##### Table of Contents



SECURITIES AND EXCHANGE COMMISSION
 Washington, D.C. 20549
 FORM 10-K
  þ
    
    Annual Report pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934
For the fiscal year ended December 31, 2005
 o
    
    Transition Report pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934
For the transition period from to
 0-368
 OTTER TAIL CORPORATION
  MINNESOTA
    
    41-0462685(State or other jurisdiction of incorporation or organization)
    
    (I.R.S. Employer Identification No.)215 SOUTH CASCADE STREET BOX 496, FERGUS FALLS, MINNESOTA
    
    56538-0496(Address of principal executive offices)
    
    (Zip Code)
 866-410-8780
 NONE
  COMMON SHARES, par value $5.00 per share
PREFERRED SHARE PURCHASE RIGHTS
CUMULATIVE PREFERRED SHARES, without par value
 þ o
 o þ
 þ o
 þ
  Large Accelerated Filer þ
    
    Accelerated Filer o
    
    Non-Accelerated Filer o
 o þ
 $774,287,870.
 29,438,047 Common Shares ($5 par value) as of February 28, 2006.
  2005 Annual Report to Shareholders-Portions incorporated by reference into Parts I and II
Proxy Statement dated March 6, 2006-Portions incorporated by reference into Part III




---



TABLE OF CONTENTS  PART IItem 1. BUSINESSItem 1A. RISK FACTORSItem 1B. UNRESOLVED STAFF COMMENTSItem 2. PROPERTIESItem 3. LEGAL PROCEEDINGSItem 4. SUBMISSION OF MATTERS TO A VOTE OF SECURITY HOLDERSItem 4A. EXECUTIVE OFFICERS OF THE REGISTRANT (AS OF MARCH 1, 2006)PART IIItem 5. MARKET FOR THE REGISTRANTS COMMON EQUITY, RELATED STOCKHOLDER MATTERS AND ISSUER PURCHASES OF EQUITY SECURITIESItem 6. SELECTED FINANCIAL DATAItem 7. MANAGEMENTS DISCUSSION AND ANALYSIS OF FINANCIAL CONDITIONItem 7A. QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISKItem 8. FINANCIAL STATEMENTS AND SUPPLEMENTARY DATAItem 9. CHANGES IN AND DISAGREEMENTS WITH ACCOUNTANTS ON ACCOUNTING AND FINANCIAL DISCLOSUREItem 9A. CONTROLS AND PROCEDURESItem 9B. OTHER INFORMATIONPART IIIItem 10. DIRECTORS AND EXECUTIVE OFFICERS OF THE REGISTRANTItem 11. EXECUTIVE COMPENSATIONItem 12. SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND MANAGEMENT AND RELATED STOCKHOLDER MATTERSItem 13. CERTAIN RELATIONSHIPS AND RELATED TRANSACTIONSItem 14. PRINCIPAL ACCOUNTANT FEES AND SERVICESPART IVItem 15. EXHIBITS AND FINANCIAL STATEMENT SCHEDULESSIGNATURESForm of Stock Option AgreementForm of Restricted Stock AgreementPortions of 2005 Annual Report to ShareholdersSubsidiaries of RegistrantConsent of Deloitte & Touche LLPPowers of AttorneyCertification of CEO Pursuant to Section 302Certification of CFO Pursuant to Section 302Certification of CEO Pursuant to Section 906Certification of CFO Pursuant to Section 906    Table of Contents  
  
 BUSINESS
 General Development of Business
 th
     
    
    ability to provide returns on invested capital that exceed the Companys weighted
average cost of capital over the long term; and
    
    the operating companys business and the potential for future earnings growth.
  1




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##### Table of Contents




    
    Electric (the Utility) consists of the production, transmission,
distribution and sale of electric energy in Minnesota, North Dakota and South Dakota
under the name Otter Tail Power Company. Electric utility operations have been the
Companys primary business since incorporation.
    
    Plastics consist of businesses producing polyvinyl chloride and polyethylene
pipe in the Upper Midwest and Southwest regions of the United States.
    
    Manufacturing consists of businesses in the following manufacturing
activities: production of waterfront equipment; wind towers; material and handling
trays and horticultural containers; contract machining; and metal parts stamping and
fabrication. These businesses have manufacturing facilities in Minnesota, North Dakota,
South Carolina, Missouri, California, Florida and Ontario, Canada and sell products
primarily in the United States.
    
    Health Services consists of businesses involved in the sale of diagnostic
medical equipment, patient monitoring equipment and related supplies and accessories.
These businesses also provide equipment maintenance, diagnostic imaging services and
rental of diagnostic medical imaging equipment to various medical institutions located
throughout the United States.
    
    Food Ingredient Processing consists of Idaho Pacific Holdings, Inc. (IPH),
which owns and operates potato dehydration plants in Ririe, Idaho; Center, Colorado and
Souris, Prince Edward Island, Canada. IPH produces dehydrated potato products that are
sold in the United States, Canada, Europe, the Middle East, the Pacific Rim and Central
America. Approximately 25% of IPHs sales are to customers outside of the United
States.
    
    Other Business Operations consists of businesses involved in residential,
commercial and industrial electric contracting industries; fiber optic and electric
distribution systems; waste-water, water and HVAC systems construction; transportation;
energy services and natural gas marketing as well as the portion of corporate general
and administrative expenses that are not allocated to other segments. These businesses
operate primarily in the Central United States, except for the transportation company
which operates in 48 states and 6 Canadian provinces.
   
    
    Emerging or middle market company;
    
    Proven entrepreneurial management team that will remain after the acquisition;
    
    Preference for 100% ownership of the acquired company;
    
    Products and services intended for commercial rather than retail consumer use; and
    
    The potential to provide immediate earnings and future growth.
 2




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##### Table of Contents




    
    On January 3, 2005 the Companys wholly-owned subsidiary, BTD Manufacturing, Inc.
acquired the assets of Performance Tool & Die, Inc. of Lakeville, Minnesota for $4.1
million in cash. Performance Tool & Die specializes in manufacturing mid to large
progressive dies for customers throughout the Midwest, East and West Coasts, and the
Southern United States. Performance Tool & Dies revenues for the year ended December
31, 2004 were $4.1 million. The Company expects this acquisition to provide expanded
growth opportunities for both BTD Manufacturing and Performance Tool & Die.
    
    On January 3, 2005 the Companys wholly-owned subsidiary, ShoreMaster, Inc. acquired
the common stock of Shoreline Industries, Inc. of Pine River, Minnesota for $2.4
million in cash. Shoreline is a manufacturer of boatlift motors and other accessories
for lifts and docks with sales throughout the United States, but primarily in Minnesota
and Wisconsin. Shorelines revenues for the year ended December 31, 2004 were $2.1
million. The acquisition of Shoreline secures a source of components and expands
potential markets for ShoreMaster products.
    
    On May 31, 2005 ShoreMaster acquired the assets of Southeast Floating Docks, Inc. of
St. Augustine, Florida for $4.0 million in cash. Southeast Floating Docks is a leading
manufacturer of concrete floating dock systems for marinas. They have designed custom
floating systems and conducted installations mainly in the Southeast United States and
the Caribbean. Southeast Floating Docks had revenues of $4.5 million in 2004. This
acquisition enables ShoreMaster to offer a wider range of products to its customers and
expands its geographic reach in the Southeast region of the United States.
   
    
    In June 2005, the Company completed the sale of MIS, a telecommunications company
located in Parkers Prairie, Minnesota, for an after-tax gain of $11.9 million.
    
    Also in June 2005, the Company completed the sale of SGS, a structural steel
fabricator located in St. George, Utah, for an after-tax loss of $1.7 million.
    
    In November 2005, the Company completed the sale of CLC, a manufacturer of auto and
truck frame-straightening equipment and accessories located in Alexandria, Minnesota,
for an after-tax loss of $0.2 million.
 Accounting
for the Impairment of Disposal of Long-Lived Assets
 3




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##### Table of Contents



Financial Information About Industry Segments
  Narrative Description of Business
 ELECTRIC
 General
  State
    
    2005
    
    
    2004Minnesota
    
    
    50.3
    %
    
    
    50.3
    %North Dakota
    
    
    40.9
    
    
    
    41.2South Dakota
    
    
    8.8
    
    
    
    8.5Total
    
    
    100.0
    %
    
    
    100.0
    %
  4




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##### Table of Contents



Customer category
    
    2005
    
    
    2004Commercial
    
    
    33.5
    %
    
    
    35.3
    %Residential
    
    
    28.1
    
    
    
    30.3Industrial
    
    
    20.9
    
    
    
    21.5All other sources
    
    
    17.5
    
    
    
    12.9Total
    
    
    100.0
    %
    
    
    100.0
    %
    Capability and Demand
  Base load net plant capability
    
    2005
    
    
    2004Big Stone Plant
    
    256,025
    kw
    
    252,430
    kwHoot Lake Plant
    
    
    153,700
    
    
    
    152,450Coyote Station
    
    
    149,450
    
    
    
    149,450Co-generation plant  Bemidji, MN (contract)
    
    
    5,862
    
    
    
    5,661Co-generation plant  Perham, MN (contract)
    
    
    1,242
    
    
    
    1,228Total
    
    566,279
    kw
    
    561,219
    kw
  5




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##### Table of Contents



Big Stone II
   6
    Table of Contents       Fuel Supply
   2005
    
    
    2004Net Kilowatt
    
    
    % of Total
    
    
    Net Kilowatt
    
    
    % of TotalHours
    
    
    Kilowatt
    
    
    Hours
    
    
    KilowattGenerated
    
    
    Hours
    
    
    Generated
    
    
    HoursSources
    
    (Thousands)
    
    
    Generated
    
    
    (Thousands)
    
    
    GeneratedSubbituminous Coal
    
    
    2,410,719
    
    
    
    68.6
    %
    
    
    2,605,014
    
    
    
    69.0
    %Lignite Coal
    
    
    1,043,020
    
    
    
    29.7
    
    
    
    1,114,485
    
    
    
    29.5Hydro
    
    
    23,446
    
    
    
    .7
    
    
    
    20,689
    
    
    
    .6Natural Gas and Oil
    
    
    36,520
    
    
    
    1.0
    
    
    
    33,927
    
    
    
    .9Total
    
    
    3,513,705
    
    
    
    100.0
    %
    
    
    3,774,115
    
    
    
    100.0
    %
 7




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##### Table of Contents



Plant
    
    Coal Supplier
    
    Type of Coal
    
    Expiration DateBig Stone Plant
    
    Arch Coal Sales Company, Inc.
    
    Wyoming subbituminous
    
    December 31, 2007Big Stone Plant
    
    Kennecott Coal Sales Company
    
    Wyoming subbituminous
    
    December 31, 2007Hoot Lake Plant
    
    Kennecott Coal Sales Company
    
    Wyoming subbituminous
    
    December 31, 2007Coyote Station
    
    Dakota Westmoreland Corporation
    
    North Dakota lignite
    
    2016
     General Regulation
  8




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##### Table of Contents



2005
    
    
    2004% of
    
    
    % of
    
    
    % of
    
    
    % ofElectric
    
    
    kwh
    
    
    Electric
    
    
    kwhRates
    
    Regulation
    
    
    Revenues
    
    
    Sales
    
    
    Revenues
    
    
    SalesMN retail sales
    
    MN Public Utilities Commission
    
    
    31.2
    %
    
    
    30.2
    %
    
    
    29.3
    %
    
    
    25.7
    %ND retail sales
    
    ND Public Service Commission
    
    
    25.3
    
    
    
    22.9
    
    
    
    24.1
    
    
    
    19.6SD retail sales
    
    SD Public Utilities Commission
    
    
    5.5
    
    
    
    5.2
    
    
    
    4.9
    
    
    
    4.2Transmission & sales for resale
    
    Federal Energy Regulatory Commission
    
    
    38.0
    
    
    
    41.7
    
    
    
    41.7
    
    
    
    50.5100.0
    %
    
    
    100.0
    %
    
    
    100.0
    %
    
    
    100.0
    %
    Minnesota
 9




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##### Table of Contents



10
    Table of Contents       North Dakota
  11




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##### Table of Contents



South Dakota
   FERC
  
    
    The Public Utility Holding Company Act of 1935 (PUHCA) was repealed effective February
8, 2006. PUHCA significantly restricted mergers and acquisitions in the electric utility
sector.
 12




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##### Table of Contents




    
    The FERC will appoint and oversee an electric reliability organization to establish and
enforce mandatory reliability rules regarding the interstate electric transmission system.
It is expected that the electric reliability organization will be approved and begin
operation by mid-year 2006.
    
    The FERC will establish incentives for transmission companies, such as performance based
rates, recovery of costs to comply with reliability rules and accelerated depreciation for
investments in transmission infrastructure.
    
    Federal support will be available for certain clean coal power initiatives, nuclear
power projects and renewable energy technologies.
   MAPP
 MEMA
 MRO
 13




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##### Table of Contents



MISO
  Other:
 Competition, Deregulation and Legislation
     Environmental Regulation
 Impact of Environmental Laws 14
    Table of Contents    Air Quality
       15




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##### Table of Contents



.
   16




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##### Table of Contents



Water Quality
   Solid Waste
    17




---



##### Table of Contents



Capital Expenditures
   Franchises
  Employees
  PLASTICS
 General
   Northern Pipe Products, Inc.
 18




---



##### Table of Contents



Vinyltech Corporation
  Customers
  Competition
   Manufacturing and Resin Supply
   19




---



##### Table of Contents



Capital Expenditures
  Employees
  MANUFACTURING
 General
   BTD Manufacturing, Inc. (BTD)
 DMI Industries, Inc.
 ShoreMaster, Inc.,
 20




---



##### Table of Contents



T. O. Plastics, Inc.
 Competition
    Steel Supply
  Legislation
  Capital Expenditures
  21




---



##### Table of Contents



Employees
  HEALTH SERVICES
 General
   DMS Health Technologies, Inc. (DMSHT)
 DMS Imaging, Inc.
 
    
    DMS Imaging  provides shared diagnostic medical imaging services
(primarily mobile) for MR, CT, nuclear medicine, PET, PET/CT, ultrasound,
mammography and bone density analysis.
    
    DMS Interim Solutions  offers interim and rental options for diagnostic
imaging services.
    
    DMS MedSource Partners  develops long-term relationships with
healthcare providers to offer dedicated in-house diagnostic imaging
services.
    
    DMS Portable X-Ray  delivers portable x-ray, ultrasound and
electrocardiography services to nursing homes and other facilities.
 22




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##### Table of Contents



Regulation
       23




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##### Table of Contents



Reimbursement
   Competition
  24




---



##### Table of Contents



Environmental, Health or Safety Laws
 Capital Expenditures
  Employees
  FOOD INGREDIENT PROCESSING
 General
   Customers
  25
    Table of Contents  Competition
  Potato Supply
  Regulations
  Capital Expenditures
  Employees
  OTHER BUSINESS OPERATIONS
 General
  26
    Table of Contents  Foley Company
 Midwest Construction Services, Inc.
 Otter Tail Energy Services Company
 E. W. Wylie Corporation (Wylie)
 Competition
   Capital Expenditures
  27
    Table of Contents  Employees
  Forward-Looking Information  Safe Harbor Statement Under the  Private Securities Litigation Reform Act of 1995
   
    
    The Company is subject to government regulations and actions that may have a negative
impact on its business and results of operations.
    
    Weather conditions can adversely affect the Companys operations and revenues.
    
    Electric wholesale margins could be reduced as the MISO market becomes more efficient.
    
    Electric wholesale trading margins could be reduced or eliminated by losses due to
trading activities.
    
    Federal and state environmental regulation could cause the Company to incur substantial
capital expenditures which could result in increased operating costs.
    
    The Companys plans to grow and diversify through acquisitions may not be successful
and could result in poor financial performance.
    
    Competition is a factor in all of the Companys businesses.
    
    Economic uncertainty could have a negative impact on the Companys future revenues and
earnings.
    
    Volatile financial markets could restrict the Companys ability to access capital and
could increase borrowing costs and pension plan expenses.
    
    The Companys Food Ingredient Processing segment is dependent on adequate sources of
raw materials for processing. Should the supply of these raw materials be affected by
poor growing conditions, this could negatively impact the results of operations for this
segment. This segment could also be impacted by foreign currency changes between Canadian
and United States currency and prices of natural gas.
    
    The Companys Plastics segment is highly dependent on a limited number of vendors for
PVC resin, many of which are located in the Gulf Coast region. The loss of a key vendor
or an interruption or delay in the supply of PVC resin could result in reduced sales or
increased costs for this segment.
    
    The Companys Health Services businesses may not be able to retain or comply with the
dealership arrangement and other agreements with Philips Medical.
 28
    Table of Contents  RISK FACTORS
  
 UNRESOLVED STAFF COMMENTS
  
 PROPERTIES
      29
    Table of Contents  LEGAL PROCEEDINGS
  
 SUBMISSION OF MATTERS TO A VOTE OF SECURITY HOLDERS
  
 EXECUTIVE OFFICERS OF THE REGISTRANT (AS OF MARCH 1, 2006)
  DATES ELECTEDNAME AND AGE
    
    TO OFFICE
    
    PRESENT POSITION AND BUSINESS EXPERIENCEJohn D. Erickson (47)
    
    4/8/02
    
    Present:
    
    President and Chief Executive Officer4/9/01
    
    PresidentPrior to4/9/01
    
    Executive Vice President, Chief Financial Officer and
TreasurerGeorge A. Koeck (53)
    
    4/10/00
    
    Present:
    
    Corporate Secretary and General
Counsel
 30
    Table of Contents  DATES ELECTEDNAME AND AGE
    
    TO OFFICE
    
    PRESENT POSITION AND BUSINESS EXPERIENCELauris N. Molbert (48)
    
    6/10/02
    
    Present: Executive Vice President and Chief Operating Officer4/9/01
    
    Executive Vice President, Corporate Development
and Varistar President and Chief
Operating OfficerPrior to4/9/01
    
    Vice President, Chief Operating Officer, VaristarKevin G. Moug (46)
    
    4/9/01
    
    Present: Chief
Financial Officer and TreasurerPrior to4/9/01
    
    Varistar Chief Financial Officer and
TreasurerCharles S. MacFarlane (41)
    
    5/1/03
    
    President, Otter Tail Power Company6/1/02
    
    Interim President, Otter Tail Power Company1/29/02
    
    Director, Finance & Strategic Planning,
Otter Tail Power Company12/1/01
    
    Director, Finance
Planning, Otter Tail Power CompanyPrior to12/2/01
    
    Director, Electric Distribution Planning, Engineering &
Reliability, Xcel Energy
  
  
 MARKET FOR THE REGISTRANTS COMMON EQUITY, RELATED STOCKHOLDER MATTERS AND ISSUER
PURCHASES OF EQUITY SECURITIES
  
 SELECTED FINANCIAL DATA
  31
    Table of Contents  MANAGEMENTS DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS
  
 QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK
  
 FINANCIAL STATEMENTS AND SUPPLEMENTARY DATA
  
 CHANGES IN AND DISAGREEMENTS WITH ACCOUNTANTS ON ACCOUNTING AND
FINANCIAL DISCLOSURE
  
 CONTROLS AND PROCEDURES
    32
    Table of Contents  OTHER INFORMATION
  
  
 DIRECTORS AND EXECUTIVE OFFICERS OF THE REGISTRANT
   
 EXECUTIVE COMPENSATION
  
 SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND MANAGEMENT AND RELATED STOCKHOLDER MATTERS
   33
    Table of Contents  CERTAIN RELATIONSHIPS AND RELATED TRANSACTIONS
  
 PRINCIPAL ACCOUNTANT FEES AND SERVICES
  
  
 EXHIBITS AND FINANCIAL STATEMENT SCHEDULES
 (a)
    
    List of documents filed:
 (1)
    
    and (2) See Table of Contents on Page 36 hereof.(3)
    
    See Exhibit Index on Pages 37 through 43 hereof.
  34
    Table of Contents  OTTER TAIL CORPORATIONBy     /s/ Kevin G. MougKevin G. MougChief Financial Officer and
TreasurerDated:
    March 14, 2006  Signature and Title
 John D. Erickson
    
    )President and Chief Executive Officer
    
    )(principal executive officer)
    
    ))Kevin G. Moug
    
    )Chief Financial Officer and Treasurer
    
    )(principal financial and accounting officer)
    
    ))
    
    By
    
    /s/ John D. EricksonJohn C. MacFarlane
    
    )
    
    
    
    John D. EricksonChairman of the Board and Director
    
    )
    
    
    
    Pro Se and Attorney-in-Fact)
    
    
    
    Dated March 14, 2006Karen M. Bohn, Director
    
    ))Thomas M. Brown, Director
    
    ))Dennis R. Emmen, Director
    
    ))Arvid R. Liebe, Director
    
    ))Kenneth L. Nelson, Director
    
    ))Nathan I. Partain, Director
    
    ))Gary J. Spies, Director
    
    ))Robert N. Spolum, Director
    
    )
 35
    Table of Contents  TABLE OF CONTENTS
 
  Page inAnnualReport toShareholdersFinancial Statements:Managements Report Regarding Internal Controls Over Financial Reporting
    
    33Report of Independent Registered Public Accounting Firm
    
    34Consolidated Statements of Income for the Three Years Ended December 31, 2005
    
    35Consolidated Balance Sheets, December 31, 2005 and 2004
    
    36&37Consolidated Statements of Common Shareholders Equity for the
Three Years Ended December 31, 2005
    
    38Consolidated Statements of Cash Flows for the Three Years Ended December 31, 2005
    
    39Consolidated Statements of Capitalization, December 31, 2005 and 2004
    
    40Notes to Consolidated Financial Statements
    
    41-57Selected Consolidated Financial Data for the Five Years Ended December 31, 2005
    
    17Quarterly Data for the Two Years Ended December 31, 2005
    
    57
  36
    Table of Contents  Exhibit Index
to
Annual Report
on Form 10-K
For Year Ended December 31, 2005
 Previously FiledAsExhibitFile No.
    
    No.3-A
    
    8-K
filed 4/10/01
    
    
    3
    
    
    Restated Articles of Incorporation, as amended
(including resolutions creating outstanding series
of Cumulative Preferred Shares).3-C
    
    33-46071
    
    
    4-B
    
    
    Bylaws as amended through April 11, 1988.4-D-1
    
    8-A dated
1/28/97
    
    
    1
    
    
    Rights Agreement, dated as of January 28, 1997
(the Rights Agreement), between the Company and Norwest Bank Minnesota, National
Association.4-D-2
    
    8-A/A dated
9/29/98
    
    
    1
    
    
    Amendment No. 1, dated as of August 24, 1998,
to the Rights Agreement.4-D-3
    
    10-K for year
ended 12/31/01
    
    
    4-D-7
    
    
    Note Purchase Agreement dated as of
December 1, 2001.4-D-4
    
    10-K for year
ended 12/31/02
    
    
    4-D-4
    
    
    First Amendment dated as of December 1, 2002
to Note Purchase Agreement dated as of
December 1, 2001.4-D-5
    
    10-Q for quarter
ended 9/30/04
    
    
    4.2
    
    
    Second Amendment dated as of October 1, 2004
to Note Purchase Agreement dated as of
December 1, 2001.4-D-6
    
    8-K filed05/03/05
    
    
    4.1
    
    
    Credit Agreement dated as of
April 27, 2005 among the Company, the Lenders named therein, JP Morgan Chase Bank N.A.,
as Syndication Agent, Wells Fargo Bank, National Association, as Documentation
Agent, and U.S. Bank National Association, as Agent and Lead Arranger.10-A
    
    2-39794
    
    
    4-C
    
    
    Integrated Transmission Agreement dated
August 25, 1967, between Cooperative Power
Association and the Company.10-A-1
    
    10-K for year
ended 12/31/92
    
    
    10-A-1
    
    
    Amendment No. 1, dated as of September 6, 1979,
to Integrated Transmission Agreement, dated as of
August 25, 1967, between Cooperative Power
Association and the Company.
 -37-
    Table of Contents  Previously FiledAsExhibitFile No.
    
    No.10-A-2
    
    10-K for year
ended 12/31/92
    
    10-A-2
    
    Amendment No. 2, dated as of November 19, 1986,
to Integrated Transmission Agreement between
Cooperative Power Association and the Company.10-C-1
    
    2-55813
    
    5-E
    
    Contract dated July 1, 1958, between Central Power
Electric Corporation, Inc., and the Company.10-C-2
    
    2-55813
    
    5-E-1
    
    Supplement Seven dated November 21, 1973.
(Supplements Nos. One through Six have been
superseded and are no longer in effect.)10-C-3
    
    2-55813
    
    5-E-2
    
    Amendment No. 1 dated December 19, 1973,
to Supplement Seven.10-C-4
    
    10-K for year
ended 12/31/91
    
    10-C-4
    
    Amendment No. 2 dated June 17, 1986,
to Supplement Seven.10-C-5
    
    10-K for year
ended 12/31/92
    
    10-C-5
    
    Amendment No. 3 dated
June 18, 1992,
to Supplement Seven.10-C-6
    
    10-K for year
ended 12/31/93
    
    10-C-6
    
    Amendment No. 4 dated January 18, 1994
to Supplement Seven.10-D
    
    2-55813
    
    5-F
    
    Contract dated April 12, 1973, between the
Bureau of Reclamation and the Company.10-E-1
    
    2-55813
    
    5-G
    
    Contract dated January 8, 1973, between East River
Electric Power Cooperative and the Company.10-E-2
    
    2-62815
    
    5-E-1
    
    Supplement One dated
February 20, 1978.10-E-3
    
    10-K for year
ended 12/31/89
    
    10-E-3
    
    Supplement Two dated June 10, 1983.10-E-4
    
    10-K for year
ended 12/31/90
    
    10-E-4
    
    Supplement Three dated June 6, 1985.10-E-5
    
    10-K for year
ended 12/31/92
    
    10-E-5
    
    Supplement No. Four, dated as of September 10, 1986.10-E-6
    
    10-K for year
ended 12/31/92
    
    10-E-6
    
    Supplement No. Five, dated as of January 7, 1993.10-E-7
    
    10-K for year
ended 12/31/93
    
    10-E-7
    
    Supplement No. Six,
dated as of December 2, 1993.
 -38-
    Table of Contents  Previously FiledAsExhibitFile No.
    
    No.10-F
    
    10-K for yearended 12/31/89
    
    
    10-F
    
    
    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).10-F-1
    
    10-K for year
ended 12/31/89
    
    
    10-F-1
    
    
    Letter of Intent for purchase of share of Big Stone Plant
from Northwestern Public Service Company
(dated as of May 8, 1984).10-F-2
    
    10-K for year
ended 12/31/91
    
    
    10-F-2
    
    
    Supplemental Agreement No. 1 to Agreement for
Sharing Ownership of Big Stone Plant
(dated as of July 1, 1983).10-F-3
    
    10-K for year
ended 12/31/91
    
    
    10-F-3
    
    
    Supplemental Agreement No. 2 to Agreement for
Sharing Ownership of Big Stone Plant
(dated as of March 1, 1985).10-F-4
    
    10-K for year
ended 12/31/91
    
    
    10-F-4
    
    
    Supplemental Agreement No. 3 to Agreement for
Sharing Ownership of Big Stone Plant
(dated as of March 31, 1986).10-F-5
    
    10-Q for quarter
ended 9/30/03
    
    
    10.1
    
    
    Supplemental Agreement No. 4 to Agreement for
Sharing Ownership of Big Stone Plant
(dated as of April 24, 2003).10-F-6
    
    10-K for year
ended 12/31/92
    
    
    10-F-5
    
    
    Amendment I to Letter of Intent dated May 8, 1984,
for purchase of share of Big Stone Plant.10-G
    
    10-Q for quarter
ended 06/30/04
    
    
    10.3
    
    
    Master Coal Purchase and Sale Agreement
by and between the Company, Montana-Dakota
Utilities Co., Northwestern Corporation and
Kennecott Coal Sales Company-Big Stone Plant
(dated as of June 1, 2004).10-G-1
    
    10-Q for quarter
ended 06/30/04
    
    
    10.4
    
    
    Coal Supply Confirmation Letter by and between
the Company, Montana-Dakota Utilities Co.,
Northwestern Corporation and Kennecott Coal Sales
Company for shipments of coal from January 1, 2005
through December 31, 2007  Big Stone Plant
(dated as of July 14, 2004).10-G-2
    
    10-Q for quarter
ended 06/30/04
    
    
    10.5
    
    
    Coal Supply Agreement by and between
the Company, Montana-Dakota Utilities Co.,
Northwestern Corporation and Arch Coal Sales
Company, Inc. for the period January 1, 2005 through
December 31, 2007  Big Stone Plant
(dated as of July 22, 2004).
 -39-
    Table of Contents  Previously FiledAsExhibitFile No.
    
    No.10-H
    
    2-61043
    
    
    5-H
    
    
    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).10-H-1
    
    10-K for year
ended 12/31/89
    
    
    10-H-1
    
    
    Supplemental Agreement No. One dated as of
November 30, 1978, to Agreement for Sharing
Ownership of Coyote Generating Unit No. 1.10-H-2
    
    10-K for year
ended 12/31/89
    
    
    10-H-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.10-H-3
    
    10-K for year
ended 12/31/89
    
    
    10-H-3
    
    
    Amendment dated as of July 29, 1983, to Agreement for Sharing Ownership of Coyote Generating Unit No. 1.10-H-4
    
    10-K for year
ended 12/31/92
    
    
    10-H-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, 1978.10-H-5
    
    10-Q for quarter
ended 9/30/01
    
    
    10-A
    
    
    Amendment dated as of June 14, 2001, to Agreement
for Sharing Ownership of Coyote Generating Unit No. 1.10-H-6
    
    10-Q for quarter
ended 9/30/03
    
    
    10.2
    
    
    Amendment dated as of April 24, 2003, to Agreement for Sharing Ownership of Coyote Generating Unit No. 1.10-I
    
    2-63744
    
    
    5-I
    
    
    Coyote Plant Coal Agreement by and between the
Company, Minnkota Power Cooperative, Inc.,
Montana-Dakota Utilities Co., Northwestern Public
Service Company, Minnesota Power & Light
Company, and Knife River Coal Mining Company
(dated as of January 1, 1978).10-I-1
    
    10-K for year
ended 12/31/92
    
    
    10-I-1
    
    
    Addendum, dated as of March 10, 1980, to Coyote
Plant Coal Agreement.10-I-2
    
    10-K for year
ended 12/31/92
    
    
    10-I-2
    
    
    Amendment (No. 3), dated as of May 28, 1980, to
Coyote Plant Coal Agreement.10-I-3
    
    10-K for year
ended 12/31/92
    
    
    10-I-3
    
    
    Fourth Amendment, dated as of August 19, 1985 to
Coyote Plant Coal Agreement.
 -40-
    Table of Contents  Previously FiledAsExhibitFile No.
    
    No.10-I-4
    
    10-Q for quarter
ended 6/30/93
    
    
    19-A
    
    
    Sixth Amendment, dated as of February 17, 1993 to
Coyote Plant Coal Agreement.10-I-5
    
    10-K for year
ended 12/31/01
    
    
    10-I-5
    
    
    Agreement and Consent to Assignment of the
Coyote Plant Coal Agreement.10-J
    
    10-Q for quarter
ended 06/30/05
    
    
    10.1
    
    
    Big Stone II Power Plant Participation Agreement
by and among the Company, Central Minnesota Municipal Power Agency, Great River
Energy, Heartland Consumers Power District, Montana-Dakota Utilities Co., a
division of MDU Resources Group, Inc., Southern Minnesota Municipal Power Agency
and Western Minnesota Municipal Power Agency, as Owners
(dated as of June 30, 2005).10-J-1
    
    10-Q for quarter
ended 06/30/05
    
    
    10.2
    
    
    Big Stone II Power Plant Operation & Maintenance
Services Agreement by and among the Company, Central Minnesota Municipal Power
Agency, Great River Energy, Heartland Consumers Power District, Montana-Dakota
Utilities Co., a division of MDU Resources Group, Inc., Southern Minnesota
Municipal Power Agency and Western Minnesota Municipal Power Agency, as Owners,
and the Company, as Operator (dated as of June 30, 2005).10-J-2
    
    10-Q for quarter
ended 06/30/05
    
    
    10.3
    
    
    Big Stone I and Big Stone II 2005 Joint Facilities
Agreement by and among the Company, Central Minnesota Municipal Power Agency,
Great River Energy, Heartland Consumers Power District, Montana-Dakota Utilities
Co., a division of MDU Resources Group, Inc., NorthWestern Corporation dba
NorthWestern Energy, Southern Minnesota Municipal Power Agency and Western
Minnesota Municipal Power Agency, as Owners (dated as of June 30, 2005).10-K-1
    
    10-Q for quarter
ended 9/30/99
    
    
    10
    
    
    Power Sales Agreement between the Company and Manitoba Hydro Electric Board (dated as of July 1, 1999).10-L
    
    10-K for year
ended 12/31/91
    
    
    10-L
    
    
    Integrated Transmission
Agreement by and between the Company, Missouri Basin Municipal Power Agency and Western Minnesota
Municipal Power Agency (dated as of March 31, 1986).10-L-1
    
    10-K for year
ended 12/31/88
    
    
    10-L-1
    
    
    Amendment No. 1, dated as of December 28, 1988, to
Integrated Transmission Agreement (dated as of
March 31, 1986).
 -41-
    Table of Contents  Previously FiledAsExhibitFile No.
    
    No.10-M
    
    10-Q for quarter
ended 06/30/04
    
    
    10.1
    
    
    Master Coal Purchase Agreement by and between
the Company and Kennecott Coal Sales Company
- Hoot Lake Plant (dated as of December 31, 2001).10-M-1
    
    10-Q for quarter
ended 06/30/04
    
    
    10.2
    
    
    Coal Supply Confirmation
Letter by and between the
Company and Kennecott Coal Sales Company for
shipments of coal from July 1, 2004 through
December 31, 2007  Hoot Lake Plant
(dated as of May 26, 2004).10-N-1
    
    10-K for year
ended 12/31/02
    
    
    10-N-1
    
    
    Deferred Compensation Plan
for Directors, as amended.*10-N-2
    
    8-K filed
02/04/05
    
    
    10.1
    
    
    Executive Survivor and Supplemental Retirement Plan
(2005 Restatement).*10-N-3
    
    10-K for year
ended 12/31/93
    
    
    10-N-5
    
    
    Nonqualified Profit Sharing Plan.*10-N-4
    
    10-Q for quarter
ended 3/31/02
    
    
    10-B
    
    
    Nonqualified Retirement Savings Plan, as amended.*10-N-5
    
    10-K for year
ended 12/31/98
    
    
    10-N-6
    
    
    1999 Employee Stock Purchase Plan.10-N-6
    
    10-K for year
ended 12/31/98
    
    
    10-N-7
    
    
    1999 Stock Incentive Plan.*10-N-7
    
    
    
    
    
    
    
    Form of Stock Option
Agreement.*10-N-8
    
    
    
    
    
    
    
    Form of Restricted Stock
Agreement.*10-N-9
    
    8-K filed
04/15/05
    
    
    10.1
    
    
    Form of 2005 Performance Award Agreement.*10-N-10
    
    8-K filed
04/15/05
    
    
    10.2
    
    
    Executive Annual Incentive Plan
(Effective April 1, 2005).*10-O-1
    
    10-Q for quarter
ended 6/30/02
    
    
    10-A
    
    
    Executive Employment Agreement, John Erickson.*10-O-2
    
    10-Q for quarter
ended 6/30/02
    
    
    10-B
    
    
    Executive Employment Agreement
and amendment no. 1, Lauris Molbert.*
 -42-
    Table of Contents  Previously FiledAsExhibitFile No.
    
    No.10-O-3
    
    10-Q for quarter
ended 6/30/02
    
    10-C
    
    Executive Employment Agreement, Kevin Moug.*10-O-4
    
    10-Q for quarter
ended 6/30/02
    
    10-D
    
    Executive Employment Agreement, George Koeck.*10-P-1
    
    10-Q for quarter
ended 6/30/02
    
    10-E
    
    Change in Control Severance Agreement,
John Erickson.*10-P-2
    
    10-Q for quarter
ended 6/30/02
    
    10-F
    
    Change in Control Severance Agreement,
Lauris Molbert.*10-P-3
    
    10-Q for quarter
ended 6/30/02
    
    10-G
    
    Change in Control Severance Agreement,
Kevin Moug.*10-P-4
    
    10-Q for quarter
ended 6/30/02
    
    10-H
    
    Change in Control Severance Agreement,
George Koeck.*13-A
    
    
    
    
    
    Portions of 2005 Annual Report to Shareholders
incorporated by reference in this Form 10-K.21-A
    
    
    
    
    
    Subsidiaries of Registrant.23
    
    
    
    
    
    Consent of Deloitte & Touche LLP.24-A
    
    
    
    
    
    Powers of Attorney.31.1
    
    
    
    
    
    Certification of Chief Executive Officer Pursuant to
Section 302 of the Sarbanes-Oxley Act of 2002.31.2
    
    
    
    
    
    Certification of Chief Financial Officer Pursuant to
Section 302 of the Sarbanes-Oxley Act of 2002.32.1
    
    
    
    
    
    Certification of Chief Executive Officer Pursuant to
Section 906 of the Sarbanes-Oxley Act of 2002.32.2
    
    
    
    
    
    Certification of Chief Financial Officer Pursuant to
Section 906 of the Sarbanes-Oxley Act of 2002.
 
 *
    
    Management contract or compensatory plan or arrangement required to be filed pursuant to Item
601(b)(10)(iii)(A) of Regulation S-K. -43-