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) | ||||
| 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 | ||||||
Large Accelerated Filer ☑ | Accelerated Filer ☐ | ||||||||||||||||
Non-Accelerated Filer ☐ | Smaller Reporting Company ☐ | Emerging Growth Company ☐ | |||||||||||||||
| TABLE OF CONTENTS | |||||||||||
| Description | Page | |||||||
| ITEM 1. | ||||||||
| ITEM 1A. | ||||||||
| ITEM 1B. | ||||||||
| ITEM 1C. | ||||||||
| ITEM 2. | ||||||||
| ITEM 3. | ||||||||
| ITEM 3A. | Information About Our Executive Officers (as of February 19, 2025) | |||||||
| ITEM 4. | ||||||||
| ITEM 5. | ||||||||
| ITEM 6. | ||||||||
| ITEM 7. | ||||||||
| ITEM 7A. | ||||||||
| ITEM 8. | ||||||||
Report of Independent Registered Public Accounting Firm (PCAOB ID No. 34) | ||||||||
| ITEM 9. | ||||||||
| ITEM 9A. | ||||||||
| ITEM 9B. | ||||||||
| ITEM 9C. | ||||||||
| ITEM 10. | ||||||||
| ITEM 11. | ||||||||
| ITEM 12. | ||||||||
| ITEM 13. | ||||||||
| ITEM 14. | ||||||||
| ITEM 15. | ||||||||
| ITEM 16. | ||||||||
| DEFINITIONS | |||||||||||
ADP | Advanced Determination of Prudence | kV | kiloVolt | |||||||||||
| AFUDC | Allowance for Funds Used During Construction | kW | kiloWatt | |||||||||||
| AME | Available Maximum Energy | kwh | kilowatt-hour | |||||||||||
| ARO | Asset Retirement Obligation | LSA | Lignite Sales Agreement | |||||||||||
| ARP | Alternative Revenue Program | MDT | Metering and Distribution Technology | |||||||||||
| ASC | Accounting Standards Codification | MISO | Midcontinent Independent System Operator | |||||||||||
BSER | Best System of Emission Reduction | MPUC | Minnesota Public Utilities Commission | |||||||||||
| BTD | BTD Manufacturing, Inc. | MW | Megawatt | |||||||||||
| CCMC | Coyote Creek Mining Company, L.L.C. | NAV | Net Asset Value | |||||||||||
CCR | Coal Combustion Residual | NDDEQ | North Dakota Department of Environmental Quality | |||||||||||
| CDD | Cooling Degree Day | NDPSC | North Dakota Public Service Commission | |||||||||||
| CIS | Center for Information Security | NERC | North American Electric Reliability Corporation | |||||||||||
CO2 | Carbon dioxide | Northern Pipe | Northern Pipe Products, Inc. | |||||||||||
CODM | Chief Operating Decision Maker | NOx | Nitrogen Oxides | |||||||||||
| COSO | Committee of Sponsoring Organizations of the Treadway Commission | OTC | Otter Tail Corporation | |||||||||||
DOE | U.S. Department of Energy | OTP | Otter Tail Power Company | |||||||||||
DOJ | U.S. Department of Justice | PFAS | Polyfluoroalkyl substances | |||||||||||
| ECO | Energy Conservation and Optimization Rider | PIR | Phase-in Rider | |||||||||||
| EEI | Edison Electric Institute | PSLRA | Private Securities Litigation Reform Act of 1995 | |||||||||||
| EEP | Energy Efficiency Plan | PTCs | Production tax credits | |||||||||||
| EPA | Environmental Protection Agency | PVC | Polyvinyl chloride | |||||||||||
| ERISA | Employee Retirement Income Security Act of 1974 | RHR | Regional Haze Rule | |||||||||||
| ESSRP | Executive Survivor and Supplemental Retirement Plan | ROE | Return on equity | |||||||||||
| EUIC | Electric Utility Infrastructure Costs Rider | REC | Renewable Energy Certificate | |||||||||||
| FASB | Financial Accounting Standards Board | RRR | Renewable Resource Rider | |||||||||||
| FCA | Fuel Clause Adjustment | RTOs | Regional Transmission Organizations | |||||||||||
| FERC | Federal Energy Regulatory Commission | SDPUC | South Dakota Public Utilities Commission | |||||||||||
| FOB | Free on Board | SEC | Securities and Exchange Commission | |||||||||||
| GCR | Generation Cost Recovery Rider | SIP | State Implementation plan | |||||||||||
| GHG | Greenhouse Gas | SO2 | Sulfur Dioxide | |||||||||||
| HDD | Heating Degree Day | SOFR | Secured Overnight Financing Rate | |||||||||||
HDPE | High-Density Polyethylene | SPP | Southwest Power Pool | |||||||||||
| ICSP | Information and Cybersecurity Program | T.O. Plastics | T.O. Plastics, Inc. | |||||||||||
| IRP | Integrated Resource Plan | TCR | Transmission Cost Recovery Rider | |||||||||||
IT | Information Technology | TSR | Total Shareholder Return | |||||||||||
ITC | Investment Tax Credits | VIE | Variable Interest Entity | |||||||||||
JTIQ | Joint Targeted Interconnection Queue | Vinyltech | Vinyltech Corporation | |||||||||||
| WHERE TO FIND MORE INFORMATION | ||||||||
| FORWARD-LOOKING INFORMATION | ||
| ITEM 1. | BUSINESS | |||||||||||||
| ELECTRIC SEGMENT | MANUFACTURING SEGMENT | PLASTICS SEGMENT | ||||||||||||
| Otter Tail Power Company (OTP) | BTD Manufacturing, Inc. (BTD) | Northern Pipe Products, Inc. (Northern Pipe) | ||||||||||||
| T.O. Plastics, Inc. (T.O. Plastics) | Vinyltech Corporation (Vinyltech) | |||||||||||||

| Segment/Organization | Employees | ||||
| Electric Segment | |||||
OTP (1) | 798 | ||||
| Manufacturing Segment | |||||
| BTD | 960 | ||||
| T.O. Plastics | 162 | ||||
| Segment Total | 1,122 | ||||
| Plastics Segment | |||||
| Northern Pipe | 93 | ||||
| Vinyltech | 82 | ||||
| Segment Total | 175 | ||||
| Corporate | 38 | ||||
| Total | 2,133 | ||||
(1) Includes all full-time employees of Otter Tail Power Company, including employees working at jointly owned facilities. Labor costs associated with employees working at jointly owned facilities are allocated to each of the co-owners based on their ownership interest. | |||||
| ELECTRIC | Contribution to Operating Revenues: 39% (2024), 39% (2023), 38% (2022) | ||||


| Revenue per kwh | 2024 | 2023 | |||||||||
| Residential | 11.38 | ¢ | 10.82 | ¢ | |||||||
| Commercial & Industrial | 7.03 | ¢ | 7.02 | ¢ | |||||||
| Total Retail | 7.98 | ¢ | 7.90 | ¢ | |||||||
| Capacity / Purchased Power in kW | ||||||||
| Owned Generation: | ||||||||
| Baseload Plants | ||||||||
Big Stone Plant(1) | 264,700 | |||||||
Coyote Station(2) | 151,200 | |||||||
| Total Baseload Plants | 415,900 | |||||||
| Combustion Turbine and Small Diesel Units | ||||||||
| Astoria Station | 288,800 | |||||||
Solway | 50,000 | |||||||
| All Other | 77,900 | |||||||
| Total Combustion Turbine and Small Diesel Units | 416,700 | |||||||
| Owned Wind Facilities (rated at nameplate) | ||||||||
| Merricourt | 150,000 | |||||||
| Ashtabula III | 62,400 | |||||||
| Luverne | 49,500 | |||||||
| Ashtabula | 48,000 | |||||||
| Langdon | 40,500 | |||||||
| Total Owned Wind Facilities | 350,400 | |||||||
Hoot Lake Solar (rated at nameplate) | 49,900 | |||||||
| Hydroelectric Facilities | 1,000 | |||||||
| Total Owned Generation Capacity | 1,233,900 | |||||||
Power Purchase Agreements: | ||||||||
| Purchased Wind Power (rated at nameplate and greater than 2,000 kW) | ||||||||
| Edgeley | 21,000 | |||||||
| Langdon | 19,500 | |||||||
| Total Purchased Wind | 40,500 | |||||||
| Total Generating Capacity | 1,274,400 | |||||||
(1) Reflects OTP's 53.9% ownership percentage of jointly owned facility. | ||||||||
(2) Reflects OTP's 35.0% ownership percentage of jointly owned facility. | ||||||||



| Regulatory | ||||||||
| Agency | Areas of Regulation | |||||||
| Minnesota Public Utilities Commission (MPUC) | Retail rates, issuance of securities, depreciation rates, capital structure, public utility services, construction of major facilities, establishment of exclusive assigned service areas, contracts with subsidiaries and other affiliated interests and other matters. Selection or designation of sites for new generating plants (50,000 kW or more) and routes for transmission lines (100 kV or more). Review and approval of fifteen-year Integrated Resource Plan. | |||||||
| North Dakota Public Service Commission (NDPSC) | Retail rates, certain issuances of securities, construction of major utility facilities and other matters. Approval of site and routes for new electric generating facilities (>500 kW for wind generating facilities; >50,000 kW for non-wind generating facilities) and high voltage transmission lines (>115 kV). Review and approval of fifteen-year Integrated Resource Plan. | |||||||
| South Dakota Public Utilities Commission (SDPUC) | Retail rates, public utility services, construction of major facilities, establishment of assigned service areas and other matters. Approval of sites and routes for new electric generating facilities (100,000 kW or more) and most transmission lines (115 kV or more). | |||||||
| Federal Energy Regulatory Commission (FERC) | Wholesale electricity sales, transmission and sale of electric energy in interstate commerce, interconnection of facilities, hydroelectric licensing and accounting policies and practices. Compliance with North American Electric Reliability Corporation (NERC) reliability standards, including standards on cybersecurity and protection of critical infrastructure. | |||||||
| Recovery Mechanism | Jurisdiction(s) | Additional Information | ||||||||||||
| Fuel Clause Adjustment (FCA) | MN, ND, SD | Provides for periodic billing adjustments for changes in prudently incurred costs of fuel and purchased power. In North and South Dakota, fuel and purchased power costs are generally adjusted on a monthly basis. In Minnesota, fuel and purchased power costs are estimated on an annual basis and the accumulated difference between actual and estimated cost is refunded or recovered, subject to regulatory approval, in subsequent periods. | ||||||||||||
| Transmission Cost Recovery Rider (TCR) | MN, ND, SD | Provides for the recovery of costs outside of a general rate case for investments in new or modified electric transmission assets and certain MISO transmission service and related costs. | ||||||||||||
| Renewable Resource Rider (RRR) | MN, ND | Provides for the recovery of costs outside of a general rate case for investments in certain new renewable energy projects. | ||||||||||||
| Energy Conservation and Optimization Rider (ECO) | MN | Under Minnesota law, OTP is required to save 1.75% of its gross retail energy revenues through the energy conservation and optimization program. Recovery of these costs outside of a general rate case occurs through the ECO rider. | ||||||||||||
| Electric Utility Infrastructure Costs Rider (EUIC) | MN | Provides for the recovery of costs for investments made to replace or modify existing infrastructure if the replacement or modification conserves energy or uses energy more efficiently. | ||||||||||||
| Metering and Distribution Technology Cost Recovery Rider (MDT) | ND | Provides for the recovery of costs for advanced metering infrastructure, outage management systems and demand response projects. | ||||||||||||
| Generation Cost Recovery Rider (GCR) | ND | Provides for the recovery of costs outside of a general rate case for investments in new generation facilities. | ||||||||||||
| Energy Efficiency Plan (EEP) | SD | Provides for the recovery of costs from energy efficiency investments. | ||||||||||||
| Phase-In Rider (PIR) | SD | Provides for the recovery of costs outside of a general rate case for investments in new generation facilities and advanced grid infrastructure. | ||||||||||||
| MANUFACTURING | Contribution to Operating Revenues: 26% (2024), 30% (2023), 27% (2022) | ||||

| PLASTICS | Contribution to Operating Revenues: 35% (2024), 31% (2023), 35% (2022) | ||||

| ITEM 1A. | RISK FACTORS | |||||||||||||
| ITEM 1B. | UNRESOLVED STAFF COMMENTS | ||||||||||
| ITEM 1C. | CYBERSECURITY | ||||||||||
| ITEM 2. | PROPERTIES | |||||||||||||
| Description | Location | Year Placed in Service | Fuel Type | Capacity - kW (Nameplate Rating) | ||||||||||
Big Stone Plant(1) | Big Stone City, SD | 1975 | Subbituminous Coal | 223,146 | ||||||||||
Coyote Station(2) | Beulah, ND | 1981 | Lignite Coal | 144,900 | ||||||||||
| Jamestown Combustion Turbines | Jamestown, ND | 1975 | Fuel Oil | 48,108 | ||||||||||
| Lake Preston Combustion Turbine | Lake Preston, SD | 1978 | Fuel Oil | 24,100 | ||||||||||
| Solway Combustion Turbine | Solway, MN | 2003 | Natural Gas/Fuel Oil | 44,500 | ||||||||||
| Astoria Station | Astoria, SD | 2021 | Natural Gas | 245,000 | ||||||||||
| Langdon Wind Energy Center | Cavalier County, ND | 2007 | Wind | 40,500 | ||||||||||
| Ashtabula Wind Energy Center | Barnes County, ND | 2008 | Wind | 48,000 | ||||||||||
| Luverne Wind Energy Center | Griggs and Steele Counties, ND | 2009 | Wind | 49,500 | ||||||||||
| Merricourt Wind Energy Center | McIntosh and Dickey Counties, ND | 2020 | Wind | 150,000 | ||||||||||
Ashtabula III Wind Energy Center(3) | Barnes County, ND | 2023 | Wind | 62,400 | ||||||||||
| Hoot Lake Solar | Otter Tail County, MN | 2023 | Solar | 49,900 | ||||||||||
(1) OTP holds a 53.9% joint ownership interest in this jointly owned facility. The nameplate capacity indicated reflects OTP's ownership percentage. | ||||||||||||||
(2) OTP holds a 35.0% joint ownership interest in this jointly owned facility. The nameplate capacity indicated reflects OTP's ownership percentage. | ||||||||||||||
(3) Originally placed in service in 2010 and owned by an unrelated third party. OTP acquired this facility in 2023. | ||||||||||||||
| Segment/Location | Owned/Leased | Facility Type/Use | Approximate Square Feet | ||||||||
| Manufacturing Segment | |||||||||||
| Otsego, MN | Leased | Manufacturing/Warehouse | 86,000 | ||||||||
| Clearwater, MN | Owned | Office/Manufacturing/Warehouse | 204,000 | ||||||||
| Washington, IL | Leased | Office/Manufacturing/Warehouse | 218,000 | ||||||||
Sauk Rapids, MN | Leased | Warehouse | 278,000 | ||||||||
| Dawsonville, GA | Owned | Office/Manufacturing/Warehouse | 334,000 | ||||||||
| Detroit Lakes, MN | Owned | Office/Manufacturing/Warehouse | 354,000 | ||||||||
| Lakeville, MN | Leased | Office/Manufacturing/Warehouse | 413,000 | ||||||||
| Plastics Segment | |||||||||||
| Fargo, ND | Owned | Office/Manufacturing/Warehouse | 122,000 | ||||||||
| Phoenix, AZ | Owned | Office/Manufacturing/Warehouse | 149,000 | ||||||||
| ITEM 3. | LEGAL PROCEEDINGS | ||||||||||
| ITEM 3A. | INFORMATION ABOUT OUR EXECUTIVE OFFICERS | |||||||
| Name and Age | Date Elected to Office | Current Position | ||||||
| Charles S. MacFarlane (60) | 04/13/15 | President and Chief Executive Officer | ||||||
| Todd R. Wahlund (54) | 01/01/24 | Vice President, Chief Financial Officer | ||||||
| Timothy J. Rogelstad (58) | 04/14/14 | Senior Vice President, Electric Platform | ||||||
| John S. Abbott (66) | 02/11/15 | Senior Vice President, Manufacturing Platform | ||||||
| Jennifer O. Smestad (54) | 01/01/18 | Vice President, General Counsel and Corporate Secretary | ||||||
| ITEM 4. | MINE SAFETY DISCLOSURES | ||||||||||
| ITEM 5. | MARKET FOR THE REGISTRANT'S COMMON EQUITY, RELATED STOCKHOLDER MATTERS AND ISSUER PURCHASES OF EQUITY SECURITIES | ||||

| 2019 | 2020 | 2021 | 2022 | 2023 | 2024 | ||||||||||||||||||||||||||||||
| OTTR | $ | 100.00 | $ | 85.52 | $ | 147.06 | $ | 125.37 | $ | 185.62 | $ | 166.48 | |||||||||||||||||||||||
| EEI | $ | 100.00 | $ | 98.84 | $ | 115.76 | $ | 117.09 | $ | 106.90 | $ | 127.32 | |||||||||||||||||||||||
| Nasdaq | $ | 100.00 | $ | 121.27 | $ | 152.67 | $ | 122.55 | $ | 154.93 | $ | 192.86 | |||||||||||||||||||||||
| ITEM 6. | [RESERVED] | ||||
| ITEM 7. | MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS | ||||
| OVERVIEW | |||||
| FINANCIAL AND OTHER METRICS | |||||
| RESULTS OF OPERATIONS | |||||
| (in thousands) | 2024 | 2023 | $ change | % change | |||||||||||||||||||
| Operating Revenues | $ | 1,330,548 | $ | 1,349,166 | $ | (18,618) | (1.4) | % | |||||||||||||||
| Operating Expenses | 950,298 | 971,247 | (20,949) | (2.2) | |||||||||||||||||||
| Operating Income | 380,250 | 377,919 | 2,331 | 0.6 | |||||||||||||||||||
| Interest Expense | (41,815) | (37,677) | (4,138) | 11.0 | |||||||||||||||||||
| Nonservice Components of Postretirement Benefits | 9,609 | 10,597 | (988) | (9.3) | |||||||||||||||||||
| Other Income | 18,848 | 12,650 | 6,198 | 49.0 | |||||||||||||||||||
| Income Before Income Taxes | 366,892 | 363,489 | 3,403 | 0.9 | |||||||||||||||||||
| Income Tax Expense | 65,230 | 69,298 | (4,068) | (5.9) | |||||||||||||||||||
| Net Income | $ | 301,662 | $ | 294,191 | $ | 7,471 | 2.5 | % | |||||||||||||||
| (in thousands) | 2024 | 2023 | $ change | % change | |||||||||||||||||||
Retail Revenue | $ | 453,214 | $ | 455,840 | $ | (2,626) | (0.6) | % | |||||||||||||||
Transmission Services Revenue | 53,517 | 52,555 | 962 | 1.8 | |||||||||||||||||||
Wholesale Revenue | 11,077 | 12,459 | (1,382) | (11.1) | |||||||||||||||||||
| Other Electric Revenues | 6,707 | 7,505 | (798) | (10.6) | |||||||||||||||||||
| Total Operating Revenue | 524,515 | 528,359 | (3,844) | (0.7) | |||||||||||||||||||
| Production Fuel | 60,945 | 60,339 | 606 | 1.0 | |||||||||||||||||||
| Purchased Power | 61,561 | 78,292 | (16,731) | (21.4) | |||||||||||||||||||
| Operating and Maintenance Expenses | 190,422 | 191,263 | (841) | (0.4) | |||||||||||||||||||
| Depreciation and Amortization | 82,136 | 75,330 | 6,806 | 9.0 | |||||||||||||||||||
| Property Taxes | 15,662 | 16,614 | (952) | (5.7) | |||||||||||||||||||
| Operating Income | 113,789 | 106,521 | 7,268 | 6.8 | |||||||||||||||||||
Interest Expense | (38,216) | (33,864) | (4,352) | 12.9 | |||||||||||||||||||
| Nonservice Cost Components of Postretirement Benefits | 10,578 | 11,661 | (1,083) | (9.3) | |||||||||||||||||||
| Other Income | 3,268 | 1,754 | 1,514 | 86.3 | |||||||||||||||||||
| Income Before Income Taxes | 89,419 | 86,072 | 3,347 | 3.9 | |||||||||||||||||||
Income Tax (Benefit) Expense | (1,544) | 1,648 | (3,192) | (193.7) | |||||||||||||||||||
| Net Income | $ | 90,963 | $ | 84,424 | $ | 6,539 | 7.7 | % | |||||||||||||||
Electric kwh Sales (in thousands) | 2024 | 2023 | kwh change | % change | |||||||||||||||||||
| Retail kwh Sales | 5,681,268 | 5,772,215 | (90,947) | (1.6) | % | ||||||||||||||||||
| Wholesale kwh Sales | 273,365 | 351,729 | (78,364) | (22.3) | |||||||||||||||||||
| Heating Degree Days | 5,313 | 6,259 | (946) | (15.1) | |||||||||||||||||||
| Cooling Degree Days | 440 | 590 | (150) | (25.4) | % | ||||||||||||||||||
| 2024 | 2023 | ||||||||||
| Heating Degree Days | 83.7 | % | 98.4 | % | |||||||
| Cooling Degree Days | 93.8 | % | 127.2 | % | |||||||
| 2024 vs Normal | 2024 vs 2023 | 2023 vs Normal | |||||||||||||||
| Effect on Diluted Earnings Per Share | $ | (0.13) | $ | (0.15) | $ | 0.02 | |||||||||||
| (in thousands) | 2024 | 2023 | $ change | % change | |||||||||||||||||||
| Operating Revenues | $ | 342,592 | $ | 402,781 | $ | (60,189) | (14.9) | % | |||||||||||||||
| Cost of Products Sold (excluding depreciation) | 267,904 | 310,601 | (42,697) | (13.7) | |||||||||||||||||||
| Selling, General, and Administrative Expenses | 35,203 | 44,545 | (9,342) | (21.0) | |||||||||||||||||||
| Depreciation and Amortization | 20,393 | 18,495 | 1,898 | 10.3 | |||||||||||||||||||
| Operating Income | 19,092 | 29,140 | (10,048) | (34.5) | |||||||||||||||||||
Interest Expense | (2,516) | (2,295) | (221) | 9.6 | |||||||||||||||||||
| Other Income | — | (1) | 1 | (100.0) | |||||||||||||||||||
| Income Before Income Taxes | 16,576 | 26,844 | (10,268) | (38.3) | |||||||||||||||||||
| Income Tax Expense | 2,895 | 5,390 | (2,495) | (46.3) | |||||||||||||||||||
| Net Income | $ | 13,681 | $ | 21,454 | $ | (7,773) | (36.2) | % | |||||||||||||||
| (in thousands) | 2024 | 2023 | $ change | % change | |||||||||||||||||||
| Operating Revenues | $ | 463,441 | $ | 418,026 | $ | 45,415 | 10.9 | % | |||||||||||||||
| Cost of Products Sold (excluding depreciation) | 166,628 | 143,521 | 23,107 | 16.1 | |||||||||||||||||||
| Selling, General, and Administrative Expenses | 20,414 | 16,076 | 4,338 | 27.0 | |||||||||||||||||||
| Depreciation and Amortization | 4,494 | 4,027 | 467 | 11.6 | |||||||||||||||||||
| Operating Income | 271,905 | 254,402 | 17,503 | 6.9 | |||||||||||||||||||
Interest Expense | (590) | (602) | 12 | (2.0) | |||||||||||||||||||
| Other Income | 76 | 14 | 62 | 442.9 | |||||||||||||||||||
| Income Before Income Taxes | 271,391 | 253,814 | 17,577 | 6.9 | |||||||||||||||||||
| Income Tax Expense | 70,644 | 66,066 | 4,578 | 6.9 | |||||||||||||||||||
| Net Income | $ | 200,747 | $ | 187,748 | $ | 12,999 | 6.9 | % | |||||||||||||||
| (in thousands) | 2024 | 2023 | $ change | % change | |||||||||||||||||||
| Selling, General, and Administrative Expenses | $ | 24,438 | $ | 12,042 | $ | 12,396 | 102.9 | % | |||||||||||||||
| Depreciation and Amortization | 98 | 102 | (4) | (3.9) | |||||||||||||||||||
Operating Income (Loss) | (24,536) | (12,144) | (12,392) | 102.0 | |||||||||||||||||||
Interest Expense | (493) | (916) | 423 | (46.2) | |||||||||||||||||||
| Nonservice Cost Components of Postretirement Benefits | (969) | (1,064) | 95 | (8.9) | |||||||||||||||||||
| Other Income | 15,504 | 10,883 | 4,621 | 42.5 | |||||||||||||||||||
Income (Loss) Before Income Taxes | (10,494) | (3,241) | (7,253) | 223.8 | |||||||||||||||||||
| Income Tax (Benefit) | (6,765) | (3,806) | (2,959) | 77.7 | |||||||||||||||||||
Net Income (Loss) | $ | (3,729) | $ | 565 | $ | (4,294) | (760.0) | % | |||||||||||||||
| REGULATORY MATTERS | |||||
| Revenue | Allowed | ||||||||||||||||
| Implementation | Requirement | Return on | Return | Equity | |||||||||||||
| Jurisdiction | Date | (in millions) | Rate Base | on Equity | Ratio | ||||||||||||
| Minnesota | 07/01/22 | $ | 209.0 | 7.18 | % | 9.48 | % | 52.50 | % | ||||||||
North Dakota(1)(2) | 03/15/25 | 225.6 | 7.53 | 10.10 | 53.50 | ||||||||||||
South Dakota(3) | 08/01/19 | 35.5 | 7.09 | 8.75 | 52.92 | ||||||||||||
(1) Includes an earnings sharing mechanism to share with North Dakota customers any earnings above an ROE of 10.20%. The mechanism requires 70% of any revenue creating annual earnings in excess of the authorized ROE be returned to customers. | |||||||||||||||||
(2) A compliance filing affirming the implementation date, revenue requirement, return on rate base, allowed return on equity, and equity ratio was made on February 7, 2025, and remained subject to final approval by the NDPSC as of the date of this annual report on Form 10-K. | |||||||||||||||||
(3) Includes an earnings sharing mechanism to share with South Dakota customers any weather-normalized earnings above the authorized ROE of 8.75%. The mechanism requires 50% of any weather-normalized revenue creating annual earnings in excess of the authorized ROE up to a maximum of 9.50% be returned to customers and 100% returns of revenue creating annual earnings above 9.50%. | |||||||||||||||||
| Recovery | Filing | Amount | Effective | |||||||||||||||||||||||||||||||||||
| Mechanism | Jurisdiction | Status | Date | (in millions) | Date | Notes | ||||||||||||||||||||||||||||||||
| RRR - 2023 | 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. | ||||||||||||||||||||||||||||||||
| ECO - 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. | ||||||||||||||||||||||||||||||||
ECO - 2024 | MN | Approved | 04/01/24 | 8.8 | 10/01/24 | Recovery of energy conservation improvement costs as well as a demand side management financial incentive. | ||||||||||||||||||||||||||||||||
| RRR - 2024 | MN | Approved | 12/04/23 | 8.0 | 09/01/24 | Recovery of Hoot Lake Solar costs, Ashtabula III costs, wind upgrade project costs at our four owned wind facilities, and true up of PTCs for Merricourt. | ||||||||||||||||||||||||||||||||
EUIC - 2025 | MN | Approved | 05/03/24 | 4.1 | 02/01/25 | Recovery of advanced metering infrastructure, outage management system, geographic information system, and demand response 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 PTCs. | ||||||||||||||||||||||||||||||||
| TCR - 2023 | ND | Approved | 09/15/22 | 7.5 | 01/01/23 | Recovery of transmission project costs. | ||||||||||||||||||||||||||||||||
| TCR - 2024 | ND | Approved | 11/02/23 | 4.5 | 01/01/24 | Recovery of transmission project costs. | ||||||||||||||||||||||||||||||||
| GCR - 2022 | ND | Approved | 03/01/22 | 3.3 | 07/01/22 | Annual update to generation cost recovery rider. | ||||||||||||||||||||||||||||||||
| MDT - 2023 | ND | Approved | 07/08/22 | 3.1 | 01/01/23 | Recovery of advanced metering infrastructure, outage management system and demand response projects. | ||||||||||||||||||||||||||||||||
TCR - 2025 | ND | Approved | 09/16/24 | 3.1 | 01/01/25 | Recovery of transmission project costs. | ||||||||||||||||||||||||||||||||
PIR - 2024 | SD | Approved | 06/03/24 | 3.2 | 09/01/24 | Recovery of Ashtabula III, Merricourt, Astoria Station, wind upgrade projects, Advanced Grid Infrastructure project costs, and impact of load growth credits. | ||||||||||||||||||||||||||||||||
PIR - 2025 | SD | Requested | 12/20/24 | 3.2 | 09/01/25 | Recovery of Ashtabula III, Merricourt, Astoria Station, wind upgrade projects, advanced metering infrastructure, outage management system, demand response system, and impact of load growth credits. | ||||||||||||||||||||||||||||||||
| 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 - 2023 | SD | Approved | 11/01/22 | 3.0 | 03/01/23 | Recovery of transmission project costs. | ||||||||||||||||||||||||||||||||
| LIQUIDITY | |||||
| 2024 | |||||||||||||||||||||||
| (in thousands) | Line Limit | Amount Outstanding | Letters of Credit | Amount Available | |||||||||||||||||||
| OTC Credit Agreement | $ | 170,000 | $ | — | $ | — | $ | 170,000 | |||||||||||||||
| OTP Credit Agreement | 220,000 | 69,615 | 8,772 | 141,613 | |||||||||||||||||||
| Total | $ | 390,000 | $ | 69,615 | $ | 8,772 | $ | 311,613 | |||||||||||||||
| (in thousands) | 2024 | 2023 | |||||||||
| Net Cash Provided by Operating Activities | $ | 452,731 | $ | 404,499 | |||||||
| (in thousands) | 2024 | 2023 | |||||||||
| Net Cash Used in Investing Activities | $ | 411,374 | $ | 289,287 | |||||||
| (in thousands) | 2024 | 2023 | |||||||||
Net Cash Provided by (Used in) Financing Activities | $ | 22,921 | $ | (3,835) | |||||||
| CAPITAL REQUIREMENTS | |||||
| (in millions) | 2023 | 2024 | 2025 | 2026 | 2027 | 2028 | 2029 | Total 2025 - 2029 | ||||||||||||||||||||||||||||||||||||||||||
| Electric Segment: | ||||||||||||||||||||||||||||||||||||||||||||||||||
Renewable Generation | $ | 106 | $ | 134 | $ | 101 | $ | 127 | $ | 118 | $ | 179 | $ | 4 | $ | 529 | ||||||||||||||||||||||||||||||||||
| Transmission | 49 | 60 | 59 | 93 | 162 | 114 | 100 | 528 | ||||||||||||||||||||||||||||||||||||||||||
| Distribution | 45 | 46 | 37 | 37 | 36 | 37 | 34 | 181 | ||||||||||||||||||||||||||||||||||||||||||
| Other | 41 | 61 | 54 | 51 | 31 | 27 | 25 | 188 | ||||||||||||||||||||||||||||||||||||||||||
| Total Electric Segment | 241 | 301 | 251 | 308 | 347 | 357 | 163 | 1,426 | ||||||||||||||||||||||||||||||||||||||||||
| Manufacturing and Plastics Segments | 46 | 58 | 27 | 27 | 27 | 25 | 23 | 129 | ||||||||||||||||||||||||||||||||||||||||||
| Total Capital Expenditures | $ | 287 | $ | 359 | $ | 278 | $ | 335 | $ | 374 | $ | 382 | $ | 186 | $ | 1,555 | ||||||||||||||||||||||||||||||||||
| (in millions) | Total | Less than 1 Year | 1-3 Years | 3-5 Years | More than 5 Years | ||||||||||||||||||||||||
| Debt Obligations | $ | 1,017 | $ | 70 | $ | 122 | $ | 70 | $ | 755 | |||||||||||||||||||
| Interest on Debt Obligations | 700 | 42 | 81 | 71 | 506 | ||||||||||||||||||||||||
| Coal Contracts | 441 | 24 | 50 | 53 | 314 | ||||||||||||||||||||||||
| Land Easements | 62 | 2 | 4 | 4 | 52 | ||||||||||||||||||||||||
| Postretirement Benefit Obligations | 65 | 5 | 11 | 11 | 38 | ||||||||||||||||||||||||
| Operating Lease Obligations | 35 | 6 | 10 | 6 | 13 | ||||||||||||||||||||||||
Other Obligations | 11 | 2 | 2 | 1 | 6 | ||||||||||||||||||||||||
Total Contractual Obligations | $ | 2,331 | $ | 151 | $ | 280 | $ | 216 | $ | 1,684 | |||||||||||||||||||
| CAPITAL RESOURCES | |||||
| Otter Tail Corporation | Otter Tail Power Company | ||||||||||||||||||||||
| Moody's | Fitch | S&P | Moody's | Fitch | S&P | ||||||||||||||||||
| Corporate Credit/Long-Term Issuer Default Rating | Baa2 | BBB | BBB | A3 | BBB+ | BBB+ | |||||||||||||||||
| Senior Unsecured Debt | n/a | BBB | n/a | n/a | A- | n/a | |||||||||||||||||
| Outlook | Stable | Stable | Stable | Negative | Stable | Stable | |||||||||||||||||
CRITICAL ACCOUNTING POLICIES INVOLVING SIGNIFICANT ESTIMATES | |||||
| (in thousands) | +0.25 | -0.25 | |||||||||
| Pension Plan: | |||||||||||
| Discount Rate | $ | (96) | $ | 931 | |||||||
| Rate of Increase in Future Compensation | 573 | (424) | |||||||||
| Long-Term Return on Plan Assets | (911) | 911 | |||||||||
| Other Postretirement Benefits: | |||||||||||
| Discount Rate | (14) | 15 | |||||||||
| ITEM 7A. | QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK | ||||
| ITEM 8. | FINANCIAL STATEMENTS | ||||
| December 31, | |||||||||||
| (in thousands, except share data) | 2024 | 2023 | |||||||||
| Assets | |||||||||||
| Current Assets | |||||||||||
| Cash and Cash Equivalents | $ | 294,651 | $ | 230,373 | |||||||
| Receivables, net of allowance for credit losses | 145,964 | 157,143 | |||||||||
| Inventories | 148,885 | 149,701 | |||||||||
| Regulatory Assets | 9,962 | 16,127 | |||||||||
| Other Current Assets | 30,579 | 16,826 | |||||||||
| Total Current Assets | 630,041 | 570,170 | |||||||||
| Noncurrent Assets | |||||||||||
| Investments | 121,177 | 62,516 | |||||||||
| Property, Plant and Equipment, net of accumulated depreciation | 2,692,460 | 2,418,375 | |||||||||
| Regulatory Assets | 98,673 | 95,715 | |||||||||
| Intangible Assets, net of accumulated amortization | 5,743 | 6,843 | |||||||||
| Goodwill | 37,572 | 37,572 | |||||||||
| Other Noncurrent Assets | 66,416 | 51,377 | |||||||||
| Total Noncurrent Assets | 3,022,041 | 2,672,398 | |||||||||
| Total Assets | $ | 3,652,082 | $ | 3,242,568 | |||||||
| Liabilities and Shareholders' Equity | |||||||||||
| Current Liabilities | |||||||||||
| Short-Term Debt | $ | 69,615 | $ | 81,422 | |||||||
| Accounts Payable | 113,574 | 94,428 | |||||||||
| Accrued Salaries and Wages | 34,398 | 38,134 | |||||||||
| Accrued Taxes | 17,314 | 26,590 | |||||||||
| Regulatory Liabilities | 29,307 | 25,408 | |||||||||
| Other Current Liabilities | 45,582 | 43,775 | |||||||||
| Total Current Liabilities | 309,790 | 309,757 | |||||||||
| Noncurrent Liabilities and Deferred Credits | |||||||||||
| Pension Benefit Liability | 32,614 | 33,101 | |||||||||
| Other Postretirement Benefits Liability | 27,385 | 27,676 | |||||||||
| Regulatory Liabilities | 288,928 | 276,547 | |||||||||
| Deferred Income Taxes | 267,745 | 237,273 | |||||||||
| Deferred Tax Credits | 14,990 | 15,172 | |||||||||
| Other Noncurrent Liabilities | 98,397 | 75,977 | |||||||||
| Total Noncurrent Liabilities and Deferred Credits | 730,059 | 665,746 | |||||||||
Commitments and Contingencies (Note 14) | |||||||||||
| Capitalization | |||||||||||
| Long-Term Debt | 943,734 | 824,059 | |||||||||
| Shareholders' Equity | |||||||||||
Common Stock: 50,000,000 shares authorized of $5 par value; 41,827,967 and 41,710,521 outstanding at December 31, 2024 and 2023 | 209,140 | 208,553 | |||||||||
| Additional Paid-In Capital | 429,089 | 426,963 | |||||||||
| Retained Earnings | 1,029,738 | 806,342 | |||||||||
| Accumulated Other Comprehensive Income | 532 | 1,148 | |||||||||
| Total Shareholders' Equity | 1,668,499 | 1,443,006 | |||||||||
| Total Capitalization | 2,612,233 | 2,267,065 | |||||||||
| Total Liabilities and Shareholders' Equity | $ | 3,652,082 | $ | 3,242,568 | |||||||
| Years Ended December 31, | |||||||||||||||||
| (in thousands, except per-share amounts) | 2024 | 2023 | 2022 | ||||||||||||||
| Operating Revenues | |||||||||||||||||
| Electric | $ | 524,515 | $ | 528,359 | $ | 549,699 | |||||||||||
| Product Sales | 806,033 | 820,807 | 910,510 | ||||||||||||||
| Total Operating Revenues | 1,330,548 | 1,349,166 | 1,460,209 | ||||||||||||||
| Operating Expenses | |||||||||||||||||
| Electric Production Fuel | 60,945 | 60,339 | 65,110 | ||||||||||||||
| Electric Purchased Power | 61,561 | 78,292 | 100,281 | ||||||||||||||
| Electric Operating and Maintenance Expenses | 190,422 | 191,263 | 181,378 | ||||||||||||||
| Cost of Products Sold (excluding depreciation) | 434,522 | 454,122 | 542,944 | ||||||||||||||
| Nonelectric Selling, General, and Administrative Expenses | 80,065 | 72,663 | 69,718 | ||||||||||||||
| Depreciation and Amortization | 107,121 | 97,954 | 92,597 | ||||||||||||||
| Electric Property Taxes | 15,662 | 16,614 | 17,742 | ||||||||||||||
| Total Operating Expenses | 950,298 | 971,247 | 1,069,770 | ||||||||||||||
| Operating Income | 380,250 | 377,919 | 390,439 | ||||||||||||||
Other Income and (Expense) | |||||||||||||||||
| Interest Expense | (41,815) | (37,677) | (36,016) | ||||||||||||||
| Nonservice Cost Components of Postretirement Benefits | 9,609 | 10,597 | 1,075 | ||||||||||||||
| Other Income (Expense), net | 18,848 | 12,650 | 2,037 | ||||||||||||||
| Income Before Income Taxes | 366,892 | 363,489 | 357,535 | ||||||||||||||
| Income Tax Expense | 65,230 | 69,298 | 73,351 | ||||||||||||||
| Net Income | $ | 301,662 | $ | 294,191 | $ | 284,184 | |||||||||||
| Weighted-Average Common Shares Outstanding: | |||||||||||||||||
| Basic | 41,778 | 41,668 | 41,586 | ||||||||||||||
| Diluted | 42,072 | 42,039 | 41,931 | ||||||||||||||
| Earnings Per Share: | |||||||||||||||||
| Basic | $ | 7.22 | $ | 7.06 | $ | 6.83 | |||||||||||
| Diluted | $ | 7.17 | $ | 7.00 | $ | 6.78 | |||||||||||
| Years Ended December 31, | |||||||||||||||||
| (in thousands) | 2024 | 2023 | 2022 | ||||||||||||||
| Net Income | $ | 301,662 | $ | 294,191 | $ | 284,184 | |||||||||||
| Other Comprehensive Income (Loss): | |||||||||||||||||
Unrealized Gain (Loss) on Available-for-Sale Securities, net of tax (expense) benefit of $(128), $(51) and $115 | 386 | 192 | (432) | ||||||||||||||
Unrealized Gain (Loss) on Pension and Other Postretirement Benefit Plans, net of tax (expense) benefit of $352, $(14) and $(2,769) | (1,002) | 41 | 7,871 | ||||||||||||||
Total Other Comprehensive Income (Loss) | (616) | 233 | 7,439 | ||||||||||||||
| Total Comprehensive Income | $ | 301,046 | $ | 294,424 | $ | 291,623 | |||||||||||
| (in thousands, except common stock outstanding) | Common Stock Outstanding | Par Value, Common Stock | Additional Paid-In Capital | Retained Earnings | Accumulated Other Comprehensive Income (Loss) | Total Shareholders' Equity | |||||||||||||||||||||||||||||
| Balance, December 31, 2021 | 41,551,524 | $ | 207,758 | $ | 419,760 | $ | 369,783 | $ | (6,524) | $ | 990,777 | ||||||||||||||||||||||||
| Employee Stock Purchase Plan Expenses | — | — | (219) | — | — | (219) | |||||||||||||||||||||||||||||
| Stock Issued Under Share-Based Compensation Plans, Net of Shares Withheld for Employee Taxes | 79,589 | 398 | (3,321) | — | — | (2,923) | |||||||||||||||||||||||||||||
| Stock Compensation Expense | — | — | 6,814 | — | — | 6,814 | |||||||||||||||||||||||||||||
| Net Income | — | — | — | 284,184 | — | 284,184 | |||||||||||||||||||||||||||||
| Other Comprehensive Income | — | — | — | — | 7,439 | 7,439 | |||||||||||||||||||||||||||||
Common Dividends ($1.65 per share) | — | — | — | (68,755) | — | (68,755) | |||||||||||||||||||||||||||||
| Balance, December 31, 2022 | 41,631,113 | $ | 208,156 | $ | 423,034 | $ | 585,212 | $ | 915 | $ | 1,217,317 | ||||||||||||||||||||||||
| Employee Stock Purchase Plan Expenses | — | — | (339) | — | — | (339) | |||||||||||||||||||||||||||||
| Stock Issued Under Share-Based Compensation Plans, Net of Shares Withheld for Employee Taxes | 79,408 | 397 | (3,485) | — | — | (3,088) | |||||||||||||||||||||||||||||
| Stock Compensation Expense | — | — | 7,753 | — | — | 7,753 | |||||||||||||||||||||||||||||
| Net Income | — | — | — | 294,191 | — | 294,191 | |||||||||||||||||||||||||||||
| Other Comprehensive Income | — | — | — | — | 233 | 233 | |||||||||||||||||||||||||||||
Common Dividends ($1.75 per share) | — | — | — | (73,061) | — | (73,061) | |||||||||||||||||||||||||||||
| Balance, December 31, 2023 | 41,710,521 | $ | 208,553 | $ | 426,963 | $ | 806,342 | $ | 1,148 | $ | 1,443,006 | ||||||||||||||||||||||||
| Employee Stock Purchase Plan Expenses | — | — | (359) | — | — | (359) | |||||||||||||||||||||||||||||
| Stock Issued Under Share-Based Compensation Plans, Net of Shares Withheld for Employee Taxes | 117,446 | 587 | (7,044) | — | — | (6,457) | |||||||||||||||||||||||||||||
| Stock Compensation Expense | — | — | 9,529 | — | — | 9,529 | |||||||||||||||||||||||||||||
| Net Income | — | — | — | 301,662 | — | 301,662 | |||||||||||||||||||||||||||||
Other Comprehensive Loss | — | — | — | — | (616) | (616) | |||||||||||||||||||||||||||||
Common Dividends ($1.87 per share) | — | — | — | (78,266) | — | (78,266) | |||||||||||||||||||||||||||||
| Balance, December 31, 2024 | 41,827,967 | $ | 209,140 | $ | 429,089 | $ | 1,029,738 | $ | 532 | $ | 1,668,499 | ||||||||||||||||||||||||
| Years Ended December 31, | |||||||||||||||||
| (in thousands) | 2024 | 2023 | 2022 | ||||||||||||||
| Operating Activities | |||||||||||||||||
| Net Income | $ | 301,662 | $ | 294,191 | $ | 284,184 | |||||||||||
| Adjustments to Reconcile Net Income to Net Cash Provided by Operating Activities: | |||||||||||||||||
| Depreciation and Amortization | 107,121 | 97,954 | 92,597 | ||||||||||||||
| Deferred Tax Credits | (182) | (744) | (745) | ||||||||||||||
| Deferred Income Taxes | 23,057 | 13,508 | 32,424 | ||||||||||||||
| Discretionary Contribution to Pension Plan | — | — | (20,000) | ||||||||||||||
| Investment (Gains) Losses | (5,482) | (7,222) | 3,296 | ||||||||||||||
| Stock Compensation Expense | 9,529 | 7,753 | 6,814 | ||||||||||||||
| Other, net | (3,111) | (423) | (1,473) | ||||||||||||||
| Changes in Operating Assets and Liabilities: | |||||||||||||||||
| Receivables | 11,179 | (12,750) | 30,560 | ||||||||||||||
| Inventories | 3,691 | (2,450) | 5,339 | ||||||||||||||
| Regulatory Assets | 5,194 | 12,479 | (2,464) | ||||||||||||||
| Other Assets | (11,640) | 2,817 | (368) | ||||||||||||||
| Accounts Payable | 14,826 | (9,988) | (29,763) | ||||||||||||||
| Accrued and Other Liabilities | (10,371) | 6 | (5,490) | ||||||||||||||
| Regulatory Liabilities | 16,821 | 20,973 | (6,846) | ||||||||||||||
| Pension and Other Postretirement Benefits | (9,563) | (11,605) | 1,244 | ||||||||||||||
| Net Cash Provided by Operating Activities | 452,731 | 404,499 | 389,309 | ||||||||||||||
| Investing Activities | |||||||||||||||||
| Capital Expenditures | (358,650) | (287,134) | (171,134) | ||||||||||||||
| Proceeds from Disposal of Noncurrent Assets | 8,849 | 6,225 | 4,346 | ||||||||||||||
| Purchases of Investments and Other Assets | (61,573) | (8,378) | (8,283) | ||||||||||||||
| Net Cash Used in Investing Activities | (411,374) | (289,287) | (175,071) | ||||||||||||||
| Financing Activities | |||||||||||||||||
Net (Repayments) Borrowings on Short-Term Debt | (11,807) | 73,218 | (82,959) | ||||||||||||||
| Proceeds from Issuance of Long-Term Debt | 120,000 | — | 90,000 | ||||||||||||||
| Payments for Retirement of Long-Term Debt | — | — | (30,000) | ||||||||||||||
| Dividends Paid | (78,266) | (73,061) | (68,755) | ||||||||||||||
| Payments for Shares Withheld for Employee Tax Obligations | (6,457) | (3,088) | (2,942) | ||||||||||||||
| Other, net | (549) | (904) | (2,123) | ||||||||||||||
Net Cash Provided by (Used in) Financing Activities | 22,921 | (3,835) | (96,779) | ||||||||||||||
| Net Change in Cash and Cash Equivalents | 64,278 | 111,377 | 117,459 | ||||||||||||||
| Cash and Cash Equivalents at Beginning of Period | 230,373 | 118,996 | 1,537 | ||||||||||||||
| Cash and Cash Equivalents at End of Period | $ | 294,651 | $ | 230,373 | $ | 118,996 | |||||||||||
| Supplemental Disclosures of Cash Flow Information | |||||||||||||||||
| Cash Paid During the Year for: | |||||||||||||||||
| Interest, net of amount capitalized | $ | 39,484 | $ | 36,956 | $ | 35,699 | |||||||||||
| Income Taxes | $ | 57,614 | $ | 46,284 | $ | 43,411 | |||||||||||
| Supplemental Disclosure of Noncash Investing Activities | |||||||||||||||||
| Accrued Property, Plant and Equipment Additions | $ | 20,281 | $ | 13,001 | $ | 12,420 | |||||||||||
| (in thousands) | 2024 | 2023 | |||||||||
| Finished Goods | $ | 43,345 | $ | 47,614 | |||||||
| Work in Process | 22,637 | 26,354 | |||||||||
| Raw Material, Fuel and Supplies | 82,903 | 75,733 | |||||||||
| Total Inventories | $ | 148,885 | $ | 149,701 | |||||||
| Service Life Range | |||||||||||
| (years) | Low | High | |||||||||
| Electric Assets: | |||||||||||
| Production Plant | 21 | 114 | |||||||||
| Transmission Plant | 51 | 80 | |||||||||
| Distribution Plant | 10 | 72 | |||||||||
| General Plant | 5 | 56 | |||||||||
| Nonelectric Assets: | |||||||||||
| Equipment | 2 | 20 | |||||||||
| Buildings and Leasehold Improvements | 2 | 40 | |||||||||
| (in thousands) | 2024 | 2023 | |||||||||
| Cloud Computing Costs | $ | 15,741 | $ | 12,782 | |||||||
| Accumulated Amortization | (3,796) | (1,505) | |||||||||
| Cloud Computing Costs, net | $ | 11,945 | $ | 11,277 | |||||||
| (in thousands) | 2024 | 2023 | 2022 | ||||||||||||||
| Operating Revenue | $ | 524,515 | $ | 528,359 | $ | 549,699 | |||||||||||
| Production Fuel and Purchased Power | 122,506 | 138,631 | 165,391 | ||||||||||||||
| Operating and Maintenance Expenses | 190,422 | 191,263 | 181,378 | ||||||||||||||
| Depreciation and Amortization | 82,136 | 75,330 | 72,050 | ||||||||||||||
| Property Taxes | 15,662 | 16,614 | 17,742 | ||||||||||||||
| Interest Expense | 38,216 | 33,864 | 31,950 | ||||||||||||||
Income Tax Expense (Benefit) | (1,544) | 1,648 | 5,065 | ||||||||||||||
Other Segment Items(1) | (13,846) | (13,415) | (3,851) | ||||||||||||||
| Net Income | $ | 90,963 | $ | 84,424 | $ | 79,974 | |||||||||||
(1) Other segment items includes nonservice components of postretirement benefits, allowance for funds used during construction, and other expenses (income). | |||||||||||||||||
| (in thousands) | 2024 | 2023 | 2022 | ||||||||||||||
| Operating Revenue | $ | 342,592 | $ | 402,781 | $ | 397,983 | |||||||||||
| Cost of Goods Sold | 283,390 | 324,245 | 327,228 | ||||||||||||||
| Selling, General, and Administrative Expenses | 40,110 | 49,396 | 41,690 | ||||||||||||||
| Interest Expense | 2,516 | 2,295 | 2,796 | ||||||||||||||
| Income Tax Expense | 2,895 | 5,390 | 5,321 | ||||||||||||||
| Other Segment Items | — | 1 | (2) | ||||||||||||||
| Net Income | $ | 13,681 | $ | 21,454 | $ | 20,950 | |||||||||||
| (in thousands) | 2024 | 2023 | 2022 | ||||||||||||||
| Operating Revenue | $ | 463,441 | $ | 418,026 | $ | 512,527 | |||||||||||
| Cost of Goods Sold | 166,628 | 143,521 | 227,571 | ||||||||||||||
| Selling, General, and Administrative Expenses | 24,908 | 20,103 | 20,378 | ||||||||||||||
| Interest Expense | 590 | 602 | 585 | ||||||||||||||
| Income Tax Expense | 70,644 | 66,066 | 68,688 | ||||||||||||||
| Other Segment Items | (76) | (14) | (69) | ||||||||||||||
| Net Income | $ | 200,747 | $ | 187,748 | $ | 195,374 | |||||||||||
| (in thousands) | 2024 | 2023 | 2022 | ||||||||||||||
| Capital Expenditures | |||||||||||||||||
| Electric | 301,454 | 240,695 | 147,869 | ||||||||||||||
| Manufacturing | 32,159 | 23,284 | 17,954 | ||||||||||||||
| Plastics | 24,749 | 23,029 | 5,245 | ||||||||||||||
| Corporate | 288 | 126 | 66 | ||||||||||||||
Total | $ | 358,650 | $ | 287,134 | $ | 171,134 | |||||||||||
| (in thousands) | 2024 | 2023 | |||||||||
| Identifiable Assets | |||||||||||
| Electric | $ | 2,785,522 | $ | 2,533,831 | |||||||
| Manufacturing | 254,445 | 251,343 | |||||||||
| Plastics | 186,043 | 164,179 | |||||||||
| Corporate | 426,072 | 293,215 | |||||||||
Total | $ | 3,652,082 | $ | 3,242,568 | |||||||
| (in thousands) | 2024 | 2023 | 2022 | ||||||||||||||
| Depreciation and Amortization | |||||||||||||||||
| Electric | $ | 82,136 | $ | 75,330 | $ | 72,050 | |||||||||||
| Manufacturing | 20,393 | 18,495 | 16,202 | ||||||||||||||
| Plastics | 4,494 | 4,027 | 4,205 | ||||||||||||||
| Corporate | 98 | 102 | 140 | ||||||||||||||
Total | 107,121 | 97,954 | 92,597 | ||||||||||||||
| Interest Expense | |||||||||||||||||
| Total Interest Expense of Reportable Segments | 41,322 | 36,761 | 35,331 | ||||||||||||||
| Corporate Interest Expense | 493 | 916 | 685 | ||||||||||||||
Total | 41,815 | 37,677 | 36,016 | ||||||||||||||
| Income Tax Expense (Benefit) | |||||||||||||||||
| Total Income Tax Expense of Reportable Segments | 71,995 | 73,104 | 79,074 | ||||||||||||||
| Corporate Income Tax Benefit | (6,765) | (3,806) | (5,723) | ||||||||||||||
Total | 65,230 | 69,298 | 73,351 | ||||||||||||||
| Net Income (Loss) | |||||||||||||||||
| Total Net Income of Reportable Segments | 305,391 | 293,626 | 296,298 | ||||||||||||||
| Corporate Net Income (Loss) | (3,729) | 565 | (12,114) | ||||||||||||||
Total | 301,662 | 294,191 | 284,184 | ||||||||||||||
| (in thousands) | 2024 | 2023 | 2022 | ||||||||||||||
| Operating Revenues | |||||||||||||||||
| Electric Segment | |||||||||||||||||
| Retail: Residential | $ | 133,408 | $ | 135,570 | $ | 143,888 | |||||||||||
| Retail: Commercial and Industrial | 311,968 | 312,551 | 318,494 | ||||||||||||||
| Retail: Other | 7,838 | 7,719 | 7,918 | ||||||||||||||
| Total Retail | 453,214 | 455,840 | 470,300 | ||||||||||||||
| Transmission | 53,517 | 52,555 | 52,213 | ||||||||||||||
| Wholesale | 11,077 | 12,459 | 18,539 | ||||||||||||||
| Other | 6,707 | 7,505 | 8,647 | ||||||||||||||
| Total Electric Segment | 524,515 | 528,359 | 549,699 | ||||||||||||||
| Manufacturing Segment | |||||||||||||||||
| Metal Parts and Tooling | 303,077 | 351,267 | 338,865 | ||||||||||||||
| Plastic Products and Tooling | 32,210 | 41,395 | 49,080 | ||||||||||||||
| Scrap Metal | 7,305 | 10,119 | 10,038 | ||||||||||||||
| Total Manufacturing Segment | 342,592 | 402,781 | 397,983 | ||||||||||||||
| Plastics Segment | |||||||||||||||||
| PVC Pipe | 463,441 | 418,026 | 512,527 | ||||||||||||||
| Total Operating Revenue | 1,330,548 | 1,349,166 | 1,460,209 | ||||||||||||||
| Less: Noncontract Revenues Included Above | |||||||||||||||||
| Electric Segment - ARP Revenues | 575 | (4,310) | (9,266) | ||||||||||||||
| Total Operating Revenues from Contracts with Customers | $ | 1,329,973 | $ | 1,353,476 | $ | 1,469,475 | |||||||||||
| (in thousands) | 2024 | 2023 | |||||||||
| Receivables | |||||||||||
| Trade | $ | 112,169 | $ | 129,257 | |||||||
| Other | 13,799 | 9,084 | |||||||||
| Unbilled Receivables | 21,916 | 21,324 | |||||||||
| Total Receivables | 147,884 | 159,665 | |||||||||
| Less Allowance for Credit Losses | 1,920 | 2,522 | |||||||||
| Receivables, net of allowance for credit losses | $ | 145,964 | $ | 157,143 | |||||||
| (in thousands) | 2024 | 2023 | |||||||||
| Beginning Balance | $ | 2,522 | $ | 1,648 | |||||||
| Additions Charged to Expense | 1,242 | 2,014 | |||||||||
| Reductions for Amounts Written Off, Net of Recoveries | (1,844) | (1,140) | |||||||||
| Ending Balance | $ | 1,920 | $ | 2,522 | |||||||
| (in thousands) | 2024 | 2023 | |||||||||
| Short-term Investments | |||||||||||
Government Debt Securities | $ | 753 | $ | — | |||||||
| Long-term Investments | |||||||||||
| Corporate-Owned Life Insurance Policies | 47,895 | 42,287 | |||||||||
Government Debt Securities | 60,378 | 7,724 | |||||||||
Corporate Debt Securities | 1,628 | 1,579 | |||||||||
| Mutual Funds | 10,653 | 7,771 | |||||||||
| Money Market Funds | 596 | 3,125 | |||||||||
| Other Investments | 27 | 30 | |||||||||
| Total Long-term Investments | 121,177 | 62,516 | |||||||||
| Total Investments | $ | 121,930 | $ | 62,516 | |||||||
| December 31, 2024 | |||||||||||||||||||||||
| (in thousands) | Amortized Cost | Gross Unrealized Gains | Gross Unrealized (Losses) | Fair Value | |||||||||||||||||||
| Government Debt Securities | $ | 60,891 | $ | 424 | $ | (184) | $ | 61,131 | |||||||||||||||
| Corporate Debt Securities | 1,629 | 9 | (10) | 1,628 | |||||||||||||||||||
| Total | $ | 62,520 | $ | 433 | $ | (194) | $ | 62,759 | |||||||||||||||
| (in thousands) | December 31, 2024 | ||||
Due in one year or less | $ | 753 | |||
Due in one to five years | 62,006 | ||||
| Total | $ | 62,759 | |||
| Period of | 2024 | 2023 | |||||||||||||||||||||||||||
| (in thousands) | Recovery/Refund | Current | Long-Term | Current | Long-Term | ||||||||||||||||||||||||
| Regulatory Assets | |||||||||||||||||||||||||||||
Pension and Other Postretirement Benefit Plans1 | See below | $ | — | $ | 88,161 | $ | 154 | $ | 86,134 | ||||||||||||||||||||
Alternative Revenue Program Riders2 | Up to 2 years | 4,257 | 195 | 3,719 | 158 | ||||||||||||||||||||||||
| Deferred Income Taxes | Asset lives | — | 8,944 | — | 6,940 | ||||||||||||||||||||||||
Fuel Clause Adjustments1 | Up to 1 year | 2,218 | — | 7,294 | — | ||||||||||||||||||||||||
Derivative Instruments1 | Up to 1 year | 1,989 | — | 4,210 | — | ||||||||||||||||||||||||
Other1 | Various | 1,498 | 1,373 | 750 | 2,483 | ||||||||||||||||||||||||
| Total Regulatory Assets | 9,962 | 98,673 | 16,127 | 95,715 | |||||||||||||||||||||||||
| Regulatory Liabilities | |||||||||||||||||||||||||||||
| Deferred Income Taxes | Asset lives | — | 130,387 | — | 136,022 | ||||||||||||||||||||||||
| Plant Removal Obligations | Asset lives | — | 126,263 | — | 117,030 | ||||||||||||||||||||||||
| Fuel Clause Adjustments | Up to 1 year | 11,432 | — | 11,350 | — | ||||||||||||||||||||||||
| Alternative Revenue Program Riders | Up to 1 year | 14,255 | — | 6,885 | — | ||||||||||||||||||||||||
| North Dakota PTC Refunds | Asset lives | — | 20,099 | — | 12,011 | ||||||||||||||||||||||||
| Pension and Other Postretirement Benefit Plans | See below | 2,547 | 10,758 | 6,138 | 11,307 | ||||||||||||||||||||||||
| Other | Various | 1,073 | 1,421 | 1,035 | 177 | ||||||||||||||||||||||||
| Total Regulatory Liabilities | $ | 29,307 | $ | 288,928 | $ | 25,408 | $ | 276,547 | |||||||||||||||||||||
1Costs subject to recovery without a rate of return. | |||||||||||||||||||||||||||||
2Amount eligible for recovery includes an incentive or rate of return. | |||||||||||||||||||||||||||||
| (in thousands) | 2024 | 2023 | |||||||||
| Electric Plant in Service | |||||||||||
| Production | $ | 1,469,008 | $ | 1,412,826 | |||||||
| Transmission | 820,415 | 777,613 | |||||||||
| Distribution | 726,159 | 654,704 | |||||||||
| General | 165,361 | 144,738 | |||||||||
| Electric Plant in Service | 3,180,943 | 2,989,881 | |||||||||
| Construction Work in Progress | 231,890 | 137,212 | |||||||||
| Total Gross Electric Plant | 3,412,833 | 3,127,093 | |||||||||
Less Accumulated Depreciation | 899,049 | 851,148 | |||||||||
| Net Electric Plant | 2,513,784 | 2,275,945 | |||||||||
| Nonelectric Property, Plant and Equipment | |||||||||||
| Equipment | 260,307 | 233,571 | |||||||||
| Buildings and Leasehold Improvements | 88,680 | 64,753 | |||||||||
| Land | 13,578 | 13,600 | |||||||||
| Nonelectric Property, Plant and Equipment | 362,565 | 311,924 | |||||||||
| Construction Work in Progress | 40,536 | 38,062 | |||||||||
| Total Gross Nonelectric Property, Plant and Equipment | 403,101 | 349,986 | |||||||||
Less Accumulated Depreciation | 224,425 | 207,556 | |||||||||
| Net Nonelectric Property, Plant and Equipment | 178,676 | 142,430 | |||||||||
| Net Property, Plant and Equipment | $ | 2,692,460 | $ | 2,418,375 | |||||||
| (dollars in thousands) | Ownership Percentage | Electric Plant in Service | Construction Work in Progress | Accumulated Depreciation | Net Plant | ||||||||||||||||||||||||
| December 31, 2024 | |||||||||||||||||||||||||||||
| Big Stone Plant | 53.9 | % | $ | 345,990 | $ | 459 | $ | (135,065) | $ | 211,384 | |||||||||||||||||||
| Coyote Station | 35.0 | % | 188,066 | 813 | (118,268) | 70,611 | |||||||||||||||||||||||
| Big Stone South–Ellendale 345 kV line | 50.0 | % | 106,185 | — | (8,445) | 97,740 | |||||||||||||||||||||||
| Fargo–Monticello 345 kV line | 14.2 | % | 78,184 | — | (12,247) | 65,937 | |||||||||||||||||||||||
| Big Stone South–Brookings 345 kV line | 50.0 | % | 53,167 | — | (5,822) | 47,345 | |||||||||||||||||||||||
| Brookings–Southeast Twin Cities 345 kV line | 4.8 | % | 28,013 | 1,131 | (3,941) | 25,203 | |||||||||||||||||||||||
| Bemidji–Grand Rapids 230 kV line | 14.8 | % | 16,331 | — | (3,693) | 12,638 | |||||||||||||||||||||||
| Jamestown– Ellendale 345 kV line | 50.0 | % | — | 5,509 | — | 5,509 | |||||||||||||||||||||||
| Big Stone South–Alexandria 345 kV line | 40.0 | % | — | 2,418 | — | 2,418 | |||||||||||||||||||||||
| Alexandria–Big Oaks 345 kV line | 14.2 | % | — | 417 | — | 417 | |||||||||||||||||||||||
| Oslo - Lake Ardoch 115 kV line | 72.0 | % | — | 2,646 | — | 2,646 | |||||||||||||||||||||||
| December 31, 2023 | |||||||||||||||||||||||||||||
| Big Stone Plant | 53.9 | % | $ | 341,683 | $ | 820 | $ | (126,904) | $ | 215,599 | |||||||||||||||||||
| Coyote Station | 35.0 | % | 188,656 | 104 | (115,306) | 73,454 | |||||||||||||||||||||||
| Big Stone South–Ellendale 345 kV line | 50.0 | % | 106,185 | — | (7,181) | 99,004 | |||||||||||||||||||||||
| Fargo–Monticello 345 kV line | 14.2 | % | 78,184 | — | (11,238) | 66,946 | |||||||||||||||||||||||
| Big Stone South–Brookings 345 kV line | 50.0 | % | 53,170 | — | (5,207) | 47,963 | |||||||||||||||||||||||
| Brookings–Southeast Twin Cities 345 kV line | 4.8 | % | 26,409 | 83 | (3,617) | 22,875 | |||||||||||||||||||||||
| Bemidji–Grand Rapids 230 kV line | 14.8 | % | 16,331 | — | (3,568) | 12,763 | |||||||||||||||||||||||
Jamestown–Ellendale 345 kV line | 50.0 | % | — | 1,121 | — | 1,121 | |||||||||||||||||||||||
| Big Stone South–Alexandria 345 kV line | 40.0 | % | — | 555 | — | 555 | |||||||||||||||||||||||
| Alexandria–Big Oaks 345 kV line | 14.2 | % | — | 343 | — | 343 | |||||||||||||||||||||||
| (in thousands) | 2024 | 2023 | |||||||||
| Manufacturing | $ | 18,270 | $ | 18,270 | |||||||
| Plastics | 19,302 | 19,302 | |||||||||
| Total Goodwill | $ | 37,572 | $ | 37,572 | |||||||
| (in thousands) | Gross Amount | Accumulated Amortization | Net Carrying Amount | ||||||||||||||
| December 31, 2024 | |||||||||||||||||
| Customer Relationships | $ | 22,491 | $ | 16,766 | $ | 5,725 | |||||||||||
| Other | 26 | 8 | 18 | ||||||||||||||
| Total | $ | 22,517 | $ | 16,774 | $ | 5,743 | |||||||||||
| December 31, 2023 | |||||||||||||||||
| Customer Relationships | $ | 22,491 | $ | 15,667 | $ | 6,824 | |||||||||||
| Other | 26 | 7 | 19 | ||||||||||||||
| Total | $ | 22,517 | $ | 15,674 | $ | 6,843 | |||||||||||
| (in thousands) | 2025 | 2026 | 2027 | 2028 | 2029 | ||||||||||||||||||||||||
| Amortization Expense | $ | 1,100 | $ | 1,092 | $ | 1,090 | $ | 554 | $ | 285 | |||||||||||||||||||
| (in thousands) | 2024 | 2023 | 2022 | ||||||||||||||
| Lease Cost | |||||||||||||||||
| Operating Lease Cost | $ | 6,688 | $ | 6,309 | $ | 5,606 | |||||||||||
| Variable Lease Cost | 1,460 | 1,433 | 1,386 | ||||||||||||||
| Short-Term Lease Cost | 2,746 | 2,525 | 1,517 | ||||||||||||||
| Total Lease Cost | $ | 10,894 | $ | 10,267 | $ | 8,509 | |||||||||||
| Lease Cash Flows | |||||||||||||||||
| Operating Cash Flows from Operating Leases | $ | 6,762 | $ | 6,424 | $ | 5,592 | |||||||||||
| (in thousands) | 2024 | 2023 | ||||||||||||
Right of Use Lease Assets1 | $ | 28,179 | $ | 16,788 | ||||||||||
| Lease Liabilities | ||||||||||||||
Current2 | 4,776 | 5,756 | ||||||||||||
Long-Term3 | 23,567 | 11,258 | ||||||||||||
| Total Lease Liabilities | $ | 28,343 | $ | 17,014 | ||||||||||
| (in thousands) | Operating Leases | ||||
| 2025 | $ | 6,350 | |||
| 2026 | 5,638 | ||||
| 2027 | 4,785 | ||||
| 2028 | 3,604 | ||||
| 2029 | 2,750 | ||||
| Thereafter | 12,921 | ||||
| Total Lease Payments | 36,048 | ||||
| Less: Interest | 7,705 | ||||
| Present Value of Lease Liabilities | $ | 28,343 | |||
| 2024 | 2023 | ||||||||||
| Weighted-Average Remaining Lease Term (in years) | 7.9 | 3.4 | |||||||||
| Weighted-Average Discount Rate | 6.37 | % | 5.40 | % | |||||||
| 2024 | 2023 | ||||||||||||||||||||||||||||||||||
| (in thousands) | OTC | OTP | Total | OTC | OTP | Total | |||||||||||||||||||||||||||||
| Short-Term Debt | $ | — | $ | 69,615 | $ | 69,615 | $ | — | $ | 81,422 | $ | 81,422 | |||||||||||||||||||||||
| Long-Term Debt | 79,900 | 863,834 | 943,734 | 79,849 | 744,210 | 824,059 | |||||||||||||||||||||||||||||
| Total | $ | 79,900 | $ | 933,449 | $ | 1,013,349 | $ | 79,849 | $ | 825,632 | $ | 905,481 | |||||||||||||||||||||||
| 2024 | 2023 | ||||||||||||||||||||||||||||
| (in thousands) | Line Limit | Amount Outstanding | Letters of Credit | Amount Available | Amount Available | ||||||||||||||||||||||||
| OTC Credit Agreement | $ | 170,000 | $ | — | $ | — | $ | 170,000 | $ | 170,000 | |||||||||||||||||||
| OTP Credit Agreement | 220,000 | 69,615 | 8,772 | 141,613 | 79,446 | ||||||||||||||||||||||||
| Total | $ | 390,000 | $ | 69,615 | $ | 8,772 | $ | 311,613 | $ | 249,446 | |||||||||||||||||||
| (in thousands) | ||||||||||||||||||||||||||||||||
| Entity | Debt Instrument | Rate | Maturity | 2024 | 2023 | |||||||||||||||||||||||||||
| 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 2024A Senior Unsecured Notes | 5.48% | 04/01/34 | 60,000 | — | |||||||||||||||||||||||||||
| 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 | |||||||||||||||||||||||||||
| OTP | Series 2024B Senior Unsecured Notes | 5.77% | 04/01/54 | 60,000 | — | |||||||||||||||||||||||||||
| Total | 947,000 | 827,000 | ||||||||||||||||||||||||||||||
| Less: | Unamortized Long-Term Debt Issuance Costs | 3,266 | 2,941 | |||||||||||||||||||||||||||||
| Total Long-Term Debt Net of Unamortized Debt Issuance Costs | $ | 943,734 | $ | 824,059 | ||||||||||||||||||||||||||||
| (in thousands) | 2025 | 2026 | 2027 | 2028 | 2029 | ||||||||||||||||||||||||
| Debt Maturities | $ | — | $ | 80,000 | $ | 42,000 | $ | — | $ | 70,000 | |||||||||||||||||||
| Permitted | Actual Allocation | ||||||||||||||||||||||
| Asset Class | Range | 2024 | 2023 | ||||||||||||||||||||
| Return Enhancement | 35 | – | 60% | 41 | % | 48 | % | ||||||||||||||||
| Risk Management | 40 | – | 80% | 59 | 51 | ||||||||||||||||||
| Alternatives | 0 | – | 20% | — | 1 | ||||||||||||||||||
| Total | 100 | % | 100 | % | |||||||||||||||||||
| (in thousands) | Level 1 | Level 2 | Level 3 | NAV | Total | ||||||||||||||||||||||||
| December 31, 2024 | |||||||||||||||||||||||||||||
| Equity Funds | $ | 116,889 | $ | — | $ | — | $ | — | $ | 116,889 | |||||||||||||||||||
| Fixed Income Funds | 175,310 | — | — | — | 175,310 | ||||||||||||||||||||||||
| Hybrid Funds | 10,106 | — | — | — | 10,106 | ||||||||||||||||||||||||
| U.S. Treasury Securities | 23,909 | — | — | — | 23,909 | ||||||||||||||||||||||||
| SEI Energy Debt Collective Fund | — | — | — | 1,061 | 1,061 | ||||||||||||||||||||||||
| Total | $ | 326,214 | $ | — | $ | — | $ | 1,061 | $ | 327,275 | |||||||||||||||||||
| December 31, 2023 | |||||||||||||||||||||||||||||
| Equity Funds | $ | 127,159 | $ | — | $ | — | $ | — | $ | 127,159 | |||||||||||||||||||
| Fixed Income Funds | 167,604 | — | — | — | 167,604 | ||||||||||||||||||||||||
| Hybrid Funds | 10,980 | — | — | — | 10,980 | ||||||||||||||||||||||||
| U.S. Treasury Securities | 23,218 | — | — | — | 23,218 | ||||||||||||||||||||||||
| SEI Energy Debt Collective Fund | — | — | — | 1,518 | 1,518 | ||||||||||||||||||||||||
| Total | $ | 328,961 | $ | — | $ | — | $ | 1,518 | $ | 330,479 | |||||||||||||||||||
| Pension Benefits (Pension Plan) | Pension Benefits (ESSRP) | Postretirement Benefits | |||||||||||||||||||||||||||||||||
| (in thousands) | 2024 | 2023 | 2024 | 2023 | 2024 | 2023 | |||||||||||||||||||||||||||||
| Change in Fair Value of Plan Assets: | |||||||||||||||||||||||||||||||||||
| Fair Value of Plan Assets at January 1 | $ | 330,479 | $ | 313,797 | $ | — | $ | — | $ | — | $ | — | |||||||||||||||||||||||
| Actual Return on Plan Assets | 14,976 | 34,196 | — | — | — | — | |||||||||||||||||||||||||||||
| Company Contributions | — | — | 2,694 | 2,197 | 1,568 | 3,167 | |||||||||||||||||||||||||||||
| Benefit Payments | (18,180) | (17,514) | (2,694) | (2,197) | (3,734) | (8,900) | |||||||||||||||||||||||||||||
| Participant Premium Payments | — | — | — | — | 2,166 | 5,733 | |||||||||||||||||||||||||||||
| Fair Value of Plan Assets at December 31 | $ | 327,275 | $ | 330,479 | $ | — | $ | — | $ | — | $ | — | |||||||||||||||||||||||
| Change in Benefit Obligation: | |||||||||||||||||||||||||||||||||||
| Benefit Obligation at January 1 | $ | 318,801 | $ | 308,055 | $ | 35,780 | $ | 35,624 | $ | 30,145 | $ | 49,947 | |||||||||||||||||||||||
| Service Cost | 3,886 | 3,698 | — | 72 | 490 | 565 | |||||||||||||||||||||||||||||
| Interest Cost | 17,189 | 16,436 | 1,897 | 1,889 | 1,600 | 2,416 | |||||||||||||||||||||||||||||
| Benefit Payments | (18,180) | (17,514) | (2,694) | (2,197) | (3,734) | (8,900) | |||||||||||||||||||||||||||||
| Participant Premium Payments | — | — | — | — | 2,166 | 5,733 | |||||||||||||||||||||||||||||
| Plan Amendments | — | — | — | — | — | (17,493) | |||||||||||||||||||||||||||||
| Actuarial (Gain) Loss | (7,686) | 8,126 | 331 | 392 | (664) | (2,123) | |||||||||||||||||||||||||||||
| Benefit Obligation at December 31 | 314,010 | 318,801 | 35,314 | 35,780 | 30,003 | 30,145 | |||||||||||||||||||||||||||||
| Funded Status | $ | 13,265 | $ | 11,678 | $ | (35,314) | $ | (35,780) | $ | (30,003) | $ | (30,145) | |||||||||||||||||||||||
| Amounts Recognized in Consolidated Balance Sheets at December 31: | |||||||||||||||||||||||||||||||||||
| Noncurrent Assets | $ | 13,265 | $ | 11,678 | $ | — | $ | — | $ | — | $ | — | |||||||||||||||||||||||
| Current Liabilities | — | — | (2,700) | (2,679) | (2,618) | (2,469) | |||||||||||||||||||||||||||||
Noncurrent Liabilities | — | — | (32,614) | (33,101) | (27,385) | (27,676) | |||||||||||||||||||||||||||||
| Net Asset (Liability) | $ | 13,265 | $ | 11,678 | $ | (35,314) | $ | (35,780) | $ | (30,003) | $ | (30,145) | |||||||||||||||||||||||
| Pension Benefits (Pension Plan) | Pension Benefits (ESSRP) | Postretirement Benefits | |||||||||||||||||||||||||||||||||||||||||||||||||||
| (in thousands) | 2024 | 2023 | 2022 | 2024 | 2023 | 2022 | 2024 | 2023 | 2022 | ||||||||||||||||||||||||||||||||||||||||||||
| Service Cost | $ | 3,886 | $ | 3,698 | $ | 6,576 | $ | — | $ | 72 | $ | 195 | $ | 490 | $ | 565 | $ | 1,338 | |||||||||||||||||||||||||||||||||||
| Interest Cost | 17,189 | 16,436 | 12,344 | 1,897 | 1,889 | 1,341 | 1,600 | 2,416 | 2,041 | ||||||||||||||||||||||||||||||||||||||||||||
| Expected Return on Assets | (25,518) | (25,914) | (23,684) | — | — | — | — | — | — | ||||||||||||||||||||||||||||||||||||||||||||
| Amortization of Prior Service Cost | — | — | — | — | — | — | (6,302) | (6,649) | (5,733) | ||||||||||||||||||||||||||||||||||||||||||||
| Amortization of Net Actuarial Loss | 158 | — | 7,865 | — | — | 567 | — | — | 3,063 | ||||||||||||||||||||||||||||||||||||||||||||
| Net Periodic Benefit Cost | $ | (4,285) | $ | (5,780) | $ | 3,101 | $ | 1,897 | $ | 1,961 | $ | 2,103 | $ | (4,212) | $ | (3,668) | $ | 709 | |||||||||||||||||||||||||||||||||||
| (in thousands) | 2024 | 2023 | 2022 | ||||||||||||||
| Net Periodic Benefit Cost | $ | (6,600) | $ | (7,487) | $ | 5,913 | |||||||||||
| Net Amount Amortized Due to the Effect of Regulation | 1,367 | 1,225 | 1,121 | ||||||||||||||
| Net Periodic Benefit Cost Recognized | $ | (5,233) | $ | (6,262) | $ | 7,034 | |||||||||||
| Pension Benefits (Pension Plan) | Pension Benefits (ESSRP) | Postretirement Benefits | |||||||||||||||||||||||||||||||||
| (in thousands) | 2024 | 2023 | 2024 | 2023 | 2024 | 2023 | |||||||||||||||||||||||||||||
| Regulatory Assets (Liabilities): | |||||||||||||||||||||||||||||||||||
| Unrecognized Prior Service Cost | $ | — | $ | — | $ | — | $ | — | $ | (12,703) | $ | (18,845) | |||||||||||||||||||||||
| Unrecognized Actuarial Loss | 87,868 | 85,227 | 292 | 1,061 | 1,121 | 1,759 | |||||||||||||||||||||||||||||
| Net Regulatory Assets (Liabilities) | $ | 87,868 | $ | 85,227 | $ | 292 | $ | 1,061 | $ | (11,582) | $ | (17,086) | |||||||||||||||||||||||
| Accumulated Other Comprehensive Income (Loss): | |||||||||||||||||||||||||||||||||||
| Unrecognized Prior Service Cost | $ | — | $ | — | $ | — | $ | — | $ | 339 | $ | 498 | |||||||||||||||||||||||
| Unrecognized Actuarial Gain (Loss) | 1,937 | 1,994 | (2,502) | (1,403) | 732 | 707 | |||||||||||||||||||||||||||||
| Total Accumulated Other Comprehensive Income (Loss) | $ | 1,937 | $ | 1,994 | $ | (2,502) | $ | (1,403) | $ | 1,071 | $ | 1,205 | |||||||||||||||||||||||
| (in thousands) | 2025 | 2026 | 2027 | 2028 | 2029 | 2030-2034 | |||||||||||||||||||||||||||||
| Projected Pension Plan Benefit Payments | $ | 19,274 | $ | 19,804 | $ | 20,284 | $ | 20,859 | $ | 21,420 | $ | 111,275 | |||||||||||||||||||||||
| Projected ESSRP Benefit Payments | 2,769 | 2,899 | 3,059 | 2,999 | 3,070 | 14,275 | |||||||||||||||||||||||||||||
| Projected Postretirement Benefit Payments | 2,618 | 2,614 | 2,576 | 2,488 | 2,517 | 12,019 | |||||||||||||||||||||||||||||
| Total | $ | 24,661 | $ | 25,317 | $ | 25,919 | $ | 26,346 | $ | 27,007 | $ | 137,569 | |||||||||||||||||||||||
| (in thousands) | 2024 | 2023 | |||||||||
| Beginning Balance | $ | 36,477 | $ | 25,182 | |||||||
| New Obligations Recognized | 2,991 | 4,506 | |||||||||
| Adjustments Due to Revisions in Cash Flow Estimates | 1,098 | 8,394 | |||||||||
| Accrued Accretion | 1,676 | 1,191 | |||||||||
| Settlements | (79) | (2,796) | |||||||||
| Ending Balance | $ | 42,163 | $ | 36,477 | |||||||
| (in thousands) | 2024 | 2023 | 2022 | ||||||||||||||
| Current | |||||||||||||||||
| Federal Income Taxes | $ | 36,238 | $ | 41,253 | $ | 31,949 | |||||||||||
| State Income Taxes | 6,533 | 15,126 | 9,568 | ||||||||||||||
| Deferred | |||||||||||||||||
| Federal Income Taxes | 13,078 | 9,832 | 22,480 | ||||||||||||||
| State Income Taxes | 9,979 | 3,676 | 9,943 | ||||||||||||||
| Tax Credits | |||||||||||||||||
| North Dakota Wind Tax Credit Amortization, Net of Federal Tax | (586) | (586) | (586) | ||||||||||||||
| Investment Tax Credit Amortization | (12) | (3) | (3) | ||||||||||||||
| Total | $ | 65,230 | $ | 69,298 | $ | 73,351 | |||||||||||
| 2024 | 2023 | 2022 | ||||||||||||||||||||||||
| Income Taxes at Federal Statutory Rate | $ | 77,047 | 21.0 | % | $ | 76,332 | 21.0 | % | $ | 75,082 | 21.0 | % | ||||||||||||||
| Increases (Decreases) in Tax from: | ||||||||||||||||||||||||||
| State Taxes on Income, Net of Federal Tax | 14,360 | 3.9 | 14,429 | 4.0 | 15,049 | 4.2 | ||||||||||||||||||||
| Production Tax Credits (PTCs) | (20,106) | (5.5) | (17,394) | (4.8) | (14,985) | (4.2) | ||||||||||||||||||||
| Amortization of Excess Deferred Income Taxes | (2,788) | (0.8) | (2,205) | (0.6) | (1,625) | (0.5) | ||||||||||||||||||||
| North Dakota Wind Tax Credit Amortization, Net of Federal Tax | (586) | (0.2) | (586) | (0.2) | (586) | (0.2) | ||||||||||||||||||||
| Other, Net | (2,697) | (0.6) | (1,278) | (0.3) | 416 | 0.2 | ||||||||||||||||||||
| Income Taxes at Effective Tax Rate | $ | 65,230 | 17.8 | % | $ | 69,298 | 19.1 | % | $ | 73,351 | 20.5 | % | ||||||||||||||
| (in thousands) | 2024 | 2023 | |||||||||
| Deferred Tax Assets | |||||||||||
| Employee Benefits | $ | 37,456 | $ | 39,959 | |||||||
| Regulatory Liabilities | 52,664 | 56,479 | |||||||||
| Tax Credit Carryforwards | 18,268 | 21,836 | |||||||||
| Cost of Removal | 35,374 | 32,993 | |||||||||
| Asset Retirement Obligations | 10,948 | 9,494 | |||||||||
| Net Operating Loss Carryforward | 2,289 | 2,336 | |||||||||
| Other | 19,449 | 11,310 | |||||||||
| Total Deferred Tax Assets | $ | 176,448 | $ | 174,407 | |||||||
| Deferred Tax Liabilities | |||||||||||
| Differences Related to Property | $ | (375,120) | $ | (347,885) | |||||||
| Retirement Benefits Regulatory Asset | (22,892) | (22,458) | |||||||||
| Pension Expense | (26,034) | (24,875) | |||||||||
| Other | (20,147) | (16,462) | |||||||||
| Total Deferred Tax Liabilities | (444,193) | (411,680) | |||||||||
| Deferred Income Taxes | $ | (267,745) | $ | (237,273) | |||||||
| (in thousands) | 2024 | 2023 | 2022 | ||||||||||||||
| Balance on January 1 | $ | 1,489 | $ | 923 | $ | 827 | |||||||||||
Increases (Decreases) for tax positions taken during a prior period | (189) | 596 | 44 | ||||||||||||||
| Increases for tax positions taken during the current period | 188 | 163 | 260 | ||||||||||||||
| Decreases due to settlements with taxing authorities | — | — | — | ||||||||||||||
| Decreases as a result of a lapse of applicable statutes of limitations | (363) | (193) | (208) | ||||||||||||||
| Balance on December 31 | $ | 1,125 | $ | 1,489 | $ | 923 | |||||||||||
| (in thousands) | Coal Purchase Commitments | Land Easement Payments | Other Commitments | ||||||||||||||||||||
| 2025 | $ | 24,192 | $ | 1,897 | $ | 1,817 | |||||||||||||||||
| 2026 | 24,416 | 1,902 | 1,518 | ||||||||||||||||||||
| 2027 | 25,127 | 1,941 | 661 | ||||||||||||||||||||
| 2028 | 25,859 | 1,981 | 544 | ||||||||||||||||||||
| 2029 | 27,102 | 2,021 | 272 | ||||||||||||||||||||
| Beyond 2029 | 314,713 | 52,261 | 5,758 | ||||||||||||||||||||
| Total | $ | 441,409 | $ | 62,003 | $ | 10,570 | |||||||||||||||||
| Shares | Weighted-Average Grant-Date Fair Value | ||||||||||
| Nonvested, Beginning of Year | 148,913 | $ | 56.48 | ||||||||
| Granted | 52,425 | 85.25 | |||||||||
| Vested | (57,771) | 52.78 | |||||||||
| Forfeited | (150) | 66.39 | |||||||||
| Nonvested, End of Year | 143,417 | $ | 68.47 | ||||||||
| 2024 | 2023 | 2022 | |||||||||||||||
| Risk-free interest rate | 4.16 | % | 4.15 | % | 1.52 | % | |||||||||||
| Expected term (in years) | 3.00 | 3.00 | 3.00 | ||||||||||||||
| Expected volatility | 35.10 | % | 34.00 | % | 32.00 | % | |||||||||||
| Dividend yield | 2.40 | % | 2.50 | % | 2.90 | % | |||||||||||
| Shares | Weighted-Average Grant-Date Fair Value | ||||||||||
| Nonvested, Beginning of Year | 194,200 | $ | 50.33 | ||||||||
| Granted | 43,400 | 94.45 | |||||||||
| Vested | (92,800) | 42.06 | |||||||||
| Forfeited | — | — | |||||||||
| Nonvested, End of Year | 144,800 | $ | 68.85 | ||||||||
| (in thousands) | 2024 | 2023 | 2022 | ||||||||||||||
| Weighted Average Common Shares Outstanding – Basic | 41,778 | 41,668 | 41,586 | ||||||||||||||
| Effect of Dilutive Securities: | |||||||||||||||||
| Stock Performance Awards | 196 | 269 | 248 | ||||||||||||||
| Restricted Stock Awards | 96 | 100 | 95 | ||||||||||||||
| Employee Stock Purchase Plan Shares and Other | 2 | 2 | 2 | ||||||||||||||
| Dilutive Effect of Potential Common Shares | 294 | 371 | 345 | ||||||||||||||
| Weighted Average Common Shares Outstanding – Diluted | 42,072 | 42,039 | 41,931 | ||||||||||||||
| (in thousands) | 2024 | 2023 | |||||||||
| Megawatt hours of electricity | 167 | 187 | |||||||||
| Derivative Liabilities: | |||||||||||
| Other Current Liabilities | $ | 1,989 | $ | 4,210 | |||||||
| Other Noncurrent Liabilities | — | — | |||||||||
| Total Derivative Liabilities | $ | 1,989 | $ | 4,210 | |||||||
| Level 1 | Level 2 | Level 3 | |||||||||||||||
| December 31, 2024 | |||||||||||||||||
| Assets | |||||||||||||||||
| Investments: | |||||||||||||||||
| Money Market Funds | $ | 596 | $ | — | $ | — | |||||||||||
| Mutual Funds | 10,653 | — | — | ||||||||||||||
| Corporate Debt Securities | — | 1,628 | — | ||||||||||||||
| Government Debt Securities | — | 61,131 | — | ||||||||||||||
| Total Assets | 11,249 | 62,759 | — | ||||||||||||||
| Liabilities | |||||||||||||||||
| Derivative Instruments | — | 1,989 | — | ||||||||||||||
| Total Liabilities | $ | — | $ | 1,989 | $ | — | |||||||||||
| (in thousands) | Level 1 | Level 2 | Level 3 | ||||||||||||||
| December 31, 2023 | |||||||||||||||||
| Assets | |||||||||||||||||
| Investments: | |||||||||||||||||
| Money Market Funds | $ | 3,125 | $ | — | $ | — | |||||||||||
| Mutual Funds | 7,771 | — | — | ||||||||||||||
| Corporate Debt Securities | — | 1,579 | — | ||||||||||||||
| Government Debt Securities | — | 7,724 | — | ||||||||||||||
| Total Assets | $ | 10,896 | $ | 9,303 | $ | — | |||||||||||
| Liabilities | |||||||||||||||||
| Derivative Instruments | $ | — | $ | 4,210 | $ | — | |||||||||||
| Total Liabilities | $ | — | $ | 4,210 | $ | — | |||||||||||
| December 31, 2024 | December 31, 2023 | ||||||||||||||||||||||
| (in thousands) | Carrying Amount | Fair Value | Carrying Amount | Fair Value | |||||||||||||||||||
| Assets: | |||||||||||||||||||||||
| Cash and Cash Equivalents | $ | 294,651 | $ | 294,651 | $ | 230,373 | $ | 230,373 | |||||||||||||||
| Total | 294,651 | 294,651 | 230,373 | 230,373 | |||||||||||||||||||
| Liabilities: | |||||||||||||||||||||||
| Short-Term Debt | 69,615 | 69,615 | 81,422 | 81,422 | |||||||||||||||||||
| Long-Term Debt | 943,734 | 806,826 | 824,059 | 710,839 | |||||||||||||||||||
| Total | $ | 1,013,349 | $ | 876,441 | $ | 905,481 | $ | 792,261 | |||||||||||||||
| ITEM 9. | CHANGES IN AND DISAGREEMENTS WITH ACCOUNTANTS ON ACCOUNTING AND FINANCIAL DISCLOSURE | ||||
| ITEM 9A. | CONTROLS AND PROCEDURES | ||||
| ITEM 9B. | OTHER INFORMATION | ||||
| ITEM 9C. | DISCLOSURE REGARDING FOREIGN JURISDICTIONS THAT PREVENT INSPECTIONS | ||||
| ITEM 10. | DIRECTORS, EXECUTIVE OFFICERS AND CORPORATE GOVERNANCE | ||||
| ITEM 13. | CERTAIN RELATIONSHIPS AND RELATED TRANSACTIONS, AND DIRECTOR INDEPENDENCE | ||||
| ITEM 11. | EXECUTIVE COMPENSATION | ||||
| ITEM 12. | SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND MANAGEMENT AND RELATED STOCKHOLDER MATTERS | ||||
| Number of securities to be issued upon exercise of outstanding options, warrants and rights | Weighted average exercise price of outstanding options, warrants and rights | Number of securities remaining available for future issuance under equity compensation plans (excluding securities reflected in column (a)) | |||||||||||||||||||||
| Plan Category | (a) | (b) | (c) | ||||||||||||||||||||
| Equity compensation plans approved by security holders: | |||||||||||||||||||||||
| 2023 Stock Incentive Plan | 333,147 | '(1) | N/A | 828,761 | '(2) | ||||||||||||||||||
| 1999 Employee Stock Purchase Plan | — | N/A | '(3) | ||||||||||||||||||||
| Equity compensation plans not approved by security holders | — | — | 206,115 | ||||||||||||||||||||
| Total | 333,147 | — | 1,034,876 | ||||||||||||||||||||
| ITEM 14. | PRINCIPAL ACCOUNTANT FEES AND SERVICES | ||||
| ITEM 15. | EXHIBITS AND FINANCIAL STATEMENT SCHEDULES | ||||
| Page | |||||
Consolidated Balance Sheets | |||||
Consolidated Statements of Income | |||||
| December 31, | |||||||||||
| (in thousands) | 2024 | 2023 | |||||||||
| Assets | |||||||||||
| Current Assets | |||||||||||
| Cash and Cash Equivalents | $ | 291,575 | $ | 228,137 | |||||||
| Accounts Receivable from Subsidiaries | 5,642 | 2,555 | |||||||||
| Interest Receivable from Subsidiaries | 117 | 117 | |||||||||
| Notes Receivable from Subsidiaries | 4,706 | — | |||||||||
| Other | 3,538 | 977 | |||||||||
| Total Current Assets | 305,578 | 231,786 | |||||||||
| Investments in Subsidiaries | 2,006,239 | 1,725,584 | |||||||||
| Notes Receivable from Subsidiaries | 78,900 | 78,900 | |||||||||
| Deferred Income Taxes | 69,781 | 65,244 | |||||||||
| Other Assets | 109,057 | 50,795 | |||||||||
| Total Assets | $ | 2,569,555 | $ | 2,152,309 | |||||||
| Liabilities and Stockholders' Equity | |||||||||||
| Current Liabilities | |||||||||||
| Accounts Payable to Subsidiaries | $ | 7 | $ | 7 | |||||||
| Notes Payable to Subsidiaries | 752,625 | 568,672 | |||||||||
| Other | 19,100 | 15,320 | |||||||||
| Total Current Liabilities | 771,732 | 583,999 | |||||||||
| Other Noncurrent Liabilities | 49,424 | 45,455 | |||||||||
| Commitments and Contingencies | |||||||||||
| Capitalization | |||||||||||
| Long-Term Debt | 79,900 | 79,849 | |||||||||
| Common Stockholders' Equity | 1,668,499 | 1,443,006 | |||||||||
| Total Capitalization | 1,748,399 | 1,522,855 | |||||||||
| Total Liabilities and Stockholders' Equity | $ | 2,569,555 | $ | 2,152,309 | |||||||
| Years Ended December 31, | |||||||||||||||||
| (in thousands) | 2024 | 2023 | 2022 | ||||||||||||||
| Income | |||||||||||||||||
| Equity Income in Earnings of Subsidiaries | $ | 304,525 | $ | 294,467 | $ | 296,833 | |||||||||||
| Interest Income from Subsidiaries | 3,107 | 2,898 | 3,382 | ||||||||||||||
| Other Income | 15,085 | 10,496 | 466 | ||||||||||||||
| Total Income | 322,717 | 307,861 | 300,681 | ||||||||||||||
| Expense | |||||||||||||||||
| Nonelectric Selling, General, and Administrative Expenses | 23,016 | 12,816 | 17,269 | ||||||||||||||
| Interest Expense | 3,599 | 3,813 | 4,066 | ||||||||||||||
| Interest Expense from Subsidiaries | 5 | 6 | 5 | ||||||||||||||
| Nonservice Cost Components of Postretirement Benefits | 970 | 1,063 | 1,023 | ||||||||||||||
| Total Expense | 27,590 | 17,698 | 22,363 | ||||||||||||||
| Income Before Income Taxes | 295,127 | 290,163 | 278,318 | ||||||||||||||
| Income Tax Benefit | 6,535 | 4,028 | 5,866 | ||||||||||||||
| Net Income | $ | 301,662 | $ | 294,191 | $ | 284,184 | |||||||||||
| Years Ended December 31, | |||||||||||||||||
| (in thousands) | 2024 | 2023 | 2022 | ||||||||||||||
| Cash Flows from Operating Activities | |||||||||||||||||
| Net Cash Provided by Operating Activities | $ | 76,333 | $ | 77,139 | $ | 28,807 | |||||||||||
| Cash Flows from Investing Activities | |||||||||||||||||
| Investment in Subsidiaries | (55,000) | (40,000) | (50,000) | ||||||||||||||
Purchases of Investments and Other Assets | (53,085) | (1,754) | (3,175) | ||||||||||||||
| Other, net | 1,394 | 1,686 | 1,480 | ||||||||||||||
| Net Cash Used in Investing Activities | (106,691) | (40,068) | (51,695) | ||||||||||||||
| Cash Flows from Financing Activities | |||||||||||||||||
| Net (Repayments) Borrowings on Short-Term Debt | — | — | (22,637) | ||||||||||||||
| Borrowings from Subsidiaries | 179,247 | 148,308 | 236,926 | ||||||||||||||
| Payments for Shares Withheld for Employee Tax Obligations | (6,457) | (3,088) | (2,942) | ||||||||||||||
| Dividends Paid | (78,265) | (73,061) | (68,755) | ||||||||||||||
| Other, net | (729) | (339) | (461) | ||||||||||||||
Net Cash Provided by Financing Activities | 93,796 | 71,820 | 142,131 | ||||||||||||||
| Net Change in Cash and Cash Equivalents | 63,438 | 108,891 | 119,243 | ||||||||||||||
| Cash and Cash Equivalents at Beginning of Period | 228,137 | 119,246 | 3 | ||||||||||||||
| Cash and Cash Equivalents at End of Period | $ | 291,575 | $ | 228,137 | $ | 119,246 | |||||||||||
| (in thousands) | Accounts Receivable | Interest Receivable | Current Notes Receivable | Long-Term Notes Receivable | Accounts Payable | Current Notes Payable | |||||||||||||||||||||||||||||
| December 31, 2024 | |||||||||||||||||||||||||||||||||||
| Otter Tail Power Company | $ | 5,223 | $ | — | $ | — | $ | — | $ | 7 | $ | — | |||||||||||||||||||||||
| Northern Pipe Products, Inc. | 36 | 7 | — | 5,000 | — | 66,170 | |||||||||||||||||||||||||||||
| Vinyltech Corporation | — | 17 | — | 11,500 | — | 90,764 | |||||||||||||||||||||||||||||
| BTD Manufacturing, Inc. | — | 78 | — | 52,000 | — | 5,662 | |||||||||||||||||||||||||||||
| T.O. Plastics, Inc. | 42 | 15 | 4,706 | 10,400 | — | — | |||||||||||||||||||||||||||||
| Varistar Corporation | — | — | — | — | — | 590,029 | |||||||||||||||||||||||||||||
| Otter Tail Assurance Limited | 341 | — | — | — | — | — | |||||||||||||||||||||||||||||
Total | $ | 5,642 | $ | 117 | $ | 4,706 | $ | 78,900 | $ | 7 | $ | 752,625 | |||||||||||||||||||||||
| December 31, 2023 | |||||||||||||||||||||||||||||||||||
| Otter Tail Power Company | $ | 2,415 | $ | — | $ | — | $ | — | $ | 7 | $ | — | |||||||||||||||||||||||
| Northern Pipe Products, Inc. | — | 7 | — | 5,000 | — | 56,917 | |||||||||||||||||||||||||||||
| Vinyltech Corporation | 14 | 17 | — | 11,500 | — | 98,016 | |||||||||||||||||||||||||||||
| BTD Manufacturing, Inc. | — | 78 | — | 52,000 | — | 6,291 | |||||||||||||||||||||||||||||
| T.O. Plastics, Inc. | 36 | 15 | — | 10,400 | — | 980 | |||||||||||||||||||||||||||||
| Varistar Corporation | — | — | — | — | — | 406,468 | |||||||||||||||||||||||||||||
| Otter Tail Assurance Limited | 90 | — | — | — | — | — | |||||||||||||||||||||||||||||
Total | $ | 2,555 | $ | 117 | $ | — | $ | 78,900 | $ | 7 | $ | 568,672 | |||||||||||||||||||||||
| (in thousands) | 2024 | 2023 | 2022 | ||||||||||||||
| Cash Dividends Paid to Parent by Subsidiaries | $ | 78,191 | $ | 72,982 | $ | 68,680 | |||||||||||
| (in thousands) | Balance, January 1 | Charged to Cost and Expenses | Deductions(1) | Balance, December 31 | |||||||||||||||||||
| Allowance for Credit Losses | |||||||||||||||||||||||
| 2024 | $ | 2,522 | $ | 1,242 | $ | (1,844) | $ | 1,920 | |||||||||||||||
| 2023 | 1,648 | 2,014 | (1,140) | 2,522 | |||||||||||||||||||
| 2022 | 1,836 | 909 | (1,097) | 1,648 | |||||||||||||||||||
(1)Amounts reflect deductions to the allowance for amounts written-off, net of recoveries. | |||||||||||||||||||||||
| No. | Description | ||||
| 3.1 | |||||
| 3.2 | |||||
| 4.1 | |||||
| 10.1.0 | |||||
| 10.1.1 | |||||
| 10.1.2 | |||||
| 10.1.3 | |||||
| 10.2 | |||||
| 10.3 | |||||
| 10.4 | |||||
| 10.5 | |||||
| 10.6 | |||||
10.7 | |||||
10.8 | |||||
10.9 | |||||
10.10.0 | Agreement for Sharing Ownership of Generating Plant by and between the Company, Montana-Dakota Utilities Co., and Northwestern Public Service Company (dated as of January 7, 1970). Previously filed as Exhibit 10-F in Form 10-K for the year ended December 31, 1989 | ||||
10.10.1 | Letter of Intent for purchase of share of Big Stone Plant from Northwestern Public Service Company (dated as of May 8, 1984). Previously filed as Exhibit 10-F-1 in Form 10-K for the year ended December 31, 1989 | ||||
10.10.2 | Supplemental Agreement No. 1 to Agreement for Sharing Ownership of Big Stone Plant (dated as of July 1, 1983). Previously filed as Exhibit 10-F-2 in Form 10-K for the year ended December 31, 1991 | ||||
10.10.3 | Supplemental Agreement No. 2 to Agreement for Sharing Ownership of Big Stone Plant (dated as of March 1, 1985). Previously filed as Exhibit 10-F-3 in Form 10-K for the year ended December 31, 1991 | ||||
10.10.4 | Supplemental Agreement No. 3 to Agreement for Sharing Ownership of Big Stone Plant (dated as of March 31, 1986). Previously filed as Exhibit 10-F-4 in Form 10-K for the year ended December 31, 1991 | ||||
10.10.5 | |||||
10.10.6 | Amendment I to Letter of Intent dated May 8, 1984, for purchase of share of Big Stone Plant. Previously filed as Exhibit 10-F-5 in Form 10-K for the year ended December 31, 1992 | ||||
10.11 | |||||
10.12.0 | Agreement for Sharing Ownership of Coyote Station Generating Unit No. 1 by and between the Company, Minnkota Power Cooperative, Inc., Montana-Dakota Utilities Co., Northwestern Public Service Company and Minnesota Power & Light Company (dated as of July 1, 1977). Previously filed as Exhibit 5-H in filing 2-61043 | ||||
10.12.1 | Supplemental Agreement No. One, dated as of November 30, 1978, to Agreement for Sharing Ownership of Coyote Generating Unit No. 1. Previously filed as Exhibit 10-H-1 in Form 10-K for the year ended December 31, 1989 | ||||
10.12.2 | Supplemental Agreement No. Two, dated as of March 1, 1981, to Agreement for Sharing Ownership of Coyote Generating Unit No. 1 and Amendment No. 2 dated March 1, 1981, to Coyote Plant Coal Agreement. Previously filed as Exhibit 10-H-2 in Form 10-K for the year ended December 31, 1989 | ||||
10.12.3 | Amendment, dated as of July 29, 1983, to Agreement for Sharing Ownership of Coyote Generating Unit No. 1. Previously filed as Exhibit 10-H-3 in Form 10-K for the year ended December 31, 1989 | ||||
10.12.4 | Agreement, dated as of September 5, 1985, containing Amendment No. 3 to Agreement for Sharing Ownership of Coyote Generating Unit No. 1, dated as of July 1, 1977, and Amendment No. 5 to Coyote Plant Coal Agreement, dated as of January 1, 1978. Previously filed as Exhibit 10-H-4 in Form 10-K for the year ended December 31, 1992 | ||||
10.12.5 | |||||
10.12.6 | |||||
10.13.0 | |||||
| No. | Description | ||||
10.13.1 | |||||
10.13.2 | |||||
10.14 | |||||
10.15 | |||||
10.16 | |||||
10.17 | |||||
10.18 | |||||
10.19 | |||||
10.20 | |||||
10.21 | |||||
10.22 | |||||
10.23 | |||||
10.24 | |||||
10.25 | |||||
10.26 | |||||
10.27 | |||||
10.28 | |||||
10.29 | |||||
10.30 | |||||
10.31 | |||||
10.32 | |||||
| 19 | |||||
| 21 | |||||
| 23 | |||||
| 24 | |||||
| 31.1 | |||||
| 31.2 | |||||
| 32.1 | |||||
| 32.2 | |||||
| 97 | |||||
| 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) | ||||
| ITEM 16. | FORM 10-K SUMMARY | ||||
| OTTER TAIL CORPORATION | ||||||||
| By: | /s/ Todd R. Wahlund | |||||||
| Todd R. Wahlund Vice President and Chief Financial Officer (authorized officer and principal financial officer) | ||||||||
| Dated: February 19, 2025 | ||||||||
| Charles S. MacFarlane | ) | ||||||||||
| President and Chief Executive Officer | ) | ||||||||||
| (principal executive officer) and Director | ) | ||||||||||
| ) | |||||||||||
| Todd R. Wahlund | ) | ||||||||||
| Vice President and Chief Financial Officer | ) | ||||||||||
| (principal financial and accounting officer) | ) | ||||||||||
| ) | By | /s/ Charles S. MacFarlane | |||||||||
| Nathan I. Partain | ) | Charles S. MacFarlane | |||||||||
| Chairman of the Board and Director | ) | Pro Se and Attorney-in-Fact | |||||||||
| ) | Dated: February 19, 2025 | ||||||||||
| Jeanne H. Crain, Director | ) | ||||||||||
| ) | |||||||||||
| John D. Erickson, Director | ) | ||||||||||
| ) | |||||||||||
| Steven L. Fritze, Director | ) | ||||||||||
| ) | |||||||||||
| Kathryn O. Johnson, Director | ) | ||||||||||
| ) | |||||||||||
| Michael E. LeBeau, Director | ) | ||||||||||
| ) | |||||||||||
| Mary E. Ludford, Director | ) | ||||||||||
| ) | |||||||||||
| Thomas J. Webb, Director | ) | ||||||||||
| Grant Type: | Performance Award | |||||||
| Target Number of Shares Subject to Award: | «Target» | |||||||
| Maximum Number of Shares Subject to Award: | «Max» | |||||||
| Grant Date: | ||||||||
| Performance Period: | January 1, 20[__] – December 31, 20[__] | |||||||
| Performance Goals: | Set forth in Exhibit 1 to the 20[__] Executive Performance Award Agreement | |||||||
| Threshold | Target | Maximum | |||||||||||||||
| Performance Goal | Otter Tail TSR performance relative to peer group | ||||||||||||||||
| Payment Levels | % of target shares | ||||||||||||||||
| Threshold | Target | Maximum | |||||||||||||||
| Performance Goal | Adjusted 3-Year ROE | ||||||||||||||||
| Payment Levels | % of target shares | ||||||||||||||||
| Vesting Schedule: | ||||||||
| Date | Percentage of Restricted Units Vested | |||||||
| Director’s Retainer (except Chairman) | $ | 80,000 | |||
| Chairman of the Board Retainer | $ | 148,000 | |||
| Compensation and Corporate Governance Committee Chair Retainer | $ | 15,000 | |||
| Audit Committee Chair Retainer | $ | 21,000 | |||
| Restricted Stock Award Value (except Chairman) | $ | 120,000 | |||
| Restricted Stock Award Value (Chairman of the Board) | $ | 162,000 | |||
| Restricted Stock Award Value (additional per committee) | $ | 10,500 | |||
Page | 1 | ||
Page | 2 | ||
Page | 3 | ||
Page | 4 | ||
Page | 5 | ||
Page | 6 | ||
Page | 7 | ||
Page | 8 | ||
Page | 9 | ||
Page | 10 | ||
Page | 11 | ||
Page | 12 | ||
Restricted Persons | |||||||||||||||||
| Director | Household Family Members and Controlled Entities | Executive Officers | Exhibit A Key Personnel- | Restricted Persons not Executive Officers, Directors, or Key Personnel listed in Exhibit A | |||||||||||||
Pre-Clearance | X | X | X | X | |||||||||||||
Prohibited Transactions | X | X | X | X | |||||||||||||
Subject to Black Out Periods – or whenever in possession of MNPI | X | X | X | X | X | ||||||||||||
File Form 4 with SEC within 2 business days of transaction | X | X1 | X | ||||||||||||||
Page | 13 | ||
| Company | State of Organization | ||||
| BTD Manufacturing, Inc. | Minnesota | ||||
| Northern Pipe Products, Inc. | North Dakota | ||||
| Otter Tail Assurance Limited | Cayman Islands | ||||
| Otter Tail Power Company | Minnesota | ||||
| T.O. Plastics, Inc. | Minnesota | ||||
| Varistar Corporation | Minnesota | ||||
| Vinyltech Corporation | Arizona | ||||
| /s/ Jeanne H. Crain | /s/ Charles S. MacFarlane | ||||||||||
| Jeanne H. Crain | Charles S. MacFarlane | ||||||||||
| /s/ John D. Erickson | /s/ Jennifer O. Smestad | ||||||||||
| John D. Erickson | Jennifer O. Smestad | ||||||||||
| /s/ Steven L. Fritze | /s/ Nathan I. Partain | ||||||||||
| Steven L. Fritze | Nathan I. Partain | ||||||||||
| /s/ Kathryn O. Johnson | /s/ Thomas J. Webb | ||||||||||
| Kathryn O. Johnson | Thomas J. Webb | ||||||||||
| /s/ Michael E. LeBeau | /s/ Todd R. Wahlund | ||||||||||
| Michael E. LeBeau | Todd R. Wahlund | ||||||||||
| /s/ Mary E. Ludford | |||||||||||
| Mary E. Ludford | |||||||||||
| Date: February 19, 2025 | |||||
| /s/ Charles S. MacFarlane | |||||
Charles S. MacFarlane President and Chief Executive Officer | |||||
| Date: February 19, 2025 | |||||
| /s/ Todd R. Wahlund | |||||
| Todd R. Wahlund Chief Financial Officer and Vice President | |||||
| /s/ Charles S. MacFarlane | ||||||||
Charles S. MacFarlane President and Chief Executive Officer | ||||||||
| February 19, 2025 | ||||||||
| /s/ Todd R. Wahlund | ||||||||
| Todd R. Wahlund Chief Financial Officer and Vice President | ||||||||
| February 19, 2025 | ||||||||