Document:

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                                                                     EXHIBIT 4.4

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                               AVISTA CORPORATION

                                       TO

                                 CITIBANK, N.A.

                           As Successor Trustee under
                           Mortgage and Deed of Trust,
                            dated as of June 1, 1939

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

                      THIRTY-SEVENTH SUPPLEMENTAL INDENTURE

          Providing among other things for a series of bonds designated
                 "First Mortgage Bonds, Collateral Series 2004D"
                              Due December 16, 2009

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

                          Dated as of December 1, 2004

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<PAGE>

                      THIRTY-SEVENTH SUPPLEMENTAL INDENTURE

            THIS INDENTURE, dated as of the 1st day of December 2004, between
AVISTA CORPORATION (formerly known as The Washington Water Power Company), a
corporation of the State of Washington, whose post office address is 1411 East
Mission Avenue, Spokane, Washington 99202 (the "Company"), and CITIBANK, N.A.,
formerly First National City Bank (successor by merger to First National City
Trust Company, formerly City Bank Farmers Trust Company), a national banking
association incorporated and existing under the laws of the United States of
America, whose post office address is 388 Greenwich Street, 14th Floor, New
York, New York 10013 (the "Trustee"), as Trustee under the Mortgage and Deed of
Trust, dated as of June 1, 1939 (the "Original Mortgage"), executed and
delivered by the Company to secure the payment of bonds issued or to be issued
under and in accordance with the provisions thereof, this indenture (the
"Thirty-seventh Supplemental Indenture") being supplemental to the Original
Mortgage, as heretofore supplemented and amended.

            WHEREAS pursuant to a written request of the Company made in
accordance with Section 103 of the Original Mortgage, Francis M. Pitt (then
Individual Trustee under the Mortgage, as supplemented) ceased to be a trustee
thereunder on July 23, 1969, and all of his powers as Individual Trustee have
devolved upon the Trustee and its successors alone; and

            WHEREAS by the Original Mortgage the Company covenanted that it
would execute and deliver such further instruments and do such further acts as
might be necessary or proper to carry out more effectually the purposes of the
Original Mortgage and to make subject to the lien of the Original Mortgage any
property thereafter acquired intended to be subject to the lien thereof; and

            WHEREAS the Company has heretofore executed and delivered, in
addition to the Original Mortgage, the indentures supplemental thereto, and has
issued the series of bonds, set forth in Exhibit A hereto (the Original
Mortgage, as supplemented and amended by the First through Thirty-sixth
Supplemental Indentures, being herein sometimes called the "Mortgage"); and

            WHEREAS the Original Mortgage and the First through Thirty-third
Supplemental Indentures have been appropriately filed or recorded in various
official records in the States of Washington, California, Idaho, Montana and
Oregon, as set forth in the First through Thirty-fourth supplemental Indentures
and the Instrument of Further Assurance, dated December 15, 2001, hereinafter
referred to; and

            WHEREAS the Thirty-fourth Supplemental Indenture, dated as of
November 1, 2004, and the Thirty-fifth Supplemental Indenture and the
Thirty-sixth Supplemental Indenture, each dated as of December 1, 2004, are to
be appropriately filed or recorded; and

            WHEREAS for the purpose of confirming or perfecting the lien of the
Mortgage on certain of its properties, the Company has heretofore executed and
delivered a Short Form Mortgage and Security Agreement, in multiple counterparts
dated as of various dates in 1992, and such instrument has been appropriately
filed or recorded in the various official records in the States of California,
Montana and Oregon; and

                                       2
<PAGE>

            WHEREAS for the purpose of confirming or perfecting the lien of the
Mortgage on certain of its properties, the Company has heretofore executed and
delivered an Instrument of Further Assurance, dated as of December 15, 2001, and
such instrument has been appropriately filed or recorded in the various official
records in the States of Washington, California, Idaho, Montana and Oregon; and

            WHEREAS in addition to the property described in the Mortgage the
Company has acquired certain other property, rights and interests in property;
and

            WHEREAS Section 8 of the Original Mortgage provides that the form of
each series of bonds (other than the First Series) issued thereunder and of the
coupons to be attached to coupon bonds of such series shall be established by
Resolution of the Board of Directors of the Company; that the form of such
series, as established by said Board of Directors, shall specify the descriptive
title of the bonds and various other terms thereof; and that such series may
also contain such provisions not inconsistent with the provisions of the
Mortgage as the Board of Directors may, in its discretion, cause to be inserted
therein expressing or referring to the terms and conditions upon which such
bonds are to be issued and/or secured under the Mortgage; and

            WHEREAS Section 120 of the Original Mortgage provides, among other
things, that any power, privilege or right expressly or impliedly reserved to or
in any way conferred upon the Company by any provision of the Mortgage, whether
such power, privilege or right is in any way restricted or is unrestricted, may
be in whole or in part waived or surrendered or subjected to any restriction if
at the time unrestricted or to additional restriction if already restricted, and
the Company may enter into any further covenants, limitations or restrictions
for the benefit of any one or more series of bonds issued thereunder, or the
Company may cure any ambiguity contained therein, or in any supplemental
indenture, by an instrument in writing executed and acknowledged by the Company
in such manner as would be necessary to entitle a conveyance of real estate to
record in all of the states in which any property at the time subject to the
lien of the Mortgage shall be situated; and

            WHEREAS the Company now desires to create a new series of bonds; and

            WHEREAS the execution and delivery by the Company of this
Thirty-seventh Supplemental Indenture, and the terms of the bonds of the
Thirty-sixth Series, hereinafter referred to, have been duly authorized by the
Board of Directors of the Company by appropriate Resolutions of said Board of
Directors, and all things necessary to make this Thirty-seventh Supplemental
Indenture a valid, binding and legal instrument have been performed;

            NOW, THEREFORE, THIS INDENTURE WITNESSETH: That the Company, in
consideration of the premises and of other good and valuable consideration, the
receipt and sufficiency whereof are hereby acknowledged, hereby confirms the
estate, title and rights of the Trustee (including, without limitation, the lien
of the Mortgage on the property of the Company subjected thereto, whether now
owned or hereafter acquired) held as security for the payment of both the
principal of and interest and premium, if any, on the bonds from time to time
issued under the Mortgage according to their tenor and effect and the
performance of all the provisions of the Mortgage and of such bonds, and,
without limiting the generality of the foregoing, hereby

                                       3
<PAGE>

confirms the grant, bargain, sale, release, conveyance, assignment, transfer,
mortgage, pledge, setting over and confirmation unto the Trustee, contained in
the Mortgage, of all the following described properties of the Company, whether
now owned or hereafter acquired, namely:

            All of the property, real, personal and mixed, of every character
      and wheresoever situated (except any hereinafter or in the Mortgage
      expressly excepted) which the Company now owns or, subject to the
      provisions of Section 87 of the Original Mortgage, may hereafter acquire
      prior to the satisfaction and discharge of the Mortgage, as fully and
      completely as if herein or in the Mortgage specifically described, and
      including (without in anywise limiting or impairing by the enumeration of
      the same the scope and intent of the foregoing or of any general
      description contained in Mortgage) all lands, real estate, easements,
      servitudes, rights of way and leasehold and other interests in real
      estate; all rights to the use or appropriation of water, flowage rights,
      water storage rights, flooding rights, and other rights in respect of or
      relating to water; all plants for the generation of electricity, power
      houses, dams, dam sites, reservoirs, flumes, raceways, diversion works,
      head works, waterways, water works, water systems, gas plants, steam heat
      plants, hot water plants, ice or refrigeration plants, stations,
      substations, offices, buildings and other works and structures and the
      equipment thereof and all improvements, extensions and additions thereto;
      all generators, machinery, engines, turbines, boilers, dynamos,
      transformers, motors, electric machines, switchboards, regulators, meters,
      electrical and mechanical appliances, conduits, cables, pipes and mains;
      all lines and systems for the transmission and distribution of electric
      current, gas, steam heat or water for any purpose; all towers, mains,
      pipes, poles, pole lines, conduits, cables, wires, switch racks,
      insulators, compressors, pumps, fittings, valves and connections; all
      motor vehicles and automobiles; all tools, implements, apparatus,
      furniture, stores, supplies and equipment; all franchises (except the
      Company's franchise to be a corporation), licenses, permits, rights,
      powers and privileges; and (except as hereinafter or in the Mortgage
      expressly excepted) all the right, title and interest of the Company in
      and to all other property of any kind or nature.

            TOGETHER WITH all and singular the tenements, hereditaments and
appurtenances belonging or in anywise 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 Mortgage) 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.

            THE COMPANY HEREBY CONFIRMS that, subject to the provisions of
Section 87 of the Original Mortgage, all the property, rights, and franchises
acquired by the Company after the date thereof (except any hereinbefore or
hereinafter or in the Mortgage expressly excepted) are and shall be as fully
embraced within the lien of the Mortgage as if such property, rights and
franchises had been owned by the Company at the date of the Original Mortgage
and had been specifically described therein.

                                       4
<PAGE>

            PROVIDED THAT the following were not and were not intended to be
then or now or hereafter granted, bargained, sold, released, conveyed, assigned,
transferred, mortgaged, pledged, set over or confirmed under the Mortgage and
were, are and shall be expressly excepted from the lien and operation namely:
(l) cash, shares of stock and obligations (including bonds, notes and other
securities) not hereafter specifically pledged, paid, deposited or delivered
under the Mortgage or covenanted so to be; (2) merchandise, equipment, materials
or supplies held for the purpose of sale in the usual course of business or for
consumption in the operation of any properties of the Company; (3) bills, notes
and accounts receivable, and all contracts, leases and operating agreements not
specifically pledged under the Mortgage or covenanted so to be; (4) electric
energy and other materials or products generated, manufactured, produced or
purchased by the Company for sale, distribution or use in the ordinary course of
its business; and (5) any property heretofore released pursuant to any
provisions of the Mortgage and not heretofore disposed of by the Company;
provided, however, that the property and rights expressly excepted from the lien
and operation of the Mortgage in the above subdivisions (2) and (3) shall (to
the extent permitted by law) cease to be so excepted in the event that the
Trustee or a receiver or trustee shall enter upon and take possession of the
Mortgaged and Pledged Property in the manner provided in Article XII of the
Original Mortgage by reason of the occurrence of a Completed Default as defined
in said Article XII.

            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 in the Mortgage as aforesaid, or
intended so to be, unto the Trustee, and its 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 provisos and
covenants as set forth in the Mortgage, this Thirty-seventh Supplemental
Indenture being supplemental to the Mortgage.

            AND IT IS HEREBY FURTHER CONFIRMED by the Company that all the
terms, conditions, provisos, covenants and provisions contained in the Mortgage
shall affect and apply to the property in the Mortgage described and conveyed,
and to the estates, rights, obligations and duties of the Company and the
Trustee and the beneficiaries of the trust with respect to said property, and to
the Trustee and its successors in the trust, 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 Mortgage, and had been specifically and at length
described in and conveyed to said Trustee by the Original Mortgage as a part of
the property therein stated to be conveyed.

            The Company further covenants and agrees to and with the Trustee and
its successor or successors in such trust under the Mortgage, as follows:

                                       5
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                                    ARTICLE I

                          THIRTY-SIXTH SERIES OF BONDS

            SECTION 1. (I) There shall be a series of bonds designated
"Collateral Series 2004D" (herein sometimes referred to as the "Thirty-sixth
Series"), each of which shall also bear the descriptive title First Mortgage
Bond, and the form thereof, which has been established by Resolution of the
Board of Directors of the Company, is set forth on Exhibit B hereto. Bonds of
the Thirty-sixth Series shall be issued as fully registered bonds in
denominations of One Thousand Dollars and, at the option of the Company, any
amount in excess thereof (the exercise of such option to be evidenced by the
execution and delivery thereof) and shall be dated as in Section 10 of the
Mortgage provided. Each bond of the Thirty-sixth Series shall mature on December
16, 2009 and shall bear interest, be redeemable and have such other terms and
provisions as set forth below.

            (II)  The Bonds of the Thirty-sixth Series shall have the following
terms and characteristics:

            (a)   the Bonds of the Thirty-sixth Series shall be initially
      authenticated and delivered under the Mortgage in the aggregate principal
      amount of $350,000,000;

            (b)   the Bonds of the Thirty-sixth Series shall bear interest at
      the rate of eight per centum (8%) per annum; interest on such bonds shall
      accrue from and including the date of the initial authentication and
      delivery thereof, except as otherwise provided in the form of bond
      attached hereto as Exhibit B; interest on such bonds shall be payable on
      each Interest Payment Date and at Maturity (as each of such terms is
      hereafter defined); and interest on such bonds during any period less than
      one year for which payment is made shall be computed in accordance with
      the Credit Agreement (as hereinafter defined);

            (c)   the principal of and premium, if any, and interest on each
      Bond of the Thirty-sixth Series payable at Maturity shall be payable upon
      presentation thereof at the office or agency of the Company in the Borough
      of Manhattan, The City of New York, in such coin or currency as at the
      time of payment is legal tender for public and private debts; and the
      interest on each Bond of the Thirty-sixth Series (other than interest
      payable at Maturity) shall be payable directly to the registered owner
      thereof;

            (d)   the Bonds of the Thirty-sixth Series shall not be redeemable,
      in whole or in part, at the option of the Company;

            (e)   (i) the Bonds of the Thirty-sixth Series are to be issued and
      delivered to the Administrative Agent (as hereinafter defined) in order to
      provide the benefit of the lien of the Mortgage as security for the
      obligation of the Company under the Credit Agreement to pay the
      Obligations (as hereinafter defined), to the extent and subject to the
      limitations set forth in clauses (iii) and (iv) of this subdivision;

                                       6
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            (ii)  upon the earliest of (A) the occurrence of an Event of Default
      under the Credit Agreement, and further upon the condition that, in
      accordance with the terms of the Credit Agreement, the Commitments (as
      hereinafter defined) shall have been or shall have terminated and any
      Loans (as hereinafter defined) outstanding shall have been declared to be
      or shall have otherwise become due and payable immediately and the
      Administrative Agent shall have delivered to the Company a notice
      demanding redemption of the Bonds of the Thirty-sixth Series which notice
      states that it is being delivered pursuant to Article VII of the Credit
      Agreement, (B) the occurrence of an Event of Default under clause (g) or
      (h) of Article VII of the Credit Agreement, and (C) December 16, 2009,
      then all Bonds of the Thirty-sixth Series shall be redeemed or paid
      immediately at the principal amount thereof plus accrued interest to the
      date of redemption or payment;

            (iii) the obligation of the Company to pay the accrued interest on
      Bonds of the Thirty-sixth Series on any Interest Payment Date prior to
      Maturity (a) shall be deemed to have been satisfied and discharged in full
      in the event that all amounts then due in respect of the Obligations shall
      have been paid or (b) shall be deemed to remain unsatisfied in an amount
      equal to the aggregate amount then due in respect of the Obligations and
      remaining unpaid (not in excess, however, of the amount otherwise then due
      in respect of interest on the Bonds of the Thirty-sixth Series);

            (iv)  the obligation of the Company to pay the principal of and
      accrued interest on Bonds of the Thirty-sixth Series at or after Maturity
      (x) shall be deemed to have been satisfied and discharged in full in the
      event that all amounts then due in respect of the Obligations shall have
      been paid or (y) shall be deemed to remain unsatisfied in an amount equal
      to the aggregate amount then due in respect of the Obligations and
      remaining unpaid (not in excess, however, of the amount otherwise then due
      in respect of principal of and accrued interest on the Bonds of the
      Thirty-sixth Series).

            (v)   the Trustee shall be entitled to presume that the obligation
      of the Company to pay the principal of and interest on the Bonds of the
      Thirty-sixth Series as the same shall become due and payable shall have
      been fully satisfied and discharged unless and until it shall have
      received a written notice from the Administrative Agent, signed by an
      authorized officer thereof, stating that the principal of and/or interest
      on the Bonds of the Thirty-sixth Series has become due and payable and has
      not been fully paid, and specifying the amount of funds required to make
      such payment;

            (f)   no service charge shall be made for the registration of
      transfer or exchange of Bonds of the Thirty-sixth Series;

            (g)   in the event of an application by the Administrative Agent for
      a substituted Bond of the Thirty-sixth Series pursuant to Section 16 of
      the Original Mortgage, the Administrative Agent shall not be required to
      provide any indemnity or pay any expenses or charges as contemplated in
      said Section 16; and

            (h)   the Bonds of the Thirty-sixth Series shall have such other
      terms as are set forth in the form of bond attached hereto as Exhibit B.

                                       7
<PAGE>

            Anything in this Supplemental Indenture or in the Bonds of the
Thirty-sixth Series to the contrary notwithstanding, if, at the time of the
Maturity of such Bonds, the stated aggregate principal amount of such Bonds then
Outstanding shall exceed the aggregate Commitments (as hereinafter defined), the
aggregate principal amount of such Bonds shall be deemed to have been reduced by
the amount of such excess.

            (III) For all purposes of this Thirty-seventh Supplemental
Indenture, except as otherwise expressly provided or unless the context
otherwise requires, the terms defined below shall have the meanings specified:

            "ADMINISTRATIVE AGENT" means The Bank of New York, in its capacity
      as Administrative Agent under the Credit Agreement.

            "BOND DELIVERY AGREEMENT" means the Bond Delivery Agreement, dated
      December 17, 2004 between the Company and the Administrative Agent.

            "CREDIT AGREEMENT" means the Credit Agreement, dated as of December
      17, 2004, among the Company, the banks parties thereto, Bank of America,
      N.A., as Managing Agent, KeyBank National Association, as Documentation
      Agent, U.S. Bank, National Association, as Documentation Agent, Wells
      Fargo Bank, as Documentation Agent and an Issuing Bank, Union Bank of
      California, N.A., as Syndication Agent and an Issuing Bank, and The Bank
      of New York, as Administrative Agent and an Issuing Bank..

            "INTEREST PAYMENT DATE" means March 31, June 30, September 30 and
December 31 of each year, commencing March 31, 2005.

            "MATURITY" means the date on which the principal of the Bonds of the
      Thirty-sixth Series becomes due and payable, whether at stated maturity,
      upon redemption or acceleration, or otherwise.

            "OBLIGATIONS" shall have the meaning specified in the Bond Delivery
      Agreement.

            "COMMITMENTS", "LOANS" and "REVOLVING CREDIT EXPOSURES" shall have
      the meanings specified in the Credit Agreement:

            A copy of the Credit Agreement is on file at the office of the
Administrative Agent at One Wall Street, 18th Floor, New York, NY 10286 and at
the office of the Company at 1411 East Mission Avenue, Spokane, WA 99202.

            (IV)  Upon the delivery of this Thirty-seventh Supplemental
Indenture, Bonds of the Thirty-sixth Series in an aggregate principal amount not
to exceed $350,000,000 are to be issued and will be Outstanding, in addition to
$606,050,000 aggregate principal amount of bonds of prior series Outstanding at
the date of delivery of this Thirty-seventh Supplemental Indenture.

                                       8
<PAGE>

                                   ARTICLE II

                            MISCELLANEOUS PROVISIONS

            SECTION 1. The terms defined in the Original Mortgage shall, for all
purposes of this Thirty-seventh Supplemental Indenture, have the meanings
specified in the Original Mortgage.

            SECTION 2. The Trustee hereby confirms its acceptance of the trusts
in the Original Mortgage declared, provided, created or supplemented and agrees
to perform the same upon the terms and conditions in the Original Mortgage set
forth, including the following:

            The Trustee shall not be responsible in any manner whatsoever for or
in respect of the validity or sufficiency of this Thirty-seventh Supplemental
Indenture or for or in respect of the recitals contained herein, all of which
recitals are made by the Company solely. Each and every term and condition
contained in Article XVI of the Original Mortgage, shall apply to and form part
of this Thirty-seventh Supplemental Indenture with the same force and effect as
if the same were herein set forth in full, with such omissions, variations and
insertions, if any, as may be appropriate to make the same conform to the
provisions of this Thirty-seventh Supplemental Indenture.

            SECTION 3. Whenever in this Thirty-seventh Supplemental Indenture
either of the parties hereto is named or referred to, this shall, subject to the
provisions of Articles XV and XVI of the Original Mortgage be deemed to include
the successors and assigns of such party, and all the covenants and agreements
in this Thirty-seventh Supplemental Indenture contained by or on behalf of the
Company, or by or on behalf of the Trustee, or either of them, shall, subject as
aforesaid, bind and inure to the respective benefits of the respective
successors and assigns of such parties, whether so expressed or not.

            SECTION 4. Nothing in this Thirty-seventh Supplemental Indenture,
expressed or implied, is intended, or shall be construed, to confer upon, or to
give to, any person, firm or corporation, other than the parties hereto and the
holders of the bonds and coupons Outstanding under the Mortgage, any right,
remedy or claim under or by reason of this Thirty-seventh Supplemental Indenture
or any covenant, condition, stipulation, promise or agreement hereof, and all
the covenants, conditions, stipulations, promises and agreements in this
Thirty-seventh Supplemental Indenture contained by or on behalf of the Company
shall be for the sole and exclusive benefit of the parties hereto, and of the
holders of the bonds and of the coupons Outstanding under the Mortgage.

            SECTION 5. This Thirty-seventh Supplemental Indenture shall be
executed in several counterparts, each of which shall be an original and all of
which shall constitute but one and the same instrument.

            SECTION 6. The titles of the several Articles of this Thirty-seventh
Supplemental Indenture shall not be deemed to be any part thereof.

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

                                       9
<PAGE>

            IN WITNESS WHEREOF, on the 17th day of December, 2004, AVISTA
CORPORATION has caused its corporate name to be hereunto affixed, and this
instrument to be signed and sealed by its President or one of its Vice
Presidents, and its corporate seal to be attested by its Corporate Secretary or
one of its Assistant Corporate Secretaries for and in its behalf, all in The
City of Spokane, Washington, as of the day and year first above written; and on
the 17th day of December, 2004, CITIBANK, N.A., has caused its corporate name to
be hereunto affixed, and this instrument to be signed and sealed by its
President or one of its Vice Presidents or one of its Senior Trust Officers or
one of its Trust Officers and its corporate seal to be attested by one of its
Vice Presidents or one of its Trust Officers, all in The City of New York, New
York, as of the day and year first above written.

                                         AVISTA CORPORATION

                                         By:    /s/ Malyn K. Malquist
                                             ----------------------------------
                                                    Senior Vice President

Attest:

 /s/ Susan Y. Miner
-------------------------------------
     Assistant Corporate Secretary

Executed, sealed and delivered
 by AVISTA CORPORATION
 in the presence of:

 /s/ Diane C. Thoren
-------------------------------------
     Diane C. Thoren

 /s/ Paul W. Kimball
-------------------------------------
     Paul W. Kimball

                                       10
<PAGE>

                                         CITIBANK, N.A., AS TRUSTEE

                                         By:   /s/ Wafaa Orfy
                                             ----------------------------------
                                             Wafaa Orfy, Vice President

Attest:

 /s/ Nancy Forte
-------------------------------------
 Nancy Forte, Assistant Vice President

Executed, sealed and delivered
 by CITIBANK, N.A.,
 as trustee. in the presence of:

 /s/ R.T. Kirchner
-------------------------------------
     R.T. Kirchner
     Vice President

 /s/ John J. Byrnes
-------------------------------------
     John J. Byrnes
     Vice President

                                       11
<PAGE>

STATE OF WASHINGTON )
                    ) ss.:
COUNTY OF SPOKANE   )

            On the 17th day of December 2004, before me personally appeared
Malyn Malquist, to me known to be a Senior Vice President of AVISTA CORPORATION,
one of the corporations that executed the within and foregoing instrument, and
acknowledged said instrument to be the free and voluntary act and deed of said
Corporation for the uses and purposes therein mentioned and on oath stated that
he was authorized to execute said instrument and that the seal affixed is the
corporate seal of said Corporation.

            On the 17th day of December 2004, before me, Sue Miner, a Notary
Public in and for the State and County aforesaid, personally appeared Malyn
Malquist, known to me to be a Senior Vice President of AVISTA CORPORATION, one
of the corporations that executed the within and foregoing instrument and
acknowledged to me that such Corporation executed the same.

            IN WITNESS WHEREOF, I have hereunto set my hand and affixed my
official seal the day and year first above written.

                                          /s/ Sue Miner
                                        ----------------------------------------
                                                  Notary Public

                                              Sue Miner
                                              Notary Public
                                              Commission Expires August 20, 2007
                                              State of Washington

                                       12
<PAGE>

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

            On the 13th day of December 2004, before me personally appeared
Wafaa Orfy, to me known to be a Vice President of CITIBANK, N.A., one of the
corporations that executed the within and foregoing instrument, and acknowledged
said instrument to be the free and voluntary act and deed of said Corporation
for the uses and purposes therein mentioned and on oath stated that he was
authorized to execute said instrument and that the seal affixed is the corporate
seal of said Corporation.

            On the 13th day of December 2004, before me, a Notary Public in and
for the State and County aforesaid, personally appeared Wafaa Orfy, known to me
to be an Vice President of CITIBANK, N.A., one of the corporations that executed
the within and foregoing instrument and acknowledged to me that such Corporation
executed the same.

            IN WITNESS WHEREOF, I have hereunto set my hand and affixed my
official seal the day and year first above written.

                                          /s/ Nanette Murphy
                                        ----------------------------------------
                                                      Notary Public

                                        NANETTE MURPHY
                                        Notary Public, State of New York
                                        No. 01MU6086415
                                        Qualified in Kings County
                                        Commission Expires 1/21/07

                                       13
<PAGE>

                                                                       EXHIBIT A

                        MORTGAGE, SUPPLEMENTAL INDENTURES
                               AND SERIES OF BONDS

<TABLE>
<CAPTION>
 MORTGAGE OR                                                                  PRINCIPAL         PRINCIPAL
SUPPLEMENTAL                 DATED AS                      SERIES               AMOUNT            AMOUNT
  INDENTURE                     OF           NO.         DESIGNATION            ISSUED         OUTSTANDING
------------             -----------------   ---   ----------------------    ------------      -----------
<S>                      <C>                 <C>   <C>                       <C>               <C>
Original                 June 1, 1939        1     3-1/2% Series due 1964    $ 22,000,000         None
First                    October 1, 1952     2     3-3/4% Series due 1982      30,000,000         None
Second                   May 1, 1953         3     3-7/8% Series due 1983      10,000,000         None
Third                    December 1, 1955                   None
Fourth                   March 15, 1957                     None
Fifth                    July 1, 1957        4     4-7/8% Series due 1987      30,000,000         None
Sixth                    January 1, 1958     5     4-1/8% Series due 1988      20,000,000         None
Seventh                  August 1, 1958      6     4-3/8% Series due 1988      15,000,000         None
Eighth                   January 1, 1959     7     4-3/4% Series due 1989      15,000,000         None
Ninth                    January 1, 1960     8     5-3/8% Series due 1990      10,000,000         None
Tenth                    April 1, 1964       9     4-5/8% Series due 1994      30,000,000         None
Eleventh                 March 1,1965        10    4-5/8% Series due 1995      10,000,000         None
Twelfth                  May 1, 1966                        None
Thirteenth               August 1, 1966      11    6    % Series due 1996      20,000,000         None
Fourteenth               April 1, 1970       12    9-1/4% Series due 2000      20,000,000         None
Fifteenth                May 1, 1973         13    7-7/8% Series due 2003      20,000,000         None
Sixteenth                February 1, 1975    14    9-3/8% Series due 2005      25,000,000         None
Seventeenth              November 1, 1976    15    8-3/4% Series due 2006      30,000,000         None
Eighteenth               June 1, 1980                       None
Nineteenth               January 1, 1981     16    14-1/8% Series due 1991     40,000,000         None
Twentieth                August 1, 1982      17      15-3/4% Series due        60,000,000         None
                                                         1990-1992
Twenty-First             September 1, 1983   18    13-1/2% Series due 2013     60,000,000         None
Twenty-Second            March 1, 1984       19    13-1/4% Series due 1994     60,000,000         None
Twenty-Third             December 1, 1986    20    9-1/4% Series due 2016      80,000,000         None
Twenty-Fourth            January 1, 1988     21    10-3/8% Series due 2018     50,000,000         None
Twenty-Fifth             October 1, 1989     22    7-1/8% Series due 2013      66,700,000         None
                                             23    7-2/5% Series due 2016      17,000,000         None
Twenty-Sixth             April 1, 1993       24     Secured Medium-Term       250,000,000       89,500,000
                                                           Notes,
                                                   Series A ($250,000,000
                                                         authorized)
Twenty-Seventh           January 1, 1994     25     Secured Medium-Term       161,000,000       59,000,000
                                                           Notes,
                                                   Series B ($250,000,000
                                                         authorized)
Twenty-Eighth            September 1, 2001   26    Collateral Series due      220,000,000         None
                                                            2002
Twenty-Ninth             December 1, 2001    27    7.75% Series due 2007      150,000,000      150,000,000
Thirtieth                May 1, 2002         28    Collateral Series due      225,000,000         None
                                                            2003
Thirty-First             May 1, 2003         29    Collateral Series due      245,000,000         None*
                                                            2004
Thirty-Second            September 1, 2003   30    6.125% Series due 2013      45,000,000       45,000,000
Thirty-Third             May 1, 2004         31    Collateral Series due      350,000,000      350,000,000*
                                                            2005
Thirty-Fourth            November 1, 2004    32    5.45% Series due 2019       90,000,000       90,000,000
Thirty-Fifth             December 1, 2004    33      Collateral Series         88,850,000       88,850,000
                                                           2004A
</TABLE>

<PAGE>

<TABLE>
<S>                      <C>                 <C>   <C>                       <C>               <C>
Thirty-sixth             December 1, 2004    34      Collateral Series         66,700,000       66,700,000
                                                           2004B
                                             35      Collateral Series         17,000,000       17,000,000
                                                           2004C
</TABLE>

*To be retired in connection with the authentication and delivery of the bonds
of the Thirty-sixth series.

                                       A-2
<PAGE>

                                                                       EXHIBIT B

                                 (FORM OF BOND)

              THIS BOND IS NON-TRANSFERABLE, EXCEPT TO A SUCCESSOR
       ADMINISTRATIVE AGENT UNDER THE CREDIT AGREEMENT REFERRED TO HEREIN.

                               AVISTA CORPORATION

                              First Mortgage Bond,
                             Collateral Series 2004D

REGISTERED                                                            REGISTERED

NO. _________________                                            $______________

            AVISTA CORPORATION, a corporation of the State of Washington
(hereinafter called the Company), for value received, hereby promises to pay to

, as Administrative Agent under the Credit Agreement hereinafter referred to or
registered assigns, on December 16, 2009,

                                                                         DOLLARS

and to pay the registered owner hereof interest thereon from December __, 2004
in arrears on March 31, June 30, September 30 and December 31 of each year,
commencing March 31, 2005 (each such date being hereinafter called an "Interest
Payment Date") and at Maturity (as hereinafter defined), at the rate of eight
per centum (8%) per annum computed as provided in the Thirty-seventh
Supplemental Indenture hereinafter referred to, until the Company's obligation
with respect to the payment of such principal shall have been discharged. The
principal of and premium, if any, and interest on this bond payable at Maturity
shall be payable upon presentation hereof at the office or agency of the Company
in the Borough of Manhattan, The City of New York, 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. The interest on this bond (other than interest payable
at Maturity) shall be paid directly to the registered owner hereof. Interest
payable at Maturity shall be paid to the person to whom principal shall be paid.
As used herein, the term "Maturity" shall mean the date on which the principal
of this bond becomes due and payable, whether at stated maturity, upon
redemption or acceleration, or otherwise.

            This bond is one of an issue of bonds of the Company issuable in
series and is one of a series known as its First Mortgage Bonds, Collateral
Series 2004D all bonds of all such issue of series being issued and issuable
under and equally secured (except insofar as any sinking or

<PAGE>

other fund, established in accordance with the provisions of the Mortgage
hereinafter mentioned, may afford additional security for the bonds of any
particular series) by a Mortgage and Deed of Trust, dated as of June 1, 1939,
executed by the Company (formerly known as The Washington Water Power Company)
to City Bank Farmers Trust Company and Ralph E. Morton, as Trustees (Citibank,
N.A., successor Trustee to both said Trustees). Such mortgage and deed of trust
has been amended and supplemented by various supplemental indentures, including
the Thirty-seventh Supplemental Indenture, dated as of December 1, 2004 (the
"Thirty-seventh Supplemental Indenture") and, as so amended and supplemented, is
herein called the "Mortgage". Reference is made to the Mortgage for a
description of the property mortgaged and pledged, the nature and extent of the
security, the rights of the holders of the bonds and of the Trustee in respect
thereof, the duties and immunities of the Trustee and the terms and conditions
upon which the bonds are and are to be secured and the circumstances under which
additional bonds may be issued. By its acceptance of this bond, the holder
hereof is deemed to have consented and agreed to all of the terms and provisions
of the Mortgage. The Mortgage may be modified or altered by affirmative vote of
the holders of at least 60% in principal amount of the bonds outstanding under
the Mortgage, considered as one class, or, if the rights of one or more, but
less than all, series of bonds then outstanding are to be affected, then such
modification or alteration may be effected with the affirmative vote only of 60%
in principal amount of the bonds outstanding of the series so to be affected,
considered as one class, and, furthermore, for limited purposes, the Mortgage
may be modified or altered without any consent or other action of holders of any
series of bonds. No modification or alteration shall, however, permit an
extension of the Maturity of the principal of, or interest on, this bond or a
reduction in such principal or the rate of interest hereon or any other
modification in the terms of payment of such principal or interest or the
creation of any lien equal or prior to the lien of the Mortgage or deprive the
holder of a lien on the mortgaged and pledged property without the consent of
the holder hereof.

            The bonds of this series are not redeemable, in whole or in part, at
the option of the Company.

            The bonds of this series have been issued and delivered to The Bank
of New York, as Administrative Agent under the Credit Agreement (as such terms
are defined in the Thirty-seventh Supplemental Indenture) in order to provide
the benefit of the lien of the Mortgage as security for the obligation of the
Company under the Credit Agreement to pay the Obligations (as so defined), to
the extent and subject to the limitations set forth below.

            Upon the earliest of (A) the occurrence of an Event of Default under
the Credit Agreement, and further upon the condition that, in accordance with
the terms of the Credit Agreement, the Commitments (as defined in the
Thirty-seventh Supplemental Indenture) shall have been or shall have terminated
and any Loans (as so defined) outstanding shall have been declared to be or
shall have otherwise become due and payable immediately and the Administrative
Agent shall have delivered to the Company a notice demanding redemption of the
bonds of this series which notice states that it is being delivered pursuant to
Article VII of the Credit Agreement, (B) the occurrence of an Event of Default
under clause (g) or (h) of Article VII of the Credit Agreement, and (C) December
16, 2009, then all bonds of this series shall be

                                       B-2
<PAGE>

redeemed or paid immediately at the principal amount thereof plus accrued
interest to the date of redemption or payment.

            The obligation of the Company to pay the accrued interest on bonds
of this series on any Interest Payment Date prior to Maturity (a) shall be
deemed to have been satisfied and discharged in full in the event that all
amounts then due in respect of the Obligations shall have been paid or (b) shall
be deemed to remain unsatisfied in an amount equal to the aggregate amount then
due in respect of the Obligations and remaining unpaid (not in excess, however,
of the amount otherwise then due in respect of interest on the bonds of this
series).

            The obligation of the Company to pay the principal of and accrued
interest on bonds of this series at or after Maturity (x) shall be deemed to
have been satisfied and discharged in full in the event that all amounts then
due in respect of the Obligations shall have been paid or (y) shall be deemed to
remain unsatisfied in an amount equal to the aggregate amount then due in
respect of the Obligations and remaining unpaid (not in excess, however, of the
amount otherwise then due in respect of principal of and accrued interest on the
bonds of this series).

            Anything in this bond to the contrary notwithstanding, if, at the
time of the Maturity of the bonds of this series, the stated aggregate principal
amount of such bonds then outstanding shall exceed the aggregate Commitments (as
defined in the Thirty-seventh Supplemental Indenture), the aggregate principal
amount of such bonds shall be deemed to have been reduced by the amount of such
excess.

            The principal hereof may be declared or may become due prior to the
stated maturity date on the conditions, in the manner and at the time set forth
in the Mortgage, upon the occurrence of a Completed Default as in the Mortgage
provided.

            As provided in the Mortgage and subject to certain limitations
therein set forth, this bond or any portion of the principal amount hereof will
be deemed to have been paid if there has been irrevocably deposited with the
Trustee moneys or direct obligations of or obligations guaranteed by the United
States of America, the principal of and interest on which when due, and without
regard to any reinvestment thereof, will provide moneys which, together with
moneys so deposited, will be sufficient to pay when due the principal of and
premium, if any, and interest on this bond when due.

            The Mortgage contains terms, provisions and conditions relating to
the consolidation or merger of the Company with or into, and the conveyance or
other transfer, or lease, of assets to, another Corporation and to the
assumption by such other Corporation, in certain circumstances, of all of the
obligations of the Company under the Mortgage and on the bonds secured thereby.

            This bond is non-transferable except as required to effect transfer
to any successor administrative agent under the Credit Agreement, any such
transfer to be made at the office or agency of the Company in the Borough of
Manhattan, The City of New York, upon surrender and cancellation of this bond,
together with a written instrument of transfer whenever required by the Company
duly executed by the registered owner or by its duly authorized

                                       B-3
<PAGE>

attorney, and, thereupon, a new fully registered bond of the same series for a
like principal amount will be issued to the transferee in exchange herefor as
provided in the Mortgage. 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 and for all other purposes.

            In the manner prescribed in the Mortgage, any bonds of this series,
upon surrender thereof for cancellation at the office or agency of the Company
in the Borough of Manhattan, The City of New York, are exchangeable for a like
aggregate principal amount of bonds of the same series of other authorized
denominations.

            No recourse shall be had for the payment of the principal of or
interest on this bond against any incorporator or any past, present or future
subscriber to the capital stock, stockholder, officer or director of the Company
or of any predecessor or successor corporation, as such, either directly or
through the Company or any predecessor or successor corporation, under any rule
of law, statute or constitution or by the enforcement of any assessment or
otherwise, all such liability of incorporators, subscribers, stockholders,
officers and directors being released by the holder or owner hereof by the
acceptance of this bond and being likewise waived and released by the terms of
the Mortgage.

            This bond shall not become obligatory until Citibank, N.A., the
Trustee under the Mortgage, or its successor thereunder, shall have signed the
form of certificate endorsed hereon.

            IN WITNESS WHEREOF, AVISTA CORPORATION has caused this bond to be
signed in its corporate name by its President or one of its Vice Presidents by
his signature or a facsimile thereof, and its corporate seal to be impressed or
imprinted hereon and attested by its Corporate Secretary or one of its Assistant
Corporate Secretaries by his signature or a facsimile thereof.

Dated:                                     AVISTA CORPORATION

                                           By: __________________________

ATTEST: ___________________________

                                       B-4
<PAGE>

                              TRUSTEE'S CERTIFICATE

            This bond is one of the bonds, of the series herein designated,
described or provided for in the within-mentioned Mortgage.

                                        CITIBANK, N.A.
                                        Trustee

                                        By: ____________________________
                                                 Authorized Officer

                                       B-5
<PAGE>

            FOR VALUE RECEIVED the undersigned hereby sells, assigns and
transfers unto

________________________________________

     [please insert social security or other identifying number of assignee]

________________________________________

            [please print or typewrite name and address of assignee]

________________________________________

the within bond of AVISTA CORPORATION and does hereby irrevocably constitute and
appoint _____________, Attorney, to transfer said bond on the books of the
within-mentioned Company, will full power of substitution in the premises.

Dated: ________________

_______________________            Notice: The signature to this assignment must
                                   correspond with the name as written upon the
                                   face of the bond in every particular without
                                   alteration or enlargement or any change
                                   whatsoever.

                                       B-6<PAGE>

                                                                     EXHIBIT 4.5

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

                               AVISTA CORPORATION

                                       TO

                           JPMORGAN CHASE BANK, N.A.,

                                                TRUSTEE

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

                          SUPPLEMENTAL INDENTURE NO. 1

                          DATED AS OF DECEMBER 1, 2004

                                 SUPPLEMENTAL TO
                      INDENTURE, DATED AS OF APRIL 1, 1998

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

                               DELIVERY TO TRUSTEE

                                       OF
                  FIRST MORTGAGE BONDS, COLLATERAL SERIES 2004A

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

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

<PAGE>

      SUPPLEMENTAL INDENTURE NO. 1, dated as of December 1, 2004, between AVISTA
CORPORATION, a corporation organized and existing under the laws of the State of
Washington (hereinafter sometimes called the "Company"), and JPMORGAN CHASE
BANK, N.A., a national banking corporation and successor to The Chase Manhattan
Bank, trustee (hereinafter sometimes called the "Trustee"), under the Indenture,
dated as of April 1, 1998 (hereinafter called the "Original Indenture"), this
Supplemental Indenture No. 1 being supplemental thereto. The Original Indenture
and any and all indentures and instruments supplemental thereto are hereinafter
sometimes collectively called the "Indenture."

                             RECITALS OF THE COMPANY

      The Original Indenture was duly authorized, executed and delivered by the
Company to provide for the issuance from time to time of its Securities; to be
issued in one or more series as contemplated therein;

      The Company has heretofore executed and delivered to the Trustee the
Series C Officer's Certificate establishing the Series C Notes (as such terms
are hereinafter defined) as a series of Securities under the Indenture; and the
Company has heretofore issued, and there remain outstanding, the Series C Notes
as set forth in Schedule A hereto.

      The Company has heretofore established and issued hereunder Securities in
addition to the Series C Notes, but none of such additional Securities remain
Outstanding.

      The Company desires to deliver to the Trustee, as Secured Obligations (as
hereinafter defined), $88,850,000 in aggregate principal amount of its First
Mortgage Bonds, Collateral Series 2004A, issued under the Mortgage.

      The Company further desires to set forth the terms and conditions under
which Collateral Bonds (as hereinafter defined) shall be delivered to and held
by the Trustee.

      NOW, THEREFORE, THIS SUPPLEMENTAL INDENTURE NO. 1 WITNESSETH, that, in
consideration of the premises and of the purchase of the Benefitted Securities
(as hereinafter defined) by the Holders thereof, and in order to provide for the
delivery to the Trustee of the Company's First Mortgage Bonds, Collateral Series
2004A, and to set forth the terms and conditions relating to the surrender,
transfer and voting of, the application of payments on and other matters in
respect of, the Collateral Bonds (as hereinafter defined), the Company hereby
covenants and agrees to and with the Trustee, for the equal and ratable benefit
of all Holders of Benefitted Securities from time to time Outstanding, as
follows:

<PAGE>

                                   ARTICLE ONE

                                   DEFINITIONS

SECTION 1.01.     TERMS DEFINED IN ORIGINAL INDENTURE.

      All capitalized terms used herein without definition have the meanings
assigned thereto in the Original Indenture.

SECTION 1.02.     TERMS DEFINED IN SERIES C OFFICER'S CERTIFICATE.

The terms

            "BENEFITTED SECURITIES"
            "DEBT"
            "EXCEPTED PROPERTY"
            "LIEN"
            "PERMITTED SECURED DEBT"
            "SECURED OBLIGATIONS"

have the meanings assigned thereto in the Series C Officer's Certificate.

SECTION 1.03.     ADDITIONAL TERMS.

      The following additional terms have the meanings indicated, unless the
context otherwise requires:

      "COLLATERAL BONDS" means the First Mortgage Bonds, Collateral Series
2004A, and all other bonds issued and authenticated under the Mortgage and
delivered to and held by the Trustee as Secured Obligations.

      "MORTGAGE" means the Mortgage and Deed of Trust, dated as of June 1, 1939,
between the Company and Citibank, N.A., successor trustee, as amended and
supplemented.

      "MORTGAGE TRUSTEE" means the trustee under the Mortgage.

      "SERIES C NOTES" means the Company's Medium-Term Notes, Series C,
established as a series of Securities under the Indenture.

      "SERIES C OFFICER'S CERTIFICATE" means the Officer's Certificate, dated
April 24, 1998, executed by an Authorized Officer of the Company and delivered
to the Trustee, establishing the Series C Notes as a series of Securities under
the Indenture.

                                       2
<PAGE>

                                   ARTICLE TWO

                              THE COLLATERAL BONDS

SECTION 2.01.     DELIVERY OF COLLATERAL BONDS

            (a)   In order to provide the benefit of the lien of the Mortgage to
secure the obligation of the Company to pay the principal of the Benefitted
Securities, the Company hereby delivers to the Trustee its First Mortgage Bonds,
Collateral Series 2004A issued, authenticated and delivered under the Mortgage
in the respective principal amounts, and with the respective stated maturity
dates, set forth below:

<TABLE>
<CAPTION>
Aggregate Principal Amount            Stated Maturity Date
--------------------------            --------------------
<S>                                   <C>
        $13,850,000                   December 10, 2007
         25,000,000                   December 10, 2007
         25,000,000                   October 26, 2010
         25,000,000                   June 19, 2028
        -----------
        $88,850,000
</TABLE>

      The First Mortgage Bonds, Collateral Series 2004A, do not bear interest.

      The Trustee hereby acknowledges receipt of the First Mortgage Bonds,
Collateral Series 2004A.

            (b)   It is recognized that the Company may establish one or more
additional series of Benefitted Securities under the Indenture after the date
hereof and, in connection with the establishment of each such series of
Benefitted Securities, deliver to the Trustee, as Secured Obligations,
additional Collateral Bonds of one or more series, as contemplated in the Series
C Officer's Certificate and as to be so contemplated in the Officer's
Certificate establishing such additional series of Benefitted Securities. All
Collateral Bonds delivered to the Trustee are and are to be so delivered to, and
shall be held by, the Trustee subject to the terms and provisions set forth in
this Article Two.

SECTION 2.02.     REGISTRATION AND OWNERSHIP OF COLLATERAL BONDS.

      The Collateral Bonds shall be registered in the name of the Trustee or its
nominee and shall be owned and held by the Trustee, subject to the provisions of
this Indenture, for the benefit of the Holders of all Benefitted Securities from
time to time Outstanding, and the Company shall have no interest therein. The
Trustee shall be entitled to exercise all rights of securityholders under the
Mortgage either in its discretion or as otherwise provided in this Supplemented
Indenture.

SECTION 2.03.     PAYMENTS ON COLLATERAL BONDS.

            (a)   Any payment by the Company of principal of or premium or
interest on the Collateral Bonds of any series and stated maturity shall be
applied by the Trustee to the payment of any principal, premium or interest, as
the case may be, in respect of the Benefitted Securities of the corresponding
series and Stated Maturity which

                                       3
<PAGE>

is then due, and, to the extent of such application, the obligation of the
Company hereunder to make such payment in respect of such Benefitted Securities
shall be deemed to have been satisfied and discharged.

      If, at the time of any such payment of principal of Collateral Bonds of
any series and stated maturity, there shall be no principal then due in respect
of the Benefitted Securities of the corresponding series and stated maturity,
such payment in respect of the Collateral Bonds shall be held by the Trustee and
applied to the payment of principal of such Benefitted Securities from time to
time as such principal becomes due. Pending such application, proceeds of the
payment of principal of such Collateral Bonds shall, at the direction of the
Company evidenced by Company Order, be invested in Eligible Obligations maturing
on or prior to the Stated Maturity of such Benefitted Securities; it being
understood that, subject to the terms and provisions of Article Six of the
Original Indenture, such proceeds, together with other moneys deposited with or
held by the Trustee, may be applied as provided in said Article Six.

      If, at the time of any such payment of premium or interest on Collateral
Bonds of any series and stated maturity, there shall be no premium or interest,
as the case may be, then due in respect of the Benefitted Securities of the
corresponding series and maturity, such payment in respect of such Collateral
Bonds shall be remitted to the Company upon receipt by the Trustee of a Company
Order requesting the same, together with an Officer's Certificate stating that
no Event of Default has occurred and is continuing; provided, however, that, if
an Event of Default shall have occurred and be continuing, such proceeds shall
be held by the Trustee until such Event of Default shall have been cured or
waived.

            (b)   Any payment by the Company hereunder of principal of or
premium or interest on Benefitted Securities of any series and Stated Maturity
(other than by the application of the proceeds of a payment in respect of
Collateral Bonds) shall, to the extent thereof, be deemed, for all purposes of
the Indenture, to satisfy and discharge the obligation of the Company, if any,
to make a payment of principal, premium or interest, as the case may be, in
respect of the Collateral Bonds of the corresponding series and maturity which
is then due.

            (c)   (i)   The Trustee hereby waives notice of any mandatory
redemption of Collateral Bonds.

                  (ii)  The Trustee hereby waives notice of any optional
            redemption of Collateral Bonds, as such notice would otherwise be
            required by the Mortgage; provided, however, that in the event of
            any such optional redemption, the Company shall, not less than three
            Business Days prior to the Redemption Date, provide written notice
            to the Trustee of such optional redemption in the manner set forth
            in Section 105 of the Indenture.

                                       4
<PAGE>

SECTION 2.04.     SURRENDER OF COLLATERAL BONDS.

      At the time any Benefitted Securities of any series and stated maturity
cease to be Outstanding (other than as a result of the application of the
proceeds of the payment or redemption of Collateral Bonds), the Trustee shall
surrender to, or upon the order of, the Company an equal principal amount of
Collateral Bonds of the corresponding series and maturity.

SECTION 2.05.     NO TRANSFER OF COLLATERAL BONDS.

      Anything in the Indenture to the contrary notwithstanding, the Trustee
shall not sell, assign or otherwise transfer any Collateral Bonds except to a
successor trustee under the Indenture and except as provided in Section 2.04.
The Company may take such actions as it shall deem necessary, desirable or
appropriate to effect compliance with such restrictions on transfer, including
the placing of a legend on each such Collateral Bond and the issuance of
stop-transfer instructions to the Mortgage Trustee or any other transfer agent
under the Mortgage.

SECTION 2.06.     VOTING OF COLLATERAL BONDS.

      The Trustee shall, as the holder of the Collateral Bonds, attend such
meeting or meetings of bondholders under the Mortgage or, at its option, deliver
its proxy in connection therewith, as relate to matters with respect to which
it, as such holder, is entitled to vote or consent. So long as no Event of
Default under the Indenture shall have occurred and be continuing, either at any
such meeting or meetings, or otherwise when the consent of the holders of the
Collateral Bonds outstanding under the Mortgage is sought without a meeting, the
Trustee shall vote as holder of the Collateral Bonds, or shall consent with
respect thereto, proportionately with the vote or consent of the holders of all
other bonds outstanding under the Mortgage the holders of which are eligible to
vote or consent, as indicated in a Mortgage Bondholder's Certificate delivered
to the Trustee; provided, however, that the Trustee shall not so vote in favor
of, or so consent to, any amendment or modification of the Mortgage which, if it
were an amendment or modification of the Indenture, would require the consent of
Holders, without the prior consent, obtained in the manner prescribed in Section
1102 of the Original Indenture, of Holders of Securities which would be required
under said Section 1102 for such an amendment or modification of the Indenture.

      For purposes of this Section, "Mortgage Bondholder's Certificate" means a
certificate signed by the temporary chairman, the temporary secretary, the
permanent chairman, the permanent secretary, or an inspector of votes at any
meeting or meetings of bondholders under the Mortgage, or by the Mortgage
Trustee in the case of consents of such bondholders which are sought without a
meeting, which states what the signer thereof reasonably believes will be the
proportionate votes or consents of the holders of all bonds (other than the
Collateral Bonds delivered to and held by the Trustee) outstanding under the
Mortgage and counted for the purposes of determining whether such bondholders
have approved or consented to the matter put before them.

                                       5
<PAGE>

SECTION 2.07.     DISCHARGE OF MORTGAGE.

      The Trustee shall surrender for cancellation to the Mortgage Trustee all
Collateral Bonds then held by it upon receipt by the Trustee of:

            (a)   a Company Order requesting such surrender for cancellation of
such Collateral Bonds;

            (b)   an Officer's Certificate to the effect that no bonds are
outstanding under the Mortgage other than Collateral Bonds held by the Trustee
and that promptly upon such surrender the Mortgage will be satisfied and
discharged pursuant to the terms thereof;

            (c)   an Opinion of Counsel to the effect that, or a report of a
title insurance company demonstrating that, upon satisfaction and discharge of
the Mortgage, the property formerly subject to the Lien of Mortgage, to the
extent the same is property of the Company and does not constitute Excepted
Property, will be subject to no Lien which secures Debt other than Permitted
Secured Debt; and

            (d)   copies of the instruments of conveyance, assignment and
transfer, if any, specified in the Opinion of Counsel or title report delivered
pursuant to clause (c) above.

                                  ARTICLE THREE

                            MISCELLANEOUS PROVISIONS

SECTION 3.01.     MISCELLANEOUS

      This Supplemental Indenture No. 1 is a supplement to the Indenture. As
supplemented by this Supplemental Indenture No. 1, the Indenture is in all
respects ratified, approved and confirmed, and the Indenture and this
Supplemental Indenture No. 1 shall together constitute one and the same
instrument.

      The recitals contained herein shall be taken as the statements of the
Company, and the Trustee assumes no responsibility for their correctness. The
Trustee makes no representations as to the validity or sufficiency of this
Supplemental Indenture No. 1.

                                       6
<PAGE>

      IN WITNESS WHEREOF, the parties hereto have caused this Supplemental
Indenture No. 1 to be duly executed as of the day and year first above written.

                                       AVISTA CORPORATION

                                       By: /s/ Malyn K. Malquist
                                          ------------------------------------
                                          Name:  Malyn K. Malqist
                                          Title: Senior Vice President, Chief
                                                 Financial Officer and Treasurer

                                       JPMORGAN CHASE BANK, N.A., Trustee

                                       By:  /s/ James V. Myers
                                          ------------------------------------
                                          Name:  James V. Myers
                                          Title: Vice President

<PAGE>

                                                                      SCHEDULE A

                        BENEFITTED SECURITIES OUTSTANDING

<TABLE>
<CAPTION>
SERIES OF               SERIES             PRINCIPAL
SECURITIES           DESIGNATION             AMOUNT           STATED MATURITY
----------           -----------             ------           ---------------
<S>                <C>                    <C>                 <C>
    1              Medium-Term
                   Notes, Series C        $13,850,000          Dec. 10, 2007
                                           25,000,000          Dec. 10, 2007
                                           25,000,000          Oct. 26, 2010
                                           25,000,000          June 19, 2008
                                          -----------
                                          $88,850,000
</TABLE>

Source: [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00076-of-00352.parquet"}, [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00076-of-00352.parquet"}]]