68%	02/27/29	60,000		60,000
OTP		Series 2019A Senior Unsecured Notes	3.07%	10/10/29	10,000		10,000
OTP		Series 2020A Senior Unsecured Notes	3.22%	02/25/30	10,000		10,000
OTP		Series 2020B Senior Unsecured Notes	3.22%	08/20/30	40,000		40,000
OTP		Series 2021A Senior Unsecured Notes	2.74%	11/29/31	40,000		40,000
OTP		Series 2007D Senior Unsecured Notes	6.47%	08/20/37	50,000		50,000
OTP		Series 2019B Senior Unsecured Notes	3.52%	10/10/39	26,000		26,000
OTP		Series 2020C Senior Unsecured Notes	3.62%	02/25/40	10,000		10,000
OTP		Series 2013B Senior Unsecured Notes	5.47%	02/27/44	90,000		90,000
OTP		Series 2018A Senior Unsecured Notes	4.07%	02/07/48	100,000		100,000
OTP		Series 2019C Senior Unsecured Notes	3.82%	10/10/49	64,000		64,000
OTP		Series 2020D Senior Unsecured Notes	3.92%	02/25/50	15,000		15,000
OTP		Series 2021B Senior Unsecured Notes	3.69%	11/29/51	100,000		100,000
OTP		Series 2022A Senior Unsecured Notes	3.77%	05/20/52	90,000		90,000
Total					$	827,000	$	827,000
Less:	Unamortized Long-Term Debt Issuance Costs				3,059		3,179
Total Long-Term Debt, Net of Unamortized Debt Issuance Costs					$	823,941	$	823,821

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Employee Postretirement Benefits (Tables)

6 Months Ended

Jun. 30, 2023

Retirement Benefits [Abstract]

Schedule of Net Periodic Benefit Cost (Income)

The following table includes the components of net periodic benefit cost (income) related to our defined benefit pension plans and other postretirement benefits for the three and six months ended June 30, 2023 and 2022:

	Three Months Ended June 30,
	Pension Benefits (Pension Plan)				Pension Benefits (ESSRP)				Postretirement Benefits
(in thousands)	2023		2022		2023		2022		2023		2022
Service Cost	$	924	$	1,644	$	18	$	49	$	153	$	334
Interest Cost	4,109		3,086		473		336		669		511
Expected Return on Assets	(6,478)		(5,921)		—		—		—		—
Amortization of Prior Service Cost	—		—		—		—		(1,434)		(1,434)
Amortization of Net Actuarial Loss	—		1,967		—		142		—		766
Net Periodic Benefit Cost (Income)	$	(1,445)	$	776	$	491	$	527	$	(612)	$	177
	Six Months Ended June 30,
	Pension Benefits (Pension Plan)				Pension Benefits (ESSRP)				Postretirement Benefits
(in thousands)	2023		2022		2023		2022		2023		2022
Service Cost	$	1,849	$	3,288	$	36	$	98	$	306	$	669
Interest Cost	8,218		6,172		945		671		1,338		1,021
Expected Return on Assets	(12,957)		(11,842)		—		—		—		—
Amortization of Prior Service Cost	—		—		—		—		(2,867)		(2,867)
Amortization of Net Actuarial Loss	—		3,933		—		284		—		1,532
Net Periodic Benefit Cost (Income)	$	(2,890)	$	1,551	$	981	$	1,053	$	(1,223)	$	355

The following table includes the impact of regulation on the recognition of periodic benefit cost (income) arising from pension and other postretirement benefits for the three and six months ended June 30, 2023 and 2022:

	Three Months Ended June 30,				Six Months Ended June 30,
(in thousands)	2023		2022		2023		2022
Net Periodic Benefit Cost (Income)	$	(1,566)	$	1,480	$	(3,132)	$	2,959
Net Amount Amortized (Deferred) Due to the Effect of Regulation	240		(204)		490		324
Net Periodic Benefit Cost (Income) Recognized	$	(1,326)	$	1,276	$	(2,642)	$	3,283

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Income Taxes (Tables)

6 Months Ended

Jun. 30, 2023

Income Tax Disclosure [Abstract]

Schedule of Effective Income Tax Rate Reconciliation

The reconciliation of the statutory federal income tax rate to our effective tax rate for each of the three and six months ended June 30, 2023 and 2022 is as follows:

	Three Months Ended June 30,								Six Months Ended June 30,
	2023				2022				2023				2022
Income Taxes at Federal Statutory Rate	$	21,426	21.0	%	$	23,507	21.0	%	$	37,341	21.0	%	$	42,330	21.0	%
Increases (Decreases) in Tax from:
State Taxes on Income, Net of Federal Tax	5,104		5.0		5,596		5.0		8,893		5.0		10,078		5.0
Production Tax Credits (PTCs)	(4,574)		(4.5)		(4,719)		(4.2)		(9,229)		(5.2)		(8,686)		(4.3)
Amortization of Excess Deferred Income Taxes	(622)		(0.6)		99		—		(1,420)		(0.8)		(1,078)		(0.5)
North Dakota Wind Tax Credit Amortization, Net of Federal Tax	(146)		(0.1)		(155)		(0.1)		(310)		(0.2)		(355)		(0.2)
Corporate-Owned Life Insurance	(460)		(0.5)		965		0.8		(878)		(0.5)		1,142		0.6
Other, Net	(666)		(0.6)		707		0.7		(1,032)		(0.5)		199		—
Income Tax Expense / Effective Tax Rate	$	20,062	19.7	%	$	26,000	23.2	%	$	33,365	18.8	%	$	43,630	21.6	%

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Accumulated Other Comprehensive Income (Loss) (Tables)

6 Months Ended

Jun. 30, 2023

Equity [Abstract]

Schedule of Changes in Accumulated Other Comprehensive Loss

The following presents the changes in accumulated other comprehensive loss for the three and six months ended June 30, 2023 and 2022:

	Three Months Ended June 30,
	2023								2022
(in thousands)	Pension and Other Postretirement Benefits			Net Unrealized Gains (Losses) on Available-for-Sale Securities			Total		Pension and Other Postretirement Benefits			Net Unrealized Gains (Losses) on Available-for-Sale Securities			Total
Balance, Beginning of Period	$	1,308		$	(339)		$	969	$	(6,727)		$	(218)		$	(6,945)
Other Comprehensive Loss Before Reclassifications, net of tax	—			(62)			(62)		—			(75)			(75)
Amounts Reclassified from Accumulated Other Comprehensive Income (Loss)	(27)		(1)	1		(2)	(26)		106		(1)	1		(2)	107
Total Other Comprehensive Income (Loss)	(27)			(61)			(88)		106			(74)			32
Balance, End of Period	$	1,281		$	(400)		$	881	$	(6,621)		$	(292)		$	(6,913)
	Six Months Ended June 30,
	2023								2022
(in thousands)	Pension and Other Postretirement Benefits			Net Unrealized Gains (Losses) on Available-for-Sale Securities			Total		Pension and Other Postretirement Benefits			Net Unrealized Gains (Losses) on Available-for-Sale Securities			Total
Balance, Beginning of Period	$	1,334		$	(419)		$	915	$	(6,537)		$	13		$	(6,524)
Other Comprehensive Income (Loss) Before Reclassifications, net of tax	—			18			18		—			(306)			(306)
Amounts Reclassified from Accumulated Other Comprehensive Income (Loss)	(53)		(1)	1		(2)	(52)		(84)		(1)	1		(2)	(83)
Total Other Comprehensive Income (Loss)	(53)			19			(34)		(84)			(305)			(389)
Balance, End of Period	$	1,281		$	(400)		$	881	$	(6,621)		$	(292)		$	(6,913)
(1) Included in the computation of net periodic pension and other postretirement benefit costs. See Note 7.
(2) Included in other income (expense), net on the accompanying consolidated statements of income.

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Share-Based Payments (Tables)

6 Months Ended

Jun. 30, 2023

Share-Based Payment Arrangement [Abstract]

Summary of Nonvested Restricted Stock Shares Activity

The following is a summary of stock award activity for the six months ended June 30, 2023:

	Shares	Weighted-Average Grant-Date Fair Value
Nonvested, January 1, 2023	141,551	$	49.83
Granted	55,205	68.03
Vested	(45,493)	50.02
Forfeited	(1,300)	50.00
Nonvested, June 30, 2023	149,963	$	56.47

Schedule of Share-Based Payment Award, Employee Stock Purchase Plan, Valuation Assumptions

The grant date fair value of stock performance awards granted during the six months ended June 30, 2023 and 2022 was determined using a Monte Carlo fair value simulation model incorporating the following assumptions:

	2023		2022
Risk-free interest rate	4.15	%	1.52	%
Expected term (in years)	3		3
Expected volatility	34.00	%	32.00	%
Dividend yield	2.50	%	2.90	%

Schedule of Share-based Compensation Arrangements by Share-based Payment Award

The following is a summary of stock performance award activity for the six months ended June 30, 2023 (share amounts reflect awards at target):

	Shares	Weighted-Average Grant-Date Fair Value
Nonvested, January 1, 2023	189,800	$	45.95
Granted	59,400	61.97
Vested	(55,000)	47.79
Forfeited	—	—
Nonvested, June 30, 2023	194,200	$	50.33

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Earnings Per Share (Tables)

6 Months Ended

Jun. 30, 2023

Earnings Per Share [Abstract]

Schedule of Earnings Per Share, Basic and Diluted

The following includes the computation of the denominator for basic and diluted weighted-average shares outstanding for the three and six months ended June 30, 2023 and 2022:

	Three Months Ended June 30,		Six Months Ended June 30,
(in thousands)	2023	2022	2023	2022
Weighted-Average Common Shares Outstanding – Basic	41,678	41,597	41,655	41,573
Effect of Dilutive Securities:
Stock Performance Awards	281	259	281	239
Restricted Stock Awards	92	85	97	94
Employee Stock Purchase Plan Shares and Other	2	3	2	1
Dilutive Effect of Potential Common Shares	375	347	380	334
Weighted-Average Common Shares Outstanding – Diluted	42,053	41,944	42,035	41,907

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Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2023

Fair Value Disclosures [Abstract]

Schedule of Fair Value Measurements, Recurring and Nonrecurring

The following tables present our assets and liabilities measured at fair value on a recurring basis as of June 30, 2023 and December 31, 2022 classified by the input method used to measure fair value:

(in thousands)	Level 1		Level 2		Level 3
June 30, 2023
Assets:
Investments:
Money Market Funds	$	4,069	$	—	$	—
Mutual Funds	7,505		—		—
Corporate Debt Securities	—		1,456		—
Government-Backed and Government-Sponsored Enterprises’ Debt Securities	—		7,470		—
Total Assets	$	11,574	$	8,926	$	—
Liabilities:
Derivative Instruments	$	—	$	1,728	$	—
Total Liabilities	$	—	$	1,728	$	—
December 31, 2022
Assets:
Investments:
Money Market Funds	$	1,560	$	—	$	—
Mutual Funds	5,503		—		—
Corporate Debt Securities	—		1,434		—
Government-Backed and Government-Sponsored Enterprises’ Debt Securities	—		7,327		—
Total Assets	$	7,063	$	8,761	$	—
Liabilities:
Derivative Instruments	—		7,130		—
Total Liabilities	$	—	$	7,130	$	—

Schedule of Fair Value of Assets and Liabilities

The following reflects the carrying value and estimated fair value of these assets and liabilities as of June 30, 2023 and December 31, 2022:

	June 30, 2023				December 31, 2022
(in thousands)	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Assets:
Cash and Cash Equivalents	$	150,578	$	150,578	$	118,996	$	118,996
Total	150,578		150,578		118,996		118,996
Liabilities:
Short-Term Debt	50,197		50,197		8,204		8,204
Long-Term Debt	823,941		698,831		823,821		681,615
Total	$	874,138	$	749,028	$	832,025	$	689,819

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Summary of Significant Accounting Policies (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2023 USD ($) segment	Jun. 30, 2022 USD ($)
Accounting Policies [Abstract]
Number of operating segments | segment	3
Investment losses	$ (4,295)	$ 4,440
Allowance for equity funds used during construction		$ 600

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Segment Information - Narrative (Details)	6 Months Ended
	Jun. 30, 2023 segment
Segment Reporting [Abstract]
Number of reportable segments	3

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Segment Information - Schedule of Segment Reporting Information, by Segment (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022
Segment Reporting Information [Line Items]
Total Operating Revenues	$ 337,716	$ 400,040	$ 676,797	$ 774,944
Net Income (Loss)	81,969	85,937	144,450	157,940
Identifiable Assets	3,093,986		3,093,986		$ 2,901,661
Corporate
Segment Reporting Information [Line Items]
Net Income (Loss)	974	(4,435)	(313)	(6,596)
Identifiable Assets	210,173		210,173		177,513
Electric | Operating Segments
Segment Reporting Information [Line Items]
Total Operating Revenues	113,763	130,949	265,671	261,365
Net Income (Loss)	19,634	18,858	42,854	38,091
Identifiable Assets	2,446,293		2,446,293		2,351,961
Manufacturing | Operating Segments
Segment Reporting Information [Line Items]
Total Operating Revenues	102,475	103,196	209,257	208,154
Net Income (Loss)	5,969	7,555	12,831	11,639
Identifiable Assets	260,050		260,050		245,869
Plastics | Operating Segments
Segment Reporting Information [Line Items]
Total Operating Revenues	121,478	165,895	201,869	305,425
Net Income (Loss)	55,392	$ 63,959	89,078	$ 114,806
Identifiable Assets	$ 177,470		$ 177,470		$ 126,318

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Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Disaggregation of Revenue [Line Items]
Total Operating Revenues	$ 337,716	$ 400,040	$ 676,797	$ 774,944
Operating Segments
Disaggregation of Revenue [Line Items]
Total Operating Revenues from Contracts with Customers	338,050	404,968	678,342	782,332
Operating Segments | Electric
Disaggregation of Revenue [Line Items]
Total Operating Revenues	113,763	130,949	265,671	261,365
Electric Segment - ARP Revenues	(334)	(4,928)	(1,545)	(7,388)
Operating Segments | Manufacturing
Disaggregation of Revenue [Line Items]
Total Operating Revenues	102,475	103,196	209,257	208,154
Operating Segments | Plastics
Disaggregation of Revenue [Line Items]
Total Operating Revenues	121,478	165,895	201,869	305,425
Operating Segments | Total Retail | Electric
Disaggregation of Revenue [Line Items]
Total Operating Revenues	93,715	113,603	230,168	227,242
Operating Segments | Retail: Residential | Electric
Disaggregation of Revenue [Line Items]
Total Operating Revenues	26,974	33,011	70,951	73,743
Operating Segments | Retail: Commercial and Industrial | Electric
Disaggregation of Revenue [Line Items]
Total Operating Revenues	64,989	78,521	155,474	149,527
Operating Segments | Retail: Other | Electric
Disaggregation of Revenue [Line Items]
Total Operating Revenues	1,752	2,071	3,743	3,972
Operating Segments | Transmission | Electric
Disaggregation of Revenue [Line Items]
Total Operating Revenues	14,829	11,697	26,936	24,254
Operating Segments | Wholesale | Electric
Disaggregation of Revenue [Line Items]
Total Operating Revenues	2,670	3,537	4,508	6,000
Operating Segments | Other | Electric
Disaggregation of Revenue [Line Items]
Total Operating Revenues	2,549	2,112	4,059	3,869
Operating Segments | Metal Parts and Tooling | Manufacturing
Disaggregation of Revenue [Line Items]
Total Operating Revenues	89,396	88,296	179,463	177,869
Operating Segments | Plastic Products and Tooling | Manufacturing
Disaggregation of Revenue [Line Items]
Total Operating Revenues	10,068	11,416	24,211	23,860
Operating Segments | Scrap Metal Sales | Manufacturing
Disaggregation of Revenue [Line Items]
Total Operating Revenues	$ 3,011	$ 3,484	$ 5,583	$ 6,425

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Select Balance Sheet Information - Schedule of Receivables (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022	Jun. 30, 2022	Dec. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Trade	$ 166,267	$ 112,126
Other	11,183	9,983
Unbilled Receivables	19,715	23,932
Total Receivables	197,165	146,041
Less: Allowance for Credit Losses	2,214	1,648	$ 1,757	$ 1,836
Receivables, net of allowance for credit losses	$ 194,951	$ 144,393

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Select Balance Sheet Information - Summary of Activity in Allowance for Credit Losses (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance, January 1	$ 1,648	$ 1,836
Additions Charged to Expense	1,001	382
Reductions for Amounts Written Off, Net of Recoveries	(435)	(461)
Ending Balance, June 30	$ 2,214	$ 1,757

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Select Balance Sheet Information - Schedule of Inventories (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Raw Material, Fuel and Supplies	$ 73,314	$ 70,374
Work in Process	29,326	31,766
Finished Goods	41,801	43,812
Total Inventories	$ 144,441	$ 145,952

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Select Balance Sheet Information - Schedule of Investments (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Corporate-Owned Life Insurance Policies	$ 39,352	$ 38,991
Corporate and Government Debt Securities	8,926	8,761
Money Market Funds	4,069	1,560
Mutual Funds	7,505	5,503
Other Investments	30	30
Total Investments	$ 59,882	$ 54,845

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Select Balance Sheet Information - Schedule of Property, Plant and Equipment (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, net of accumulated depreciation	$ 2,316,246	$ 2,212,717
Electric Plant
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	3,074,852	2,958,311
Less Accumulated Depreciation and Amortization	888,374	859,988
Property, Plant and Equipment, net of accumulated depreciation	2,186,478	2,098,323
Nonelectric Property, Plant and Equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	332,055	309,098
Less Accumulated Depreciation and Amortization	202,287	194,704
Property, Plant and Equipment, net of accumulated depreciation	129,768	114,394
Electric Plant in Service | Electric Plant
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	2,933,603	2,844,379
Construction Work in Progress | Electric Plant
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	141,249	113,932
Construction Work in Progress | Nonelectric Property, Plant and Equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	34,147	15,170
Nonelectric Property, Plant and Equipment in Service | Nonelectric Property, Plant and Equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 297,908	$ 293,928

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Select Balance Sheet Information - Narrative (Details) - Ashtabula III Wind Farm $ in Millions	Jan. 03, 2023 USD ($) MWh windTurbine
Business Acquisition [Line Items]
Number of wind turbines | windTurbine	39
Wind farm, megawatts | MWh	62.4
Purchase price	$ 50.6
Asset retirement obligation	$ 3.3

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Regulatory Matters - Schedule of Regulatory Assets and Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory assets - current	$ 19,058	$ 24,999
Regulatory assets, long-term	96,128	94,655
Regulatory liabilities, current	41,743	17,300
Regulatory liabilities, long -term	245,935	244,497
Deferred Income Taxes
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory liabilities, current	0	0
Regulatory liabilities, long -term	129,567	131,480
Plant Removal Obligations
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory liabilities, current	8,474	8,509
Regulatory liabilities, long -term	106,393	105,733
Fuel Clause Adjustments
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory liabilities, current	22,358	365
Regulatory liabilities, long -term	$ 0	0
Regulatory liabilities - Remaining Recovery/Refund Period	1 year
Alternative Revenue Program Riders
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory liabilities, current	$ 4,560	2,504
Regulatory liabilities, long -term	$ 0	0
Regulatory liabilities - Remaining Recovery/Refund Period	1 year
North Dakota PTC Refunds
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory liabilities, current	$ 0	0
Regulatory liabilities, long -term	9,512	7,136
Pension and Other Postretirement Benefit Plans
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory liabilities, current	5,589	5,589
Regulatory liabilities, long -term	$ 0	0
Regulatory liabilities - Remaining Recovery/Refund Period	1 year
Other
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory liabilities, current	$ 762	333
Regulatory liabilities, long -term	463	148
Pension and Other Postretirement Benefit Plans
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory assets - current	0	0
Regulatory assets, long-term	90,602	88,354
Alternative Revenue Program Riders
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory assets - current	6,563	5,679
Regulatory assets, long-term	$ 79	2,508
Regulatory assets - Remaining Recovery/Refund Period	2 years
Asset Retirement Obligations
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory assets - current	$ 0	0
Regulatory assets, long-term	2,327	1,467
Deferred Income Taxes
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory assets - current	0	0
Regulatory assets, long-term	847	0
ISO Cost Recovery Trackers
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory assets - current	288	575
Regulatory assets, long-term	$ 207	314
Regulatory assets - Remaining Recovery/Refund Period	2 years
Unrecovered Project Costs
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory assets - current	$ 349	320
Regulatory assets, long-term	$ 1,048	990
Regulatory assets - Remaining Recovery/Refund Period	4 years
Deferred Rate Case Expenses
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory assets - current	$ 377	377
Regulatory assets, long-term	$ 566	754
Regulatory assets - Remaining Recovery/Refund Period	3 years
Fuel Clause Adjustments
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory assets - current	$ 9,935	10,893
Regulatory assets, long-term	$ 0	0
Regulatory assets - Remaining Recovery/Refund Period	1 year
Derivative Instruments
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory assets - current	$ 1,521	7,130
Regulatory assets, long-term	$ 207	0
Regulatory assets - Remaining Recovery/Refund Period	2 years
Other
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory assets - current	$ 25	25
Regulatory assets, long-term	$ 245	$ 268

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Short-Term and Long-Term Borrowings - Lines of Credit (Details) - USD ($)	Jun. 30, 2023	Dec. 31, 2022
Line of Credit Facility [Line Items]
Borrowing Limit	$ 340,000,000
Amount Outstanding	50,197,000	$ 8,204,000
Letters of Credit	9,573,000
Amount Available	280,230,000	322,223,000
OTC Credit Agreement
Line of Credit Facility [Line Items]
Borrowing Limit	170,000,000
Amount Outstanding	0
Letters of Credit	0
Amount Available	170,000,000	170,000,000
OTP Credit Agreement
Line of Credit Facility [Line Items]
Borrowing Limit	170,000,000
Amount Outstanding	50,197,000
Letters of Credit	9,573,000
Amount Available	$ 110,230,000	$ 152,223,000

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Short-Term and Long-Term Borrowings - Breakdown of Outstanding Long-term Debt (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Debt Instrument [Line Items]
Long-term debt	$ 827,000	$ 827,000
Less: Unamortized Long-Term Debt Issuance Costs	3,059	3,179
Total Long-Term Debt, Net of Unamortized Debt Issuance Costs	$ 823,941	823,821
Guaranteed Senior Notes
Debt Instrument [Line Items]
Rate	3.55%
Long-term debt	$ 80,000	80,000
Series 2007C Senior Unsecured Notes
Debt Instrument [Line Items]
Rate	6.37%
Long-term debt	$ 42,000	42,000
Series 2013A Senior Unsecured Notes
Debt Instrument [Line Items]
Rate	4.68%
Long-term debt	$ 60,000	60,000
Series 2019A Senior Unsecured Notes
Debt Instrument [Line Items]
Rate	3.07%
Long-term debt	$ 10,000	10,000
Series 2020A Senior Unsecured Notes
Debt Instrument [Line Items]
Rate	3.22%
Long-term debt	$ 10,000	10,000
Series 2020B Senior Unsecured Notes
Debt Instrument [Line Items]
Rate	3.22%
Long-term debt	$ 40,000	40,000
Series 2021A Senior Unsecured Notes
Debt Instrument [Line Items]
Rate	2.74%
Long-term debt	$ 40,000	40,000
Series 2007D Senior Unsecured Notes
Debt Instrument [Line Items]
Rate	6.47%
Long-term debt	$ 50,000	50,000
Series 2019B Senior Unsecured Notes
Debt Instrument [Line Items]
Rate	3.52%
Long-term debt	$ 26,000	26,000
Series 2020C Senior Unsecured Notes
Debt Instrument [Line Items]
Rate	3.62%
Long-term debt	$ 10,000	10,000
Series 2013B Senior Unsecured Notes
Debt Instrument [Line Items]
Rate	5.47%
Long-term debt	$ 90,000	90,000
Series 2018A Senior Unsecured Notes
Debt Instrument [Line Items]
Rate	4.07%
Long-term debt	$ 100,000	100,000
Series 2019C Senior Unsecured Notes
Debt Instrument [Line Items]
Rate	3.82%
Long-term debt	$ 64,000	64,000
Series 2020D Senior Unsecured Notes
Debt Instrument [Line Items]
Rate	3.92%
Long-term debt	$ 15,000	15,000
Series 2021B Senior Unsecured Notes
Debt Instrument [Line Items]
Rate	3.69%
Long-term debt	$ 100,000	100,000
Series 2022A Senior Unsecured Notes
Debt Instrument [Line Items]
Rate	3.77%
Long-term debt	$ 90,000	$ 90,000

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Short-Term and Long-Term Borrowings - Narrative (Details)	Jun. 30, 2023
Maximum
Debt Instrument [Line Items]
Debt to total capitalization ratio	60.00%
Minimum
Debt Instrument [Line Items]
Interest and dividend coverage ratio	1.50

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Employee Postretirement Benefits - Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Defined Benefit Plan Disclosure [Line Items]
Net Periodic Benefit Cost (Income)	$ (1,566)	$ 1,480	$ (3,132)	$ 2,959
Pension Benefits (Pension Plan)
Defined Benefit Plan Disclosure [Line Items]
Service Cost	924	1,644	1,849	3,288
Interest Cost	4,109	3,086	8,218	6,172
Expected Return on Assets	(6,478)	(5,921)	(12,957)	(11,842)
Amortization of Prior Service Cost	0	0	0	0
Amortization of Net Actuarial Loss	0	1,967	0	3,933
Net Periodic Benefit Cost (Income)	(1,445)	776	(2,890)	1,551
Pension Benefits (ESSRP)
Defined Benefit Plan Disclosure [Line Items]
Service Cost	18	49	36	98
Interest Cost	473	336	945	671
Expected Return on Assets	0	0	0	0
Amortization of Prior Service Cost	0	0	0	0
Amortization of Net Actuarial Loss	0	142	0	284
Net Periodic Benefit Cost (Income)	491	527	981	1,053
Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service Cost	153	334	306	669
Interest Cost	669	511	1,338	1,021
Expected Return on Assets	0	0	0	0
Amortization of Prior Service Cost	(1,434)	(1,434)	(2,867)	(2,867)
Amortization of Net Actuarial Loss	0	766	0	1,532
Net Periodic Benefit Cost (Income)	$ (612)	$ 177	$ (1,223)	$ 355

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Employee Postretirement Benefits - Composition of Periodic Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Retirement Benefits [Abstract]
Net Periodic Benefit Cost (Income)	$ (1,566)	$ 1,480	$ (3,132)	$ 2,959
Net Amount Amortized (Deferred) Due to the Effect of Regulation	240	(204)	490	324
Net Periodic Benefit Cost (Income) Recognized	$ (1,326)	$ 1,276	$ (2,642)	$ 3,283

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Employee Postretirement Benefits - Narrative (Details) - USD ($)	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Contributions by employer	$ 0	$ 20,000,000

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Income Taxes - Effective Income Tax Rate (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Income Tax Disclosure [Abstract]
Income Taxes at Federal Statutory Rate	$ 21,426	$ 23,507	$ 37,341	$ 42,330
Income Taxes at Federal Statutory Rate	21.00%	21.00%	21.00%	21.00%
Increases (Decreases) in Tax from:
State Taxes on Income, Net of Federal Tax	$ 5,104	$ 5,596	$ 8,893	$ 10,078
Production Tax Credits (PTCs)	(4,574)	(4,719)	(9,229)	(8,686)
Amortization of Excess Deferred Income Taxes	(622)	99	(1,420)	(1,078)
North Dakota Wind Tax Credit Amortization, Net of Federal Tax	(146)	(155)	(310)	(355)
Corporate-Owned Life Insurance	(460)	965	(878)	1,142
Other, Net	(666)	707	(1,032)	199
Income Tax Expense / Effective Tax Rate	$ 20,062	$ 26,000	$ 33,365	$ 43,630
Increases (Decreases) in Tax from:
State Taxes on Income, Net of Federal Tax	5.00%	5.00%	5.00%	5.00%
Production Tax Credits (PTCs)	(4.50%)	(4.20%)	(5.20%)	(4.30%)
Amortization of Excess Deferred Income Taxes	(0.60%)	0.00%	(0.80%)	(0.50%)
North Dakota Wind Tax Credit Amortization, Net of Federal Tax	(0.10%)	(0.10%)	(0.20%)	(0.20%)
Corporate-Owned Life Insurance	(0.50%)	0.80%	(0.50%)	0.60%
Other, Net	(0.60%)	0.70%	(0.50%)	0.00%
Income Tax Expense / Effective Tax Rate	19.70%	23.20%	18.80%	21.60%

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Commitments and Contingencies (Details) $ in Millions	Jan. 03, 2023 USD ($) landEasement	Jun. 30, 2023 USD ($)
Ashtabula III Wind Farm
Other Commitments [Line Items]
Purchase price	$ 50.6
Otter Tail Power Company | Federal Energy Regulatory Commission
Other Commitments [Line Items]
Estimated liability of refund obligation		$ 2.7
Otter Tail Power Company | Ashtabula III Wind Farm
Other Commitments [Line Items]
Purchase price	$ 50.6
Otter Tail Power Company | Ashtabula III Wind Farm | Land Easement Payments
Other Commitments [Line Items]
Number of land easements | landEasement	51
Remaining payments under easements		$ 4.1

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Stockholders' Equity (Details) - USD ($) $ in Thousands			6 Months Ended
	Nov. 08, 2022	May 03, 2021	Jun. 30, 2023	Dec. 31, 2022
Class of Stock [Line Items]
Total capitalization			$ 2,152,380	$ 2,041,138
Otter Tail Power Company
Class of Stock [Line Items]
Equity to total capitalization ratio			53.80%
Net assets restricted from distribution			$ 778,600
Minimum | Otter Tail Power Company | Minnesota Public Utilities Commission
Class of Stock [Line Items]
Public utilities, requested equity capital structure, percentage	47.50%
Maximum | Otter Tail Power Company
Class of Stock [Line Items]
Total capitalization			$ 1,800,000
Maximum | Otter Tail Power Company | Minnesota Public Utilities Commission
Class of Stock [Line Items]
Public utilities, requested equity capital structure, percentage	58.00%
Second Shelf Registration
Class of Stock [Line Items]
Shelf registration (in shares)		1,500,000
Number of shares issued (in shares)			56,311
Number of shares available for grant (in shares)			1,194,682

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Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 1,263,777	$ 1,047,138	$ 1,217,317	$ 990,777
Other Comprehensive Income (Loss) Before Reclassifications, net of tax	(62)	(75)	18	(306)
Amounts Reclassified from Accumulated Other Comprehensive Income (Loss)	(26)	107	(52)	(83)
Total Other Comprehensive Income (Loss)	(88)	32	(34)	(389)
Ending balance	1,328,439	1,116,543	1,328,439	1,116,543
Pension and Other Postretirement Benefits
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	1,308	(6,727)	1,334	(6,537)
Other Comprehensive Income (Loss) Before Reclassifications, net of tax	0	0	0	0
Amounts Reclassified from Accumulated Other Comprehensive Income (Loss)	(27)	106	(53)	(84)
Total Other Comprehensive Income (Loss)	(27)	106	(53)	(84)
Ending balance	1,281	(6,621)	1,281	(6,621)
Net Unrealized Gains (Losses) on Available-for-Sale Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(339)	(218)	(419)	13
Other Comprehensive Income (Loss) Before Reclassifications, net of tax	(62)	(75)	18	(306)
Amounts Reclassified from Accumulated Other Comprehensive Income (Loss)	1	1	1	1
Total Other Comprehensive Income (Loss)	(61)	(74)	19	(305)
Ending balance	(400)	(292)	(400)	(292)
Accumulated Other Comprehensive Income (Loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	969	(6,945)	915	(6,524)
Total Other Comprehensive Income (Loss)	(88)	32	(34)	(389)
Ending balance	$ 881	$ (6,913)	$ 881	$ (6,913)

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Share-Based Payments - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based payment arrangement, expense	$ 1.2	$ 0.6	$ 6.5	$ 5.5
Restricted Stock Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards vesting period			4 years
Fair value of awards vested			$ 3.1	3.0
Restricted Stock Awards | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period			3 years
Restricted Stock Awards | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period			4 years
Stock Performance Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period			3 years
Fair value of awards vested			$ 5.3	$ 5.1
Stock Performance Awards | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of target amount as actual payment			0.00%
Stock Performance Awards | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of target amount as actual payment			150.00%

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Share-Based Payments - Summary of Restricted Stock Awards and Stock Performance Awards (Details)	6 Months Ended
	Jun. 30, 2023 $ / shares shares
Restricted Stock Awards
Shares
Beginning of year (in shares) | shares	141,551
Granted (in shares) | shares	55,205
Vested (in shares) | shares	(45,493)
Forfeited (in shares) | shares	(1,300)
End of year (in shares) | shares	149,963
Weighted-Average Grant-Date Fair Value
Beginning of year (in dollars per share) | $ / shares	$ 49.83
Granted (in dollars per share) | $ / shares	68.03
Vested (in dollars per share) | $ / shares	50.02
Forfeited (in dollars per share) | $ / shares	50.00
End of year (in dollars per share) | $ / shares	$ 56.47
Stock Performance Awards
Shares
Beginning of year (in shares) | shares	189,800
Granted (in shares) | shares	59,400
Vested (in shares) | shares	(55,000)
Forfeited (in shares) | shares	0
End of year (in shares) | shares	194,200
Weighted-Average Grant-Date Fair Value
Beginning of year (in dollars per share) | $ / shares	$ 45.95
Granted (in dollars per share) | $ / shares	61.97
Vested (in dollars per share) | $ / shares	47.79
Forfeited (in dollars per share) | $ / shares	0
End of year (in dollars per share) | $ / shares	$ 50.33

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Share-Based Payments - Weighted-Average Assumptions (Details) - Stock Performance Awards	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	4.15%	1.52%
Expected term (in years)	3 years	3 years
Expected volatility	34.00%	32.00%
Dividend yield	2.50%	2.90%

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Earnings Per Share (Details) - shares shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Weighted-Average Common Shares Outstanding – Basic (in shares)	41,678	41,597	41,655	41,573
Effect of Dilutive Securities:
Total Dilutive Shares (in shares)	375	347	380	334
Weighted-Average Common Shares Outstanding – Diluted (in shares)	42,053	41,944	42,035	41,907
Stock Performance Awards
Effect of Dilutive Securities:
Effect of Dilutive Securities (in shares)	281	259	281	239
Restricted Stock Awards
Effect of Dilutive Securities:
Effect of Dilutive Securities (in shares)	92	85	97	94
Employee Stock Purchase Plan Shares and Other
Effect of Dilutive Securities:
Effect of Dilutive Securities (in shares)	2	3	2	1

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Derivative Instruments (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2023 USD ($)	Jun. 30, 2022 USD ($)	Jun. 30, 2023 USD ($) MWh	Jun. 30, 2022 USD ($)	Dec. 31, 2022 USD ($)
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Current derivative liability	$ 1,700,000		$ 1,700,000		$ 7,100,000
Other Current Liabilities
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative liability	1,500,000		1,500,000
Other Noncurrent Liabilities
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative liability	200,000		$ 200,000
Swap
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional amount of outstanding swap agreements | MWh			195,400
Gain (loss) on derivatives, net	$ 0	$ 0	$ (16,000,000)	$ 2,800,000

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Fair Value Measurements - Schedule of Fair Value Measurements, Recurring and Nonrecurring (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Investments:
Corporate and Government Debt Securities	$ 8,926	$ 8,761
Level 1 | Fair Value, Recurring
Investments:
Money Market Funds	4,069	1,560
Mutual Funds	7,505	5,503
Total Assets	11,574	7,063
Liabilities:
Derivative Instruments	0	0
Total Liabilities	0	0
Level 1 | Fair Value, Recurring | Corporate Debt Securities
Investments:
Corporate and Government Debt Securities	0	0
Level 1 | Fair Value, Recurring | Government-Backed and Government-Sponsored Enterprises’ Debt Securities
Investments:
Corporate and Government Debt Securities	0	0
Level 2 | Fair Value, Recurring
Investments:
Money Market Funds	0	0
Mutual Funds	0	0
Total Assets	8,926	8,761
Liabilities:
Derivative Instruments	1,728	7,130
Total Liabilities	1,728	7,130
Level 2 | Fair Value, Recurring | Corporate Debt Securities
Investments:
Corporate and Government Debt Securities	1,456	1,434
Level 2 | Fair Value, Recurring | Government-Backed and Government-Sponsored Enterprises’ Debt Securities
Investments:
Corporate and Government Debt Securities	7,470	7,327
Level 3 | Fair Value, Recurring
Investments:
Money Market Funds	0	0
Mutual Funds	0	0
Total Assets	0	0
Liabilities:
Derivative Instruments	0	0
Total Liabilities	0	0
Level 3 | Fair Value, Recurring | Corporate Debt Securities
Investments:
Corporate and Government Debt Securities	0	0
Level 3 | Fair Value, Recurring | Government-Backed and Government-Sponsored Enterprises’ Debt Securities
Investments:
Corporate and Government Debt Securities	$ 0	$ 0

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Fair Value Measurements - Schedule of Fair Value of Assets and Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Carrying Amount
Assets:
Cash and Cash Equivalents	$ 150,578	$ 118,996
Total Assets	150,578	118,996
Liabilities:
Short-Term Debt	50,197	8,204
Long-Term Debt	823,941	823,821
Total	874,138	832,025
Fair Value
Assets:
Cash and Cash Equivalents	150,578	118,996
Total Assets	150,578	118,996
Liabilities:
Short-Term Debt	50,197	8,204
Long-Term Debt	698,831	681,615
Total	$ 749,028	$ 689,819