Executed in
                                                                100 Counterparts
                                                                of which this is
                                                             Counterpart No. ___






================================================================================

                               IDAHO POWER COMPANY

                                       TO

                      DEUTSCHE BANK TRUST COMPANY AMERICAS

                                       AND

                                  STANLEY BURG,

                                      As Trustees under its Mortgage and Deed of
                                      Trust dated as of October 1, 1937.

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

                      Thirty-seventh Supplemental Indenture
             providing among other things for Bonds of MTN Series E
                            Dated as of April 1, 2003


================================================================================





                               TABLE OF CONTENTS\1

                                                                            Page
Parties and Recitals...........................................................1
Granting Clause and Property Description.......................................5

                 ARTICLE I Description of Bonds of MTN Series E

Section 1. General terms and redemption provisions.............................7
Section 2. Exchange and transfers of Bonds.....................................8
Section 3. Form of Bonds.......................................................9
Section 4. Temporary Bonds.....................................................9

                    ARTICLE II Issue of Bonds of MTN Series E

Section 5. Issue of Bonds......................................................9

                              ARTICLE III Covenants

Section 6. Application of Original Indenture...................................9
Section 7. Lawful ownership...................................................10
Section 8. Annual certificate as to defaults..................................10

                             ARTICLE IV The Trustees

Acceptance of trust...........................................................10
Recitals deemed made by the Company...........................................10

                       ARTICLE V Miscellaneous Provisions

Meanings of terms.............................................................10
Ratification and Confirmation.................................................11
Counterparts..................................................................11

Testimonium...................................................................12
Signatures and seals..........................................................12
Acknowledgments...............................................................14
Affidavits....................................................................17


- ---------------------------
1   This table of contents shall not have any bearing upon the interpretation of
    this Supplemental Indenture.

                                       i




               SUPPLEMENTAL INDENTURE, dated as of the first day of April, 2003,
made and entered into by and between IDAHO POWER COMPANY, a corporation of the
State of Idaho (successor by merger to Idaho Power Company, a corporation of the
State of Maine, hereinafter sometimes called the "Maine Company"), whose address
is 1221 West Idaho Street, Boise, Idaho 83702-5627 (hereinafter sometimes called
the "Company"), party of the first part, and DEUTSCHE BANK TRUST COMPANY
AMERICAS, formerly known as Bankers Trust Company, a corporation of the State of
New York, whose post office address is 280 Park Avenue, 9th Floor, New York, NY
10017 (hereinafter sometimes called the "Corporate Trustee"), and Stanley Burg
(hereinafter sometimes called the "Individual Trustee"), parties of the second
part (the Corporate Trustee and the Individual Trustee being hereinafter
together sometimes called the "Trustees"), as Trustees under the Mortgage and
Deed of Trust dated as of October 1, 1937 hereinafter referred to; and

               WHEREAS, the Maine Company has heretofore executed and delivered
to the Trustees its Mortgage and Deed of Trust (hereinafter sometimes referred
to as the "Original Indenture"), dated as of October 1, 1937, to secure the
payment both of the principal of and interest and premium, if any, on all Bonds
at any time issued and outstanding thereunder and to declare the terms and
conditions upon which Bonds are to be issued thereunder; and

               WHEREAS, the Maine Company was merged into the Company on June
30, 1989; and

               WHEREAS, in order to evidence the succession of the Company to
the Maine Company and the assumption by the Company of the covenants and
conditions of the Maine Company in the Bonds and in the Original Indenture, as
supplemented, contained, and to enable the Company to have and exercise the
powers and rights of the Maine Company under the Original Indenture, as
supplemented, in accordance with the terms thereof, the Company executed and
delivered to the Trustees a Twenty-eighth Supplemental Indenture, dated as of
June 30, 1989 (which supplemental indenture is hereinafter sometimes called the
"Twenty-eighth Supplemental Indenture"); and

               WHEREAS, said Twenty-eighth Supplemental Indenture was recorded
in the records of the County of Elko, Nevada; the Counties of Baker, Grant,
Harney, Malheur, Union and Wallowa, Oregon; the Counties of Ada, Adams, Bannock,
Bear Lake, Bingham, Blaine, Boise, Bonneville, Butte, Camas, Canyon, Caribou,
Cassia, Clark, Elmore, Gem, Gooding, Idaho, Jefferson, Jerome, Lemhi, Lincoln,
Minidoka, Oneida, Owyhee, Payette, Power, Twin Falls, Valley and Washington,
Idaho; the Counties of Lincoln and Sweetwater, Wyoming; and with the Secretary
of State of Montana; and

               WHEREAS, in accordance with the terms of the Original Indenture
the Maine Company or the Company has executed and delivered to the Trustees the
following supplemental indentures in addition to the Twenty-eighth Supplemental
Indenture:





       Designation                                             Dated as of
First Supplemental Indenture                                July 1, 1939
Second Supplemental Indenture                               November 15, 1943
Third Supplemental Indenture                                February 1, 1947
Fourth Supplemental Indenture                               May 1, 1948
Fifth Supplemental Indenture                                November 1, 1949
Sixth Supplemental Indenture                                October 1, 1951
Seventh Supplemental Indenture                              January 1, 1957
Eighth Supplemental Indenture                               July 15, 1957
Ninth Supplemental Indenture                                November 15, 1957
Tenth Supplemental Indenture                                April 1, 1958
Eleventh Supplemental Indenture                             October 15, 1958
Twelfth Supplemental Indenture                              May 15, 1959
Thirteenth Supplemental Indenture                           November 15, 1960
Fourteenth Supplemental Indenture                           November 1, 1961
Fifteenth Supplemental Indenture                            September 15, 1964
Sixteenth Supplemental Indenture                            April 1, 1966
Seventeenth Supplemental Indenture                          October 1, 1966
Eighteenth Supplemental Indenture                           September 1, 1972
Nineteenth Supplemental Indenture                           January 15, 1974
Twentieth Supplemental Indenture                            August 1, 1974
Twenty-first Supplemental Indenture                         October 15, 1974
Twenty-second Supplemental Indenture                        November 15, 1976
Twenty-third Supplemental Indenture                         August 15, 1978
Twenty-fourth Supplemental Indenture                        September 1, 1979
Twenty-fifth Supplemental Indenture                         November 1, 1981
Twenty-sixth Supplemental Indenture                         May 1, 1982
Twenty-seventh Supplemental Indenture                       May 1, 1986
Twenty-ninth Supplemental Indenture                         January 1, 1990
Thirtieth Supplemental Indenture                            January 1, 1991
Thirty-first Supplemental Indenture                         August 15, 1991
Thirty-second Supplemental Indenture                        March 15, 1992
Thirty-third Supplemental Indenture                         April 1, 1993
Thirty-fourth Supplemental Indenture                        December 1, 1993
Thirty-fifth Supplemental Indenture                         November 1, 2000
Thirty-sixth Supplemental Indenture                         October 1, 2001

each of which is supplemental to the Original Indenture (the Original Indenture
and all indentures supplemental thereto together being hereinafter sometimes
referred to as the "Indenture"); and

               WHEREAS, the Original Indenture and said Supplemental Indentures
(except said Fifteenth Supplemental Indenture) have each been recorded in the
records of the County of Elko, Nevada; the Counties of Baker, Grant, Harney,
Malheur, Union and Wallowa, Oregon; the Counties of Ada, Adams, Bannock, Bear
Lake, Bingham, Blaine, Boise, Bonneville, Butte, Camas, Canyon, Caribou, Cassia,
Clark, Elmore, Gem, Gooding, Idaho, Jefferson, Jerome,


                                       2



Lemhi, Lincoln, Minidoka, Oneida, Owyhee, Payette, Power, Twin Falls, Valley and
Washington, Idaho; the Counties of Lincoln and Sweetwater, Wyoming; and with the
Secretary of State of Montana; and

               WHEREAS, the Maine Company or the Company has heretofore issued
Bonds, under and in accordance with the terms of the Indenture in the following
series and aggregate principal amounts:

                                                   Principal      Principal
                                                    Amount          Amount
                   Series                           Issued       Outstanding
                   ------                           ------       -----------
3-3/4% Series due 1967                             $18,000,000       None
3-1/8% Series due 1973                             18,000,000        None
2-3/4% Series due 1977                             5,000,000         None
3% Series due 1978                                 10,000,000        None
2-3/4% Series due 1979                             12,000,000        None
3-1/4% Series due 1981                             15,000,000        None
4-1/2% Series due 1987                             20,000,000        None
4-3/4% Series due 1987                             15,000,000        None
4% Series due April 1988                           10,000,000        None
4-1/2% Series due October 1988                     15,000,000        None
5% Series due 1989                                 15,000,000        None
4-7/8% Series due 1990                             15,000,000        None
4-1/2% Series due 1991                             10,000,000        None
5-1/4% Series due 1996                             20,000,000        None
6-1/8% Series due 1996                             30,000,000        None
7-3/4% Series due 2002                             30,000,000        None
8-3/8% Series due 2004                             35,000,000        None
10% Series due 2004                                50,000,000        None
8-1/2% Series due 2006                             30,000,000        None
9% Series due 2008                                 60,000,000        None
10-1/4% Series due 2003                            62,000,000        None
First Mortgage Bonds, 1984 Series                  10,100,000        None
16.10% Series due 1991-1992                        50,000,000        None
Pollution Control Series A                         49,800,000        49,800,000
8.65% Series due 2000                              80,000,000        None
9.50% Series due 2021                              75,000,000        None
9.52% Series due 2031                              25,000,000        None
8% Series due 2004                                 50,000,000        50,000,000
8 3/4% Series due 2027                             50,000,000        None
Secured Medium-Term Notes, Series A                190,000,000       160,000,000
Secured Medium-Term Notes, Series B                197,000,000       140,000,000
Secured Medium-Term Notes, Series C                200,000,000       200,000,000
Secured Medium-Term Notes, Series D                200,000,000       200,000,000

which bonds are hereinafter sometimes called bonds of the First through
Thirty-third Series; and


                                       3



               WHEREAS, the Company, in accordance with the provisions of the
Indenture and pursuant to appropriate resolutions of its Board of Directors, has
duly determined to make, execute and deliver to the Trustees this Thirty-seventh
Supplemental Indenture for the purposes herein provided, including the issuance
of a Thirty-fourth Series of Bonds under the Indenture, in the aggregate
principal amount of up to Two Hundred and Fifty Million Dollars ($250,000,000),
to be designated as "First Mortgage Bonds, Secured Medium-Term Notes, Series E"
(herein sometimes called the "Bonds of MTN Series E"); and

               WHEREAS, it is also now desired, for the purpose of more
effectually carrying out the purposes of the Original Indenture, to confirm
specifically the subjection to the lien thereof and of the Indenture of the
certain property acquired by the Company in addition to the property
specifically described in the Original Indenture and in said First, Second,
Third, Fourth, Fifth, Sixth, Seventh, Ninth, Tenth, Eleventh, Twelfth,
Thirteenth, Fourteenth, Sixteenth, Seventeenth, Eighteenth, Nineteenth,
Twenty-first, Twenty-second, Twenty-third, Twenty-fourth, Twenty-fifth,
Twenty-sixth, Twenty-seventh, Twenty-eighth, Twenty-ninth, Thirtieth,
Thirty-first, Thirty-second, Thirty-third, Thirty-fourth, Thirty-fifth and
Thirty-sixth Supplemental Indentures; and

               WHEREAS, all things necessary to make said Bonds of MTN Series E,
when duly authenticated by the Corporate Trustee and issued by the Company,
valid and legally binding obligations of the Company and to make the Original
Indenture, as heretofore supplemented and as supplemented hereby, a valid and
legally binding instrument for the security thereof, have been performed, and
the execution and delivery of this Thirty-seventh Supplemental Indenture and the
issue of said Bonds as in this Thirty-seventh Supplemental Indenture provided
have been in all respects duly authorized:

               NOW, THEREFORE, THIS INDENTURE WITNESSETH:

               That in consideration of the premises and of One Dollar to it
duly paid by the Trustees at or before the ensealing and delivery of these
presents, the receipt whereof is hereby acknowledged, and in order to secure the
payment both of the principal of and interest and premium, if any, on all Bonds
at any time issued and outstanding under the Indenture, according to their tenor
and effect, and the performance of all the provisions of the Indenture and of
said Bonds, the Company has duly executed and delivered to the Trustees this
Thirty-seventh Supplemental Indenture and has granted, bargained, sold,
released, conveyed, assigned, transferred, mortgaged, pledged, set over and
confirmed and by these presents does grant, bargain, sell, release, convey,
assign, transfer, mortgage, pledge, set over and confirm unto Stanley Burg and
(to the extent of its legal capacity to hold the same for the purposes hereof)
unto Deutsche Bank Trust Company Americas, as Trustees as aforesaid, and to
their successor or successors in said trust, and to them and their successors,
heirs and assigns forever, all property, whether real, personal or mixed (except
any hereinafter expressly excepted), and wheresoever situated, acquired since
the date of said Original Indenture by and now or hereafter owned by the Company
including the following described properties, rights and interests in property
(in addition to all other properties heretofore subjected to the lien of the
Indenture and not heretofore released from the lien thereof)--that is to say:


                                       4




                       PROPERTIES ACQUIRED OR CONSTRUCTED

GENERATING PLANTS


Danskin Power Plant                                         Elmore County, Idaho

TRANSMISSION LINES & SYSTEMS




                                                      
404 Norco Tap                   15 Miles added 138KV        Canyon County, Idaho
438 Stoddard Tap                3.80 Miles added 183 KV     Ada County, Idaho
447 Jerome Tap                  2.54 Miles added 138KV      Twin Falls County, Idaho
456 Joplin Loop                 27 Miles added 138KV        Ada County, Idaho
707 Boise Bench-Paddock Tap     2.13 Miles added 230KV      Washington County, Idaho
    Brownlee-Ontario            48.87 Miles added 230KV     Washington County, Idaho
712 Cloverdale-Locust Tap       4.37 Miles added 230KV      Ada County, Idaho
919 Danskin Loop                10 Miles added 138KV        Elmore County, Idaho



DISTRIBUTION LINES & SYSTEMS

34, 35, 36, 37 and 38 - Branches and extensions of the Company's Distribution
Lines and Systems situated in the States of Idaho, Oregon and Nevada

SUBSTATIONS

Boulder Substation                                         Valley County, Idaho
Quartz South Baker                                         Baker County, Oregon
Norco Substation                                           Canyon County, Idaho
Joplin Substation                                          Ada County, Idaho
Rim View Fish Hatchery CSPP                                Gooding County, Idaho
Stoddard Substation                                        Ada County, Idaho

FRANCHISES

None

ALL OTHER LANDS, IMPROVEMENTS, BUILDINGS AND OTHER SUBSTATIONS

None

All other property, whether real, personal or mixed (except any hereinafter
expressly excepted), and wheresoever situated, acquired since the date of said
Original Indenture by and now or hereafter owned by the Company.

                                       5


               TOGETHER with all and singular the tenements, hereditaments and
appurtenances belonging or in any wise appertaining to the aforesaid property or
any part thereof, with the reversion and reversions, remainder and remainders,
and (subject to the provisions of Section 57 of the Original Indenture) the
tolls, rents, revenues, issues, earnings, income, product and profits thereof,
and all the estate, right, title and interest and claim whatsoever, at law as
well as in equity, which the Company now has or may hereafter acquire in and to
the aforesaid property and franchises and every part and parcel thereof.

               It is not intended herein or hereby to include in or subject to
the lien of the Indenture, and the granting clauses hereof shall not be deemed
to apply to, (1) any revenues, earnings, rents, issues, income or profits of the
mortgaged and pledged property, or any bills, notes or accounts receivable,
contracts or choses in action, except to the extent permitted by law in case a
completed default specified in Section 65 of the Indenture shall have occurred
and be continuing and either or both of the Trustees, or a receiver or trustee,
shall have entered upon or taken possession of the mortgaged and pledged
property, or (2) in any case, unless specifically subjected to the lien thereof,
any bonds, notes, evidences of indebtedness, shares of stock, or other
securities or any cash (except cash deposited with the Corporate Trustee
pursuant to any provisions of the Indenture) or any goods, wares, merchandise,
equipment or apparatus manufactured or acquired for the purpose of sale or
resale in the usual course of business.

               TO HAVE AND TO HOLD all such properties, real, personal and
mixed, granted, bargained, sold, released, conveyed, assigned, transferred,
mortgaged, pledged, set over or confirmed by the Company as aforesaid, or
intended so to be, unto the Individual Trustee and (to the extent of its legal
capacity to hold the same for the purposes hereof) unto the Corporate Trustee,
and their successors, heirs and assigns forever;

               IN TRUST, NEVERTHELESS, for the same purposes and upon the same
terms, trusts and conditions and subject to and with the same provisions and
covenants as are set forth in the Original Indenture, as amended or modified by
said First, Second, Third, Fourth, Fifth, Sixth, Seventh, Eighth, Ninth, Tenth,
Eleventh, Twelfth, Thirteenth, Fourteenth, Fifteenth, Sixteenth, Seventeenth,
Eighteenth, Nineteenth, Twentieth, Twenty-first, Twenty-second, Twenty-third,
Twenty-fourth, Twenty-fifth, Twenty-sixth, Twenty-seventh, Twenty-eighth,
Twenty-ninth, Thirtieth, Thirty-first, Thirty-second, Thirty-third,
Thirty-fourth, Thirty-fifth and Thirty-sixth Supplemental Indentures and this
Thirty-seventh Supplemental Indenture.

               And it is hereby covenanted, declared and decreed by and between
the parties hereto, for the benefit of those who shall hold the Bonds and
interest coupons, or any of them, issued and to be issued under the Indenture,
as follows:

                                       6


                                   ARTICLE I

                      Description of Bonds of MTN Series E

               Section 1. The Thirty-fourth Series of Bonds to be executed,
authenticated and delivered under and secured by the Indenture shall be Bonds of
MTN Series E, designated as "First Mortgage Bonds, Secured Medium-Term Notes,
Series E" of the Company. The Bonds of MTN Series E shall be executed,
authenticated and delivered in accordance with the provisions of, and shall in
all respects be subject to, all of the terms, conditions and covenants of the
Original Indenture, except insofar as the terms and provisions of the Original
Indenture have been or are amended or modified by said First through
Thirty-sixth Supplemental Indentures or by this Thirty-seventh Supplemental
Indenture. Bonds of MTN Series E shall be issued from time to time in an
aggregate principal amount not to exceed $250,000,000, be issued as registered
Bonds without coupons in the denominations of $1,000 or in any multiple thereof;
each Bond of MTN Series E shall mature on such date not less than nine months
nor more than thirty years from date of issue, shall bear interest at such rate
or rates (which may be either fixed or variable) and have such other terms and
provisions not inconsistent with the Indenture as the Board of Directors may
determine in accordance with a resolution filed with the Corporate Trustee and a
written order referring to this Thirty-seventh Supplemental Indenture; the
principal of and interest on each said Bond to be payable at the office or
agency of the Company in the Borough of Manhattan, The City of New York and, at
the option of the Company, interest on each said Bond may also be payable at the
office of the Company in Boise, Idaho, in such coin or currency of the United
States of America as at the time of payment is legal tender for public and
private debts. Interest on Bonds of MTN Series E which bear interest at a fixed
rate shall be payable semiannually on April 1 and October 1 of each year or on
such other dates as set forth in a resolution filed with the Corporate Trustee
referring to this Thirty-seventh Supplemental Indenture and at maturity or upon
earlier redemption (each an interest payment date). Interest on Bonds of MTN
Series E which bear interest at a variable rate shall be payable on the dates
(each an interest payment date) set forth in a resolution filed with the
Corporate Trustee referring to this Thirty-seventh Supplemental Indenture.

               Notwithstanding the foregoing, so long as there is no existing
default in the payment of interest on the Bonds of MTN Series E, all Bonds of
MTN Series E authenticated by the Corporate Trustee after the Record Date
hereinafter specified for any interest payment date, and prior to such interest
payment date (unless the date of first authentication of Bonds of such
designated interest rate and maturity is after such Record Date), shall be dated
the date of authentication, but shall bear interest from such interest payment
date, and the person in whose name any Bond of MTN Series E is registered at the
close of business on any Record Date with respect to any interest payment date
shall be entitled to receive the interest payable on such interest payment date,
notwithstanding the cancellation of such Bond of MTN Series E, upon any transfer
or exchange thereof subsequent to the Record Date and on or prior to such
interest payment date. If the date of first authentication of the Bonds of MTN
Series E of a designated interest rate and maturity is after such Record Date
and prior to the corresponding interest payment date, such Bonds shall bear
interest from the Original Interest Accrual Date but payment of interest shall
commence on the second interest payment date succeeding the Original Interest
Accrual Date. "Record Date" for Bonds of MTN Series E which bear interest at a
fixed rate shall mean March 15 for interest payable April 1 and September 15 for
interest payable

                                       7


October 1, for Bonds of MTN Series E which bear interest at a fixed rate that is
payable on other dates, shall mean the last day of the calendar month preceding
such interest payment date if such interest payment date is the fifteenth day of
a calendar month and shall mean the fifteenth day of the calendar month
preceding such interest payment date if such interest payment date is the first
day of a calendar month, as determined by the Board of Directors and set forth
in a resolution filed with the Corporate Trustee referring to this
Thirty-seventh Supplemental Indenture; and for Bonds of MTN Series E which bear
interest at a variable rate, the date 15 calendar days prior to any interest
payment date, provided that, interest payable on the maturity date will be
payable to the person to whom the principal thereof shall be payable. "Original
Interest Accrual Date" with respect to Bonds of MTN Series E of a designated
interest rate and maturity shall mean the date of first authentication of Bonds
of such designated interest rate and maturity unless a written order filed with
the Corporate Trustee on or before such date shall specify another date from
which interest shall accrue, in which case "Original Interest Accrual Date"
shall mean such other date specified in the written order for Bonds of such
designated interest rate and maturity.

               The Bonds of MTN Series E, in definitive form, shall be, at the
option of the Company, fully engraved or shall be lithographed or printed on
steel engraved borders or shall be partially lithographed or printed and
partially engraved on steel borders or shall be printed on safety paper or shall
be typewritten.

               The holders of the Bonds of MTN Series E consent that the Company
may, but shall not be obligated to, fix a record date for the purpose of
determining the holders of Bonds of MTN Series E entitled to consent to any
amendment, supplement or waiver. If a record date is fixed, those persons who
are holders at such record date (or their duly designated proxies), and only
those persons, shall be entitled to consent to such amendment, supplement or
waiver or to revoke any consent previously given, whether or not such persons
continue to be holders after such record date. No such consent shall be valid or
effective for more than 90 days after such record date.

               The Bonds of MTN Series E may be redeemable at the option of the
Company (including without limitation redemptions by the application of cash
deposited with the Corporate Trustee pursuant to Section 39 of the Indenture) in
whole at any time, or in part from time to time, prior to maturity, as provided
in Section 52 of the Indenture, upon giving notice of such redemption by first
class mail, postage prepaid, by or on behalf of the Company at least thirty (30)
days prior to the date fixed for redemption as the Board of Directors may
determine in accordance with a resolution filed with the Corporate Trustee and a
written order referring to this Thirty-seventh Supplemental Indenture.

               Section 2. At the option of the registered holder, any Bonds of
MTN Series E, upon surrender thereof for cancellation at the office or agency of
the Company in the Borough of Manhattan, The City of New York, together with a
written instrument of transfer (if so required by the Company or by the
Trustees) in form approved by the Company duly executed by the registered holder
or by his duly authorized attorney, shall be exchangeable for a like aggregate
principal amount and maturity of Bonds of MTN Series E of other authorized
denominations. Bonds of MTN Series E may bear such legends as may be necessary
to comply with any law or with any rules or regulations made pursuant thereto or
with the rules or regulations of any stock exchange or to conform to usage with
respect thereto.

                                       8


               Bonds of MTN Series E shall be transferable at the office or
agency of the Company in the Borough of Manhattan, The City of New York.

               Notwithstanding the foregoing provisions of this Section 2, the
Company shall not be required to make any transfers or exchanges of Bonds of MTN
Series E for a period of fifteen (15) days next preceding any mailing of notice
of redemption, and the Company shall not be required to make transfers or
exchanges of the principal amount of any Bonds of MTN Series E so called or
selected for redemption.

               Section 3. The Bonds of MTN Series E shall be substantially of
the tenor and purport recited in the Original Indenture, and the form thereof
shall be as established by resolution of the Board of Directors or the Executive
Committee of the Board of Directors of the Company, which resolution may provide
that any provisions of such form of Bond may appear on the reverse of such form.

               Section 4. Until Bonds of MTN Series E in definitive form are
ready for delivery, the Company may execute, and upon its request in writing,
the Corporate Trustee shall authenticate and deliver, in lieu thereof, Bonds of
MTN Series E in temporary form, as provided in Section 15 of the Original
Indenture.

                                   ARTICLE II

                         Issue of Bonds of MTN Series E.

               Section 5. The Bonds of MTN Series E for the aggregate principal
amount of up to Two Hundred Fifty Million Dollars ($250,000,000) may be executed
by the Company and delivered to the Corporate Trustee and shall be authenticated
by the Corporate Trustee and delivered to or upon the order or orders of the
Company, evidenced by a writing or writings signed by the Company by its
President or a Vice President and its Treasurer or an Assistant Treasurer,
pursuant to and upon compliance with the provisions of Article V, Article VI or
Article VII of the Indenture.

                                  ARTICLE III

                                   Covenants.

               The Company hereby covenants, warrants and agrees:

               Section 6. That all the terms, conditions, provisos, covenants
and provisions contained in the Indenture shall affect and apply to the property
hereinabove described and conveyed and to the estate, rights, obligations and
duties of the Company and Trustees and the beneficiaries of the trust with
respect to said property, and to the Trustees and their successors as trustees
of said property, in the same manner and with the same effect as if the said
property had been owned by the Company at the time of the execution of the
Original Indenture and had been specifically and at length described in and
conveyed to the Individual Trustee and (to the extent of its legal capacity to
hold the same for the purposes of the Indenture) the Corporate Trustee by the
Original Indenture as a part of the property therein stated to be conveyed.

                                       9


               Section 7. That it is lawfully seized and possessed of all of the
mortgaged and pledged property described in the granting clauses of the
Indenture, which has not heretofore been released from the lien thereof; that it
had or has, at the respective times of execution and delivery of the Original
Indenture, the First, Second, Third, Fourth, Fifth, Sixth, Seventh, Eighth,
Ninth, Tenth, Eleventh, Twelfth, Thirteenth, Fourteenth, Fifteenth, Sixteenth,
Seventeenth, Eighteenth, Nineteenth, Twentieth, Twenty-first (as corrected by
the Twenty-second), Twenty-second, Twenty-third, Twenty-fourth, Twenty-fifth,
Twenty-sixth, Twenty-seventh, Twenty-eighth, Twenty-ninth, Thirtieth,
Thirty-first, Thirty-second, Thirty-third, Thirty-fourth, Thirty-fifth and
Thirty-sixth Supplemental Indentures, and this Thirty-seventh Supplemental
Indenture, good right and lawful authority to mortgage and pledge the mortgaged
and pledged property described therein, as provided in and by the Indenture; and
that such mortgaged and pledged property is, at the actual date of the initial
issue of the Bonds of MTN Series E, free and clear of any mortgage, lien, charge
or encumbrance thereon or affecting the title thereto (other than excepted
encumbrances) prior to the lien of the Indenture, except as set forth in the
granting clauses of the Indenture.

               Section 8. That it will deliver to the Corporate Trustee
annually, within ninety (90) days after the close of each fiscal year,
commencing with the fiscal year 2003, a certificate from the principal executive
officer, principal financial officer or principal accounting officer as to his
or her knowledge of the Company's compliance with all conditions and covenants
under the Indenture. For purposes of this Section 8, such compliance shall be
determined without regard to any period of grace or requirement of notice
provided under the Indenture.

                                   ARTICLE IV

                                  The Trustees.

               The Trustees hereby accept the trust hereby declared and provided
and agree to perform the same upon the terms and conditions in the Original
Indenture, as heretofore supplemented and as supplemented by this Thirty-seventh
Supplemental Indenture, and in this Thirty-seventh Supplemental Indenture set
forth, and upon the following terms and conditions:

               The Trustees shall not be responsible in any manner whatsoever
for or in respect of the validity or sufficiency of this Thirty-seventh
Supplemental Indenture or the due execution hereof by the Company or for or in
respect of the recitals contained herein, all of which recitals are made by the
Company only.

                                    ARTICLE V

                            Miscellaneous Provisions.

               All terms contained in the Thirty-seventh Supplemental Indenture
shall, for all purposes hereof, have the meanings given to such terms in Article
I of the Original Indenture, as amended by Article IV of the Second Supplemental
Indenture.

                                       10


               Except as hereby expressly amended and supplemented, the Original
Indenture heretofore amended and supplemented is in all respects ratified and
confirmed, and all the terms and provisions thereof shall be and remain in full
force and effect.

               This Thirty-seventh Supplemental Indenture may be executed in any
number of counterparts, each of which when so executed shall be deemed to be an
original; but such counterparts together constitute but one and the same
instrument.

                                       11


               IN WITNESS WHEREOF, Idaho Power Company, party hereto of the
first part, caused its corporate name to be hereunto affixed and this instrument
to be signed and sealed by its President or a Vice President and its corporate
seal to be attested by its Secretary or an Assistant Secretary for and on its
behalf, and Deutsche Bank Trust Company Americas, one of the parties hereto of
the second part, in token of its acceptance of the trust hereby created has
caused its corporate name to be hereunto affixed and this instrument to be
signed and sealed by a Vice President and its corporate seal to be attested by
an Associate and Stanley Burg, one of the parties hereto of the second part, has
for all like purposes hereunto set his hand and affixed his seal, each on the
date hereinafter acknowledged, as of the day and year first above written.

                                       IDAHO POWER COMPANY


                                       By /s/ Darrel T. Anderson
                                         --------------------------------------
                                         Darrel T. Anderson
                                         Vice President, Chief Financial Officer
                                         and Treasurer
Attest:

/s/ Robert W. Stahman
- -------------------------------
Robert W. Stahman
Secretary

Executed, sealed and delivered by
     IDAHO POWER COMPANY
     in the presence of:

/s/ Joanne M. Butler
- -------------------------------

/s/ Teresa Meeker
- -------------------------------


                                       12


                                        DEUTSCHE BANK TRUST COMPANY AMERICAS

                                        By /s/ Susan Johnson
                                          --------------------------------------
                                          Susan Johnson
                                          Vice-President

Attest:

/s/ Dorothy Robinson
- -------------------------------
Dorothy Robinson
Vice-President

Executed, sealed and delivered by
     DEUTSCHE BANK TRUST COMPANY AMERICAS,
     in the presence of:

/s/ David J. Rocco
- -------------------------------

/s/ Teddy Banica
- -------------------------------
Attest:

                                          /s/ Stanley Burg
                                          ------------------------------- [L.S.]
                                                    Stanley Burg


Executed, sealed and delivered by
     STANLEY BURG,
     in the presence of:

/s/ David J. Rocco
- -------------------------------

/s/ Teddy Banica
- -------------------------------


                                       13



STATE OF IDAHO  )
                ) ss.:
COUNTY OF ADA   )

               On the 11th day of April, in the year 2003, before me personally
came DARREL T. ANDERSON, to me known, who being by me duly sworn did depose and
say that he resides at 1677 W. Spanish Bay Drive, Eagle, Idaho 83616; that he is
the Vice President, Chief Financial Officer and Treasurer of Idaho Power
Company, one of the corporations described in and which executed the above
instrument; that he knows the seal of said corporation; that the seal affixed to
said instrument is such corporate seal; that it was so affixed by order of the
Board of Directors of said corporation, and that he signed his name thereto by
like order; the said DARREL T. ANDERSON, having personally appeared and known to
me to be the Vice President, Chief Financial Officer and Treasurer of said
corporation that executed the instrument, acknowledged to me that said
corporation executed the same.

               IN WITNESS WHEREOF, I have hereunto subscribed my name and
affixed my official seal the day and year in this certificate first above
written.

                                        /s/ Mary Gray
                                        ----------------------------------------
                                        Mary Gray
                                        Notary Public, State of Idaho
                                        Commission expires July 17, 2004


                                       14



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

               On the 11th day of April, in the year 2003, before me personally
came Susan Johnson, to me known, who being by me duly sworn did depose and say
that she resides at 154 East 46th Brooklyn, New York; that she is a Vice
President of Deutsche Bank Trust Company Americas, one of the corporations
described in and which executed the above instrument; that she knows the seal of
said corporation; that the seal affixed to said instrument is such corporate
seal; that it was so affixed by order of the Board of Directors of said
corporation, and that she signed her name thereto by like order; the said Susan
Johnson, having personally appeared and known to me to be a Vice President of
said corporation that executed the instrument, acknowledged to me that said
corporation executed the same.

               IN WITNESS WHEREOF, I have hereunto subscribed my name and
affixed my official seal the day and year in this certificate first above
written.


                                        /s/ Tracy A. Salzmann
                                        ----------------------------------------
                                        Tracy A. Salzmann
                                        Notary Public, State of New York
                                        Registration #01SA6040727
                                        Qualified in New York County
                                        My Commission Expires April 24, 2006

                                       15




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

               On the 11th day of April, in the year 2003, before me, Tracy A.
Salzmann, a Notary Public in and for the State of New York in the County of New
York, personally appeared and came STANLEY BURG, to me known and known to me to
be the person described in and who executed the within and foregoing instrument
and whose name is subscribed thereto and acknowledged to me that he executed the
same.

               IN WITNESS WHEREOF, I have hereunto subscribed my name and
affixed my official seal the day and year in this certificate first above
written.

                                        /s/ Tracy A. Salzmann
                                        ----------------------------------------
                                        Tracy A. Salzmann
                                        Notary Public, State of New York
                                        Registration #01SA6040727
                                        Qualified in New York County
                                        My Commission Expires April 24, 2006


                                       16



STATE OF IDAHO    )
                  ) ss.:
COUNTY OF ADA     )

               DARREL T. ANDERSON, being first duly sworn, upon oath, deposes
and says: that he is an officer, to wit, the Vice President, Chief Financial
Officer and Treasurer of Idaho Power Company, a corporation, the mortgagor
described in the foregoing indenture or mortgage, and makes this affidavit on
behalf of said Idaho Power Company; that said indenture or mortgage is made in
good faith without any design to hinder, delay or defraud creditors, to secure
the indebtedness mentioned to be thereby secured.

                                        /s/ Darrel T. Anderson
                                        ----------------------------------------


Subscribed and sworn to before me
this 11th day of April, 2003.

Mary Gray

/s/ Mary Gray
- -------------------------------
Notary Public, State of Idaho
Commission expires July 17, 2004

                                       17


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

               Susan Johnson, being first duly sworn, upon oath, deposes and
says: that she is an officer, to wit, a Vice President of Deutsche Bank Trust
Company Americas, a corporation, one of the mortgagees and trustees named in the
foregoing indenture or mortgage, and makes this affidavit on behalf of said
Deutsche Bank Trust Company Americas; that said indenture or mortgage is made in
good faith without any design to hinder, delay or defraud creditors, to secure
the indebtedness mentioned or provided for therein.

                                        /s/ Susan Johnson
                                        ----------------------------------------
                                        Susan Johnson
                                        Vice President


Subscribed and sworn to before me
this 11th day of April, 2003.

/s/ Tracy A. Salzmann
- -------------------------------
Tracy A. Salzmann
Notary Public, State of New York
Registration #01SA6040727
Qualified in New York County
My Commission Expires April 24, 2006


                                       18



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

               STANLEY BURG, being first duly sworn, upon oath, deposes and
says: that he is one of the mortgagees and trustees named in the foregoing
indenture or mortgage; that said indenture or mortgage is made in good faith
without any design to hinder, delay or defraud creditors, to secure the
indebtedness mentioned or provided for therein.

                                        /s/ Stanley Burg
                                        ----------------------------------------
                                        Stanley Burg


Subscribed and sworn to before me
this 11th day of April, 2003.


/s/ Tracy A. Salzmann
- -------------------------------
Tracy A. Salzmann
Notary Public, State of New York
Registration #01SA6040727
Qualified in New York County
My Commission Expires April 24, 2006



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