Exhibit 10.1

                             BLACK HILLS POWER, INC.



                                       TO



                              JPMORGAN CHASE BANK,



                                   As Trustee



                          ----------------------------



                          FIRST SUPPLEMENTAL INDENTURE



                           Dated as of August 13, 2002



                          ----------------------------


Supplemental to Restated and Amended
Indenture of Mortgage and Deed of Trust
Dated as of September 1, 1999



First Mortgage Bonds, 7.23%
Series AE Due 2032



                  FIRST SUPPLEMENTAL INDENTURE, dated as of the 13 `h day of
August, 2002, between Black Hills Power, Inc., a corporation duly organized and
existing under the laws of the State of South Dakota (formerly known as Black
Hills Corporation) (hereinafter called the "Company"), party of the first part,
and JPMORGAN CHASE BANK, a corporation organized and existing under the laws of
the State of New York, as Trustee under the Indenture hereinafter mentioned
(hereinafter called the "Trustee"), party of the second part.

                  WHEREAS, in order to secure an authorized issue of First
Mortgage Bonds of the Company, the Company has executed and delivered a Restated
and Amended Indenture of Mortgage and Deed of Trust to JPMorgan Chase Bank f/k/a
The Chase Manhattan Bank, as Trustee, dated as of September 1, 1999 (hereinafter
referred to as the "Indenture"), which amended and restated the Indenture of
Mortgage and Deed of Trust to Central Hanover Bank and Trust Company (the
successor by various mergers of which is JPMorgan Chase Bank) hereinafter
referred to as the "Original Indenture."

                  WHEREAS, pursuant to the provisions of the Indenture, First
Mortgage Bonds have been duly issued under the Original Indenture and are
presently outstanding and continue to be secured by the Indenture as follows:

                                                      Principal Amount
              Series                                     Outstanding

Series Y, 9.49%, due June 15, 2018                        $4,550,000
Series Z, 9.35%, due May 29, 2021                         31,635,000
Series AA, 9.00%, due September 1, 2003                    1,650,904
Series AB, 8.30%, due September 1, 2024                   45,000,000
Series AC, 8.06%, due February 1, 2010                    30,000,000
                                                          ----------
                                                        $112,835,904

                  and

                  WHEREAS, as permitted by the Indenture, the Company, by
resolutions of its Board of Directors duly adopted, has determined to create a
new series of bonds to be known as its "First Mortgage Bonds, 7.23% Series AE
Due 2032" (herein called the "Series AE Bonds"), to be initially authenticated
and delivered in the aggregate principal amount of $75,000,000 in the form,
having the characteristics and being entitled to the benefits as in the
Indenture or as in this Supplemental Indenture provided; and

                  WHEREAS, the Company, in exercise of the powers and authority
conferred upon and reserved to it under and by virtue of the provisions of the
Indenture, and particularly the provisions contained in Articles Two and Sixteen
thereof, and pursuant to appropriate resolutions of its Board of Directors, has
duly resolved and determined to make, execute and deliver to the Trustee a First
Supplemental Indenture in the form hereof (herein sometimes referred to as "this
Supplemental Indenture") for the purposes herein provided; and

                  WHEREAS, all conditions and requirements necessary to make
this Supplemental Indenture a valid, binding and legal instrument in accordance
with its terms have been done,

                                        1


performed and fulfilled, and the execution and delivery hereof have been in
all respects duly authorized;

                  NOW THEREFORE, in consideration of the premises and of one
dollar to it duly paid by the Trustee at or before the ensealing and delivery of
these presents, the receipt whereof is hereby acknowledged, and of other good
and valuable consideration, in order to establish the terms of the Series AE
Bonds, the Company hereby further covenants and agrees to and with the Trustee
and its successors in the trust under the Indenture for the benefit of all those
who shall from time to time hold the Series AE Bonds as follows:

                  The Company does hereby ratify and confirm its Mortgage and
Pledge to the Trustee of all property described in the Indenture and does hereby
grant, bargain, sell, release, convey, assign, transfer, mortgage, pledge and
set over unto the Trustee, and to its successors and assigns forever, the
following described property acquired by the Company and not specifically
described under the Indenture which following described property shall be
incorporated into the terms of Exhibit A to the Indenture as if more fully set
forth therein:

                       LANDS IN BUTTE COUNTY, SOUTH DAKOTA

1.   Tracts C, D and E of the  Southeast  Quarter  (SE1/4) of Section  Ten (10),
     Township Eight (8) North, Range Two (2) East of the Black Hills Meridian in
     the City of Belle Fourche, Butte County, South Dakota, as shown by the Plat
     recorded in Plat Book 5, Page 18, excepting  therefrom that part of Tract C
     and Tract D deeded to Floyd  Cooper,  in instrument  recorded  December 22,
     1949,  in Book 137,  Page 137; and also  excepting  therefrom  that part of
     Tract C  deeded  to  Albert  W.  Turbiville  and  Alice L.  Turbiville,  in
     instrument  recorded  October 24,  1961 in Book 156,  Page 585 of the Butte
     County real estate records.

                       LANDS IN MEADE COUNTY, SOUTH DAKOTA

1.   Lots Twenty-seven (27), Twenty-eight (28), Twenty-nine (29), and Thirty
     (30), in Block Four of Fort Meade Addition to Sturgis, in the County of
     Meade and State of South Dakota.

2.   A parcel of land approximately 3.08 acres known as the BHP&L Utility Lot
     formerly a portion of lot four (4) of the Northeast Quarter of the
     Southeast Quarter (SE 1/4) of Section Thirty-six (36), Township Five (5)
     North, Range Five (5) East of the Black Hills Meridian, in Meade County,
     South Dakota.

3.   Plat of Piedmont Valley Substation Lot being a portion of Lot Eight (8),
     Block One (1), Coopers Subdivision located in the Northwest Quarter of the
     Northeast Quarter (NW 1/4NE1/4), Section Fifteen (15), Township Three (3)
     North, Range Six (6) East of the Black Hills Meridian, in Meade County,
     South Dakota.


                                        2


                         LANDS IN PENNINGTON COUNTY, SOUTH DAKOTA

1.   A Forty (40) acre parcel described as the Southwest Quarter of the
     Southwest Quarter (SW 1ASW1/4) of Section Twenty-four (24), in Township One
     (1) North, Range Seven (7) East of the Black Hills Meridian in Pennington
     County, South Dakota excepting therefrom Highway 16 Bypass and also
     excepting therefrom Lot H 1 as shown on the plat filed in Highway Plat Book
     6, Page 22 of the Pennington County real estate records.

2.   Lot Two (2) in Prairie Hills Subdivision, Rapid City, located in the
     Southwest Quarter of the Southwest Quarter (SW 1/4SW 1/4) of Section
     Nineteen (19), Township Two (2) North, Range Eight (8) East of the Black
     Hills Meridian, Pennington County, South Dakota.


                                   ARTICLE ONE

                                   DEFINITIONS

         SECTION 1.01. General. For all purposes of this Supplemental Indenture:

          (a) capitalized  terms used herein without  definition  shall have the
     meanings specified in the Indenture;

          (b) all references herein to Articles and Sections, unless otherwise
     specified, refer to the corresponding Articles and Sections of this
     Supplemental Indenture;

          (c) the terms  "herein,"  "hereof,"  "hereunder"  and  other  words of
     similar import refer to this Supplemental Indenture; and

          (d) in the event of a conflict between any definition set forth in the
     Indenture and any definition set forth in this Supplemental Indenture, the
     definition set forth in this Supplemental Indenture shall control.

          SECTION 1.02.  Definitions.  The following  definitions shall apply to
     this Supplemental Indenture:

          "Business Day" means any day other than a Saturday or Sunday and other
     than a day on which banking institutions in Rapid City, South Dakota, or
     New York, New York, are authorized or obligated by law or executive order
     to close.

          "Comparable Treasury Issue" means the United States Treasury security
     selected by an Independent Investment Banker as having a maturity
     comparable to the remaining term of the Series AE Bonds to be redeemed 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 Series AE
     Bonds.


                                        3


          "Comparable Treasury Price" means the average of two Reference
     Treasury Dealer Quotations obtained with respect to any redemption date.

          "Depository" means The Depository Trust Company, a New York
     corporation, or any successor thereto.

          "Global Bond" shall have the meaning set forth in Section 2.05(a).
     "Independent Investment Banker" means ABN AMRO Incorporated or one of the
     Reference Treasury Dealers appointed by the Trustee after consultation with
     the Company.

          "Reference Treasury Dealer" means ABN AMRO Incorporated and its
     successors; provided, however, that if ABN AMRO Incorporated or its
     successors shall cease to be a primary United States government securities
     dealer (a "Primary Treasury Dealer"), the Company will substitute for it
     another nationally recognized investment bank that is a Primary Treasury
     Dealer.

          "Reference Treasury Dealer Quotations" means, with respect to each
     Reference Treasury Dealer and any redemption date, the average, as
     determined by the Independent Investment Banker, 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 Independent
     Investment Banker at 5:00 p.m., New York City time, on the third Business
     Day preceding such redemption date.

          "Treasury Rate" means, for 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 maturity is within three months before or after the remaining
     term of the Series AE Bonds, yields for the two published maturities most
     closely corresponding to the Comparable Treasury Issue shall be determined
     and the 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 annum equal to the semiannual 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. The Treasury Rate shall be calculated on the
     third Business Day preceding the redemption date.


                                        4


                                   ARTICLE TWO

                     TERMS AND CONDITIONS OF SERIES AE BONDS

     SECTION 2.01. General.

          (a) There is hereby created a series of Bonds, known as and entitled
     "First Mortgage Bonds, 7.23% Series AE Due 2032," and the form thereof
     shall be as provided in this Supplemental Indenture.

          (b) The aggregate principal amount of Series AE Bonds which may be
     authenticated and delivered and outstanding under the Indenture and this
     Supplemental Indenture shall be limited in aggregate principal amount to
     $75,000,000, except as provided under Section 2.02 of the Indenture. The
     Series AE Bonds shall bear interest at the rate of 7.23% per annum until
     the principal thereof becomes due and payable and shall bear interest on
     overdue principal (including any overdue mandatory prepayment of principal)
     and premium, if any, and (to the extent legally enforceable) on any overdue
     installment of interest at the rate of 8.23% per annum until such overdue
     principal, premium or interest shall be paid. The Series AE Bonds shall
     mature August 15, 2032.

          (c) The Series AE Bonds shall be registered Bonds without coupons in
     denominations of $100,000 and any multiples of $1,000 which may be executed
     by the Company and delivered to the Trustee for authentication and
     delivery. The date of commencement of the first interest period for the
     Series AE Bonds shall be the date of initial authentication and delivery
     thereof. The Series AE Bonds shall be dated as provided in Section 2.06 of
     the Indenture. All Series AE Bonds shall bear interest from their
     respective issue dates. The principal and interest shall be due and payable
     as provided in the Bond form set forth in Section 2.02 of this Supplemental
     Indenture. The principal of, premium, if any, and interest on the Series AE
     Bonds shall be payable at the principal corporate trust office of the
     Trustee, in the Borough of Manhattan, The City of New York, in any coin or
     currency of the United States of America which at the time of payment shall
     be legal tender for the payment of public and private debts. The Series AE
     Bonds shall be subject to redemption only as provided in Section 2.03 of
     this Supplemental Indenture and Section 8.08 of the Indenture.

          (d) Without limiting the other indemnities provided to the Trustee,
     the Company shall indemnify and save the Trustee harmless from any
     liabilities and costs incurred by the Trustee arising out of the making of
     the final payment when due of the principal owing on any of the Series AE
     Bonds without the surrender of such Bond to the Trustee.

          (e) The Trustee is hereby appointed Registrar in respect of the Series
     AE Bonds, and the principal corporate trust office of the Trustee in the
     Borough of Manhattan, The City of New York, is hereby designated as the
     office or agency of the Company in said Borough where notices or demands in
     respect of Series AE Bonds may be served.


                                        5


     SECTION  2.02.  Form of Bonds.  The text of the  Series  AE Bonds,  and the
certificate of authentication  of the Trustee to be executed thereon,  are to be
substantially in the following forms, respectively:

                              [FORM OF GLOBAL BOND]

     Unless this Bond is presented by an authorized representative of The
Depository Trust Company, a New York corporation ("DTC"), to the issuer or its
agent for registration of transfer, exchange or payment, and any Bond 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.

     Unless and until it is exchanged in whole or in part for Bonds in
definitive registered form, this Bond may not be transferred except as a whole
by the Depositary to the nominee of the Depositary or by a nominee of the
Depositary to the Depositary or another nominee of the Depositary or by the
Depositary or any such nominee to a successor Depositary or a nominee of such
successor Depositary.



No.___________________                                  $______________________
CUSIP No. 092114 AA 5

                             BLACK HILLS POWER, INC.

                           FIRST MORTGAGE BOND, 7.23%
                               SERIES AE DUE 2032

     BLACK HILLS POWER, INC. (hereinafter called the "Company"), a corporation
organized and existing under the laws of the State of South Dakota, for value
received, hereby promises to pay to , or registered assigns, on the 15th day of
August, 2032, at the principal corporate trust office of the Trustee, in the
Borough of Manhattan, The City of New York, Dollars, in any coin or currency of
the United States of America which at the time of payment shall be legal tender
for the payment of public and private debts, and to pay interest thereon from
the date hereof, at the rate of 7.23 percent, per annum (computed on the basis
of a 360-day year of 12 thirty-day months), payable at said principal office of
the Trustee in like coin or currency semi-annually on February 15 and August 15
in each year until the principal hereof shall have become due and payable, and
thereafter if default be made in the payment of such principal and premium, if
any, and on any overdue installment of interest, at the rate of 8.23 percent,
per annum until the overdue principal, premium or interest shall be paid.


                                        6


     This Bond shall not be valid or become obligatory for any purpose until the
certificate of authentication hereon shall have been signed by the Trustee, or
its successor as Trustee, under the Indenture.

     This Bond is one of an authorized issue of Bonds of the Company known as
its "First Mortgage Bonds," issued and to be issued in one or more series under,
and all equally and ratably secured (except as any sinking, amortization,
improvement, renewal or other analogous fund, established in accordance with the
provisions of the Indenture hereinafter mentioned, may afford additional
security for the Bonds of any particular series) by a Restated and Amended
Indenture of Mortgage and Deed of Trust, dated as of September 1, 1999, executed
by the Company to JPMorgan Chase Bank f/k/a The Chase Manhattan Bank, as
Trustee, as supplemented and amended by a First Supplemental Indenture, dated
August 13, 2002 (said Restated Indenture as so supplemented and amended being
hereinafter collectively called the "Indenture"), to which Indenture and all
further instruments supplemental thereto reference is hereby made for a
description of the properties mortgaged and pledged, the nature and extent of
the security, the rights of the holders of said Bonds and the coupons
appurtenant to coupon Bonds, if any, and of the Trustee and of the Company in
respect of such security, and the terms and conditions upon which said Bonds are
and are to be issued and secured.

     To the extent permitted by the Indenture and as provided therein, with the
consent of the Company and upon the written consent or affirmative vote of at
least sixty-six and twothirds percent in principal amount of the Bonds then
outstanding and entitled to consent, and of not less than sixty-six and two-
third percent, in principal amount of the Bonds then outstanding and entitled to
consent of each series affected thereby in case one or more but less than all of
the series of Bonds issued under the Indenture are so affected, the rights and
obligations of the Company and of the holders of Bonds and coupons appurtenant
to coupon Bonds, if any, and the terms and provisions of the Indenture and of
any instrument supplemental thereto may be modified from time to time, provided
that no such modification or alteration shall be made which would postpone the
date fixed herein or in the Indenture for the payment of the principal of, or
any installment of interest on, the Bonds, or reduce the principal of, or the
rate of interest payable on, the Bonds, or reduce the percentage of the
principal amount of Bonds the consent of which is required for the authorization
of any such modification or alteration, without the consent of all of the
holders affected thereby. The rights, duties or immunities of the Trustee shall
not be modified without the written consent of the Trustee.

     As provided in the Indenture, said Bonds are issuable in series which may
vary as in the Indenture provided or permitted. This Bond is one of a series of
Bonds authorized by the First Supplemental Indenture and entitled "First
Mortgage Bonds, 7.23% Series AE Due 2032" (the "Series AE Bonds").

     Pursuant to the provisions of Section 8.05 of the Indenture, the Company
may request the Trustee to apply moneys deposited with the Trustee ("Trust
Moneys") for various reasons toward the redemption of those Bonds, including
payment of premium and accrued interest, selected by the Company. In the First
Supplemental Indenture, the Company has covenanted that the Bonds may only be
called for redemption by 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) 100% of the
principal amount of Series AE Bonds to be redeemed or (ii) the sum of the
present values of the


                                        7


remaining scheduled payments of principal and interest thereon (exclusive of
interest accrued to the date of redemption) discounted, at the then current
Treasury Rate (as defined in the Supplemental Indenture) plus 30 basis points,
to the date of redemption on a semiannual basis (assuming a 360-day year
consisting of twelve 30-day months) plus in each case, accrued and unpaid
interest on the principal amount being redeemed to the date of redemption.

     Notice of each redemption shall be mailed to all registered owners not less
than thirty nor more than forty-five days before the redemption date.

     Pursuant to the provisions of Section 8.08 of the Indenture, the Series AE
Bonds are further subject to redemption, in whole or in part, by the Trustee
applying certain Trust Moneys which have been held by the Trustee for a period
of over two years. Any such redemption is made pro rata among the series of
Bonds then outstanding in the ratio of principal amount. Redemption is at 100
percent of principal, plus any premium due at the time of redemption and accrued
interest to the redemption date.

     If this Bond or any portion thereof ($1,000 or a multiple) shall be duly
called for redemption as provided in the Indenture, this Bond or such portion
thereof shall (unless the Company shall default in the payment of the redemption
price) cease to bear interest from and after the date fixed for redemption.

     Upon any partial redemption of this Bond, this Bond may, at the option of
the registered holder hereof, be either (a) surrendered to the Trustee in
exchange for one or more new Series AE Bonds for the principal amount of the
unredeemed portion of this Bond or (b) submitted to the Trustee for notation
hereon by the Trustee of the payment of the portion of the principal hereof so
called for redemption.

     If an Event of Default, as defined in the Indenture, shall occur, the
principal of this Bond may become or be declared due and payable, in the manner
and with the effect provided in the Indenture.

     A certificate in global form representing all of a portion of the Bonds may
not be transferred except as a whole by the Depositary for such series to a
nominee of such Depositary or by a nominee of such Depositary to such Depositary
or another nominee of such Depositary or by such Depositary or any such nominee
to a successor Depositary for such Bonds or a nominee of such successor
Depositary.

     The Series AE Bonds are issuable as fully registered Bonds without coupons
of the denominations of $100,000 and any multiple of $1,000 which may be
executed by the Company and delivered to the Trustee for authentication and
delivery. The Series AE Bonds, upon surrender thereof to the Trustee at its
principal corporate trust office in the Borough of Manhattan, The City of New
York, are exchangeable for other Bonds of the same series in such authorized
denomination or denominations in the same aggregate principal amount, as may be
requested by the holders surrendering the same.

     The Company and the Trustee may deem and treat the person in whose name
this Bond is registered as the absolute owner hereof, for the purpose of
receiving payment of or on account of the principal hereof and interest due
hereon, and neither the Company nor the Trustee

                                        8


shall be affected by any notice to the contrary. Interest payable herein shall
be paid to the person in whose name the Bond is registered at the close of
business on February 1 or August 1 (whether or not on a business day) next
preceding the interest payment date, except for defaulted interest and unmatured
accrued interest on the Series AE Bonds called for redemption on a date other
than an interest payment date.

     No recourse shall be had for the payment of the principal of or the
interest on this Bond, or for any claim based hereon or otherwise in respect
hereof or of the Indenture or of any indenture supplemental thereto, against any
incorporator, stockholder, director or officer, as such, past, present or
future, of the Company or of any predecessor or successor corporation, either
directly or through the Company or any predecessor or successor corporation,
whether by virtue of any constitution, statute or rule of law, or by the
enforcement of any assessment or penalty or by any legal or equitable proceeding
or otherwise howsoever; all such liability being, by the acceptance hereof and
as a part of the consideration for the issuance hereof, expressly waived and
released by every holder hereof, as more fully provided in the Indenture;
provided, however, that nothing herein or in the Indenture contained shall be
taken to prevent recourse to and the enforcement of the liability, if any, of
any shareholder or any stockholder or subscriber to capital stock upon or in
respect of shares of capital stock not fully paid up.

     IN WITNESS WHEREOF, the Company has caused this Bond to be signed in its
name by its President or one of its Vice Presidents, and its corporate seal to
be impressed or imprinted hereon and attested by its Secretary or one of its
Assistant Secretaries.

                Dated:

                                    BLACK HILLS POWER, INC.


                                    By:__________________________________
                                      Name:
                                     Title:

ATTEST:


- -----------------------------------
Secretary


                                        9



                (FORM OF TRUSTEE'S CERTIFICATE OF AUTHENTICATION)

     This is one of the Bonds, of the series designated therein, described in
the within mentioned Indenture.


                                        JPMORGAN CHASE BANK, as Trustee


                                        By:__________________________________
                                           Authorized Officer


     SECTION 2.03. Optional Redemption.

          (a) Notwithstanding the provisions of Section 8.05 of the Indenture,
     the Series AE Bonds, upon the mailing of notice and in the manner provided
     in Section 10.03 of the Indenture, 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) 100% of the principal amount
     of Series AE Bonds to be redeemed or (ii) the sum of the present values of
     the remaining scheduled payments of principal and interest thereon
     (exclusive of interest accrued to the date of redemption) discounted, at
     the then current Treasury Rate plus 30 basis points, to the date of
     redemption on a semiannual basis (assuming a 360-day year consisting of
     twelve 30-day months) plus in each case, accrued and unpaid interest on the
     principal amount being redeemed to the date of redemption.

          (b) Notwithstanding the provisions of Section 10.03 of the Indenture,
     in case of the redemption at any time of less than all the outstanding
     Series AE Bonds, the particular Bonds or parts thereof to be redeemed shall
     be selected by the Trustee from the outstanding Series AE Bonds not
     previously called for redemption as nearly as practicable pro rata among
     the registered holders of the Series AE Bonds according to the respective
     principal amounts of such Bonds, provided that the portions of the
     principal of Series AE Bonds at any time so selected for redemption in part
     shall be equal to $1,000 or a multiple thereof. (c) Notwithstanding that
     Section 8.05 of the Indenture authorizes the Company to request the Trustee
     to apply Trust Moneys toward the redemption of Bonds to be selected by the
     Company, the Company does hereby covenant that the Company will not request
     the Trustee to apply any Trust Moneys to the redemption of the Series AE
     Bonds except pursuant to Section 2.03(a) of this Supplemental Indenture.

     SECTION 2.04. No Sinking Fund.  The Series AE Bonds are not entitled to the
benefit of any sinking fund.


                                       10


     SECTION 2.05. Bonds to be Issued in Global Form.

          (a) The Series AE Bonds will be initially represented by one or more
     Bonds in global form (the "Global Bonds"). The Company hereby designates
     The Depository Trust Company as the initial Depositary for the Global
     Bonds. The Global Bonds will be deposited with the Trustee, as custodian
     for the Depositary. Unless and until it is exchanged in whole or in part
     for Bonds in certificated form, the Global Bonds may not be transferred
     except as a whole by the Depositary to a nominee of the Depositary or by a
     nominee of the Depositary to the Depositary or another nominee of the
     Depositary or by the Depositary or any such nominee to a successor
     Depositary for the Bonds or a nominee of such successor Depositary. The
     Depositary may surrender the Global Bonds in exchange in whole or in part
     for Bonds in certificated form on such terms as are acceptable to the
     Company and the Depositary.

          (b) If at any time the Depositary for the Global Bonds notifies the
     Company that it is unwilling or unable to continue as Depositary for such
     Global Bonds or if at any time the Depositary for the Series AE Bonds shall
     no longer be eligible or in good standing under the Securities Exchange Act
     of 1934, as amended, or other applicable statute or regulation, the Company
     shall appoint a successor Depositary with respect to such Global Bonds. If
     a successor Depositary for such Global Bonds is not appointed by the
     Company within 90 days after the Company receives notice or becomes aware
     of such ineligibility, the Series AE Bonds shall no longer be represented
     by Global Bonds and, subject to Section 2.07 of the Indenture, the Company
     will execute, and the Trustee, upon receipt of a Written Order of the
     Company for the authentication and delivery of individual Bonds in exchange
     for such Global Bonds, will authenticate and deliver individual Bonds of
     like tenor and terms in definitive form in an aggregate principal amount
     equal to the principal amount of such Global Bonds in exchange for such
     Global Bonds.

          (c) The Company may at any time and in its sole discretion determine
     that the Series AE Bonds issued or issuable in the form of one or more
     Global Bonds shall no longer be represented by such Global Bond or Bonds.
     In such event, subject to Section 2.07 of the Indenture, the Company will
     execute, and the Trustee, upon receipt of a Written Order of the Company
     for the authentication and delivery of individual Bonds in exchange in
     whole or in part for such Global Bonds, will authenticate and deliver
     individual Bonds of like tenor and terms in definitive form in an aggregate
     principal amount equal to the principal amount of such Global Bonds in
     exchange for such Global Bonds.

          (d) In any exchange provided for in Section 2.05(b) or (c), the
     Company will execute and the Trustee will authenticate and deliver
     individual Bonds in definitive registered form in authorized denominations.
     Upon the exchange of Global Bonds for individual Bonds, such Global Bonds
     shall be canceled by the Trustee. Series AE Bonds issued in exchange for
     Global Bonds pursuant to this Section 2.05 shall be registered in such
     names and in such authorized denominations as the Depositary for such
     Global Bonds, pursuant to instructions from its direct or indirect
     participants or otherwise, shall instruct the Trustee. The Trustee shall
     deliver such Bonds to the Persons in whose names such Bonds are so
     registered.


                                       11


                                  ARTICLE THREE

                                  MISCELLANEOUS

     SECTION 3.01. Outstanding Bonds. The aggregate principal amount of Bonds
which, immediately after the authentication and delivery of the Series AE Bonds
to be issued under this Supplemental Indenture, will be outstanding under the
provisions of, and secured by, the Indenture, as amended by this Supplemental
Indenture, will be $187,835,904, consisting of the Bonds of Series Y, Z, AA, AB
and AC hereinbefore set forth in the second recital of this Supplemental
Indenture and $75,000,000 aggregate principal amount of Series AE Bonds hereby
created.

     SECTION  3.02.  Receipt of  Supplemental  Indenture.  The  Company,  by the
execution hereof,  acknowledges that a true copy of this Supplemental  Indenture
has been delivered to and received by it.

     SECTION 3.03. Ratification of Indenture. Except as amended by this
Supplemental Indenture, all the provisions, terms and conditions of the
Indenture shall continue in full force and effect. The Company does hereby
ratify and confirm its mortgage and pledge to the Trustee of that property,
real, personal and mixed described in the Indenture as being subject to the Lien
of the Indenture.

     SECTION 3.04. Sufficiency of Supplemental  Indenture.  The Trustee makes no
representation as to the validity or sufficiency of this Supplemental Indenture.

     SECTION 3.05. Counterparts.  This Supplemental Indenture may be executed in
several counterparts, all or any of which may be treated for all purposes as one
original and shall constitute and be one and the same instrument.

     SECTION 3.06. Governing Law. This Supplemental Indenture and each Series AE
Bond shall be governed by and construed in accordance with the laws of the State
of South Dakota without regard to the choice of law principles thereof.
Notwithstanding the foregoing, the immunities and standard of care of the
Trustee, Registrar and paying agent in connection with the administration of
trusts and duties hereunder shall be governed by and construed in accordance
with the laws of the State of New York.


                                       12


     IN WITNESS WHEREOF, BLACK HILLS POWER, INC., party hereto of the first
part, has caused this Supplemental Indenture to be executed on its behalf by its
Chairman of the Board or its President or one of its Vice Presidents and its
corporate seal to be hereto affixed and to be attested by its Secretary or an
Assistant Secretary, and JPMORGAN CHASE BANK, party hereto of the second part,
in evidence of its acceptance of the trust hereby created, has caused this
Supplemental Indenture to be executed on its behalf by one of its Vice
Presidents or Assistant Vice Presidents and its corporate seal to be hereto
affixed and to be attested by a Trust Officer, all as of the day and year first
above written.

                                            BLACK HILLS POWER, INC.


                                            By:________________________________
                                               Name:
                                               Title:

ATTEST:



- -------------------------------------
Secretary

Signed, sealed and delivered by
BLACK HILLS POWER, INC.
in the presence of:

- -------------------------------------

- -------------------------------------

                                            JPMORGAN CHASE BANK, as Trustee


                                            By:________________________________
                                               Name:
                                               Title:

ATTEST:



- -------------------------------------
Trust Officer

Signed, sealed and delivered by JPMORGAN CHASE BANK, as Trustee in the presence
of:

- -------------------------------------

- -------------------------------------


                                       13


STATE OF SOUTH DAKOTA           )
                                )SS.:
COUNTY OF PENNINGTON            )


     On this 12th day of August, 2002, before me, Karen R. Tucker, the
undersigned officer, personally appeared Everett E. Hoyt, to me personally
known, who acknowledged himself to be, and being by me duly sworn, did say that
he is President of BLACK HILLS POWER, INC., a corporation, and that the seal
affixed to the foregoing instrument is the corporate seal of said corporation
and that said instrument was executed by, and signed in the name of, the
corporation, by him, as such President and sealed on behalf of the corporation
by authority of its Board of Directors for the purposes therein contained, and
the said Everett E. Hoyt acknowledged the same as the free act and deed of said
corporation.

     IN WITNESS WHEREOF, I hereunto set my hand and official seal.

[Notarial Seal]


                                               --------------------------------
                                               Notary Public
                                               My Commission expires___________


STATE OF NEW YORK               )
                                )SS.:
COUNTY OF NEW YORK              )

     On this 9TH day of August, 2002, before me, James M. Foley, the undersigned
officer, personally appeared L. O'Brien, to me personally known, who
acknowledged himself to be, and being by me duly sworn, did say that he is A
Vice President of JPMORGAN CHASE BANK, a corporation, and that the seal affixed
to the foregoing instrument is the corporate seal of said corporation and that
said instrument was executed by, and signed in the name of, the corporation, by
him, as such Vice President, and sealed on behalf of the corporation by
authority of its Board of Directors for the purposes therein contained, and the
said L.O'Brien acknowledged the same as the free act and deed of said
corporation.

     IN WITNESS WHEREOF, I hereunto set my hand and official seal.

[Notarial Seal]


                                               --------------------------------
                                               Notary Public
                                               My Commission expires___________


                                       14