UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

PURSUANT TO SECTION 13 OR 15(d) OF THE

SECURITIES EXCHANGE ACT OF 1934

Date of Report (Date of earliest event reported) May 11, 2009

BLACK HILLS CORPORATION

(Exact name of registrant as specified in its charter)

South Dakota

(State or other jurisdiction of incorporation)

605.721.1700

(Registrant’s telephone number, including area code)

Not Applicable

(Former name or former address, if changed since last report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2. below):

o            Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

o            Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

o            Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

o            Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Item 1.01               Entry into a Material Definitive Agreement.

On May 11, 2009, Black Hills Corporation (the “Company”) entered into an underwriting agreement (the “Underwriting Agreement”) with Credit Suisse Securities (USA) LLC and RBS Securities Inc., acting for themselves and as representatives of the several underwriters named in Schedule A to the Underwriting Agreement, in connection with an underwritten public offering (the “Offering”) of $250 million aggregate principal amount of 9% notes due 2014 (the “Notes”). The Notes have been registered under the Securities Act of 1933, as amended, pursuant to the Company’s existing shelf registration statement (File No. 333-150669) (the “Registration Statement”). The closing of the Offering is expected to occur on May 14, 2009, subject to satisfaction of customary closing conditions.

The Company intends to use the net proceeds of the Offering to repay a portion of the borrowings under its $383 million acquisition credit facility with The Royal Bank of Scotland Group, as successor administrative agent, and certain other lenders. The acquisition credit facility provided funding for a portion of the purchase price for the Company’s acquisition of Aquila, Inc.’s regulated electric utility in Colorado and its regulated gas utilities in Colorado, Kansas, Nebraska and Iowa, and expires on December 29, 2009.

A copy of the Underwriting Agreement is attached as Exhibit 1 hereto and is incorporated by reference into this Item 1.01 as though fully set forth herein.

This Current Report on Form 8-K shall not constitute an offer to sell or a solicitation of an offer to buy the securities described herein, nor shall there be any sale of these securities in any state or jurisdiction in which such an offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such jurisdiction. The Offering is being made only by means of a prospectus and related prospectus supplement.

Item 8.01               Other Events.

The Company is offering and selling the Notes under the Registration Statement and accompanying prospectus and prospectus supplement, which Registration Statement relates to the offer and sale on a delayed basis from time to time of an indeterminate amount of the Company’s securities. This Current Report on Form 8-K is being filed in connection with the offer and sale of the Notes as described herein and to file with the Securities and Exchange Commission in connection with the Registration Statement the documents and instruments attached hereto as exhibits. A copy of the Press Release announcing the pricing of the Notes is also attached as Exhibit 99 hereto.

Item 9.01               Financial Statements and Exhibits

(d)           Exhibits.

The Registrant files the following exhibits as part of this report:

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SIGNATURES

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

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Exhibit Index

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Exhibit 1

$250,000,000

Black Hills Corporation

9% Senior Notes due 2014

UNDERWRITING AGREEMENT

May 11, 2009

CREDIT SUISSE SECURITIES (USA) LLC

RBS SECURITIES INC.,

As Representatives (the “Representatives”) of the Several Underwriters,

Dear Sirs:

1.  Introductory.  Black Hills Corporation, a South Dakota corporation (the “Company”), agrees with the several Underwriters named in Schedule A hereto (the “Underwriters”) to issue and sell to the several Underwriters $250,000,000 principal amount of its 9% Senior Notes due 2014 (the “Offered Securities”) to be issued under an indenture dated as of May 21, 2003, between the Company and Wells Fargo Bank, National Association (as successor to LaSalle Bank National Association), as Trustee, as supplemented by a first supplemental indenture dated as of May 21, 2003, between the Company and Wells Fargo Bank, National Association (as successor to LaSalle Bank National Association), as Trustee, and a second supplemental indenture to be dated as of May 14, 2009, between the Company and Wells Fargo Bank, National Association, as Trustee with respect to the Offered Securities (as so supplemented, the “Indenture”).

2.  Representations and Warranties of the Company.  The Company represents and warrants to, and agrees with, the several Underwriters that:

(a)  Filing and Effectiveness of Registration Statement; Certain Defined Terms.  The Company has filed with the Commission a registration statement on Form S-3 (No. 333-150669), including a related prospectus or prospectuses, covering the registration of the Offered Securities under the Act, which has become effective.  “Registration Statement” at any particular time means such registration statement in the form then filed with the Commission, including any amendment thereto, any document incorporated by reference therein and all 430B Information and all 430C Information with respect to such registration statement, that in any case has not been superseded or modified.  “Registration Statement” without reference to a time means the Registration Statement as of the Effective Time.  For purposes of this definition, 430B Information shall be considered to be included in the Registration Statement as of the time specified in Rule 430B.

For purposes of this Agreement:

“430B Information” means information included in a prospectus then deemed to be a part of the Registration Statement pursuant to Rule 430B(e) or retroactively deemed to be a part of the Registration Statement pursuant to Rule 430B(f).

“430C Information” means information included in a prospectus then deemed to be a part of the Registration Statement pursuant to Rule 430C.

“Act” means the Securities Act of 1933, as amended.

“Applicable Time” means approximately 5:00 p.m. (Eastern time) on the date of this Agreement.

“Closing Date” has the meaning defined in Section 3 hereof.

“Commission” means the Securities and Exchange Commission.

“Effective Time” of the Registration Statement relating to the Offered Securities means the time of the first contract of sale for the Offered Securities.

“Energy Policy Act” means the Energy Policy Act of 2005, as amended.

“Exchange Act” means the Securities Exchange Act of 1934, as amended.

“Federal Power Act” means the Federal Power Act, as amended.

“Final Prospectus” means the Statutory Prospectus that discloses the public offering price, other 430B Information and other final terms of the Offered Securities and otherwise satisfies Section 10(a) of the Act.

“General Use Issuer Free Writing Prospectus” means any Issuer Free Writing Prospectus that is intended for general distribution to prospective investors, as evidenced by its being so specified in Schedule B to this Agreement.

“Issuer Free Writing Prospectus” means any “issuer free writing prospectus”, as defined in Rule 433, relating to the Offered Securities in the form filed or required to be filed with the Commission or, if not required to be filed, in the form retained in the Company’s records pursuant to Rule 433(g).

“Limited Use Issuer Free Writing Prospectus” means any Issuer Free Writing Prospectus that is not a General Use Issuer Free Writing Prospectus.

“Rules and Regulations” means the rules and regulations of the Commission.

“Securities Laws” means, collectively, the Sarbanes-Oxley Act of 2002 (“Sarbanes-Oxley”), the Act, the Exchange Act, the Trust Indenture Act, the Rules and Regulations, the auditing principles, rules, standards and practices applicable to auditors of “issuers” (as defined in Sarbanes-Oxley) promulgated or approved by the Public Company Accounting Oversight Board and, as applicable, the rules of the New York Stock Exchange and the NASDAQ Stock Market (“Exchange Rules”).

“Statutory Prospectus” with reference to any particular time means the prospectus relating to the Offered Securities that is included in the Registration Statement immediately prior to that time, including all 430B Information and all 430C Information with respect to the Registration Statement.  For purposes of the foregoing definition, 430B Information shall be considered to be included in the Statutory Prospectus only as of the actual time that form of prospectus (including a prospectus supplement) is filed with the Commission pursuant to Rule 424(b) and not retroactively.

“Trust Indenture Act” means the Trust Indenture Act of 1939, as amended.

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Unless otherwise specified, a reference to a “rule” is to the indicated rule under the Act.

(b)  Compliance with Securities Act Requirements.  (i) (A) At the time the Registration Statement initially became effective, (B) at the time of each amendment thereto for the purposes of complying with Section 10(a)(3) of the Act (whether by post-effective amendment, incorporated report or form of prospectus), (C) at the Effective Time relating to the Offered Securities and (D) on the Closing Date, the Registration Statement conformed and will conform in all material respects to the requirements of the Act, the Trust Indenture Act and the Rules and Regulations and did not and will not include any untrue statement of a material fact or omit to state any material fact required to be stated therein or necessary to make the statements therein not misleading and (ii) (A) on its date, (B) at the time of filing the Final Prospectus pursuant to Rule 424(b) and (C) on the Closing Date, the Final Prospectus will conform in all material respects to the requirements of the Act, the Trust Indenture Act and the Rules and Regulations, and will not include any untrue statement of a material fact or omit to state any material fact required to be stated therein or necessary to make the statements therein not misleading.  The preceding sentence does not apply to statements in or omissions from any such document based upon written information furnished to the Company by any Underwriter through the Representatives specifically for use therein, it being understood and agreed that the only such information is that described as such in Section 8(b) hereof.

(c)  Automatic Shelf Registration Statement.  (i)  Well-Known Seasoned Issuer Status.  (A) At the time of initial filing of the Registration Statement, (B) at the time of the most recent amendment thereto for the purposes of complying with Section 10(a)(3) of the Act (whether such amendment was by post-effective amendment, incorporated report filed pursuant to Section 13 or 15(d) of the Exchange Act or form of prospectus), and (C) at the time the Company or any person acting on its behalf (within the meaning, for this clause only, of Rule 163(c)) made any offer relating to the Offered Securities in reliance on the exemption of Rule 163, the Company was a “well known seasoned issuer” as defined in Rule 405, including not having been an “ineligible issuer” as defined in Rule 405.

(ii)  Effectiveness of Automatic Shelf Registration Statement.  The Registration Statement is an “automatic shelf registration statement”, as defined in Rule 405, that initially became effective within three years of the date of this Agreement.  If immediately prior to the Renewal Deadline (as hereinafter defined), any of the Offered Securities remain unsold by the Underwriters, the Company will prior to the Renewal Deadline file, if it has not already done so and is eligible to do so, a new automatic shelf registration statement relating to the Offered Securities, in a form reasonably satisfactory to Credit Suisse Securities (USA) LLC (“Credit Suisse”).  If the Company is no longer eligible to file an automatic shelf registration statement, the Company will prior to the Renewal Deadline, if it has not already done so, file a new shelf registration statement relating to the Offered Securities, in a form reasonably satisfactory to Credit Suisse, and will use its best efforts to cause such registration statement to be declared effective within 180 days after the Renewal Deadline.  The Company will take all other action necessary or appropriate to permit the public offering and sale of the Offered Securities to continue as contemplated in the expired registration statement relating to the Offered Securities.  References herein to the Registration Statement shall include such new automatic shelf registration statement or such new shelf registration statement, as the case may be.  “Renewal Deadline” means the third anniversary of the initial effective time of the Registration Statement.

(iii)  Eligibility to Use Automatic Shelf Registration Form.  The Company has not received from the Commission any notice pursuant to Rule 401(g)(2) objecting to use of the automatic shelf registration statement form.  If at any time when Offered Securities remain unsold by the Underwriters the Company receives from the Commission a notice

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pursuant to Rule 401(g)(2) or otherwise ceases to be eligible to use the automatic shelf registration statement form, the Company will (A) promptly notify Credit Suisse, (B) promptly file a new registration statement or post-effective amendment on the proper form relating to the Offered Securities, in a form reasonably satisfactory to Credit Suisse, (C) use its best efforts to cause such registration statement or post-effective amendment to be declared effective as soon as practicable, and (D) promptly notify Credit Suisse of such effectiveness.  The Company will take all other action necessary or appropriate to permit the public offering and sale of the Offered Securities to continue as contemplated in the registration statement that was the subject of the Rule 401(g)(2) notice or for which the Company has otherwise become ineligible.  References herein to the Registration Statement shall include such new registration statement or post-effective amendment, as the case may be.

(iv)  Filing Fees.  The Company has paid or shall pay the required Commission filing fees relating to the Offered Securities within the time required by Rule 456(b)(1) without regard to the proviso therein and otherwise in accordance with Rules 456(b) and 457(r).

(d)  Ineligible Issuer Status.  (i) At the earliest time after the filing of the Registration Statement that the Company or another offering participant made a bona fide offer (within the meaning of Rule 164(h)(2)) of the Offered Securities and (ii) at the date of this Agreement, the Company was not and is not an “ineligible issuer”, as defined in Rule 405, including (A) the Company or any subsidiary of the Company in the preceding three years not having been convicted of a felony or misdemeanor or having been made the subject of a judicial or administrative decree or order as described in Rule 405 and (B) the Company in the preceding three years not having been the subject of a bankruptcy petition or insolvency or similar proceeding, not having had a registration statement be the subject of a proceeding under Section 8 of the Act and not being the subject of a proceeding under Section 8A of the Act in connection with the offering of the Securities, all as described in Rule 405.

(e)  General Disclosure Package.  As of the Applicable Time, neither (i) the General Use Issuer Free Writing Prospectus(es) issued at or prior to the Applicable Time and the preliminary prospectus supplement, dated May 11, 2009, including the base prospectus, dated May 6, 2008 (which is the most recent Statutory Prospectus distributed to investors generally), and the other information, if any, stated in Schedule B to this Agreement to be included in the General Disclosure Package, all considered together (collectively, the “General Disclosure Package”), nor (ii) any individual Limited Use Issuer Free Writing Prospectus, when considered together with the General Disclosure Package, included any untrue statement of a material fact or omitted to state any material fact necessary in order to make the statements therein, in the light of the circumstances under which they were made, not misleading.  The preceding sentence does not apply to statements in or omissions from any Statutory Prospectus or any Issuer Free Writing Prospectus in reliance upon and in conformity with written information furnished to the Company by any Underwriter through the Representatives specifically for use therein, it being understood and agreed that the only such information furnished by any Underwriter consists of the information described as such in Section 8(b) hereof.

(f)  Issuer Free Writing Prospectuses.  Each Issuer Free Writing Prospectus, as of its issue date and at all subsequent times through the completion of the public offer and sale of the Offered Securities or until any earlier date that the Company notified or notifies Credit Suisse as described in the next sentence, did not, does not and will not include any information that conflicted, conflicts or will conflict with the information then contained in the Registration Statement.  If at any time following issuance of an Issuer Free Writing Prospectus there occurred or occurs an event or development as a result of which

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such Issuer Free Writing Prospectus conflicted or would conflict with the information then contained in the Registration Statement or as a result of which such Issuer Free Writing Prospectus, if republished immediately following such event or development, would include an untrue statement of a material fact or omitted or would omit to state a material fact necessary in order to make the statements therein, in the light of the circumstances under which they were made, not misleading, (i) the Company has promptly notified or will promptly notify Credit Suisse and (ii) the Company has promptly amended or will promptly amend or supplement such Issuer Free Writing Prospectus to eliminate or correct such conflict, untrue statement or omission.

(g)  Good Standing of the Company.  The Company has been duly incorporated and is existing and in good standing under the laws of the State of South Dakota, with power and authority (corporate and other) to own its properties and conduct its business as described in the General Disclosure Package; and the Company is duly qualified to do business as a foreign corporation in good standing in all other jurisdictions in which its ownership or lease of property or the conduct of its business requires such qualification, except where the failure to be so qualified and in good standing would not, individually or in the aggregate, result in a material adverse effect on the condition (financial or otherwise), results of operations, business, properties or prospects of the Company and its subsidiaries taken as a whole (“Material Adverse Effect”).

(h)  Subsidiaries.  Each subsidiary of the Company has been duly incorporated or organized, as the case may be, and is existing and in good standing under the laws of the jurisdiction of its incorporation or organization, as the case may be, with power and authority (corporate and other) to own its properties and conduct its business as described in the General Disclosure Package; and each subsidiary of the Company is duly qualified to do business as a foreign corporation, limited partnership, general partnership or limited liability company, as the case may be, in good standing in all other jurisdictions in which its ownership or lease of property or the conduct of its business requires such qualification, except where the failure to be so qualified and in good standing would not, individually or in the aggregate, result in a Material Adverse Effect; all of the issued and outstanding capital stock or partnership or limited liability company interests, as the case may be, of each subsidiary of the Company has been duly authorized and validly issued and is fully paid and nonassessable; and the capital stock or partnership or limited liability company interests, as the case may be, of each subsidiary owned by the Company, directly or through subsidiaries, is owned free from liens, encumbrances and defects.

(i)  Execution and Delivery of Indenture.  The Indenture has been duly authorized and has been duly qualified under the Trust Indenture Act; the Offered Securities have been duly authorized and, when the Offered Securities are delivered and paid for pursuant to this Agreement on each Closing Date, the Indenture will have been duly executed and delivered, such Offered Securities will have been duly executed, authenticated, issued and delivered, will conform to the information in the General Disclosure Package and to the description of such Offered Securities contained in the Final Prospectus and the Indenture and such Offered Securities will constitute valid and legally binding obligations of the Company, enforceable in accordance with their terms, subject to bankruptcy, insolvency, fraudulent transfer, reorganization, moratorium and similar laws of general applicability relating to or affecting creditors’ rights and to general equity principles.

(j)  No Finder’s Fee.  Except as disclosed in the General Disclosure Package, there are no contracts, agreements or understandings between the Company and any person that would give rise to a valid claim against the Company or any Underwriter for a brokerage commission, finder’s fee or other like payment in connection with this offering.

(k)  Registration Rights.  Except as disclosed in the General Disclosure Package, there are no contracts, agreements or understandings between the Company and any person granting such person the right to require the Company to file a registration statement under the Act with respect to any securities of the Company owned or to be owned by such person or to require the Company to include such securities in the securities registered pursuant to a Registration Statement or in any

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securities being registered pursuant to any other registration statement filed by the Company under the Act (collectively, “registration rights”), and any person to whom the Company has granted registration rights has agreed, if necessary, not to exercise such rights until after the expiration of the Lock-Up Period referred to in Section 5 hereof.

(l)  Absence of Further Requirements.  No consent, approval, authorization, or order of, or filing or registration with, any person (including any governmental agency or body or any court) is required for the consummation of the transactions contemplated by this Agreement or the Indenture in connection with the offering, issuance and sale of the Offered Securities by the Company, except such as have been obtained or made and such as may be required under state securities laws.

(m)  Title to Property.  Except as disclosed in the General Disclosure Package, the Company and its subsidiaries have good and defensible title to all interests in oil and gas properties owned by them and good and marketable title to all other real properties and all other properties and assets owned by them that are material to the Company and its subsidiaries taken as a whole, in each case free from liens, charges, encumbrances and defects that would materially affect the value thereof or materially interfere with the use made or to be made thereof by them and, except as disclosed in the General Disclosure Package, the Company and its subsidiaries hold any leased real or personal property that is material to the Company and its subsidiaries taken as a whole under valid and enforceable leases with no terms or provisions that would materially interfere with the use made or to be made thereof by them.

(n)  Absence of Defaults and Conflicts Resulting from Transaction.  The execution, delivery and performance of the Indenture and this Agreement, and the issuance and sale of the Offered Securities and compliance with the terms and provisions thereof, will not result in a breach or violation of any of the terms and provisions of, or constitute a default or a Debt Repayment Triggering Event (as defined below) under, or result in the imposition of any lien, charge or encumbrance upon any property or assets of the Company or any of its subsidiaries pursuant to, (i) the charter or by-laws or other organizational documents of the Company or any of its subsidiaries, (ii) any statute, rule, regulation or order of any governmental agency or body or any court, domestic or foreign, having jurisdiction over the Company or any of its subsidiaries or any of their properties, or (iii) any agreement or instrument to which the Company or any of its subsidiaries is a party or by which the Company or any of its subsidiaries is bound or to which any of the properties of the Company or any of its subsidiaries is subject, except, in the case of clauses (ii) and (iii), as would not, individually or in the aggregate, result in a Material Adverse Effect.  A “Debt Repayment Triggering Event” means any event or condition that gives, or with the giving of notice or lapse of time would give, the holder of any note, debenture, or other evidence of indebtedness (or any person acting on such holder’s behalf) the right to require the repurchase, redemption or repayment of all or a portion of such indebtedness by the Company or any of its subsidiaries.

(o)  Absence of Existing Defaults and Conflicts.  Neither the Company nor any of its subsidiaries is in violation of its respective charter, by-laws or organizational documents or in default (or with the giving of notice or lapse of time would be in default) under any existing obligation, agreement, covenant or condition contained in any indenture, loan agreement, mortgage, lease or other agreement or instrument to which any of them is a party or by which any of them is bound or to which any of the properties of any of them is subject, except such defaults that would not, individually or in the aggregate, result in a Material Adverse Effect.

(p)  Authorization of Agreement.  This Agreement has been duly authorized, executed and delivered by the Company.

(q)  Possession of Licenses.  The Company and its subsidiaries possess, and are in compliance with the terms of, all adequate certificates, authorizations, franchises, licenses and permits

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(“Licenses”) necessary or material to the conduct of the business now conducted or proposed in the General Disclosure Package to be conducted by them and have not received any notice of proceedings relating to the revocation or modification of any Licenses that, if determined adversely to the Company or any of its subsidiaries, would individually or in the aggregate have a Material Adverse Effect.

(r)  Absence of Labor Dispute.  No labor dispute with the employees of the Company or any of its subsidiaries exists or, to the knowledge of the Company, is imminent that could have a Material Adverse Effect.

(s)  Possession of Intellectual Property.  The Company and its subsidiaries own, possess or can acquire on reasonable terms, adequate trademarks, trade names and other rights to inventions, know-how, patents, copyrights, confidential information and other intellectual property (collectively, “intellectual property rights”) necessary to conduct the business now operated by them, or presently employed by them, and have not received any notice of infringement of or conflict with asserted rights of others with respect to any intellectual property rights that, if determined adversely to the Company or any of its subsidiaries, would individually or in the aggregate have a Material Adverse Effect.

(t)  Environmental Laws.  Except as disclosed in the General Disclosure Package, neither the Company nor any of its subsidiaries is in violation of any statute, any rule, regulation, decision or order of any governmental agency or body or any court, domestic or foreign, relating to the use, disposal or release of hazardous or toxic substances or relating to the protection or restoration of the environment or human exposure to hazardous or toxic substances (collectively, “environmental laws”), owns or operates any real property contaminated with any substance that is subject to any environmental laws, is liable for any off-site disposal or contamination pursuant to any environmental laws, or is subject to any claim relating to any environmental laws, which violation, contamination, liability or claim would individually or in the aggregate have a Material Adverse Effect; and the Company is not aware of any pending investigation which might lead to such a claim.

(u)  Accurate Disclosure.  The statements in the Registration Statement, General Disclosure Package and the Final Prospectus under the headings “Description of the Notes”, “Description of Senior Debt Securities”, “Description of Subordinated Debt Securities”, “Description of Capital Stock”, “Description of Warrants”, “Description of Purchase Contracts”, “Description of Units”, “Material United States Federal Income Tax Considerations” and “Underwriting”, insofar as such statements summarize legal matters, agreements, documents or proceedings discussed therein, are accurate and fair summaries of such legal matters, agreements, documents or proceedings in all material respects and present the information required to be shown.

(v)  Absence of Manipulation.  The Company has not taken, directly or indirectly, any action that is designed to or that has constituted or that would reasonably be expected to cause or result in the stabilization or manipulation of the price of any security of the Company to facilitate the sale or resale of the Offered Securities.

(w)  Internal Controls and Compliance with the Sarbanes-Oxley Act.  Except as set forth in the General Disclosure Package, the Company, its subsidiaries and the Company’s Board of Directors (the “Board”) are in compliance in all material respects with Sarbanes-Oxley and all applicable Exchange Rules. The Company maintains a system of internal controls, including, but not limited to, disclosure controls and procedures, internal controls over accounting matters and financial reporting, an internal audit function and legal and regulatory compliance controls (collectively, “Internal Controls”) that comply in all material respects with the Securities Laws and are sufficient to provide reasonable assurances that (i) transactions are executed in accordance with management’s general or specific authorizations, (ii) transactions are recorded as necessary to permit preparation of financial statements in conformity with generally accepted accounting

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principles in the United States and to maintain accountability for assets, (iii) access to assets is permitted only in accordance with management’s general or specific authorization and (iv) the recorded accountability for assets is compared with the existing assets at reasonable intervals and appropriate action is taken with respect to any differences.  The Internal Controls are, or upon consummation of the offering of the Offered Securities will be, overseen by the Audit Committee (the “Audit Committee”) of the Board in accordance with Exchange Rules.  Since the date of the filing of the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2008, the Company has not publicly disclosed or reported to the Audit Committee or the Board, and within the next 90 days the Company does not reasonably expect to publicly disclose or report to the Audit Committee or the Board, (i) any significant deficiency in the design or operation of Internal Controls that could adversely affect the Company’s ability to record, process, summarize and report financial data, any material weakness in Internal Controls, any material change in Internal Controls or any fraud involving management or other employees who have a significant role in Internal Controls (each, an “Internal Control Event”) or (ii) any material violation of, or failure to comply with, the Securities Laws.

(x)  Absence of Accounting Issues.  A member of the Audit Committee has confirmed to the Chief Executive Officer, Chief Financial Officer or General Counsel of the Company that, except as set forth in the General Disclosure Package, the Audit Committee is not reviewing or investigating, and neither the Company’s independent auditors nor its internal auditors have recommended that the Audit Committee review or investigate, (i) adding to, deleting, changing the application of, or changing the Company’s disclosure with respect to, any of the Company’s material accounting policies; (ii) any matter which could result in a restatement of the Company’s financial statements for any annual or interim period during the current or prior three fiscal years; or (iii) any Internal Control Event.

(y)  Litigation.  Except as disclosed in the General Disclosure Package, there are no pending actions, suits or proceedings (including any inquiries or investigations by any court or governmental agency or body, domestic or foreign) against or affecting the Company, any of its subsidiaries or any of their respective properties that, if determined adversely to the Company or any of its subsidiaries, would individually or in the aggregate have a Material Adverse Effect, or would materially and adversely affect the ability of the Company to perform its obligations under the Indenture or this Agreement, or which are otherwise material in the context of the sale of the Offered Securities; and no such actions, suits or proceedings (including any inquiries or investigations by any court or governmental agency or body, domestic or foreign) are, to the Company’s knowledge, threatened or contemplated.

(z)  Financial Statements.  The financial statements included in the Registration Statement and the General Disclosure Package present fairly the financial position of the Company and its consolidated subsidiaries as of the dates shown and their results of operations and cash flows for the periods shown, and such financial statements have been prepared in conformity with the generally accepted accounting principles in the United States applied on a consistent basis; the schedules included in the Registration Statement present fairly the information required to be stated therein; and the assumptions used in preparing the pro forma financial statements included in the Registration Statement and the General Disclosure Package provide a reasonable basis for presenting the significant effects directly attributable to the transactions or events described therein, the related pro forma adjustments give appropriate effect to those assumptions, and the pro forma columns therein reflect the proper application of those adjustments to the corresponding historical financial statement amounts.

(aa)  No Material Adverse Change in Business.  Except as disclosed in the General Disclosure Package, since the end of the period covered by the latest audited financial statements included in the General Disclosure Package (i) there has been no change, nor any development or event involving a prospective change, in the condition (financial or otherwise), results of operations,

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business, properties or prospects of the Company and its subsidiaries, taken as a whole that is material and adverse, (ii) except as disclosed in or contemplated by the General Disclosure Package, there has been no dividend or distribution of any kind declared, paid or made by the Company on any class of its capital stock (other than regular quarterly cash dividends of not more than $0.355 per share in respect of the Company’s common stock) and (iii) except as disclosed in or contemplated by the General Disclosure Package, there has been no material adverse change in the capital stock, short-term indebtedness, long-term indebtedness, net current assets or net assets of the Company and its subsidiaries.

(bb)  Investment Company Act.  The Company is not and, after giving effect to the offering and sale of the Offered Securities and the application of the proceeds thereof as described in the General Disclosure Package, will not be an “investment company” as defined in the Investment Company Act of 1940 (the “Investment Company Act”).

(cc)  Ratings.  No “nationally recognized statistical rating organization” as such term is defined for purposes of Rule 436(g)(2) (i) has imposed (or has informed the Company that it is considering imposing) any condition (financial or otherwise) on the Company’s retaining any rating assigned to the Company or any securities of the Company or (ii) has indicated to the Company that it is considering any of the actions described in Section 7(f)(ii) hereof.

(dd)  Reserve Report Data.  The oil and gas reserve estimates of the Company and its subsidiaries for the fiscal years ended December 31, 2006, December 31, 2007, and December 31, 2008, contained in the General Disclosure Package are derived from reports that have been prepared by Ralph E. Davis Associates, Inc., in the case of the fiscal year ended December 31, 2006, and Cawley, Gillespie & Associates, Inc., in the case of the fiscal years ended December 31, 2007, and December 31, 2008, as set forth therein, such reserve estimates fairly reflect the estimated oil and gas reserves of the Company and its subsidiaries at the dates indicated therein and are in accordance with the Commission guidelines applicable thereto applied on a consistent basis throughout the periods involved.

(ee)  Independent Reserve Engineers.  Each of Cawley, Gillespie & Associates, Inc., and Ralph E. Davis Associates, Inc., have represented to the Company that they are, and the Company believes each of them to be, independent reserve engineers with respect to the Company and its subsidiaries and for the periods set forth in the General Disclosure Package.

3.  Purchase, Sale and Delivery of Offered Securities.  On the basis of the representations, warranties and agreements and subject to the terms and conditions set forth herein, the Company agrees to sell to the several Underwriters, and each of the Underwriters agrees, severally and not jointly, to purchase from the Company, at a purchase price of 99.4% of the principal amount thereof plus accrued interest from May 14, 2009, to the Closing Date (as hereinafter defined), the respective principal amounts of Offered Securities set forth opposite the names of the Underwriters in Schedule A hereto.

The Company will deliver the Offered Securities to or as instructed by the Representatives for the accounts of the several Underwriters in a form reasonably acceptable to the Representatives against payment of the purchase price by the Underwriters in Federal (same day) funds by wire transfer to an account at a bank acceptable to Credit Suisse drawn to the order of the Company at the office of Cravath, Swaine & Moore LLP, 825 Eighth Avenue, New York, NY 10019-7416 at 9:00 a.m., New York time, on May 14, 2009, or at such other time not later than seven full business days thereafter as Credit Suisse and the Company determine, such time being herein referred to as the “Closing Date”.  For purposes of Rule 15c6-1 under the Exchange Act, the Closing Date (if later than the otherwise applicable settlement date) shall be the settlement date for payment of funds and delivery of securities for all the Offered Securities sold pursuant to the offering.  The Offered Securities so to be delivered or evidence of their issuance will be made available for checking at the above office of Cravath, Swaine & Moore LLP at least 24 hours prior to the Closing Date.

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4.  Offering by Underwriters.  It is understood that the several Underwriters propose to offer the Offered Securities for sale to the public as set forth in the Final Prospectus.

5.  Certain Agreements of the Company.  The Company agrees with the several Underwriters that:

(a)  Filing of Prospectuses.  The Company has filed or will file each Statutory Prospectus (including the Final Prospectus) pursuant to and in accordance with Rule 424(b)(2) (or, if applicable and consented to by Credit Suisse, subparagraph (5), such consent not to be unreasonably withheld or delayed) not later than the second business day following the earlier of the date it is first used or the execution and delivery of this Agreement.  The Company has complied and will comply with Rule 433.

(b)  Filing of Amendments; Response to Commission Requests.  The Company will promptly advise Credit Suisse of any proposal to amend or supplement the Registration Statement or any Statutory Prospectus at any time and will offer Credit Suisse a reasonable opportunity to comment on any such amendment or supplement; and the Company will also advise Credit Suisse promptly of (i) the filing of any such amendment or supplement, (ii) any request by the Commission or its staff for any amendment to the Registration Statement, for any supplement to any Statutory Prospectus or for any additional information, (iii) the institution by the Commission of any stop order proceedings in respect of the Registration Statement or the threatening of any proceeding for that purpose, and (iv) the receipt by the Company of any notification with respect to the suspension of the qualification of the Offered Securities in any jurisdiction or the institution or threatening of any proceedings for such purpose.  The Company will use its best efforts to prevent the issuance of any such stop order or the suspension of any such qualification and, if issued, to obtain as soon as possible the withdrawal thereof.

(c)  Continued Compliance with Securities Laws.  If, at any time when a prospectus relating to the Offered Securities is (or but for the exemption in Rule 172 would be) required to be delivered under the Act by any Underwriter or dealer, any event occurs as a result of which the Final Prospectus as then amended or supplemented would include an untrue statement of a material fact or omit to state any material fact necessary to make the statements therein, in the light of the circumstances under which they were made, not misleading, or if it is necessary at any time to amend the Registration Statement or supplement the Final Prospectus to comply with the Act, the Company will promptly notify Credit Suisse of such event and will promptly prepare and file with the Commission and furnish, at its own expense, to the Underwriters and the dealers and any other dealers upon request of Credit Suisse, an amendment or supplement which will correct such statement or omission or an amendment which will effect such compliance.  Neither Credit Suisse’s consent to, nor the Underwriters’ delivery of, any such amendment or supplement shall constitute a waiver of any of the conditions set forth in Section 7 hereof.

(d)  Rule 158.  As soon as practicable, but not later than 16 months, after the date of this Agreement, the Company will make generally available to its securityholders an earnings statement covering a period of at least 12 months beginning after the date of this Agreement and satisfying the provisions of Section 11(a) of the Act and Rule 158.

(e)  Furnishing of Prospectuses.  The Company will furnish to the Representatives copies of the Registration Statement, including all exhibits, any Statutory Prospectus, the Final Prospectus and all amendments and supplements to such documents, in each case as soon as available and  in such quantities as Credit Suisse reasonably requests.  The Company will pay the expenses of printing and distributing to the Underwriters all such documents.

(f)  Blue Sky Qualifications.  The Company will arrange for the qualification of the Offered Securities for sale and the determination of their eligibility for investment under the laws of such jurisdictions as Credit Suisse reasonably designates and will continue such qualifications in effect so long as required for the distribution; provided that, in connection therewith, the Company shall

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not be required to qualify as a foreign corporation or to take any action that would subject it to a general consent to service of process in any such jurisdiction.

(g)  Reporting Requirements.  For so long as the Offered Securities remain outstanding, the Company will furnish to the Representatives and, upon request, to each of the other Underwriters, as soon as practicable after the end of each fiscal year, a copy of its annual report to stockholders for such year; and the Company will furnish to the Representatives (i) as soon as available, a copy of each report and any definitive proxy statement of the Company filed with the Commission under the Exchange Act or mailed to stockholders, and (ii) from time to time, such other information concerning the Company as Credit Suisse may reasonably request.  However, so long as the Company is subject to the reporting requirements of either Section 13 or Section 15(d) of the Exchange Act and is timely filing reports with the Commission on its Electronic Data Gathering, Analysis and Retrieval system (“EDGAR”), it is not required to furnish such reports or statements to the Representatives or the Underwriters.

(h)  Payment of Expenses.  The Company will pay all expenses incident to the performance of its obligations under this Agreement, including but not limited to any filing fees and other expenses (including fees and disbursements of counsel to the Underwriters) incurred in connection with qualification of the Offered Securities for sale under the laws of such jurisdictions as Credit Suisse reasonably designates and the preparation and printing of memoranda relating thereto, any fees charged by investment rating agencies for the rating of the Offered Securities, costs and expenses relating to investor presentations or any “road show” in connection with the offering and sale of the Offered Securities including, without limitation, any travel expenses of the Company’s officers and employees and any other expenses of the Company including the chartering of airplanes (but excluding any separately-incurred travel expenses of employees and representatives of the Representatives and the Underwriters), fees and expenses incident to listing the Offered Securities on the New York Stock Exchange, American Stock Exchange, NASDAQ Stock Market and other national and foreign exchanges, fees and expenses in connection with the registration of the Offered Securities under the Exchange Act, and expenses incurred in distributing preliminary prospectuses and the Final Prospectus (including any amendments and supplements thereto) to the Underwriters and for expenses incurred for preparing, printing and distributing any Issuer Free Writing Prospectuses to investors or prospective investors.

(i)  Use of Proceeds.  The Company will use the net proceeds received in connection with this offering in the manner described in the “Use of Proceeds” section of the General Disclosure Package and, except as disclosed in the General Disclosure Package, the Company does not intend to use any of the proceeds from the sale of the Offered Securities hereunder to repay any outstanding debt owed to any affiliate of any Underwriter.

(j)  Absence of Manipulation.  The Company will not take, directly or indirectly, any action designed to or that would constitute or that might reasonably be expected to cause or result in stabilization or manipulation of the price of any securities of the Company to facilitate the sale or resale of the Offered Securities.

(k)  Restriction on Sale of Securities.  The Company will not offer, sell, contract to sell, pledge or otherwise dispose of, directly or indirectly, or file with the Commission a registration statement under the Act relating to United States dollar-denominated debt securities issued or guaranteed by the Company and having a maturity of more than one year from the date of issue, or publicly disclose the intention to make any such offer, sale, pledge, disposition or filing, without the prior written consent of Credit Suisse for a period beginning on the date hereof and ending 90 days after the Closing Date (the “Lock-Up Period”); provided, however, that this paragraph (k) shall not prohibit the filing of a post-effective amendment to the Registration Statement for the sole purpose of registering first mortgage bonds issued by a subsidiary of the Company but not guaranteed by the Company.

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6.  Free Writing Prospectuses.  (a)  Issuer Free Writing Prospectuses.  The Company represents and agrees that, unless it obtains the prior consent of Credit Suisse, and each Underwriter represents and agrees that, unless it obtains the prior consent of the Company and Credit Suisse, it has not made and will not make any offer relating to the Offered Securities that would constitute an Issuer Free Writing Prospectus, or that would otherwise constitute a “free writing prospectus”, as defined in Rule 405, required to be filed with the Commission.  Any such free writing prospectus consented to by the Company and Credit Suisse is hereinafter referred to as a “Permitted Free Writing Prospectus”.  The Company represents that it has treated and agrees that it will treat each Permitted Free Writing Prospectus as an “issuer free writing prospectus”, as defined in Rule 433, and has complied and will comply with the requirements of Rules 164 and 433 applicable to any Permitted Free Writing Prospectus, including timely Commission filing where required, legending and record keeping.

(b)  Term Sheets.  The Company will prepare a final term sheet relating to the Offered Securities, containing only information that describes the final terms of the Offered Securities and otherwise in a form consented to by Credit Suisse, and will file such final term sheet within the period required by Rule 433(d)(5)(ii) following the date such final terms have been established for all classes of the offering of the Offered Securities.  Any such final term sheet is an Issuer Free Writing Prospectus and a Permitted Free Writing Prospectus for purposes of this Agreement.  The Company also consents to the use by any Underwriter of a free writing prospectus that contains only (i) (A) information describing the preliminary terms of the Offered Securities or their offering or (B) information that describes the final terms of the Offered Securities or their offering and that is included in the final term sheet of the Company contemplated in the first sentence of this subsection or (ii) other information that is not “issuer information”, as defined in Rule 433, it being understood that any such free writing prospectus referred to in clause (i) or (ii) above shall not be an Issuer Free Writing Prospectus for purposes of this Agreement.

7.  Conditions of the Obligations of the Underwriters.  The obligations of the several Underwriters to purchase and pay for the Offered Securities on the Closing Date will be subject to the accuracy of the representations and warranties of the Company herein (as though made on the Closing Date), to the accuracy of the statements of Company officers made pursuant to the provisions hereof, to the performance by the Company of its obligations hereunder and to the following additional conditions precedent:

(a)  Accountants’ Comfort Letter.  The Representatives shall have received letters, dated, respectively, the date hereof and the Closing Date, of Deloitte & Touche LLP confirming that they are a registered public accounting firm and independent public accountants within the meaning of the Securities Laws and substantially in the form of Schedule C hereto (except that, in any letter dated the Closing Date, the specified date referred to in Schedule C hereto shall be a date no more than three days prior to the Closing Date).

(b)  Accountants’ Comfort Letter.  The Representatives shall have received letters, dated, respectively, the date hereof and the Closing Date, of KPMG LLP confirming that they are a registered public accounting firm and independent public accountants within the meaning of the Securities Laws and substantially in the form of Schedule D hereto (except that, in any letter dated the Closing Date, the specified date referred to in Schedule D hereto shall be a date no more than three days prior to the Closing Date).

(c)  Reserve Report Confirmation Letter.  The Representatives shall have received letters, dated, respectively, the date hereof and the Closing Date, of Cawley, Gillespie & Associates, Inc., containing statements and information with respect to the estimated oil and gas reserves of the Company and its subsidiaries and substantially in the form of Schedule E hereto.

(d)  Reserve Report Confirmation Letter.  The Representatives shall have received letters, dated, respectively, the date hereof and the Closing Date, of Ralph E. Davis Associates, Inc., containing statements and information with respect to the estimated oil and gas reserves of the Company and its subsidiaries and substantially in the form of Schedule F hereto.

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(e)  Filing of Prospectus.  The Final Prospectus shall have been filed with the Commission in accordance with the Rules and Regulations and Section 5(a) hereof.  No stop order suspending the effectiveness of the Registration Statement or of any part thereof shall have been issued and no proceedings for that purpose shall have been instituted or, to the knowledge of the Company or any Underwriter, shall be contemplated by the Commission.

(f)  No Material Adverse Change.  Subsequent to the execution and delivery of this Agreement, there shall not have occurred (i) any change, or any development or event involving a prospective change, in the condition (financial or otherwise), results of operations, business, properties or prospects of the Company and its subsidiaries taken as a whole which, in the judgment of Credit Suisse, is material and adverse and makes it impractical or inadvisable to market the Offered Securities; (ii) any downgrading in the rating of any debt securities of the Company by any “nationally recognized statistical rating organization” (as defined for purposes of Rule 436(g)), or any public announcement that any such organization has under surveillance or review its rating of any debt securities of the Company (other than an announcement with positive implications of a possible upgrading, and no implication of a possible downgrading, of such rating); (iii) any change in U.S. or international financial, political or economic conditions or currency exchange rates or exchange controls the effect of which is such as to make it, in the judgment of Credit Suisse, impractical to market or to enforce contracts for the sale of the Offered Securities, whether in the primary market or in respect of dealings in the secondary market; (iv) any suspension or material limitation of trading in securities generally on the New York Stock Exchange, or any setting of minimum or maximum prices for trading on such exchange; (v) or any suspension of trading of any securities of the Company on any exchange or in the over-the-counter market; (vi) any banking moratorium declared by any U.S. Federal or New York authorities; (vii) any major disruption of settlements of securities, payment or clearance services in the United States or any other country where such securities are listed or (viii) any attack on, outbreak or escalation of hostilities or act of terrorism involving the United States, any declaration of war by Congress or any other national or international calamity or emergency if, in the judgment of Credit Suisse, the effect of any such attack, outbreak, escalation, act, declaration, calamity or emergency is such as to make it impractical or inadvisable to market the Offered Securities or to enforce contracts for the sale of the Offered Securities.

(g)  Opinion of Counsel for Company.  The Representatives shall have received an opinion, dated the Closing Date, of Conner & Winters, LLP, counsel for the Company, to the effect that:

(i)  Indenture; Offered Securities.  The Indenture has been duly qualified under the Trust Indenture Act; the Offered Securities delivered on the Closing Date conform to the information in the General Disclosure Package and to the description of such Offered Securities contained in the Final Prospectus; and the Indenture and the Offered Securities delivered on the Closing Date constitute valid and legally binding obligations of the Company enforceable in accordance with their terms and the Offered Securities are entitled to the benefits provided by the Indenture, subject in each case to bankruptcy, insolvency, fraudulent transfer, reorganization, moratorium and similar laws of general applicability relating to or affecting creditors’ rights and to general equity principles;

(ii)  Investment Company Act.  The Company is not and, after giving effect to the offering and sale of the Offered Securities and the application of the proceeds thereof as described in the General Disclosure Package, will not be an “investment company” as defined in the Investment Company Act;

(iii)  Absence of Further Requirements.  No consent, approval, authorization or order of, or filing with, any person (including any governmental agency or body or any court) is required for the consummation of the transactions contemplated by this Agreement in connection with the offering, issuance and sale of the Offered Securities by

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the Company, except such as have been obtained or made and such as may be required under state securities laws, the Energy Policy Act or the Federal Power Act;

(iv)  Absence of Defaults and Conflicts Resulting from Transaction.  The execution, delivery and performance of the Indenture and this Agreement and the issuance and sale of the Offered Securities and compliance with the terms and provisions thereof will not result in a breach or violation of any of the terms and provisions of, or constitute a default under, or result in the imposition of any lien, charge or encumbrance upon any property or assets of the Company or any of its subsidiaries pursuant to (A) the charter or by-laws of the Company, (B) any statute, rule, regulation or, to such counsel’s knowledge, order of any governmental agency or body or any court having jurisdiction over the Company or any of its subsidiaries or any of their properties (other than the Energy Policy Act or the Federal Power Act or any rule, regulation or order of any governmental agency or body relating to the Energy Policy Act or the Federal Power Act or any court having jurisdiction over the Company or any subsidiary of the Company or any of their properties in a proceeding relating to the Energy Policy Act or the Federal Power Act), except in the case of this clause (B) for such breaches, violations, defaults or impositions as would not, individually or in the aggregate, have a Material Adverse Effect, or (C) any agreement or instrument filed as an exhibit to the Registration Statement or as an exhibit to any document incorporated by reference in the Registration Statement (it being understood that such counsel’s opinion under this clause (C) need not extend to compliance with any financial ratio or any limitation in any contractual restriction expressed as a dollar (or other currency) amount);

(v)  Compliance with Registration Requirements; Effectiveness.  The Registration Statement has become effective under the Act, the Final Prospectus was filed with the Commission pursuant to the subparagraph of Rule 424(b) specified in such opinion on the date specified therein, and, to the knowledge of such counsel, no stop order suspending the effectiveness of the Registration Statement or any part thereof has been issued and no proceedings for that purpose have been instituted or are pending or contemplated under the Act; the statements (A) under the headings “Description of the Notes”, “Description of Senior Debt Securities”, “Description of Subordinated Debt Securities”, “Description of Capital Stock”, “Description of Warrants”, “Description of Purchase Contracts”, “Description of Units”, “Material United States Federal Tax Considerations” and “Underwriting” in the Registration Statement, General Disclosure Package and Final Prospectus and (B) in Item 15 of the Registration Statement, in each case, of legal matters, agreements, documents or proceedings are accurate and fair summaries thereof in all material respects and present the information required to be shown; and such counsel do not know of any legal or governmental proceedings required to be described in the Registration Statement or the Final Prospectus which are not described as required or of any contracts or documents of a character required to be described in the Registration Statement or the Final Prospectus or to be filed as exhibits to the Registration Statement which are not described and filed as required;

(vi)  Absence of Existing Defaults and Conflicts.  To such counsel’s knowledge, the Company is not in violation of its charter or by-laws and, to such counsel’s knowledge, no default (or event which, with the giving of notice or lapse of time would be a default) has occurred in the due performance or observance of any material obligation, agreement, covenant or condition contained in any contract, indenture, mortgage, loan agreement, note, lease or other agreement or instrument that is described or referred to in the Registration Statement or the General Disclosure Package or filed or incorporated by reference as an exhibit to the Registration Statement; and

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(vii)  Accurate Disclosure.  The Registration Statement, as of the Effective Time relating to the Offered Securities, and the Final Prospectus, as of the date of this Agreement, and each amendment or supplement thereto, as of its issue date, complied as to form in all material respects with the requirements of the Act, the Trust Indenture Act and the Rules and Regulations (it being understood that such counsel need express no opinion as to the content of the financial statements or the other financial data or assessments of or reports on the effectiveness of internal control over financial reporting contained in the Registration Statement, the General Disclosure Package, the Final Prospectus or the Statement of Eligibility on Form T-1 (the “Form T-1”) of the Trustee with respect to the Offered Securities).

In addition, such counsel shall state that such counsel has participated in conferences with officers and other representatives of the Company, representatives of the independent registered public accountants of the Company, and representatives of the Underwriters at which the contents of the Registration Statement, the General Disclosure Package and the Final Prospectus were discussed and, although such counsel is not passing upon and does not assume responsibility for the accuracy, completeness or fairness of the statements contained in the Registration Statement, the General Disclosure Package or the Final Prospectus (except and to the extent stated in subparagraph (v) of this Section 7(g)), on the basis of the foregoing, nothing has come to the attention of such counsel that causes them to believe that (A) any part of the Registration Statement, as of the Effective Time relating to the Offered Securities, contained any untrue statement of a material fact or omitted to state any material fact required to be stated therein or necessary to make the statements therein not misleading; (B) the Final Prospectus, as of the date of this Agreement or as of the Closing Date, or any amendment or supplement thereto, as of its issue date or as of the Closing Date, contained any untrue statement of a material fact or omitted to state any material fact necessary in order to make the statements therein, in the light of the circumstances under which they were made, not misleading; or (C) the General Disclosure Package, as of the Applicable Time, contained any untrue statement of a material fact or omitted to state any material fact necessary in order to make the statements therein, in the light of the circumstances under which they were made, not misleading (it being understood that such counsel need express no comment or belief as to the content of the financial statements or the other financial data or assessments of or reports on the effectiveness of internal control over financial reporting contained in the Registration Statement, the General Disclosure Package, the Final Prospectus or the Form T-1).

(h)  Opinion of General Counsel to the Company.  The Representatives shall have received an opinion, dated the Closing Date, of Steven J. Helmers, Esq., General Counsel to the Company, to the effect that:

(i)  Good Standing of the Company.  The Company has been duly incorporated and is an existing corporation in good standing under the laws of the State of South Dakota, with corporate power and authority to own its properties and conduct its business as described in the General Disclosure Package; and the Company is duly qualified to do business as a foreign corporation in good standing in all other jurisdictions in which its ownership or lease of property or the conduct of its business requires such qualification, except where the failure to be so qualified and in good standing would not, individually or in the aggregate, result in a Material Adverse Effect;

(ii)  Significant Subsidiaries.  Each subsidiary of the Company listed on Schedule G hereto (each, a “Significant Subsidiary”) has been duly incorporated or organized, as the case may be, and is existing and in good standing under the laws of the jurisdiction of its incorporation or organization, as the case may be, with power and authority (corporate

15

and other) to own its properties and conduct its business as described in the General Disclosure Package; and each Significant Subsidiary is duly qualified to do business as a foreign corporation, limited partnership, general partnership or limited liability company, as the case may be, in good standing in all other jurisdictions in which its ownership or lease of property or the conduct of its business requires such qualification, except where the failure to be so qualified and in good standing would not, individually or in the aggregate, result in a Material Adverse Effect; all of the issued and outstanding capital stock or partnership or limited liability company interests, as the case may be, of each Significant Subsidiary have been duly authorized and validly issued and are fully paid and nonassessable; and the capital stock or partnership or limited liability company interests, as the case may be, of each Significant Subsidiary owned by the Company, directly or through subsidiaries, is owned free from liens, encumbrances and defects;

(iii)  Indenture; Offered Securities.  The Indenture has been duly authorized, executed and delivered by the Company; and the Offered Securities delivered on the Closing Date have been duly authorized, executed, authenticated, issued and delivered;

(iv)  Authority.  The Company has full corporate power and authority to authorize, issue and sell the Offered Securities as contemplated by this Agreement;

(v)  Authorization of Agreement.  This Agreement has been duly authorized, executed and delivered by the Company;

(vi)  Registration Rights.  Except as disclosed in the General Disclosure Package, there are no contracts, agreements or understandings known to such General Counsel between the Company and any person granting such person the right to require the Company to file a registration statement under the Act with respect to any securities of the Company owned or to be owned by such person or to require the Company to include such securities in the securities registered pursuant to the Registration Statement or in any securities being registered pursuant to any other registration statement filed by the Company under the Act;

(vii)  Possession of Licenses.  To such General Counsel’s knowledge, the Company and each of its subsidiaries possess adequate Licenses issued by appropriate governmental agencies or bodies necessary to conduct the business as now operated by them as described in the General Disclosure Package and, except as described in the General Disclosure Package, such General Counsel is not aware of the receipt of any notice of proceedings relating to the revocation or modification of any such License that, if determined adversely to the Company or any of its subsidiaries, would individually or in the aggregate have a Material Adverse Effect;

(viii)  Environmental Laws.  To such General Counsel’s knowledge, except as disclosed in the General Disclosure Package, the Company and each subsidiary of the Company (A) is in compliance with any and all applicable environmental laws, (B) has received all permits, licenses and other approvals required of it under applicable environmental laws to conduct its business and (C) is in compliance with all terms and conditions of each such permit, license and approval, except where such noncompliance with environmental laws, failure to receive required permits, licenses or other approvals or failure to comply with the terms and conditions of such permits, licenses or approvals would not, individually or in the aggregate, have a Material Adverse Effect;

(ix)  Absence of Further Requirements.  No consent, approval, authorization or order of, or filing with, any governmental agency or body or any court is required under South Dakota law, the Energy Policy Act or the Federal Power Act for the consummation of the transactions contemplated by this Agreement in connection with the issuance and

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sale of the Offered Securities by the Company, except such as have been obtained and such as may be required under state securities laws;

(x)  Absence of Defaults and Conflicts Resulting from Transaction.  The execution, delivery and performance of the Indenture and this Agreement and the issuance and sale of the Offered Securities and compliance with the terms and provisions thereof will not result in a breach or violation of any of the terms and provisions of, or constitute a default under, or result in the imposition of any lien, charge or encumbrance upon any property or assets of the Company or any of its subsidiaries pursuant to (A) the Energy Policy Act or the Federal Power Act or any rule, regulation or, to such General Counsel’s knowledge, order of any governmental agency or body relating to the Energy Policy Act or the Federal Power Act or any court having jurisdiction over the Company or any subsidiary of the Company or any of their properties in a proceeding relating to the Energy Policy Act or the Federal Power Act or (B) any agreement or instrument to which the Company or any of its subsidiaries is a party or by which the Company or any of its subsidiaries is bound or to which any of the properties of the Company or any of its subsidiaries is subject, except in the case of this clause (B) for such breaches, violations, defaults or impositions as would not, individually or in the aggregate, have a Material Adverse Effect; and

(xi)  Accurate Disclosure.  The descriptions under the headings “Risk Factors”, “Business” and “Black Hills Corporation” in the Registration Statement, the General Disclosure Package and the Final Prospectus of statutes, legal and governmental proceedings and contracts and other documents are accurate in all material respects and fairly present the information required to be shown (it being understood that such General Counsel need express no opinion as to the content of the financial statements or the other financial data or assessments of or reports on the effectiveness of internal control over financial reporting contained in the Registration Statement, the General Disclosure Package, the Final Prospectus or the Form T-1).

In addition, such General Counsel shall state that such General Counsel has participated in conferences with officers and other representatives of the Company, representatives of the independent registered public accountants of the Company, and representatives of the Underwriters at which the contents of the Registration Statement, the General Disclosure Package and the Final Prospectus were discussed and, although such General Counsel is not passing upon and does not assume responsibility for the accuracy, completeness or fairness of the statements contained in the Registration Statement, the General Disclosure Package or the Final Prospectus (except and to the extent stated in subparagraph (xi) of this Section 7(h)), on the basis of the foregoing, nothing has come to the attention of such General Counsel that causes him to believe that (A) any part of the Registration Statement, as of the Effective Time relating to the Offered Securities, contained any untrue statement of a material fact or omitted to state any material fact required to be stated therein or necessary to make the statements therein not misleading; (B) the Final Prospectus, as of the date of this Agreement or as of the Closing Date, or any amendment or supplement thereto, as of its issue date or as of the Closing Date, contained any untrue statement of a material fact or omitted to state any material fact necessary in order to make the statements therein, in the light of the circumstances under which they were made, not misleading; or (C) the General Disclosure Package, as of the Applicable Time, contained any untrue statement of a material fact or omitted to state any material fact necessary in order to make the statements therein, in the light of the circumstances under which they were made, not misleading (it being understood that such General Counsel need express no comment or belief as to the content of the financial statements or the other financial data or assessments of or reports on the effectiveness of internal control over financial reporting

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contained in the Registration Statement, the General Disclosure Package, the Final Prospectus or the Form T-1).

(i)  Opinion of Counsel for Underwriters.  The Representatives shall have received from Cravath, Swaine & Moore LLP, counsel for the Underwriters, such opinion or opinions, dated the Closing Date, with respect to such matters as the Representatives may require, and the Company shall have furnished to such counsel such documents as they request for the purpose of enabling them to pass upon such matters.  In rendering such opinion, Cravath, Swaine & Moore LLP may rely as to the incorporation of the Company and all other matters governed by South Dakota law upon the opinion of Steven J. Helmers, Esq., General Counsel to the Company, referred to above.

(j)  Officers’ Certificate.  The Representatives shall have received a certificate, dated the Closing Date, of an executive officer of the Company and a principal financial or accounting officer of the Company in which such officers shall state that:  the representations and warranties of the Company in this Agreement are true and correct; the Company has complied with all agreements and satisfied all conditions on its part to be performed or satisfied hereunder at or prior to the Closing Date; no stop order suspending the effectiveness of the Registration Statement has been issued and no proceedings for that purpose have been instituted or, to the best of their knowledge and after reasonable investigation, are contemplated by the Commission; and, subsequent to the date of the most recent financial statements in the General Disclosure Package, there has been no material adverse change, nor any development or event involving a prospective material adverse change, in the condition (financial or otherwise), results of operations, business or properties of the Company and its subsidiaries taken as a whole except as set forth in or contemplated by the General Disclosure Package or as described in such certificate.

The Company will furnish the Representatives with such conformed copies of such opinions, certificates, letters and documents as the Representatives reasonably request.  Credit Suisse may in its sole discretion waive on behalf of the Underwriters compliance with any conditions to the obligations of the Underwriters hereunder.

8.  Indemnification and Contribution.  (a)  Indemnification of Underwriters.  The Company will indemnify and hold harmless each Underwriter, its partners, members, directors, officers, employees, agents, affiliates and each person, if any, who controls such Underwriter within the meaning of Section 15 of the Act or Section 20 of the Exchange Act (each, an “Indemnified Party”), against any and all losses, claims, damages or liabilities, joint or several, to which such Indemnified Party may become subject, under the Act, the Exchange Act, other Federal or state statutory law or regulation or otherwise, insofar as such losses, claims, damages or liabilities (or actions in respect thereof) arise out of or are based upon any untrue statement or alleged untrue statement of any material fact contained in any part of the Registration Statement at any time, any Statutory Prospectus as of any time, the Final Prospectus or any Issuer Free Writing Prospectus, or arise out of or are based upon the omission or alleged omission of a material fact required to be stated therein or necessary to make the statements therein not misleading, and will reimburse each Indemnified Party for any legal or other expenses reasonably incurred by such Indemnified Party in connection with investigating or defending against any loss, claim, damage, liability, action, litigation, investigation or proceeding whatsoever (whether or not such Indemnified Party is a party thereto), whether threatened or commenced, and in connection with the enforcement of this provision with respect to any of the above as such expenses are incurred; provided, however, that the Company will not be liable in any such case to the extent that any such loss, claim, damage or liability arises out of or is based upon an untrue statement or alleged untrue statement in or omission or alleged omission from any of such documents in reliance upon and in conformity with written information furnished to the Company by any Underwriter through the Representatives specifically for use therein, it being understood and agreed that the only such information furnished by any Underwriter consists of the information described as such in subsection (b) below.

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(b)  Indemnification of Company.  Each Underwriter will severally and not jointly indemnify and hold harmless the Company, each of its directors and each of its officers who signs a Registration Statement and each person, if any, who controls the Company within the meaning of Section 15 of the Act or Section 20 of the Exchange Act (each, an “Underwriter Indemnified Party”), against any losses, claims, damages or liabilities to which such Underwriter Indemnified Party may become subject, under the Act, the Exchange Act, other Federal or state statutory law or regulation or otherwise, insofar as such losses, claims, damages or liabilities (or actions in respect thereof) arise out of or are based upon any untrue statement or alleged untrue statement of any material fact contained in any part of the Registration Statement at any time, any Statutory Prospectus as of any time, the Final Prospectus, or any Issuer Free Writing Prospectus, or arise out of or are based upon the omission or the alleged omission of a material fact required to be stated therein or necessary to make the statements therein not misleading, in each case to the extent, but only to the extent, that such untrue statement or alleged untrue statement or omission or alleged omission was made in reliance upon and in conformity with written information furnished to the Company by such Underwriter through the Representatives specifically for use therein, and will reimburse any legal or other expenses reasonably incurred by such Underwriter Indemnified Party in connection with investigating or defending against any such loss, claim, damage, liability, action, litigation, investigation or proceeding whatsoever (whether or not such Underwriter Indemnified Party is a party thereto), whether threatened or commenced, based upon any such untrue statement or omission, or any such alleged untrue statement or omission as such expenses are incurred, it being understood and agreed that the only such information furnished by any Underwriter consists of the following information in the Final Prospectus furnished on behalf of each Underwriter:  the concession and reallowance figures appearing in the fourth paragraph under the caption “Underwriting” and the information contained in the ninth (pertaining to stabilizing transactions, over-allotment transactions, syndicate covering transactions and penalty bids) and tenth (pertaining to the effect of stabilizing transactions, syndicate covering transactions and penalty bids) paragraphs under the caption “Underwriting”.

(c)  Actions against Parties; Notification.  Promptly after receipt by an indemnified party under this Section of notice of the commencement of any action, such indemnified party will, if a claim in respect thereof is to be made against the indemnifying party under subsection (a) or (b) above, notify the indemnifying party of the commencement thereof; but the failure to notify the indemnifying party shall not relieve it from any liability that it may have under subsection (a) or (b) above except to the extent that it has been materially prejudiced (through the forfeiture of substantive rights or defenses) by such failure; and provided further that the failure to notify the indemnifying party shall not relieve it from any liability that it may have to an indemnified party otherwise than under subsection (a) or (b) above.  In case any such action is brought against any indemnified party and it notifies the indemnifying party of the commencement thereof, the indemnifying party will be entitled to participate therein and, to the extent that it may wish, jointly with any other indemnifying party similarly notified, to assume the defense thereof, with counsel satisfactory to such indemnified party (who shall not, except with the consent of the indemnified party, be counsel to the indemnifying party), and after notice from the indemnifying party to such indemnified party of its election so to assume the defense thereof, the indemnifying party will not be liable to such indemnified party under this Section for any legal or other expenses subsequently incurred by such indemnified party in connection with the defense thereof other than reasonable costs of investigation.  No indemnifying party shall, without the prior written consent of the indemnified party, effect any settlement of any pending or threatened action in respect of which any indemnified party is or could have been a party and indemnity could have been sought hereunder by such indemnified party unless such settlement (i) includes an unconditional release of such indemnified party from all liability on any claims that are the subject matter of such action and (ii) does not include a statement as to, or an admission of, fault, culpability or a failure to act by or on behalf of an indemnified party.

(d)  Contribution.  If the indemnification provided for in this Section is unavailable or insufficient to hold harmless an indemnified party under subsection (a) or (b) above, then each indemnifying party shall contribute to the amount paid or payable by such indemnified party as a result of the losses, claims, damages or liabilities referred to in subsection (a) or (b) above (i) in such proportion as is appropriate to reflect the relative benefits received by the Company on the one hand and the Underwriters on the other

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from the offering of the Offered Securities or (ii) if the allocation provided by clause (i) above is not permitted by applicable law, in such proportion as is appropriate to reflect not only the relative benefits referred to in clause (i) above but also the relative fault of the Company on the one hand and the Underwriters on the other in connection with the statements or omissions which resulted in such losses, claims, damages or liabilities as well as any other relevant equitable considerations.  The relative benefits received by the Company on the one hand and the Underwriters on the other shall be deemed to be in the same proportion as the total net proceeds from the offering (before deducting expenses) received by the Company bear to the total underwriting discounts and commissions received by the Underwriters.  The relative fault shall be determined by reference to, among other things, whether the untrue or alleged untrue statement of a material fact or the omission or alleged omission to state a material fact relates to information supplied by the Company or the Underwriters and the parties’ relative intent, knowledge, access to information and opportunity to correct or prevent such untrue statement or omission. The amount paid by an indemnified party as a result of the losses, claims, damages or liabilities referred to in the first sentence of this subsection (d) shall be deemed to include any legal or other expenses reasonably incurred by such indemnified party in connection with investigating or defending any action or claim which is the subject of this subsection (d).  Notwithstanding the provisions of this subsection (d), no Underwriter shall be required to contribute any amount in excess of the amount by which the total price at which the Offered Securities underwritten by it and distributed to the public were offered to the public exceeds the amount of any damages which such Underwriter has otherwise been required to pay by reason of such untrue or alleged untrue statement or omission or alleged omission.  No person guilty of fraudulent misrepresentation (within the meaning of Section 11(f) of the Act) shall be entitled to contribution from any person who was not guilty of such fraudulent misrepresentation.  The Underwriters’ obligations in this subsection (d) to contribute are several in proportion to their respective underwriting obligations and not joint.  The Company and the Underwriters agree that it would not be just and equitable if contribution pursuant to this Section 8(d) were determined by pro rata allocation (even if the Underwriters were treated as one entity for such purpose) or by any other method of allocation which does not take account of the equitable considerations referred to in this Section 8(d).

9.  Default of Underwriters.  If any Underwriter or Underwriters default in their obligations to purchase Offered Securities hereunder on the  Closing Date and the aggregate principal amount of Offered Securities that such defaulting Underwriter or Underwriters agreed but failed to purchase does not exceed 10% of the total principal amount of Offered Securities that the Underwriters are obligated to purchase on the Closing Date, Credit Suisse may make arrangements satisfactory to the Company for the purchase of such Offered Securities by other persons, including any of the Underwriters, but if no such arrangements are made by the Closing Date, the non-defaulting Underwriters shall be obligated severally, in proportion to their respective commitments hereunder, to purchase the Offered Securities that such defaulting Underwriters agreed but failed to purchase on the Closing Date. If any Underwriter or Underwriters so default and the aggregate principal amount of Offered Securities with respect to which such default or defaults occur exceeds 10% of the total principal amount of Offered Securities that the Underwriters are obligated to purchase on the Closing Date and arrangements satisfactory to Credit Suisse and the Company for the purchase of such Offered Securities by other persons are not made within 36 hours after such default, this Agreement will terminate without liability on the part of any non-defaulting Underwriter or the Company, except as provided in Section 10.  As used in this Agreement, the term “Underwriter” includes any person substituted for an Underwriter under this Section. Nothing herein will relieve a defaulting Underwriter from liability for its default.

10.  Survival of Certain Representations and Obligations.  The respective indemnities, agreements, representations, warranties and other statements of the Company or its officers and of the several Underwriters set forth in or made pursuant to this Agreement will remain in full force and effect, regardless of any investigation, or statement as to the results thereof, made by or on behalf of any Underwriter, the Company or any of their respective representatives, officers or directors or any controlling person, and will survive delivery of and payment for the Offered Securities.  If the purchase of the Offered Securities by the Underwriters is not consummated for any reason other than solely because of the termination of this Agreement pursuant to Section 9 hereof or the occurrence of any event specified in

20

clause (iii), (iv), (vi), (vii) or (viii) of Section 7(f), the Company will reimburse the Underwriters for all out-of-pocket expenses (including fees and disbursements of counsel) reasonably incurred by them in connection with the offering of the Offered Securities, and the respective obligations of the Company and the Underwriters pursuant to Section 8 hereof shall remain in effect.  In addition, if any Offered Securities have been purchased hereunder, the representations and warranties in Section 2 and all obligations under Section 5 shall also remain in effect.

11.  Notices.  All communications hereunder will be in writing and, if sent to the Underwriters, will be mailed, delivered or telegraphed and confirmed to the Representatives c/o Credit Suisse Securities (USA) LLC, Eleven Madison Avenue, New York, NY 10010-3629, Attention:  IBD Legal, or, if sent to the Company, will be mailed, delivered or telegraphed and confirmed to it at 625 Ninth Street, Rapid City, SD 57701, Attention:  Steven J. Helmers, Esq., General Counsel; provided, however, that any notice to an Underwriter pursuant to Section 8 will be mailed, delivered or telegraphed and confirmed to such Underwriter.

12.  Successors.  This Agreement will inure to the benefit of and be binding upon the parties hereto and their respective successors and the officers and directors and controlling persons referred to in Section 8, and no other person will have any right or obligation hereunder.

13.  Representation of Underwriters.  The Representatives will act for the several Underwriters in connection with this financing, and any action under this Agreement taken by the Representatives jointly or by Credit Suisse will be binding upon all the Underwriters.

14.  Counterparts.  This Agreement may be executed in any number of counterparts, each of which shall be deemed to be an original, but all such counterparts shall together constitute one and the same Agreement.

15.  Absence of Fiduciary Relationship.  The Company acknowledges and agrees that:

(a)           No Other Relationship.  Each Representative has been retained solely to act as an underwriter in connection with the sale of Offered Securities and that no fiduciary, advisory or agency relationship between the Company and either Representative has been created in respect of any of the transactions contemplated by this Agreement or the Final Prospectus, irrespective of whether either Representative has advised or is advising the Company on other matters;

(b)           Arms’ Length Negotiations.  The price of the Offered Securities set forth in this Agreement was established by the Company following discussions and arms-length negotiations with the Representatives and the Company is capable of evaluating and understanding and understands and accepts the terms, risks and conditions of the transactions contemplated by this Agreement;

(c)           Absence of Obligation to Disclose.  The Company has been advised that each Representative and its affiliates are engaged in a broad range of transactions which may involve interests that differ from those of the Company and that neither Representative has any obligation to disclose such interests and transactions to the Company by virtue of any fiduciary, advisory or agency relationship; and

(d)           Waiver.  The Company waives, to the fullest extent permitted by law, any claims it may have against either Representative for breach of fiduciary duty or alleged breach of fiduciary duty and agrees that neither Representative shall have any liability (whether direct or indirect) to the Company in respect of such a fiduciary duty claim or to any person asserting a fiduciary duty claim on behalf of or in right of the Company, including stockholders, employees or creditors of the Company.

16.  Applicable Law.  This Agreement shall be governed by, and construed in accordance with, the laws of the State of New York.

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The Company hereby submits to the non-exclusive jurisdiction of the Federal and state courts in the Borough of Manhattan in The City of New York in any suit or proceeding arising out of or relating to this Agreement or the transactions contemplated hereby.  The Company irrevocably and unconditionally waives any objection to the laying of venue of any suit or proceeding arising out of or relating to this Agreement or the transactions contemplated hereby in Federal and state courts in the Borough of Manhattan in The City of New York and irrevocably and unconditionally waives and agrees not to plead or claim in any such court that any such suit or proceeding in any such court has been brought in an inconvenient forum.

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If the foregoing is in accordance with the Representatives’ understanding of our agreement, kindly sign and return to the Company one of the counterparts hereof, whereupon it will become a binding agreement between the Company and the several Underwriters in accordance with its terms.

Very truly yours,

The foregoing Underwriting Agreement is hereby confirmed and accepted as of the date first above written.

Acting on behalf of themselves and as the Representatives of the several Underwriters.

SCHEDULE A

SCHEDULE B

1.        General Use Issuer Free Writing Prospectuses (included in the General Disclosure Package)

                           “General Use Issuer Free Writing Prospectus” includes each of the following documents:

                           1.  Final term sheet, dated May 11, 2009, a copy of which is attached hereto.

2.        Other Information Included in the General Disclosure Package

                           The following information is also included in the General Disclosure Package:

                           None.

SCHEDULE C

(Form of D&T letter)

SCHEDULE D

(Form of KPMG letter)

SCHEDULE E

(Form of Cawley, Gillespie & Associates, Inc., letter)

SCHEDULE F

(Form of Ralph E. Davis Associates, Inc., letter)

SCHEDULE G

(“Significant Subsidiaries”)

Black Hills Electric Generation, LLC

Black Hills Exploration and Production, Inc.

Black Hills Non-Regulated Holdings, LLC

Black Hills Power, Inc.

Black Hills Service Company, LLC

Black Hills Utility Holdings, Inc.

Black Hills Wyoming, Inc.

Black Hills/Colorado Electric Utility Company, LP

Black Hills/Colorado Gas Utility Company, LP

Black Hills/Colorado Utility Company, LLC

Black Hills/Colorado Utility Company II, LLC

Black Hills/Iowa Gas Utility Company, LLC

Black Hills/Kansas Gas Utility Company, LLC

Black Hills/Nebraska Gas Utility Company, LLC

Cheyenne Light, Fuel and Power Company

Enserco Energy Inc.

Wyodak Resources Development Corp.

BLACK HILLS CORPORATION

AND

WELLS FARGO BANK, NATIONAL ASSOCIATION

AS TRUSTEE

SECOND SUPPLEMENTAL INDENTURE

DATED AS OF

MAY 14, 2009

$250,000,000

9% NOTES DUE 2014

SECOND SUPPLEMENTAL INDENTURE dated as of May 14, 2009 (this “Supplemental Indenture”), to the Indenture dated as of May 21, 2003 (as supplemented by the First Supplemental Indenture dated as of May 21, 2003, and as further supplemented, amended or modified, the “Indenture”), by and between BLACK HILLS CORPORATION, a South Dakota corporation (the “Company”), and WELLS FARGO BANK, NATIONAL ASSOCIATION, a national banking association organized and existing under the laws of the United States of America (as successor to LaSalle Bank National Association), as trustee (the “Trustee”).

Each party agrees as follows for the benefit of the other party and for the equal and ratable benefit of the holders of the Notes (as defined below):

WHEREAS, the Company and the Trustee have duly authorized the execution and delivery of the Indenture to provide for the issuance from time to time of senior debt securities (the “Securities”) to be issued in one or more series as in the Indenture provided;

WHEREAS, the Company has appointed the Trustee as successor trustee under the Indenture, and the Trustee has accepted such appointment, pursuant to the Agreement of Resignation, Appointment and Acceptance dated as of February 17, 2009, among Bank of America, N.A. (as successor by merger to LaSalle Bank National Association), the Trustee and the Company;

WHEREAS, the Company desires and has requested the Trustee to join the Company in the execution and delivery of this Supplemental Indenture in order to establish and provide for the issuance by the Company of a series of Securities designated as its 9% Notes due 2014 in the aggregate principal amount of $250,000,000, substantially in the form attached hereto as Exhibit A (the “Notes”), on the terms set forth herein;

WHEREAS, Section 3.1 of the Indenture provides that a supplemental indenture may be entered into by the Company and the Trustee for such purpose provided certain conditions are met;

WHEREAS, the conditions set forth in the Indenture for the execution and delivery of this Supplemental Indenture have been complied with; and

WHEREAS, all things necessary to make this Supplemental Indenture a valid agreement of the Company and the Trustee, in accordance with its terms, and a valid amendment of, and supplement to, the Indenture have been done;

NOW, THEREFORE:

In consideration of the premises and the purchase and acceptance of the Notes by the holders thereof, the Company covenants and agrees with the Trustee, for the equal and ratable benefit of the holders, that the Indenture is supplemented and amended, to the extent expressed herein, as follows:

ARTICLE I

Scope of Supplemental Indenture; General

This Supplemental Indenture supplements and, to the extent inconsistent therewith, replaces the provisions of the Indenture, to which provisions reference is hereby made.

The changes, modifications and supplements to the Indenture effected by this Supplemental Indenture shall be applicable only with respect to, and govern the terms of, the Notes, which shall initially be in an aggregate principal amount of $250,000,000, which amount may be increased pursuant to an Officers’ Certificate (as defined in the Indenture) in accordance with this Supplemental Indenture and shall not apply to any other Securities that may be issued under the Indenture unless a supplemental indenture with respect to such other Securities specifically incorporates such changes, modifications and supplements.  Pursuant to this Supplemental Indenture, there is hereby created and designated a series of Securities under the Indenture entitled “9% Notes due 2014.”  The Notes shall be in the form of Exhibit A hereto.

In the event that the Company shall issue and the Trustee shall authenticate any Notes issued under this Supplemental Indenture subsequent to the Issue Date (as defined below) (such Notes, “Additional Securities”), the Company shall use its best efforts to obtain the same “CUSIP” number for such Notes as is printed on the Notes outstanding at such time; provided, however, that if any series of Notes issued under this Supplemental Indenture subsequent to the Issue Date is determined, pursuant to an Opinion of Counsel (as defined in the Indenture) of the Company in a form reasonably satisfactory to the Trustee, to be a different class of security than the Notes outstanding at such time for federal income tax purposes, the Company may obtain a “CUSIP” number for such Notes that is different than the “CUSIP” number printed on the Notes then outstanding. Notwithstanding the foregoing, all Notes issued under this Supplemental Indenture shall vote and consent together on all matters as one class and no series of Notes will have the right to vote or consent as a separate class on any matter.

ARTICLE II

Certain Definitions

The following terms have the meanings set forth below in this Supplemental Indenture.  Capitalized terms used but not defined herein have the meanings ascribed to such terms in the Indenture.  To the extent terms defined herein differ from the Indenture the terms defined herein shall govern.

“Adjusted Treasury Rate” means, with respect to any Redemption Date, (i) the yield, under the heading which represents the average for the immediately preceding week, appearing in the most recently published statistical release designated “H.15 (519)” or any successor publication which is published weekly by the Board of Governors of the Federal Reserve System and which establishes yields on actively traded United States Treasury securities adjusted to constant maturity under the caption “Treasury Constant Maturities” for the maturity corresponding to the Comparable Treasury Issue (if no

2

maturity is within three months before or after the Stated Maturity of the Notes, yields for the two published maturities most closely corresponding to the Comparable Treasury Issue shall be determined and the Adjusted Treasury Rate shall be interpolated or extrapolated from such yields on a straight line basis, rounding to the nearest month) or (ii) if such release (or any successor release) is not published during the week preceding the calculation date or does not contain such yields, the rate per year equal to the semi-annual equivalent yield to maturity of the Comparable Treasury Issue, calculated using a price for the Comparable Treasury Issue (expressed as a percentage of its principal amount) equal to the Comparable Treasury Price for such Redemption Date, in each case calculated on the third Business Day preceding the Redemption Date, plus in each case 0.50%.

“Assets” of any Person means the whole or any part of its business, property, assets, cash and receivables.

“Change of Control” means the occurrence of any of the following:  (i) the consummation of any transaction (including any merger or consolidation) the result of which is that any person becomes the “beneficial owner” (as defined in Rules 13d-3 and 13d-5 under the Exchange Act, except that for purposes of this clause (i) such person shall be deemed to have “beneficial ownership” of all shares that any such person has the right to acquire, whether such right is exercisable immediately or only after the passage of time) of shares representing more than 50% of the voting power of the then outstanding Voting Stock of the Company or other Voting Stock into which the Voting Stock of the Company is reclassified, consolidated, exchanged or changed, (ii) the direct or indirect sale, lease, transfer, conveyance or other disposition (other than by way of merger or consolidation), in one or a series of related transactions, of all or substantially all of the assets of the Company and the Subsidiaries taken as a whole to any person other than the Company or one of the Subsidiaries, (iii) the merger or consolidation of the Company with or into any person or the merger or consolidation of any person with or into the Company, in any such event pursuant to a transaction in which any of the outstanding shares of the Voting Stock of the Company or the Voting Stock of such other person is converted into or exchanged for cash, securities or other property, other than any such transaction in which the shares of Voting Stock of the Company outstanding immediately prior to such transaction constitute, or are converted into or exchanged for, shares representing more than 50% of the voting power of the Voting Stock of the resulting or surviving person or any direct or indirect parent company of the resulting or surviving person immediately after giving effect to such transaction, (iv) the first day on which a majority of the members of the board of directors of the Company are not Continuing Directors or (v) the adoption of a plan providing for the liquidation or dissolution of the Company.  Notwithstanding the foregoing, a transaction will not be deemed to involve a Change of Control under clause (i) above if (a) the Company becomes a direct or indirect wholly owned subsidiary of a holding company and (b)(x) the direct or indirect holders of the Voting Stock of such holding company immediately following such transaction are substantially the same as the holders of the Company’s Voting Stock immediately prior to such transaction or (y) immediately following such transaction no person (other than a holding company satisfying the requirements of this sentence) is the beneficial owner, directly or indirectly, of shares

3

representing more than 50% of the voting power of the Voting Stock of such holding company.  The term “person,” as used in this definition, has the meaning given thereto in Section 13(d)(3) of the Exchange Act.

“Change of Control Offer” has the meaning specified in Section 4.2.

“Change of Control Payment” has the meaning specified in Section 4.2.

“Change of Control Payment Date” has the meaning specified in Section 4.2.

“Change of Control Triggering Event” means the occurrence of both a Change of Control and a Rating Event.

“Comparable Treasury Issue” means the United States Treasury security selected by the Quotation Agent as having a maturity comparable to the remaining term from the Redemption Date to the Stated Maturity of the Notes that would be utilized, at the time of selection and in accordance with customary financial practice, in pricing new issues of corporate debt securities of comparable maturity to the remaining term of the Notes.

“Comparable Treasury Price” means, with respect to any Redemption Date, if clause (ii) of the definition of Adjusted Treasury Rate is applicable, the average of three, or such lesser number as is obtained by the Trustee, Reference Treasury Dealer Quotations for such Redemption Date.

“Consolidated Capitalization” means, as of any date of determination, the sum obtained by adding (i) Consolidated Shareholders’ Equity, (ii) Consolidated Indebtedness (exclusive of any that is due and payable within one year of the date such sum is determined) and, without duplication, (iii) any preference or preferred stock of the Company or any Consolidated Subsidiary that is subject to mandatory redemption or sinking fund provisions.

“Consolidated Indebtedness” means, as of any date of determination, total indebtedness as shown on the consolidated balance sheet of the Company and the Consolidated Subsidiaries.

“Consolidated Shareholders’ Equity” means, as of any date of determination, the total Assets of the Company and the Consolidated Subsidiaries less all liabilities of the Company and its Consolidated Subsidiaries that would, in accordance with generally accepted accounting principles in the United States (as in effect on the date of this Supplemental Indenture), be classified on a balance sheet as liabilities, including (i) indebtedness secured by property of the Company or any of the Consolidated Subsidiaries whether or not the Company or such Consolidated Subsidiary is liable for the payment of such indebtedness unless, in the case that the Company or such Consolidated Subsidiary is not so liable, such property has not been included among the Assets of the Company or such Consolidated Subsidiary on such balance sheet, (ii) deferred liabilities and (iii) indebtedness of the Company or any of the Consolidated Subsidiaries that is expressly subordinated in right and priority of payment to other

4

liabilities of the Company or such Consolidated Subsidiary.  As used in this definition, “liabilities” includes preference or preferred stock of the Company or any Consolidated Subsidiary only to the extent of any such preference or preferred stock that is subject to mandatory redemption or sinking fund provisions.

“Consolidated Subsidiary” means, at any date, any Subsidiary the financial statements of which under generally accepted accounting principles in the United States (as in effect on the date of this Supplemental Indenture) would be consolidated with those of the Company in its consolidated financial statements as of such date.

“Continuing Directors” means, as of any date of determination, any member of the board of directors of the Company who (i) was a member of such board of directors on the Issue Date or (ii) was nominated for election or elected to such board of directors with the approval of a majority of the Continuing Directors who were members of such board of directors at the time of such nomination or election (either by a specific vote or by approval of the Company’s proxy statement in which such member was named as a nominee for election as a director, without objection to such nomination).

“Event of Default” has the meaning specified in Section 5.1.

“Fitch” means Fitch Ratings, Inc.

“Holder” means the Person in whose name a Note is registered in the books of the Security Registrar for the Notes.

“Indebtedness” means (i) all indebtedness, whether or not represented by bonds, debentures, notes or other securities, incurred, created or assumed by the Company or any Subsidiary for the repayment of money borrowed, (ii) all indebtedness for money borrowed secured by a lien upon property owned by the Company or any Subsidiary, regardless of whether the Company or such Subsidiary has assumed or otherwise become liable for the payment of such indebtedness for money borrowed, and (iii) all indebtedness of others for money borrowed that is guaranteed as to payment of principal or interest by the Company or any Subsidiary or in effect guaranteed by the Company or such Subsidiary through a contingent agreement to purchase such indebtedness or through any “keep-well” or similar agreement to be directly or indirectly liable for the repayment of such indebtedness.

“Investment Grade Rating” means a rating equal to or higher than BBB- (or the equivalent) by Fitch, Baa3 (or the equivalent) by Moody’s and BBB- (or the equivalent) by S&P.

“Issue Date” means the date on which the Notes are originally issued under this Supplemental Indenture.

“Make-Whole Amount” means the sum, as determined by a Quotation Agent, of the present values of the principal amount of the Notes to be redeemed, together with scheduled payments of interest (exclusive of accrued and unpaid interest (if any) to the Redemption Date) from the Redemption Date to the Stated Maturity of the

5

Notes, in each case discounted to the Redemption Date on a semi-annual basis, assuming a 360-day year consisting of twelve 30-day months, at the Adjusted Treasury Rate, plus accrued and unpaid interest (if any) on the principal amount of the Notes being redeemed to the Redemption Date.

“Moody’s” means Moody’s Investors Service, Inc.

“Quotation Agent” means the Reference Treasury Dealer selected by the Trustee after consultation with the Company.

“Rating Agencies” means (i) each of Fitch, Moody’s and S&P and (ii) if any of Fitch, Moody’s or S&P ceases to rate the Notes or fails to make a rating of the Notes publicly available for reasons outside of the Company’s control, a “nationally recognized statistical rating organization” within the meaning of Rule 15c3-1(c)(2)(vi)(F) under the Exchange Act, selected by the Company (as certified by a resolution of the Board of Directors) as a replacement agency for Fitch, Moody’s or S&P, as the case may be.

“Rating Event” means the rating of the Notes is lowered by at least two of the three Rating Agencies and the Notes are rated below an Investment Grade Rating by at least two of the three Rating Agencies, on any day during the period (which period will be extended so long as the rating of the Notes is under publicly announced consideration for a possible downgrade by any of the Rating Agencies) commencing 60 days prior to the first public notice of the occurrence of a Change of Control or the intention of the Company to effect a Change of Control and ending 60 days following the consummation of such Change of Control.

“Reference Treasury Dealer” means each primary U.S. Government securities dealer selected by the Trustee after consultation with the Company.

“Reference Treasury Dealer Quotations” means, with respect to each Reference Treasury Dealer and any Redemption Date, the average, as determined by the Trustee, of the bid and asked prices for the Comparable Treasury Issue, expressed in each case as a percentage of its principal amount, quoted in writing to the Trustee by such Reference Treasury Dealer at 5:00 p.m., New York City time, on the third Business Day preceding such Redemption Date.

“S&P” means Standard & Poor’s Ratings Services, a division of The McGraw-Hill Companies, Inc.

“Subsidiary” means a corporation, limited partnership, limited liability company or trust in which more than 50% of the outstanding Voting Stock is owned, directly or indirectly, by the Company and/or by one or more other Subsidiaries.

“Voting Stock” means, with respect to any specified “person” (as that term is used in Section 13(d)(3) of the Exchange Act) as of any date, stock, partnership interests or any other participations, rights, warrants, options or other interests in the nature of an equity interest that ordinarily (without regard to the occurrence of any contingency) has voting power for the election of directors, managers or trustees of such

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person, whether at all times or only so long as no senior class of stock has that voting power by reason of any contingency.

“Trustee” means the party named as such above until a successor replaces such party in accordance with the applicable provisions of the Indenture and thereafter means the successor serving hereunder.

ARTICLE III

The Notes

Section 3.1             Payments of Principal and Interest.

The Notes shall bear interest from and including May 14, 2009, to but excluding the date of Maturity, at the rate of 9% per annum.  The Notes shall mature on May 15, 2014.  The Company shall pay interest on the Notes semiannually on May 15 and November 15 of each year, commencing November 15, 2009, to the Person in whose name any such Note or any predecessor Note is registered in the Security Register at the close of business on the May 1 and November 1 next preceding such Interest Payment Date.  The Company initially authorizes the Trustee to act as Paying Agent.

Section 3.2             Optional Redemption.

Subject to the provisions of Article XI of the Indenture, the Notes shall be redeemable at the option of the Company, as a whole at any time or in part from time to time, at a Redemption Price equal to the greater of (i) the principal amount of the Notes to be redeemed plus accrued and unpaid interest (if any) to the Redemption Date and (ii) the Make-Whole Amount with respect to the Notes to be redeemed.

Section 3.3             No Sinking Fund.

The Notes shall not be entitled to the benefit of any sinking fund.

Section 3.4             Book Entry, Delivery and Form.

The Notes shall initially be issued in the form of a Global Security (the “Global Note”).  The Global Note shall initially be deposited on or about the Issue Date with, or on behalf of, The Depository Trust Company (the “Depositary”) and registered in the name of Cede & Co., as nominee of the Depositary.

Section 3.5             Form of Legend for Global Note.

In addition to the legend set forth in Section 2.2 of the Indenture, every Global Note authenticated and delivered hereunder shall bear a legend substantially in the following form:

UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED

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REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY, A NEW YORK CORPORATION (“DTC”), TO THE COMPANY OR ITS AGENT FOR REGISTRATION OF TRANSFER, EXCHANGE OR PAYMENT, AND ANY CERTIFICATE ISSUED IS REGISTERED IN THE NAME OF CEDE & CO. OR IN SUCH OTHER NAME AS IS REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF DTC (AND ANY PAYMENT IS MADE TO CEDE & CO. OR TO SUCH OTHER ENTITY AS IS REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL INASMUCH AS THE REGISTERED OWNER HEREOF, CEDE & CO., HAS AN INTEREST HEREIN.

ARTICLE IV

Covenants

Section 4.1                                    Limitations on Liens.

So long as any Notes are Outstanding, neither the Company nor any Subsidiary shall mortgage, pledge, grant a security interest in or hypothecate, or permit any mortgage, pledge, security interest, lien or other encumbrance upon, any capital stock of any Subsidiary now or hereafter owned directly or indirectly by the Company or any Subsidiary, to secure any Indebtedness without concurrently making effective provision whereby the Outstanding Notes shall (so long as such other Indebtedness shall be so secured) be equally and ratably secured with any and all such other Indebtedness and any other indebtedness similarly entitled to be equally and ratably secured; provided, however, that this restriction shall not apply to, or prevent the creation of:

(1)                                  any mortgage, pledge, security interest, lien or encumbrance existing on the Issue Date;

(2)                                  any mortgage, pledge, security interest, lien or encumbrance upon any capital stock created at the time of the acquisition of such capital stock by the Company or any Subsidiary or within one year after such time to secure all or a portion of the purchase price for such capital stock;

(3)                                  any mortgage, pledge, security interest, lien or encumbrance upon any capital stock existing thereon at the time of the acquisition of such capital stock by the Company or any Subsidiary, whether or not the obligations secured thereby are assumed by the Company or such Subsidiary, other than any mortgage, pledge, security interest, lien or encumbrance created in connection with or in anticipation of such acquisition not for the purpose of securing the purchase price for such capital stock;

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(4)                                  any mortgage, pledge, security interest, lien or encumbrance upon any capital stock to secure or provide for the acquisition, construction, improvement, expansion or development of property by the Company or any Subsidiary; provided that such mortgage, pledge, security interest, lien or encumbrance may not extend to or cover any other property of the Company or any Subsidiary that is not the subject of the related financing;

(5)                                  any mortgage, pledge, security interest, lien or encumbrance upon any capital stock of Black Hills Wyoming, Inc. (or any of its direct or indirect Subsidiaries), or any other Subsidiary or group of Subsidiaries formed to refinance the project now known as the “Wygen I” project; provided that such mortgage, pledge, security interest, lien or encumbrance may not extend to or cover any other property of the Company or any Subsidiary that is not the subject of such refinancing;

(6)                                  so long as no additional property of the Company or any Subsidiary is encumbered or made subject to a mortgage, pledge, security interest, lien or other encumbrance, any mortgage, pledge, security interest, lien or encumbrance granted in connection with (a) extending, renewing, replacing or refinancing in whole or in part the Indebtedness secured by any mortgage, pledge, security interest, lien or encumbrance described in the foregoing clauses (1) through (5) or (b) any transaction or series of related transactions involving separate projects pursuant to which any of the mortgages, pledges, security interests, liens or encumbrances described in the foregoing clauses (1) through (5) are combined or aggregated; provided, that, for purposes of this subclause (b), all of the Indebtedness secured by such mortgages, pledges, security interests, liens or encumbrances immediately prior to such transaction or series of related transactions is repaid in connection therewith; provided further, that, for purposes of this subclause (b), the aggregate amount of Indebtedness secured by such combined or aggregated mortgages, pledges, security interests, liens or other encumbrances does not exceed the sum of (x) the aggregate amount of extended, renewed, replaced or refinanced Indebtedness secured by such mortgages, pledges, security interests, liens or encumbrances outstanding immediately prior to such transaction or series of related transactions and (y) 5% of Consolidated Capitalization, less the total amount of all Indebtedness then outstanding that has been incurred and secured pursuant to this subclause (y) in any prior, separate transactions or series of related transactions;

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(7)                                  any mortgage, pledge, security interest, lien or encumbrance upon any capital stock now or hereafter owned by the Company or any Subsidiary to secure any Indebtedness, which would otherwise be subject to the foregoing restriction and not otherwise permitted under any of the foregoing clauses (1) through (6), in an aggregate principal amount which, together with the amount of all other such Indebtedness then outstanding that has been incurred and secured under this clause (7), does not at the time of the creation of such mortgage, pledge, security interest, lien or encumbrance exceed 5% of Consolidated Capitalization; or

(8)                                  any judgment, levy, execution, attachment or other similar lien arising in connection with court proceedings, provided that:

(a)                                  the execution or enforcement of each such lien is effectively stayed within 60 days after entry of the corresponding judgment (or the corresponding judgment has been discharged within such 60-day period) and the claims secured thereby are being contested in good faith by appropriate proceedings timely commenced and diligently prosecuted;

(b)                                 the payment of each such lien is covered in full by insurance provided by a third party and the insurance company has not denied or contested coverage thereof; or

(c)                                  each such lien is adequately bonded within 60 days of the creation of such lien.

In case the Company shall propose to mortgage, pledge, grant a security interest in or hypothecate any capital stock of any Subsidiary owned directly or indirectly by the Company or any Subsidiary to secure any Indebtedness, other than as permitted by clauses (1) to (7), inclusive, of this Section 4.1, the Company shall prior thereto give written notice thereof to the Trustee, and the Company shall prior to or simultaneously with such mortgage, pledge, grant of security interest or hypothecation, by supplemental indenture executed by the Company and the Trustee (or to the extent legally necessary by another trustee or an additional or separate trustee), in form satisfactory to the Trustee, effectively secure (for so long as such other Indebtedness shall be so secured) all the Outstanding Notes equally and ratably with such Indebtedness and with any other indebtedness similarly entitled to be equally and ratably secured.

Section 4.2                                    Change of Control.

If a Change of Control Triggering Event occurs, each Holder of the Notes shall have the right to require the Company to repurchase all or any part (equal to $2,000 or an integral multiple of $1,000 in excess thereof) of such Holder’s Notes pursuant to the offer described below (the “Change of Control Offer”) on the terms set forth in this

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Section 4.2.  In the Change of Control Offer, the Company shall offer payment in cash equal to 101% of the aggregate principal amount of Notes repurchased, plus accrued and unpaid interest (if any) on the Notes repurchased, to the date of repurchase (the “Change of Control Payment”), subject to the right of Holders of record on the relevant Record Date to receive interest on the relevant Interest Payment Date.

Within 30 days following any Change of Control Triggering Event (unless the Company has previously mailed a redemption notice with respect to all Outstanding Notes pursuant to Section 3.2 of this Supplemental Indenture) or, at the option of the Company, prior to any Change of Control Triggering Event but after public announcement of the transaction or transactions that constitute or may constitute the Change of Control, the Company shall mail a notice by first-class mail to each Holder of the Notes (with a copy to the Trustee), which notice shall:

(1)                                  describe the circumstances and relevant facts regarding the Change of Control Triggering Event (including, to the extent available, information with respect to pro forma historical income, cash flow and capitalization, in each case after giving effect to the Change of Control);

(2)                                  offer to repurchase the Notes on the date specified in the notice, which date shall be no earlier than 30 days and no later than 60 days following the date such notice is mailed (the “Change of Control Payment Date”), pursuant to the procedures required by the Indenture and described in such notice, which offer will constitute the Change of Control Offer; and

(3)                                  if mailed prior to the date on which the Change of Control Triggering Event occurs, state that the Change of Control Offer is conditioned on the Change of Control Triggering Event occurring on or prior to the applicable Change of Control Payment Date.

On the Change of Control Payment Date, the Company shall, to the extent lawful:

(1)                                  accept for payment all Notes or portions of Notes properly tendered pursuant to the Change of Control Offer;

(2)                                  deposit with the Paying Agent an amount equal to the Change of Control Payment in respect of all Notes or portions of Notes properly tendered; and

(3)                                  deliver or cause to be delivered to the Trustee the Notes properly accepted together with an Officers’ Certificate stating the aggregate principal amount of Notes or portions of Notes being repurchased.

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Holders electing to have any Notes repurchased shall be required to surrender the Notes, with an appropriate form duly completed, to the Company at the address specified in the notice at least three Business Days prior to the Change of Control Payment Date.  Holders shall be entitled to withdraw their election if the Trustee or the Company receives, not later than one Business Day prior to the Change of Control Payment Date, a written notice (including by facsimile or other electronic transmission) setting forth the name of the Holder, the principal amount of the Notes which were delivered for purchase by the Holder and a statement that such Holder is withdrawing its election to have such Notes purchased.

On the Change of Control Payment Date, all Notes purchased by the Company under this Section 4.2 shall be delivered by the Company to the Trustee for cancelation, and the Company shall pay the Change of Control Payment to the Holders entitled thereto.

Notwithstanding the foregoing provisions of this Section 4.2, the Company shall not be required to make a Change of Control Offer upon the occurrence of a Change of Control Triggering Event if a third party makes a Change of Control Offer in the manner, at the times and otherwise in compliance with the requirements for a Change of Control Offer made by the Company and the third party purchases all Notes properly tendered and not withdrawn under such Change of Control Offer.

The Company shall comply with the requirements of Rule 14e-1 under the Exchange Act and any other securities laws and regulations to the extent such laws and regulations are applicable in connection with the repurchase of the Notes as a result of a Change of Control Triggering Event.  To the extent that the provisions of any securities laws or regulations conflict with the provisions of this Section 4.2, the Company shall comply with the applicable securities laws and regulations.  The Company shall not be deemed to have breached its obligations under this Section 4.2 by virtue of such compliance.

Notwithstanding anything to the contrary contained in the Indenture, the Trustee may enter into a supplemental indenture for the purpose of waiving or modifying the provisions of this Section 4.2 with the written consent of the Holders of a majority in principal amount of the Outstanding Notes.

ARTICLE V

Remedies

Section 5.1                                    Events of Default.

“Event of Default” means, with respect to the Notes, any one or more of the following events (whatever the reason for such Event of Default and whether it shall be voluntary or involuntary or be effected by operation of law or pursuant to any judgment, decree or order of any court or any order, rule or regulation of any administrative or governmental body):

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(a)                                  default in the payment of the principal of or any Make-Whole Amount on any Note at its Maturity, or any Change of Control Payment on any Change of Control Payment Date;

(b)                                 default in the payment of any interest upon any Note when it becomes due and payable, and continuance of such default for a period of 30 days;

(c)                                  default in the performance, or breach, of any covenant or warranty of the Company in this Supplemental Indenture or the Indenture (other than a covenant or warranty a default in whose performance or whose breach is elsewhere in this Section 5.1 specifically addressed or which has expressly been included in the Indenture solely for the benefit of one or more series of Securities other than the Notes), and continuance of such default or breach for a period of 60 days after there has been given, by registered or certified mail, to the Company by the Trustee or to the Company and the Trustee by the Holders of at least 25% in principal amount of the Outstanding Notes a written notice specifying such default or breach and requiring it to be remedied and stating that such notice is a “Notice of Default” hereunder (without giving effect to any applicable grace period with respect to such covenant or warranty);

(d)                                 the entry by a court having jurisdiction in the premises of (i) a decree or order for relief in respect of the Company in an involuntary case or proceeding under any applicable Federal or State bankruptcy, insolvency, reorganization or other similar law or (ii) a decree or order adjudging the Company a bankrupt or insolvent, or approving as properly filed a petition seeking reorganization, arrangement, adjustment or composition of or in respect of the Company under any applicable Federal or State law, or appointing a custodian, receiver, liquidator, assignee, trustee, sequestrator or other similar official of the Company or of any substantial part of its property, or ordering the winding up or liquidation of its affairs, and the continuance of any such decree or order for relief or any such other decree or order unstayed and in effect for a period of 90 consecutive days; and

(e)                                  the commencement by the Company of a voluntary case or proceeding under any applicable Federal or State bankruptcy, insolvency, reorganization or other similar law or of any other case or proceeding to be adjudicated a bankrupt or insolvent, or the consent by it to the entry of a decree or order for relief in respect of the Company in an involuntary case or proceeding under any applicable Federal or State bankruptcy, insolvency, reorganization or other similar law or to the commencement of any bankruptcy or insolvency case or proceeding against it, or the filing by it of a petition or answer or consent seeking reorganization or relief under any applicable Federal or State law, or the consent by it to the filing of such petition or to the appointment of or taking possession by a custodian, receiver, liquidator, assignee, trustee, sequestrator or other similar official

13

of the Company or of any substantial part of its property, or the making by it of an assignment for the benefit of creditors, or the admission by it in writing of its inability to pay its debts generally as they become due, or the taking of corporate action by the Company in furtherance of any such action.

ARTICLE VI

Miscellaneous

Section 6.1                                      Governing Law.

This Supplemental Indenture and the Notes shall be governed by and construed in accordance with the laws of the State of New York, without giving effect to such State’s conflicts of laws principles.

Section 6.2                                      Ratification of Indenture.

Except as expressly modified or amended hereby, the Indenture continues in full force and effect and is in all respects confirmed, ratified and preserved.

Section 6.3                                      Trustee.

The Trustee makes no representations as to the validity or sufficiency of this Supplemental Indenture.  The statements and recitals herein are deemed to be those of the Company and not of the Trustee.

Section 6.4                                      Counterparts.

This Supplemental Indenture may be executed in any number of counterparts, each of which shall be an original, but such counterparts shall together constitute one and the same instrument.

Section 6.5                                      Separability.

In case any provision in this Supplemental Indenture or in the Notes shall be invalid, illegal or unenforceable, the validity, legality or enforceability of the remaining provisions shall not in any way be affected or impaired thereby.

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IN WITNESS WHEREOF, the parties have caused this Supplemental Indenture to be duly executed, all as of the date first above written.

Exhibit A

FORM OF NOTE

[Face of Security]

[If this Security is a Global Note, insert:  THIS SECURITY IS A GLOBAL SECURITY WITHIN THE MEANING OF THE INDENTURE HEREINAFTER REFERRED TO AND IS REGISTERED IN THE NAME OF A DEPOSITARY OR A NOMINEE THEREOF.  THIS SECURITY MAY NOT BE EXCHANGED IN WHOLE OR IN PART FOR A SECURITY REGISTERED, AND NO TRANSFER OF THIS SECURITY IN WHOLE OR IN PART MAY BE REGISTERED, IN THE NAME OF ANY PERSON OTHER THAN SUCH DEPOSITARY OR A NOMINEE THEREOF, EXCEPT IN THE LIMITED CIRCUMSTANCES DESCRIBED IN THE INDENTURE.

UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY, A NEW YORK CORPORATION (“DTC”), TO THE COMPANY OR ITS AGENT FOR REGISTRATION OF TRANSFER, EXCHANGE OR PAYMENT, AND ANY CERTIFICATE ISSUED IS REGISTERED IN THE NAME OF CEDE & CO. OR IN SUCH OTHER NAME AS IS REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF DTC (AND ANY PAYMENT IS MADE TO CEDE & CO. OR TO SUCH OTHER ENTITY AS IS REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL INASMUCH AS THE REGISTERED OWNER HEREOF, CEDE & CO., HAS AN INTEREST HEREIN.]

9% Notes due 2014

BLACK HILLS CORPORATION

BLACK HILLS CORPORATION, a South Dakota corporation (the “Company”), for value received, hereby promises to pay to                          or registered assigns the principal sum of                          DOLLARS on May 15, 2014 (the “Stated Maturity”), or earlier at the option of the Company as provided herein (the “Redemption Date”), and to pay interest thereon from May 14, 2009, or from the most recent Interest Payment Date to which interest has been paid or duly provided for, semi-annually on May 15 and November 15 in each year (each, an “Interest Payment Date”), commencing November 15, 2009, at the rate of 9% per annum, until the principal hereof is paid or duly provided for.

All capitalized terms used herein and not otherwise defined shall have the meanings ascribed to them in the Indenture dated as of May 21, 2003, between the Company and Wells Fargo Bank, National Association (as successor to LaSalle Bank National Association), as trustee (the “Trustee”), as supplemented by the First Supplemental Indenture dated as of May 21, 2003, and the Second Supplemental Indenture dated as of May 14, 2009 (collectively, the “Indenture”).

The interest payable, and punctually paid or duly provided for, on any Interest Payment Date will, as provided in such Indenture, be paid to the Holder in whose name this Security (or one or more Predecessor Securities) is registered at the close of business on the Regular Record Date for such interest, which shall be the May 1 or November 1 (whether or not a Business Day), as the case may be, next preceding such Interest Payment Date at the office or agency of the Company maintained for such purpose.  Any such interest not so punctually paid or duly provided for shall forthwith cease to be payable to the Holder on such Regular Record Date, and may be paid to the Holder in whose name this Security (or one or more Predecessor Securities) is registered at the close of business on a Special Record Date for the payment of such Defaulted Interest to be fixed by the Trustee, notice whereof shall be given to Holders of Securities of this series not less than 10 days prior to such Special Record Date, or may be paid at any time in any other lawful manner not inconsistent with the requirements of any securities exchange on which the Securities of this series may be listed, and upon such notice as may be required by such exchange, all as more fully provided in the Indenture.  Interest will be computed on the basis of a 360-day year of twelve 30-day months.

The principal of this Security payable on the Stated Maturity, or the principal of, or Make-Whole Amount, if any, and, if the Redemption Date is not an Interest Payment Date, interest on this Security payable on the Redemption Date, or the Change of Control Payment payable on the Change of Control Payment Date, will be paid against presentation of this Security at the office or agency of the Company maintained for that purpose in the City of Fort Worth, Texas, in such coin or currency of the United States of America as at the time of payment is legal tender for the payment of public and private debts.

A-2

Interest payable on this Security on any Interest Payment Date and on the Stated Maturity or Redemption Date or Change of Control Payment Date, as the case may be, will include interest accrued from and including the next preceding Interest Payment Date in respect of which interest has been paid or duly provided for (or from and including May 14, 2009, if no interest has been paid on this Security) to but excluding such Interest Payment Date or the Stated Maturity or Redemption Date or Change of Control Payment Date, as the case may be.  If any Interest Payment Date or the Stated Maturity or Redemption Date or Change of Control Payment Date falls on a day that is not a Business Day, as defined below, the principal or Make-Whole Amount or Change of Control Payment, if any, and/or interest payable with respect to such Interest Payment Date or Stated Maturity or Redemption Date or Change of Control Payment Date, as the case may be, will be paid on the next succeeding Business Day with the same force and effect as if it were paid on the date such payment was due, and no interest shall accrue on the amount so payable for the period from and after such Interest Payment Date or Stated Maturity or Redemption Date or Change of Control Payment Date, as the case may be.  “Business Day” means each Monday, Tuesday, Wednesday, Thursday or Friday which is not a day on which banking institutions in the City of Fort Worth, Texas, are authorized or obligated by law or executive order to close.

[If this Security is a Global Note, insert:  All payments of principal or Make-Whole Amount or Change of Control Payment, if any, and interest in respect of this Security will be made by the Company in immediately available funds.]

Reference is hereby made to the further provisions of this Security set forth on the reverse hereof, which further provisions shall for all purposes have the same effect as if set forth at this place.

Unless the Certificate of Authentication hereon has been executed by the Trustee by manual signature of one of its authorized signatories, this Security shall not be entitled to any benefit under the Indenture, or be valid or obligatory for any purpose.

A-3

IN WITNESS WHEREOF, the Company has caused this instrument to be duly executed under its facsimile corporate seal.

Dated:  May 14, 2009

A-4

TRUSTEE’S CERTIFICATE OF AUTHENTICATION

This is one of the Securities of the series designated herein referred to in the within-mentioned Indenture.

A-5

[Reverse of Security]

BLACK HILLS CORPORATION

9% Notes due 2014

This Security is one of a duly authorized issue of securities of the Company (herein called the “Securities”), issued and to be issued in one or more series under an Indenture dated as of May 21, 2003, as supplemented by the First Supplemental Indenture dated as of May 21, 2003, and the Second Supplemental Indenture dated as of May 14, 2009 (as so supplemented, herein called the “Indenture”), each between the Company and Wells Fargo Bank, National Association ( as successor to LaSalle Bank National Association), as trustee (herein called the “Trustee,” which term includes any successor trustee under the Indenture with respect to the series of which this Security is a part), to which Indenture and all indentures supplemental thereto reference is hereby made for a statement of the respective rights, limitations of rights, duties and immunities thereunder of the Company, the Trustee and the Holders of the Securities, and of the terms upon which the Securities are, and are to be, authenticated and delivered.  The aggregate principal amount of the Securities to be issued under such series is initially limited to $250,000,000 (except for Securities authenticated and delivered upon transfer of, or in exchange for, or in lieu of other Securities).  All terms used in this Security which are defined in the Indenture shall have the meanings assigned to them in the Indenture.

If an Event of Default, as defined in the Indenture, with respect to the Securities shall occur and be continuing, the principal of the Securities of this series may be declared due and payable in the manner and with the effect provided in the Indenture.

The Securities are subject to redemption, at the option of the Company, in whole at any time or in part from time to time at a redemption price equal to the greater of (i) the principal amount of the Securities to be redeemed plus accrued and unpaid interest (if any) to the Redemption Date and (ii) the Make-Whole Amount with respect to the Securities being redeemed.

Notice of redemption will be given by mail to Holders of Securities, not less than 30 or more than 60 days prior to the Redemption Date, all as provided in the Indenture.

In the event of redemption of this Security in part only, a new Security or Securities for the unredeemed portion hereof shall be issued in the name of the Holder hereof upon the cancelation hereof.

If a Change of Control Triggering Event occurs, each Holder of the Securities will have the right to require the Company to repurchase all or any part (equal to $2,000 or an integral multiple of $1,000 in excess thereof) of such Holder’s Securities in cash at a repurchase price equal to 101% of the aggregate principal amount of the Securities repurchased, plus accrued and unpaid interest (if any) on the Securities repurchased, to the date of repurchase, subject to the right of the Holders of record on the relevant Record Date to receive interest on the relevant Interest Payment Date, all as provided in the Indenture.

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The Indenture permits, with certain exceptions as therein provided, the amendment thereof and the modification of the rights and obligations of the Company and the rights of the Holders of the Securities under the Indenture at any time by the Company and the Trustee with the consent of the Holders of not less than a majority of the aggregate principal amount of all Securities issued under the Indenture at the time Outstanding and affected thereby.  The Indenture also contains provisions permitting the Holders of not less than a majority of the aggregate principal amount of the Outstanding Securities, on behalf of the Holders of all such Securities, to waive compliance by the Company with certain provisions of the Indenture.  Furthermore, provisions in the Indenture permit the Holders of not less than a majority of the aggregate principal amount, in certain instances, of the Outstanding Securities of any series to waive, on behalf of all of the Holders of Securities of such series, certain past defaults under the Indenture and their consequences.

No reference herein to the Indenture and no provision of this Security or of the Indenture shall alter or impair the obligation of the Company, which is absolute and unconditional, to pay the principal of (and Make-Whole Amount or Change of Control Payment, if any) and interest on this Security at the times, places and rate, and in the coin or currency, herein prescribed.

As provided in the Indenture and subject to certain limitations therein set forth, the transfer of this Security is registrable in the Security Register of the Company upon surrender of this Security for registration of transfer at the office or agency of the Company in any place where the principal of (and Make-Whole Amount or Change of Control Payment, if any) and interest on this Security are payable, duly endorsed by, or accompanied by a written instrument of transfer in form satisfactory to the Company and the Security Registrar duly executed by, the Holder hereof or by his attorney duly authorized in writing, and thereupon one or more new Securities, of authorized denominations and for the same aggregate principal amount, will be issued to the designated transferee or transferees.

As provided in the Indenture and subject to certain limitations therein set forth, this Security is exchangeable for a like aggregate principal amount of Securities of different authorized denominations but otherwise having the same terms and conditions, as requested by the Holder hereof surrendering the same.

The Securities of this series are issuable only in registered form without coupons in denominations of $2,000 and integral multiples of $1,000.

No service charge shall be made for any such registration of transfer or exchange, but the Company may require payment of a sum sufficient to cover any tax or other governmental charge payable in connection therewith.

Prior to due presentment of this Security for registration of transfer, the Company, the Trustee and any agent of the Company or the Trustee may treat the Person in whose name this Security is registered as the owner hereof for all purposes, whether or not this Security be overdue, and neither the Company, the Trustee nor any such agent shall be affected by notice to the contrary.

A-7

No recourse shall be had for the payment of the principal of or Make-Whole Amount or Change of Control Payment, if any, or the interest on this Security, or for any claim based hereon, or otherwise in respect hereof, or based on or in respect of the Indenture or any indenture supplemental thereto, against any incorporator, stockholder, employee, agent, officer, director or subsidiary, as such, past, present or future, of the Company or of any successor corporation, either directly or through the Company or any successor corporation, whether by virtue of any constitution, statute or rule of law or by the enforcement of any assessment or penalty or otherwise, all such liability being, by the acceptance hereof and as part of the consideration for the issue hereof, expressly waived and released.

The Securities and the Indenture shall be governed by and construed in accordance with the laws of the State of New York, without giving effect to such State’s conflicts of laws principles.

A-8

ASSIGNMENT FORM

To assign this Security, fill in the form below:

I or we assign and transfer this Security to

(Insert assignee’s soc. sec. or tax identification no.)

(Print or type assignee’s name, address and zip code)

and irrevocably appoint ________________________________ as agent to transfer this Security on the books of the Company.  The agent may substitute another to act for him.

Signatures must be guaranteed by an “eligible guarantor institution” meeting the requirements of the Security Registrar, which requirements include membership or participation in the Security Transfer Agent Medallion Program (“STAMP”) or such other “signature guarantee program” as may be determined by the Security Registrar in addition to, or in substitution for, STAMP, all in accordance with the Securities Exchange Act of 1934, as amended.

A-9

Exhibit 5.1

[Letterhead of Steven J. Helmers]

May 11, 2009

Black Hills Corporation

625 Ninth Street

Rapid City, South Dakota 57701

Re: Black Hills Corporation

Registration Statement on Form S-3

File No. 333-150669 (the “Registration Statement”)

Gentlemen:

I am General Counsel of Black Hills Corporation, a South Dakota corporation (the “Company”), and I have acted as counsel for the Company in connection with the Registration Statement and with respect to the issuance and sale by the Company of $250 million aggregate principal amount of 9% Notes due 2014 (the “Securities”) offered pursuant to that certain Prospectus Supplement dated May 11, 2009 (the “Prospectus Supplement”) and the accompanying Prospectus dated May 6, 2008. The Securities are to be issued under an Indenture, dated as of May 21, 2003, by and between the Company and Wells Fargo Bank, National Association, as successor Trustee (the “Trustee”), as supplemented by a First Supplemental Indenture, dated as of May 21, 2003, between the Company and the Trustee, and a Second Supplemental Indenture dated as of May 14, 2009, between the Company and the Trustee (collectively, the “Indenture”).

In reaching the conclusions expressed in this opinion, I, or persons responsible to me, have examined (i) the Company’s restated articles of incorporation and amended and restated bylaws dated January 30, 2009, (ii) the Registration Statement, and (iii) the Indenture. In addition, I have (a) examined such certificates of public officials and of corporate officers and directors and such other documents and matters as I, or persons responsible to me, have deemed necessary or appropriate, (b) relied upon the accuracy of facts and information set forth in all such documents, and (c) assumed the genuineness of all signatures, the authenticity of all documents submitted to me, or persons responsible to me, as originals, the conformity to original documents of all documents submitted to us as copies, and the authenticity of the originals from which all such copies were made.

Based on the foregoing and subject to the qualifications and limitations stated herein, I am of the opinion that the Securities have been duly authorized and, when issued, delivered and paid for in accordance with the terms and conditions of that certain Underwriting Agreement dated May 11, 2009 (the “Underwriting Agreement”) by and among the Company and the Representatives (as defined in the Underwriting Agreement), will be legally issued and constitute valid and binding obligations of the Company, enforceable in accordance with their terms.

My opinion set forth above is subject to the effects of bankruptcy, insolvency, reorganization, fraudulent transfer or conveyance, moratorium or other similar laws now or hereinafter in effect relating to or affecting the enforcement of creditors’ rights generally and by general principles of equity (regardless of whether enforcement is sought in a proceeding in equity or at law).

I am a member of the bar of the State of South Dakota. My opinion expressed above is limited to the laws of the States of South Dakota and New York and the federal law of the United States of America, and I do not express any opinion herein concerning the laws of any other jurisdiction. The Indenture provides that it is governed by the laws of the State of New York. To the extent that the opinion expressed herein relates to matters governed by the laws of the State of New York, I have relied, with their permission, as to all matters of New York law, on the opinion of Conner & Winters, LLP dated May 11, 2009, which is filed as Exhibit 5.2 to the Registration Statement, and my opinion is subject to the exceptions, qualifications and assumptions contained in such opinion.

I consent to the filing of this opinion as an exhibit to the Registration Statement and to the reference to me in the Prospectus Supplement constituting a part of the Registration Statement under the caption

“Legal Opinions.” In giving this consent, I do not thereby admit that I am in the category of persons whose consent is required under Section 7 of the Securities Act of 1933, as amended, or the rules and regulations of the Securities and Exchange Commission promulgated thereunder.

Exhibit 5.2

4000 One Williams Center

Tulsa, Oklahoma 74172

918.586.5711 Phone

918.586.8982 Fax

www.cwlaw.com

May 11, 2009

Steven J. Helmers, Esq.

General Counsel

Black Hills Corporation

625 Ninth Street

Rapid City, South Dakota 57701

Re: Black Hills Corporation

Registration Statement on Form S-3, as amended

File No. 333-150669 (the “Registration Statement”)

Dear Mr. Helmers:

You are acting as counsel for Black Hills Corporation, a South Dakota corporation (the “Company”), in connection with the preparation and filing of the Registration Statement and with respect to the issuance and sale by the Company of $250 million aggregate principal amount of 9% Notes due 2014 (the “Securities”) offered pursuant to that certain Prospectus Supplement dated May 11, 2009 (the “Prospectus Supplement”) and the accompanying Prospectus dated May 6, 2008. The Securities are to be issued under an Indenture, dated as of May 21, 2003, by and between the Company and Wells Fargo Bank, National Association, as successor Trustee (the “Trustee”), as supplemented by a First Supplemental Indenture, dated as of May 21, 2003, between the Company and the Trustee, and a Second Supplemental Indenture dated as of May 14, 2009, between the Company and the Trustee (collectively, the “Indenture”).

As such counsel, you are furnishing an opinion in accordance with the requirements of Item 601(b)(5) of Regulation S-K under the Securities Act of 1933, as amended (the “Act”). In connection with such opinion, you have asked us to opine with respect to certain matters governed by New York law.

In connection with this opinion, we have examined originals or copies, certified or otherwise identified to our satisfaction, of (i) the Company’s restated articles of incorporation and amended and restated bylaws dated January 30, 2009, (ii) the Registration Statement, and (iii) the Indenture. We have also examined originals or copies, certified or otherwise identified to our satisfaction, of such records of the Company and such agreements, certificates of public officials, certificates of officers or other representatives of the Company and others, and such other documents, certificates and records as we have deemed necessary or appropriate as a basis for the opinions set forth herein.

In our examination, we have assumed the legal capacity of all natural persons, the genuineness of all signatures, the authenticity of all documents submitted to us as originals, the conformity to original documents of all documents submitted to us as certified, conformed or photostatic copies and the authenticity of the originals of such latter documents. In making our examination of executed documents or documents to be executed, we have assumed that the parties thereto, including the Company, had or will have the power, corporate or other, to enter into and perform all obligations thereunder and have also assumed the due authorization by all requisite action, corporate or other, and execution and delivery by such parties of such documents, and, as to parties other than the Company, the validity and binding effect on such parties. We have also assumed that the Company has been duly organized and is validly existing in good standing under the laws of the State of South Dakota and that the Company has complied with all aspects of applicable laws of jurisdictions other than the United States of America and the State of New York

Steven J. Helmers, Esq.

May 11, 2009

Page 2

in connection with the transactions contemplated by the Indenture and the Registration Statement. We have also assumed that the choice of New York law to govern the Indenture is a valid and legal provision.

Our opinions set forth herein are limited to the laws of the State of New York that are normally applicable to transactions of the type contemplated by the Prospectus Supplement and to the extent that judicial or regulatory orders or decrees or consents, approvals, licenses, authorizations, validations, filings, recordings or registrations with governmental authorities are relevant, to those required under such laws (all of the foregoing being referred to as “Opined on Law”). We do not express any opinion with respect to the law of any jurisdiction other than Opined on Law or as to the effect of any such non opined law on the opinions herein stated.

Based upon and subject to the foregoing and the limitations, qualifications, exceptions and assumptions set forth herein, we are of the opinion that the Securities, when duly executed, delivered and paid for in accordance with the terms of that certain Underwriting Agreement dated May 11, 2009 (the “Underwriting Agreement”) by and among the Company and the Representatives (as defined in the Underwriting Agreement), will be legally issued and constitute valid and binding obligations of the Company, enforceable against the Company in accordance with their terms.

The opinion set forth above is subject to the following qualifications, further assumptions and limitations:

(a) the enforcement of any agreements or instruments may be limited by (1) bankruptcy, insolvency, reorganization, moratorium, fraudulent conveyance or other similar laws now or hereafter in effect relating to creditors’ rights generally and (2) general principles of equity (regardless of whether enforceability is considered in a proceeding at law or in equity); and

(b) we have assumed that the execution and delivery by the Company of the Indenture and the performance by the Company of its obligations thereunder do not and will not violate, conflict with or constitute a default under any agreement or instrument to which the Company or its properties is subject.

We understand that in relying on this opinion you may attach this opinion as an exhibit to the Registration Statement. We also consent to the reference to our firm under the caption “Legal Opinions” in the Prospectus Supplement. In giving this consent, we do not thereby admit that we are included in the category of persons whose consent is required under Section 7 of the Act or the rules and regulations of the Securities and Exchange Commission.

2

Exhibit 25

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C.  20549

FORM T-1

STATEMENT OF ELIGIBILITY

UNDER THE TRUST INDENTURE ACT OF 1939 OF A

CORPORATION DESIGNATED TO ACT AS TRUSTEE

o CHECK IF AN APPLICATION TO DETERMINE ELIGIBILITY OF A TRUSTEE PURSUANT TO SECTION 305(b)(2)

WELLS FARGO BANK, NATIONAL ASSOCIATION

(Exact name of trustee as specified in its charter)

Wells Fargo & Company
Law Department, Trust Section

MAC N9305-175

Sixth Street and Marquette Avenue, 17th Floor

Minneapolis, Minnesota 55479

(612) 667-4608

(Name, address and telephone number of agent for service)

Black Hills Corporation

(Exact name of obligor as specified in its charter)

625 Ninth Street
Rapid City, South Dakota 87701

TELEPHONE:  (605)  721-1700
 (Address, Including Zip Code, and Telephone Number, Including Area

Code, of Registrant’s Principal Executive Offices)

9% Notes due 2014

Item 1.    General Information.  Furnish the following information as to the trustee:

(a)                                  Name and address of each examining or supervising authority to which it is subject.

                                                Comptroller of the Currency

                                                Treasury Department

                                                Washington, D.C.

                                                Federal Deposit Insurance Corporation

                                                Washington, D.C.

                                                Federal Reserve Bank of San Francisco

                                                San Francisco, California 94120

(b)                                 Whether it is authorized to exercise corporate trust powers.

                                                The trustee is authorized to exercise corporate trust powers.

Item 2.             Affiliations with Obligor.  If the obligor is an affiliate of the trustee, describe each such affiliation.

None with respect to the trustee.

No responses are included for Items 3-14 of this Form T-1 because the obligor is not in default as provided under Item 13.

Item 15.  Foreign Trustee.                   Not applicable.

Item 16.  List of Exhibits.                                                               List below all exhibits filed as a part of this Statement of Eligibility.

Exhibit 1.                                                A copy of the Articles of Association of the trustee now in effect.*

Exhibit 2.                                                A copy of the Comptroller of the Currency Certificate of Corporate Existence and Fiduciary
                Powers for Wells Fargo Bank, National Association, dated February 4, 2004.**

Exhibit 3.                                                See Exhibit 2

Exhibit 4.                                                Copy of By-laws of the trustee as now in effect.***

Exhibit 5.                                                Not applicable.

Exhibit 6.                                                The consent of the trustee required by Section 321(b) of the Act.

Exhibit 7.                                             A copy of the latest report of condition of the trustee published pursuant to law or the requirements of its supervising or examining authority.

Exhibit 8.                                                Not applicable.

Exhibit 9.                                                Not applicable.

*      Incorporated by reference to the exhibit of the same number to the trustee’s Form T-1 filed as exhibit 25 to the Form S-4 dated December 30, 2005 of Hornbeck Offshore Services LLC file number 333-130784-06.

**   Incorporated by reference to the exhibit of the same number to the trustee’s Form T-1 filed as exhibit 25 to the Form T-3 dated March 3, 2004 of Trans-Lux Corporation file number 022-28721.

*** Incorporated by reference to the exhibit of the same number to the trustee’s Form T-1 filed as exhibit 25 to the Form S-4 dated May 26, 2005 of Penn National Gaming Inc. file number 333-125274.

SIGNATURE

Pursuant to the requirements of the Trust Indenture Act of 1939, as amended, the trustee, Wells Fargo Bank, National Association, a national banking association organized and existing under the laws of the United States of America, has duly caused this statement of eligibility to be signed on its behalf by the undersigned, thereunto duly authorized, all in the City of Fort Worth and State of Texas on the 29th day of April, 2009.

EXHIBIT 6

April 29, 2009

Securities and Exchange Commission

Washington, D.C.  20549

Gentlemen:

In accordance with Section 321(b) of the Trust Indenture Act of 1939, as amended, the undersigned hereby consents that reports of examination of the undersigned made by Federal, State, Territorial, or District authorities authorized to make such examination may be furnished by such authorities to the Securities and Exchange Commission upon its request thereof.

Consolidated Report of Condition of

Wells Fargo Bank National Association

of 101 North Phillips Avenue, Sioux Falls, SD 57104

And Foreign and Domestic Subsidiaries,

at the close of business December 31, 2008, filed in accordance with 12 U.S.C. §161 for National Banks.

I, Howard I. Atkins, EVP & CFO of the above-named bank do hereby declare that this Report of Condition has been prepared in conformance with the instructions issued by the appropriate Federal regulatory authority and is true to the best of my knowledge and belief.

Howard I. Atkins

EVP & CFO

We, the undersigned directors, attest to the correctness of this Report of Condition and declare that it has been examined by us and to the best of our knowledge and belief has been prepared in conformance with the instructions issued by the appropriate Federal regulatory authority and is true and correct.

Exhibit 99

BLACK HILLS CORP. ANNOUNCES PRICING OF $250 MILLION OF SENIOR NOTES

RAPID CITY, SD — May 11, 2009 — Black Hills Corp. (NYSE: BKH) today announced it has priced a public debt offering of $250 million aggregate principal amount of senior unsecured notes due 2014.  The notes were priced at par and will carry an interest rate of 9 percent.  Black Hills expects the issuance and delivery to occur on May 14, 2009, subject to customary closing conditions.

Black Hills Corp. plans to use the proceeds to pay down a portion of the $353 million of borrowings on the bridge acquisition facility established to fund the July 14, 2008 purchase of five natural gas and electric utility properties from Aquila, Inc.  The company originally drew $383 million on the facility to complete the acquisition, financing the balance of the purchase with cash proceeds from the divestiture of seven independent power production facilities.  To provide additional flexibility to complete its long-term replacement financing, on Dec. 18, 2008 the company extended the bridge acquisition facility from a Feb. 5, 2009 maturity date to a Dec. 29, 2009 maturity date.  Last month, the company used proceeds of $30.2 million from the sale of a 25 percent ownership interest in its Wygen III power plant to pay down a portion of the bridge acquisition facility.

“We are pleased with the market response to our debt offering, which allowed us to achieve a more favorable rate than was available in either the fourth quarter of 2008 or the first quarter of 2009,” said David R. Emery, chairman, president and chief executive officer of Black Hills Corp.  “By reducing the remaining acquisition facility debt to approximately $105 million, we have ample flexibility to refinance the remainder during 2009.  Our current cash and revolver availability now exceeds $450 million.”

The senior notes were offered by Black Hills Corp. pursuant to a shelf registration statement filed on May 6, 2008 with the U.S Securities and Exchange Commission.  Credit Suisse and Royal Bank of Scotland served as joint book-running managers for the offering and BMO Nesbitt Burns, Scotia Capital (USA), and Wedbush Morgan Securities served as senior co-managers.  U.S. Bancorp Investments, Wells Fargo Securities, and The Williams Capital Group served as co-managers.

Copies of the prospectus supplement relating to the offering may be obtained from the offices of Credit Suisse by writing to the Credit Suisse Securities (USA) LLC Prospectus Department, Eleven Madison Avenue, Level 1B, New York, NY 10010 or by calling 1-800-221-1037.  An electronic copy of the prospectus supplement is available on the website of the Securities and Exchange Commission at www.sec.gov.

This news release by Black Hills Corp. shall not constitute an offer to sell or the solicitation of an offer to buy nor shall there be any sale of these securities in any jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of such jurisdiction.

ABOUT BLACK HILLS CORP.

Black Hills Corp. — a diversified energy company with a tradition of exemplary service and a vision to be the energy partner of choice — is based in Rapid City, S.D., with corporate offices in Golden, Colo., and Omaha, Neb.  The company serves 759,000 utility customers in Colorado, Iowa, Kansas, Montana, Nebraska, South Dakota and Wyoming.  The company’s non-regulated businesses generate wholesale electricity, produce natural gas, oil and coal, and market energy.  Black Hills employees partner to produce results that improve life with energy.

CAUTION REGARDING FORWARD-LOOKING STATEMENTS

This news release includes “forward-looking statements” as defined by the Securities and Exchange Commission, or SEC.  We make these forward-looking statements in reliance on the safe harbor protections provided under the Private Securities Litigation Reform Act of 1995.  All statements, other than statements of historical facts, included in this news release that address activities, events or developments that we expect, believe or anticipate will or may occur in the future are forward-looking statements.  These forward-looking statements are based on assumptions which we believe are reasonable based on current expectations and projections about future events and industry conditions and trends affecting our business.  However, whether actual results and developments will conform to our expectations and predictions is subject to a number of risks and uncertainties that, among other things, could cause actual results to differ materially from those contained in the forward-looking statements, including the risk factors described in Item 1A of Part I of our 2008 Annual Report on Form 10-K filed with the SEC, and other reports that we file with the SEC from time to time.

New factors that could cause actual results to differ materially from those described in forward-looking statements emerge from time-to-time, and it is not possible for us to predict all such factors, or the extent to which any such factor or combination of factors may cause actual results to differ from those contained in any forward-looking statement.  We assume no obligation to update publicly any such forward-looking statements, whether as a result of new information, future events or otherwise.