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                                                                  Execution Copy
                                                                     EXHIBIT 4.4




                          THIRD SUPPLEMENTAL INDENTURE


                          DATED AS OF November 15, 2001





                         ALLIANT ENERGY RESOURCES, INC.,
                                    Company,


                           ALLIANT ENERGY CORPORATION,
                                  As Guarantor,

                                       and

                         U.S. BANK NATIONAL ASSOCIATION,
                                   as Trustee





                       Third Supplemental Indenture to the
                                    Indenture
                          dated as of November 4, 1999


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                  THIRD SUPPLEMENTAL INDENTURE, dated as of November 15, 2001
(the "THIRD SUPPLEMENTAL INDENTURE"), among ALLIANT ENERGY RESOURCES, INC., a
Wisconsin corporation (the "COMPANY"), ALLIANT ENERGY CORPORATION, a Wisconsin
corporation, as guarantor (the "GUARANTOR"), and U.S. BANK NATIONAL ASSOCIATION,
as successor to FIRSTAR BANK, N.A., as Trustee (the "TRUSTEE").

                    RECITALS OF THE COMPANY AND THE GUARANTOR

                  The Company and the Guarantor have heretofore executed and
delivered to the Trustee an Indenture, dated as of November 4, 1999 (as
supplemented by the First Supplemental Indenture dated as of November 4, 1999
and the Second Supplemental Indenture dated as of February 1, 2000 and as may be
further supplemented and amended from time to time, the "INDENTURE"), providing
for the issuance from time to time of the Company's unsecured unsubordinated
debentures, notes or other evidences of indebtedness (the "SECURITIES"), to be
issued in one or more series as provided in the Indenture.

                  It is provided in Section 2.02 of the Indenture that the
Company, the Guarantor and the Trustee may enter into indentures supplemental
thereto to establish the form or terms of Securities of any series.

                  The Company and the Guarantor desire to supplement and amend
the Indenture to allow for the issuance of Securities to be initially sold
within the United States to U.S. Persons that are Qualified Institutional Buyers
and issued in the form of one or more Restricted Global Securities deposited
with the Trustee, as custodian for the Depositary, and registered in the name of
a nominee of the Depositary.

                  The Company and the Guarantor desire to set forth the terms
and form of a new series of Restricted Securities to be known as the Company's
7% Senior Notes Due 2011, in an aggregate principal amount of THREE HUNDRED
MILLION DOLLARS ($300,000,000) (the "7% SENIOR NOTES" and guaranteed by the
Guarantor.

                  The 7% Senior Notes and the certificate of authentication to
be borne by the 7% Senior Notes are to be substantially in the form set forth in
Exhibit A hereto.

          NOW, THEREFORE, THIS THIRD SUPPLEMENTAL INDENTURE WITNESSETH:

                  For and in consideration of the premises and the purchase of
the 7% Senior Notes by the Holders (as defined herein) thereof, it is mutually
covenanted and agreed as follows for the equal and ratable benefit of the
Holders of the 7% Senior Notes:

                                   ARTICLE 1.

                                   AMENDMENTS

                  Section 1.01. Article 1 of the Indenture shall be amended by
inserting in Section 1.01 the following new terms with the following definitions
in the appropriate alphabetic positions:


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                           "CLOSING TIME" means, with respect to the 7% Senior
         Notes, November 15, 2001, the date of initial issuance of the
         Securities issued hereunder.

                           "REGISTRATION RIGHTS AGREEMENT" means, with respect
         to the 7% Senior Notes, the Registration Rights Agreement to be
         executed among the Company, the Guarantor and Merrill Lynch, Pierce,
         Fenner & Smith Incorporated, J.P. Morgan Securities, Inc., Banc One
         Capital Markets, Inc., First Union Securities, Inc. and Utendahl
         Capital Partners, as initial purchasers, in connection with the
         offering of the 7% Senior Notes.

                           "THIRD SUPPLEMENTAL INDENTURE" means the Third
         Supplemental Indenture dated as of November 15, 2001, among the
         Company, the Guarantor and the Trustee.

                           "7% SENIOR NOTES" has the meaning set forth in
         Section 2.01 of the Third Supplemental Indenture.

                  Section 1.02. Article 1 of the Indenture shall be amended by
amending and restating in their entirety the following definitions in Section
1.01:

                           "ADDITIONAL INTEREST" has the meaning set forth in
         Section 2.06 of the First Supplemental Indenture.

                           "COMPARABLE TREASURY ISSUE" has the meaning set forth
         in Section 2.07 of the First Supplemental Indenture.

                           "COMPARABLE TREASURY PRICE" has the meaning set forth
         in Section 2.07 of the First Supplemental Indenture.

                           "EVENT DATE" has the meaning set forth in Section
         2.06 of the First Supplemental Indenture.

                           "INDEPENDENT INVESTMENT BANKER" has the meaning set
         forth in Section 2.07 of the First Supplemental Indenture.

                           "REFERENCE TREASURY DEALER" has the meaning set forth
         in Section 2.07 of the First Supplemental Indenture.

                           "REFERENCE TREASURY DEALER QUOTATION" has the meaning
         set forth in Section 2.07 of the First Supplemental Indenture.

                           "REGISTRATION DEFAULT" has the meaning set forth in
         Section 2.06 of the First Supplemental Indenture.

                           "SUPPLEMENTAL INDENTURE" means the First Supplemental
         Indenture, the Second Supplemental Indenture, the Third Supplemental
         Indenture and any further supplemental indentures that the Company, the
         Guarantor and the Trustee may execute from time to time.


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                           "TREASURY YIELD" has the meaning set forth in Section
         2.07 of the First Supplemental Indenture.

                           "7 3/8% SENIOR NOTES" has the meaning set forth in
         Section 2.01 of the First Supplemental Indenture.

                  Section 1.03. The Indenture shall be amended by adding an
exhibit titled "Exhibit F" immediately following Exhibit E of the Indenture.
Exhibit F to the Indenture shall be the form of 7% Senior Notes and the related
guarantee attached as Exhibit A to this Third Supplemental Indenture.

                  Section 1.04. Section 2.19 of the Indenture shall be amended
and restated in its entirety to read as follows:

                           "Section 2.19. RESTRICTIVE LEGENDS. Unless and until
         (i) a Restricted Security is sold pursuant to an effective Shelf
         Registration Statement or (ii) a Restricted Security is exchanged for
         an Exchange Security in an Exchange Offer pursuant to an effective
         Exchange Offer Registration Statement, in each case pursuant to an
         applicable registration rights agreement, each Restricted Global
         Security and Restricted Physical Security shall bear the following
         legend set forth below (the "Restrictive Legend") on the face thereof:

                           THE NOTES HAVE NOT BEEN REGISTERED UNDER THE
                           SECURITIES ACT OF 1933, AS AMENDED (THE "SECURITIES
                           ACT"), OR ANY STATE OR OTHER SECURITIES LAWS. NEITHER
                           THIS NOTE NOR ANY INTEREST OR PARTICIPATION HEREIN
                           MAY BE REOFFERED, SOLD, ASSIGNED, TRANSFERRED,
                           PLEDGED, ENCUMBERED OR OTHERWISE DISPOSED OF IN THE
                           ABSENCE OF SUCH REGISTRATION OR UNLESS THE
                           TRANSACTION IS EXEMPT FROM, OR NOT SUBJECT TO, THE
                           REGISTRATION REQUIREMENTS OF THE SECURITIES ACT. BY
                           ITS ACQUISITION HEREOF, THE HOLDER (1) REPRESENTS
                           THAT IT IS A "QUALIFIED INSTITUTIONAL BUYER" (AS
                           DEFINED IN RULE 144A ("RULE 144A") UNDER THE
                           SECURITIES ACT), (2) AGREES NOT TO OFFER, SELL OR
                           OTHERWISE TRANSFER THIS NOTE PRIOR TO (X) THE DATE
                           WHICH IS TWO YEARS (OR SUCH SHORTER PERIOD OF TIME AS
                           PERMITTED BY RULE 144(K) UNDER THE SECURITIES ACT)
                           AFTER THE LATER OF THE ORIGINAL ISSUE DATE OF THE
                           NOTES AND THE LAST DATE ON WHICH ALLIANT ENERGY
                           RESOURCES, INC. OR ANY "AFFILIATE" (AS DEFINED IN
                           RULE 144 UNDER THE SECURITIES ACT) OF ALLIANT ENERGY
                           RESOURCES, INC. WAS THE OWNER OF THIS NOTE (OR ANY
                           PREDECESSOR OF THIS NOTE) OR (Y) SUCH LATER DATE, IF
                           ANY, AS MAY BE REQUIRED BY APPLICABLE LAW (THE
                           "RESALE RESTRICTION TERMINATION DATE") EXCEPT (A) TO
                           ALLIANT ENERGY RESOURCES, INC., (B) PURSUANT TO A
                           REGISTRATION STATEMENT THAT HAS BEEN


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                           DECLARED EFFECTIVE UNDER THE SECURITIES ACT, (C) FOR
                           SO LONG AS THE SECURITIES ARE ELIGIBLE FOR RESALE
                           PURSUANT TO RULE 144A, TO A PERSON IT REASONABLY
                           BELIEVES IS A "QUALIFIED INSTITUTIONAL BUYER" AS
                           DEFINED IN RULE 144A THAT PURCHASES FOR ITS OWN
                           ACCOUNT OR FOR THE ACCOUNT OF A QUALIFIED
                           INSTITUTIONAL BUYER, IN EACH CASE TO WHOM NOTICE IS
                           GIVEN THAT THE TRANSFER IS BEING MADE IN RELIANCE ON
                           RULE 144A, OR (D) PURSUANT TO ANOTHER AVAILABLE
                           EXEMPTION FROM THE REGISTRATION REQUIREMENTS OF THE
                           SECURITIES ACT SUBJECT IN EACH OF THE FOREGOING CASES
                           OF ANY REQUIREMENT OF LAW THAT THE DISPOSITION OF ITS
                           PROPERTY OR THE PROPERTY OF SUCH INVESTOR ACCOUNT OR
                           ACCOUNTS BE AT ALL TIMES WITHIN ITS OR THEIR CONTROL,
                           AND (3) AGREES THAT IT WILL GIVE TO EACH PERSON TO
                           WHOM THIS NOTE IS TRANSFERRED A NOTICE SUBSTANTIALLY
                           TO THE EFFECT OF THIS LEGEND; PROVIDED THAT ALLIANT
                           ENERGY RESOURCES, INC. AND THE TRUSTEE SHALL HAVE THE
                           RIGHT PRIOR TO ANY SUCH OFFER, SALE OR TRANSFER (I)
                           PURSUANT TO CLAUSE (D) TO REQUIRE THE DELIVERY OF AN
                           OPINION OF COUNSEL, CERTIFICATION AND/OR OTHER
                           INFORMATION SATISFACTORY TO EACH OF THEM, AND (II) IN
                           EACH OF THE FOREGOING CASES, BUT ONLY IF THIS NOTE IS
                           NOT A GLOBAL SECURITY (AS DEFINED IN THE INDENTURE
                           REFERRED TO HEREIN), TO REQUIRE THAT A CERTIFICATION
                           OF TRANSFER IN THE FORM APPEARING ON THE OTHER SIDE
                           OF THIS NOTE IS COMPLETED AND DELIVERED BY THE
                           TRANSFEROR TO ALLIANT ENERGY RESOURCES, INC. AND THE
                           TRUSTEE. THIS LEGEND WILL BE REMOVED UPON THE REQUEST
                           OF THE HOLDER AFTER THE RESALE RESTRICTION
                           TERMINATION DATE.

                  Section 1.05. Section 2.20 of the Indenture shall be amended
and restated in its entirety to read as follows:


                           "Section 2.20. TRANSFER AND EXCHANGE PROVISIONS.
         Unless and until (i) a Restricted Security is exchanged for an Exchange
         Security in an Exchange Offer under an effective Exchange Offer
         Registration Statement or (ii) a Restricted Security is sold pursuant
         to an effective Shelf Registration Statement, the following provisions
         shall apply:


                                    (a) The provisions of this Section 2.20
                  shall apply to all transfers and exchanges involving any
                  Restricted Physical Security and any beneficial interest in
                  any Restricted Global Security.



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                                    (b) As used in this Section 2.20 only,
                  "delivery" of a certificate by a transferee or transferor (or
                  holder upon exchange) means the delivery to the Registrar by
                  such transferee or transferor of the applicable certificate
                  duly completed; "holding" includes both possession of a
                  Physical Security and ownership of a beneficial interest in a
                  Global Security, as the context requires; "transferring" a
                  Global Security means transferring that portion of the
                  principal amount of the transferor's beneficial interest
                  therein that the transferor has notified the Registrar that it
                  has agreed to transfer; and "transferring" a Physical Security
                  means transferring that portion of the principal amount
                  thereof that the transferor has notified the Registrar that it
                  has agreed to transfer.


                                    As used in this Indenture, "Non-Registration
                  Opinion and Supporting Evidence" means a written Opinion of
                  Counsel reasonably acceptable to the Company to the effect
                  that, and such other certification or information as the
                  Company may reasonably require to confirm that, the proposed
                  transfer is being made pursuant to an exemption from, or in a
                  transaction not subject to, the registration requirements of
                  the Securities Act.


                                    (c) A Transfer Certificate, if not actually
                  delivered, shall be deemed delivered if (i) (A) the transferor
                  advises the Company and the Trustee in writing that the
                  relevant offer and sale were made in accordance with the
                  provisions of Rule 144A or to an Institutional Accredited
                  Investor that is acquiring the Security for its own account or
                  for the account of such an Institutional Accredited Investor
                  for investment purposes and not with a view to, or for offer
                  or sale in connection with, any distribution in violation of
                  the Securities Act (or, in the case of a transfer of a
                  Restricted Physical Security, the transferor checks the box
                  provided on such Security to that effect) and (B) the
                  transferee advises the Company and the Trustee in writing that
                  (x) it and, if applicable, each account for which it is acting
                  in connection with the relevant transfer, is a "Qualified
                  Institutional Buyer," or an "Institutional Accredited
                  Investor," (y) it is aware that the transfer of Restricted
                  Securities to it is being made in reliance on the exemption
                  from the provisions of Section 5 of the Securities Act
                  provided by Rule 144A and Regulation D and (z) prior to the
                  proposed date of transfer it has been given the opportunity to
                  obtain from the Company the information referred to in Rule
                  144A(d)(4), and has either declined such opportunity or has
                  received such information (or, in the case of a transfer of a
                  Restricted Physical Security, the transferee signs the
                  certification provided on the such Security to that effect);
                  or (ii) the transferor holds the Restricted Global Security
                  and is transferring to a transferee that shall take delivery
                  in the form of the Restricted Global Security.



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                                    (d) If the holder of a Restricted Security
                  holds:


                                            (1) a Restricted Physical Security
                           which is surrendered to the Registrar:


                                                     (A) the proposed transferor
                                    and transferee deliver (or are deemed to
                                    have delivered pursuant to clause (c) above)
                                    a Transfer Certificate and the proposed
                                    transferee requests delivery in the form of
                                    a Restricted Physical Security, then the
                                    Registrar shall (x) register such transfer
                                    in the name of such transferee and record
                                    the date thereof in its books and records,
                                    (y) cancel such surrendered Restricted
                                    Physical Security and (z) deliver a new
                                    Restricted Physical Security to such
                                    transferee duly registered in the name of
                                    such transferee in principal amount equal to
                                    the principal amount being transferred of
                                    such surrendered Restricted Physical
                                    Security; or


                                                     (B) (i) the proposed
                                    transferor and transferee deliver (or are
                                    deemed to have delivered pursuant to clause
                                    (c) above) a Transfer Certificate and the
                                    proposed transferee is or is acting through
                                    a participant with the Depositary and
                                    requests that the proposed transferee
                                    receive a beneficial interest in the
                                    Restricted Global Security or (ii) the
                                    holder delivers an Exchange Certificate and
                                    the holder requests an exchange of such
                                    Restricted Physical Security for a
                                    beneficial interest in the Restricted Global
                                    Security, then the Registrar shall (x)
                                    cancel such surrendered Restricted Physical
                                    Security, (y) record an increase in the
                                    principal amount of the Global Security
                                    equal to the principal amount being
                                    transferred or exchanged of such surrendered
                                    Restricted Physical Security and (z) notify
                                    the Depositary in accordance with the
                                    procedures of the Depositary that it has
                                    effected such transfer or exchange.


                                            In any of the cases described in
                           this Section 2.20(d)(1), the Registrar shall deliver
                           to the transferor or holder a new Restricted Physical
                           Security in principal amount equal to the principal
                           amount not being transferred or exchanged of such
                           surrendered Restricted Physical Security, as
                           applicable.


                                            (2) a beneficial interest in a
                           Restricted Global Security:



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                                                     (A) (i) the proposed
                                    transferor and transferee deliver (or are
                                    deemed to have delivered pursuant to clause
                                    (c) above) a Transfer Certificate and the
                                    proposed transferee requests delivery in the
                                    form of a Restricted Physical Security or
                                    (ii) the holder delivers an Exchange
                                    Certificate and the holder requests an
                                    exchange of such beneficial interest in a
                                    Restricted Global Security for a Restricted
                                    Physical Security, then the Registrar shall
                                    (w) register such transfer or exchange in
                                    the name of such transferee or holder, as
                                    the case may be, and record the date thereof
                                    in its books and records, (x) record a
                                    decrease in the principal amount of the
                                    Restricted Global Security in an amount
                                    equal to the beneficial interest therein
                                    being transferred or exchanged, (y) deliver
                                    a new Restricted Physical Security to such
                                    transferee or holder duly registered in the
                                    name of such transferee or holder in
                                    principal amount equal to the amount of such
                                    decrease and (z) notify the Depositary in
                                    accordance with the procedures of the
                                    Depositary that it has effected such
                                    transfer or exchange; or


                                                     (B) the proposed transferor
                                    and transferee deliver (or are deemed to
                                    have delivered pursuant to clause (c) above)
                                    a Transfer Certificate and the proposed
                                    transferee is or is acting through a
                                    participant with the Depositary and requests
                                    that the proposed transferee receive a
                                    beneficial interest in the Restricted Global
                                    Security, then the transfer shall be
                                    effected in accordance with the procedures
                                    of the Depositary therefor.


                                    (e) In any case in which the Registrar is
                  required to deliver a Restricted Physical Security to a
                  transferee or transferor (or holder upon exchange), the
                  Company shall execute, the Guarantor shall guarantee and the
                  Trustee shall authenticate and make available for delivery,
                  such Restricted Physical Security.


                                    (f) Any transferee entitled to receive a
                  Restricted Physical Security may request that the principal
                  amount thereof be evidenced by one or more Restricted Physical
                  Securities in any authorized denomination or denominations and
                  the Registrar shall comply with such request if all other
                  transfer restrictions are satisfied.


                                    (g) The Registrar shall effect and record,
                  upon receipt of a written request from the Company or the
                  Guarantor so to do, a transfer not otherwise permitted by
                  Section 2.20(d), such recording to be done in accordance with
                  the otherwise applicable provisions of Section 2.20(d), upon
                  the furnishing by the proposed transferor or transferee of a
                  Non-Registration Opinion and Supporting Evidence.



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                                    (h) By its acceptance of any Security
                  bearing the Restrictive Legend, each Holder of such Security
                  acknowledges the restrictions on transfer of such Security set
                  forth in this Indenture and in the Restrictive Legend and
                  agrees that it shall transfer such Security only as provided
                  in this Indenture. The Registrar shall not register a transfer
                  of any Security unless such transfer complies with the
                  restrictions with respect thereto set forth in this Indenture.
                  The Registrar shall not be required to determine (but may rely
                  upon a determination made by the Company) the sufficiency of
                  any such certifications, legal opinions or other information.


                                    (i) Upon the transfer, exchange or
                  replacement of Securities not bearing the Restrictive Legend,
                  the Registrar shall deliver Securities that do not bear the
                  Restrictive Legend. Upon the transfer, exchange or replacement
                  of Securities bearing the Restrictive Legend, the Registrar
                  shall deliver only Securities that bear the Restrictive Legend
                  unless (i) the requested transfer is at least two years after
                  the original issue date of the Restricted Security (with
                  respect to any Restricted Physical Security), (ii) there is
                  delivered to the Registrar an Opinion of Counsel reasonably
                  satisfactory to the Company and the Trustee to the effect that
                  neither such legend nor the related restrictions on transfer
                  are required in order to maintain compliance with the
                  provisions of the Securities Act or (iii) such Securities are
                  exchanged for Exchange Securities pursuant to an Exchange
                  Offer.


                  Section 1.06. The Indenture shall be amended by amending and
restating Exhibit C to the Indenture in its entirety to read as set forth in
Exhibit B to this Third Supplemental Indenture. To the extent necessary, the
forms of Transfer Certificate and Exchange Certificate, each as attached to the
Indenture as Exhibits B and C, respectively, shall be amended to refer to the
appropriate Securities and the appropriate dates.

                                   ARTICLE 2.

                       PROVISIONS FOR THE 7% SENIOR NOTES

                  Section 2.01. There shall be a series of Securities entitled
"7% Senior Notes Due 2011" (herein designated the "7% SENIOR NOTES"). The form
of the 7% Senior Notes, the Guarantees issued by the Guarantor and the Trustee's
certificate of authentication to be borne thereby shall be substantially in the
forms set forth in Exhibit A hereto and 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 Indenture and this
Third Supplemental Indenture, including, but not limited to, the provisions of
the Indenture with respect to the transfer, exchange and replacement thereof.
The aggregate principal amount of the 7% Senior Notes that may be executed by
the Company and authenticated by the Trustee hereunder shall be limited to THREE
HUNDRED MILLION DOLLARS ($300,000,000); provided, however, any exchanges or
replacements of the 7% Senior Notes made pursuant to the


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Indenture and the Third Supplemental Indenture following the original issuance
thereof, shall not be counted against this limit.

                  Section 2.02. In accordance with the terms and conditions of
the Indenture, the Company may issue and sell the 7% Senior Notes inside the
United States without registration under the Securities Act in reliance on Rule
144A thereunder.

                  Section 2.03. Except as provided below, the 7% Senior Notes
shall be represented initially in the form of a Restricted Global Security. Each
Restricted Global Security shall be registered in the name of a nominee of the
Depositary and deposited on behalf of the purchasers of the 7% Senior Notes
represented thereby with a custodian for the Depositary for credit to the
respective accounts of the purchasers (or to such other accounts as they may
direct). Except as set forth below, each Restricted Global Security shall be in
the form of the 7% Senior Notes attached hereto as Exhibit A and may be
transferred, in whole and not in part, only to another nominee of the Depositary
or to a successor of the Depositary or its nominee.

                  Section 2.04. (a) Each Restricted Global Security, or any 7%
Senior Notes that may be issued in exchange for an interest in a Restricted
Global Security, shall be dated as provided in Section 2.03 of the Indenture,
shall mature on December 1, 2011 and shall bear interest at the rate of 7% per
annum from November 15, 2001, payable semiannually on June 1 and December 1 in
each year, commencing with June 1, 2002, until payment of the principal amount
shall have been made or duly provided for. The record dates with respect to the
interest payment dates for the 7% Senior Notes shall be May 15 and November 15
(whether or not a business day), respectively. The holder of record of 7% Senior
Notes on any record date for the payment of interest shall be entitled to
receive the interest payable on such interest payment date.

                  (b) Both principal of and interest on the 7% Senior Notes
shall be payable at the office of the Paying Agent in the Milwaukee, Wisconsin
and the Borough of Manhattan, The City of New York, New York or at any other
office maintained by the Company or the Guarantor, as the case may be, for such
purpose; provided that interest may be payable, at the option of the Company or
the Guarantor, as the case may be, by check mailed to the registered address of
the person entitled thereto as such address shall appear on the registry books
of the Company. On each interest payment date the Trustee shall pay to the
registered holder interest accrued in respect of such 7% Senior Notes. Payment
of principal on 7% Senior Notes shall be paid to the registered holder or upon
his order only upon presentation and surrender for payment of such 7% Senior
Notes on or after the payment date at the offices of the Company or the
Guarantor, as the case may be, in Milwaukee, Wisconsin and the Borough of
Manhattan, The City of New York, New York or at any other office of the Company
or the Guarantor, as the case may be, maintained for such purpose.

                  (c) The 7% Senior Notes shall not be convertible into or
exchangeable for equity securities of the Company or the Guarantor.

                  (d) The 7% Senior Notes shall not be subject to any sinking
fund.

                  (e) The 7% Senior Notes shall not be included for listing on
any national securities exchange.


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                  (f) The Trustee, at its Corporate Trust Office located at 1555
North RiverCenter Drive, Suite 301, Milwaukee, Wisconsin 53212, shall initially
act as Paying Agent for the 7% Senior Notes.

                  Section 2.05. (a) So long as a nominee of the Depositary is
the registered owner of any Restricted Global Security, such nominee shall be
considered the sole owner and holder of the 7% Senior Notes represented by such
Restricted Global Security under the Indenture, as supplemented and amended
hereby. Except as herein provided, owners of beneficial interests in any
Restricted Global Security shall not be entitled to have 7% Senior Notes
represented by the such Restricted Global Security registered in their names,
shall not receive or be entitled to receive physical delivery of 7% Senior Notes
in certificated form and shall not be considered the owners or holders thereof
under the Indenture.

                  (b) None of the Company, the Guarantor or the Trustee shall
have any responsibility or liability for any aspect of the records relating to
or payments made on account of beneficial ownership interests in any Restricted
Global Security, or for maintaining, supervising or reviewing any records
relating to such beneficial interests.

                  Section 2.06. Upon the occurrence of a Registration Default
with respect to the 7% Senior Notes, the interest rate borne by the 7% Senior
Notes shall be increased by Additional Interest in the amount of one-quarter of
one percent (0.25%) per annum, which rate will increase by one-quarter of one
percent (0.25%) each 90-day period that such Additional Interest continues to
accrue under any such circumstance, provided that the maximum aggregate increase
in the interest rate will in no event exceed one-half of one percent (0.5%) per
annum. Following the cure of all Registration Defaults with respect to the 7%
Senior Notes the accrual of Additional Interest will cease and the interest rate
will revert to the original rate.

                  If the Shelf Registration Statement with respect to the 7%
Senior Notes is unusable by the Holders for any reason after the Shelf
Registration Statement has been declared effective by the Commission, and the
aggregate number of days in any consecutive twelve-month period for which the
Shelf Registration Statement shall not be usable exceeds 30 days in the
aggregate, then the interest rate borne by the 7% Senior Notes will be increased
by one-quarter of one percent (0.25%) per annum of the principal amount of the
7% Senior Notes for the first 90-day period (or portion thereof) beginning on
the 31st day following the date that such Shelf Registration Statement ceases to
be usable, which rate shall be increased by an additional one-quarter of one
percent (0.25%) per annum of the principal amount of the 7% Senior Notes at the
beginning of the subsequent 90-day period, provided that the maximum aggregate
increase in the interest rate will in no event exceed one-half of one percent
(0.50%) per annum. Any amounts payable under this paragraph shall also be deemed
"Additional Interest" for purposes of the Indenture and the Registration Rights
Agreement. Upon the Shelf Registration Statement once again becoming usable, the
interest rate borne by the 7% Senior Notes will be reduced to the original
interest rate if the Company and the Guarantor are otherwise in compliance with
this the Indenture and the Registration Rights Agreement at such time.
Additional Interest shall be computed based on the actual number of days elapsed
in each 90-day period in which the Shelf Registration Statement is unusable.


                                       10
<PAGE>

                  The Company and the Guarantor shall notify the Trustee within
three business days after each and every Event Date with respect to the 7%
Senior Notes. Additional Interest with respect to the 7% Senior Notes shall be
paid by depositing with the Trustee, in trust, for the benefit of the Holders of
the 7% Senior Notes, on or before the applicable semiannual interest payment
date, immediately available funds in sums sufficient to pay the Additional
Interest then due. The Additional Interest due shall be payable on each interest
payment date to the record Holder of the 7% Senior Notes entitled to receive the
interest payment to be paid on such date as set forth in the Indenture. Each
obligation to pay Additional Interest shall be deemed to accrue from and
including the day following the applicable Event Date.

                  Section 2.07. The 7% Senior Notes will be redeemable at the
Company's option in whole or in part at any time, on at least 30 days' but not
more than 60 days' prior written notice mailed to the registered holders of the
7% Senior Notes, at a price equal to the greater of (i) 100% of the principal
amount of the 7% Senior Notes being redeemed and (ii) the sum of the present
values of the principal amount of the 7% Senior Notes to be redeemed and the
remaining scheduled payments of interest on the 7% Senior Notes from the
redemption date to December 1, 2011 discounted from their respective scheduled
payment dates to the redemption date semi-annually (assuming a 360-day year
consisting of twelve 30-day months) at a discount rate equal to the Treasury
Yield plus 35 basis points, plus accrued interest on the 7% Senior Notes to the
redemption date.

                                   ARTICLE 3.

                                  MISCELLANEOUS

                  Section 3.01. Capitalized terms used but not defined herein
shall have the respective meanings set forth in the Indenture, as may be amended
and supplemented from time to time in accordance therein.

                  Section 3.02. Except as supplemented and amended hereby, the
Indenture is in all respects ratified and confirmed, and all of the terms,
provisions and conditions thereof shall be and remain in full force and effect,
and this Third Supplemental Indenture and all its provisions shall be deemed a
part thereof.

                  Section 3.03. In case any provision in this Third Supplemental
Indenture shall be invalid, illegal or unenforceable, the validity, legality and
enforceability of the remaining provisions shall not in any way be affected or
impaired thereby.

                  Section 3.04. If any provision of this Third Supplemental
Indenture limits, qualifies or conflicts with any other provision hereof or of
the Indenture which provision is required to be included in the Indenture by any
of the provisions of the Trust Indenture Act, such required provision shall
control.

                  Section 3.05. THIS THIRD SUPPLEMENTAL INDENTURE AND ALL
DISPUTES, CONTROVERSIES OR CLAIMS ARISING OUT OF OR RELATING TO THIS THIRD
SUPPLEMENTAL INDENTURE OR A BREACH HEREOF SHALL BE GOVERNED BY AND CONSTRUED IN
ACCORDANCE WITH THE LAWS OF THE STATE OF


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<PAGE>

WISCONSIN WITHOUT REGARD TO THE CONFLICTS OF LAWS AND RULES OF SAID STATE.

                  Section 3.06. This Third Supplemental Indenture has been
simultaneously executed in several counterparts, each of which shall be deemed
to be an original, and all such counterparts shall together constitute but one
and the same instrument. Delivery by telecopier of an executed signature page
hereto shall be effective as delivery of a manually executed counterpart hereof.

                  Section 3.07. This Third Supplemental Indenture shall be
deemed to have been executed on the date of the acknowledgment thereof by the
officer of the Trustee who signed it on behalf of the Trustee.



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<PAGE>

                  IN WITNESS WHEREOF, the Company, the Guarantor and the Trustee
have caused their names to be signed hereto by their respective officers
thereunto duly authorized and their respective corporate seals, duly attested,
to be hereunto affixed, all as of the day and year first above written.


                                             ALLIANT ENERGY RESOURCES, INC.
ATTEST:



By  /s/ Enrique Bacalao                      By  /s/ Edward M. Gleason
     Name:  Enrique Bacalao                      Name:  Edward M. Gleason
     Title: Assistant Treasurer                  Title: Vice President-Treasurer
                                                        and Corporate Secretary


                                             ALLIANT ENERGY CORPORATION,
ATTEST:                                      as Guarantor



By:  /s/ Enrique Bacalao                     By: /s/ Edward M. Gleason
     Name:  Enrique Bacalao                      Name:  Edward M. Gleason
     Title: Assistant Treasurer                  Title: Vice President-Treasurer
                                                        and Corporate Secretary


                                             U.S. BANK NATIONAL ASSOCIATION,
                                             as Trustee



                                             By: /s/ John R. Horvath
                                                 Vice President


                                             By: /s/ Robert M. Wagner
                                                 Trust Officer






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