TWENTY-NINTH SUPPLEMENTAL INDENTURE

Exhibit 4(D)

NEVADA POWER COMPANY

TO

DEUTSCHE BANK
TRUST COMPANY AMERICAS

(SUCCESSOR TO BANKERS TRUST COMPANY),

as Trustee

TWENTY-NINTH SUPPLEMENTAL INDENTURE

Dated as of February 23, 2004

     THIS TWENTY-NINTH SUPPLEMENTAL INDENTURE dated as of February 23, 2004, made by and between NEVADA POWER COMPANY (formerly DESERT Merger Sub, Inc., a wholly owned subsidiary of Sierra Pacific Resources and successor by merger to Nevada Power Company), a corporation duly organized and existing under the laws of the State of Nevada (the “Company”), having its principal place of business at Las Vegas, Nevada, and DEUTSCHE BANK TRUST COMPANY AMERICAS (successor to Bankers Trust Company), a banking corporation duly organized and existing under and by virtue of the banking laws of the State of New York, having its principal place of business at Sixty Wall Street, New York, New York (the “Trustee”);

     WHEREAS, the Company has heretofore executed and delivered to the Trustee its Indenture of Mortgage and Deed of Trust (“Original Indenture”) dated October 1, 1953, to secure the payment of the principal of and interest and premium, if any, on all bonds of the Company at any time outstanding thereunder; and, for the purpose of amending and supplementing and further confirming the lien of the Original Indenture, has heretofore executed and delivered the following Supplemental Indentures and Instrument of Further Assurance, each dated as hereinafter set forth:

the Original Indenture, as amended and supplemented by the instruments listed above and as to be supplemented by this Twenty-Ninth Supplemental Indenture and as it may from time to time be amended or supplemented pursuant to the provisions thereof, is hereinafter sometimes called the “Indenture”;

     WHEREAS, the Original Indenture, the Instrument of Further Assurance and the Supplemental Indentures listed in the foregoing paragraph were recorded in Offices of the County Recorders of the States of Nevada, Arizona and Utah as set forth in Exhibit A attached hereto and incorporated herein by reference;

     WHEREAS, in addition to twenty-three series of Bonds heretofore issued under the Indenture, all of which have been retired, there have heretofore been issued under the Indenture First Mortgage Bonds of series and in principal amounts as follows:

     WHEREAS, the Company in the exercise of the power and authority conferred upon and reserved to it under the provisions of the Indenture, and pursuant to a resolution duly adopted by its Board of Directors, has resolved and determined to make, execute and deliver to the Trustee this Twenty-Ninth Supplemental Indenture, in the form hereof, which further supplements the Indenture and amends Section 8.13 of the Indenture in its entirety to read as follows:

     “That the Company will not declare or pay any dividends on shares of its stock of any class (other than dividends payable or paid in shares of its stock) or make any other distribution on any shares of its stock or purchase or redeem any shares of its stock for an amount in excess of the net proceeds of the sale of shares of its capital stock sold after July 28, 1999, if as a result thereof (a) the accumulated aggregate amounts of such dividends, distributions, purchases or redemptions after July 28, 1999, will exceed (b) the sum of (i) the Net Earnings of the Company, and (ii) cash contributions to the Company’s capital from the Company’s parent, for such period, taken as one accounting period, computed by generally accepted accounting standards, excluding from such Net Earnings all adjustments properly attributable to operations prior to July 28, 1999.” ; and

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     WHEREAS, all conditions and requirements necessary to make this Twenty-Ninth Supplemental Indenture a valid, binding and legal instrument have been done, performed and fulfilled, and the execution and delivery hereof have been in all respects duly authorized;

     NOW, THEREFORE in consideration of the premises and of the sum of one dollar ($1), lawful money of the United States of America, duly paid by the Trustee to the Company, and of other good and valuable consideration, receipt whereof is hereby acknowledged, and to secure the performance and observation of each and every of the covenants and conditions contained in the Indenture, and without in any way limiting the generality or effect of the Indenture insofar as by any provision thereof any of the properties therein or hereinafter referred to are now subject, or are now intended to be subject to the lien and operation thereof, but to such extent confirming such lien and operation, the Company has executed and delivered this Twenty-Ninth Supplemental Indenture and has granted, bargained, sold, warranted, aliened, remised, released, conveyed, assigned, transferred, mortgaged, pledged, set over and confirmed, and by these presents does grant, bargain, sell, warrant, alien, remise, release, convey, assign, transfer, mortgage, pledge, set over and confirm, unto Deutsche Bank Trust Company Americas, as Trustee aforesaid, and to its successors in the trust hereby created, in trust upon the conditions, terms and provisions of the Indenture, subject to the encumbrances and other matters permitted by the Indenture, all and singular the following premises, properties, interests and rights, all to the same extent and with the same force and effect as though owned by the Company at the date of execution of the Original Indenture and described in the same detail in the Granting Clauses of the Original Indenture, such premises, properties, interests and rights having been generally described and referred to in the Original Indenture; and to such ends the Company hereby supplements, as below set forth, the Granting Clauses of the Original Indenture:

GRANTING CLAUSES

     All of the premises, property, franchises and rights of every kind and description, real, personal and mixed, tangible and intangible, now owned or hereafter acquired by the Company and wherever situate.

     Together with all and singular the tenements, hereditament and appurtenances belonging or in anywise appertaining to the aforesaid property or any part thereof, with the reversion and reversions, remainder and remainders, tolls, rents, revenues, issues, income, products and profits thereof and all the estate, right, title, 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.

     Excepting and excluding, however, any and all property, premises and rights of the kinds or classes which by the terms of the Indenture are excepted and excluded from the lien and operation thereof, and therein sometimes referred to as “Excepted Property” (subject, however, to the Trustee’s rights to possession of Excepted Property in case of default, as set forth under “Excepted Property” in the Original Indenture).

     TO HAVE AND TO HOLD in trust with power of sale for the equal and proportionate benefit and security of all holders of all Bonds and the interest coupons appertaining thereto, now

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or hereafter issued under the Indenture, and for the enforcement and payment of Bonds and interest thereon when payable, and the performance of and compliance with the covenants and conditions of the Indenture, without any preference, distinction or priority as to lien or otherwise of any Bonds or coupons over any others thereof by reason of the difference in the time of the actual issue, sale or negotiation thereof, or by reason of the date of maturity thereof, or for any other reason whatsoever, except as otherwise expressly provided in the Indenture, so that each and every Bond shall have the same lien and so that the interest and principal of every Bond shall, subject to the terms thereof, be equally and proportionately secured by said lien, as if such Bond had been made, executed, delivered, sold and negotiated simultaneously with the execution and delivery of the Original Indenture.

     The Trustee executes this Twenty-Ninth Supplemental Indenture only on the condition that it shall have and enjoy with respect thereto all of the rights, privileges and immunities as set forth in the Indenture.

     The Company has agreed and covenanted and does hereby agree and covenant with the Trustee and its successors and assigns, and with the respective holders from time to time of the Bonds, or any thereof, as follows:

PART I

ARTICLE I

AMENDMENT TO INDENTURE

     The Original Indenture as heretofore and hereafter amended and modified, is hereby amended as provided below.

     Section 8.13 of the Original Indenture, as amended by Section 9 of the Second Supplemental Indenture, Part II of the Eighth Supplemental Indenture and Part II of the Twenty-Fourth Supplemental Indenture, is hereby amended in its entirety to read as follows:

     “That the Company will not declare or pay any dividends on shares of its stock of any class (other than dividends payable or paid in shares of its stock) or make any other distribution on any shares of its stock or purchase or redeem any shares of its stock for an amount in excess of the net proceeds of the sale of shares of its capital stock sold after July 28, 1999, if as a result thereof (a) the accumulated aggregate amounts of such dividends, distributions, purchases or redemptions after July 28, 1999, will exceed (b) the sum of (i) the Net Earnings of the Company, and (ii) cash contributions to the Company’s capital from the Company’s parent, for such period, taken as one accounting period, computed by generally accepted accounting standards, excluding from such Net Earnings all adjustments properly attributable to operations prior to July 28, 1999.”

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ARTICLE II

REPRESENTATIONS AND WARRANTIES

     The Company represents and warrants that, as of the date of execution of this Twenty-Ninth Supplemental Indenture, it has good and marketable title in fee simple to all the real properties described in the Granting Clauses of the Original Indenture, the First Supplemental Indenture, the Instrument of Further Assurance, the Second Supplemental Indenture, the Third Supplemental Indenture, the Fourth Supplemental Indenture, the Fifth Supplemental Indenture, the Sixth Supplemental Indenture, the Seventh Supplemental Indenture, the Eighth Supplemental Indenture, the Ninth Supplemental Indenture, the Tenth Supplemental Indenture, the Eleventh Supplemental Indenture, the Twelfth Supplemental Indenture, the Thirteenth Supplemental Indenture, the Fourteenth Supplemental Indenture, the Fifteenth Supplemental Indenture, the Sixteenth Supplemental Indenture, the Seventeenth Supplemental Indenture, the Eighteenth Supplemental Indenture, the Nineteenth Supplemental Indenture, the Twentieth Supplemental Indenture, the Twenty-First Supplemental Indenture, the Twenty-Second Supplemental Indenture, the Twenty-Third Supplemental Indenture, the Twenty-Fourth Supplemental Indenture, the Twenty-Fifth Supplemental Indenture, the Twenty-Sixth Supplemental Indenture, the Twenty-Seventh Supplemental Indenture and the Twenty-Eighth Supplemental Indenture (except any property heretofore released from the lien of the Indenture in accordance with the terms thereof), free and clear of any liens and encumbrances except Permitted Encumbrances and those, if any, referred to in said Granting Clauses, and that it has good and marketable title and is lawfully possessed of all other properties described in said Granting Clauses (except any properties therein described as to be acquired by the Company after the date of this Twenty-Ninth Supplemental Indenture and except any property heretofore released from the lien of the Indenture in accordance with the terms thereof), and the Indenture constitutes a direct and valid first mortgage lien on all such properties, subject only to Permitted Encumbrances and those, if any, referred to in said Granting Clauses. The Company represents and warrants that it has and covenants that it will continue to have, subject to the provisions of the Indenture, good right, full power and lawful authority to grant, bargain, sell, warrant, alien, remise, release, convey, assign, transfer, mortgage, pledge, set over and confirm to the Trustee all properties of every kind and nature described or referred to in said Granting Clauses (except any properties therein described as to be acquired by the Company after the date of this Twenty-Ninth Supplemental Indenture) which by the provisions of the Indenture are intended to be subject to the lien of the Indenture and that it will defend the title to such property and every part thereof to the Trustee forever, for the benefit of the holders of the Bonds, against the claims and demands of all persons whomsoever.

PART II

MISCELLANEOUS PROVISIONS

     Except insofar as herein otherwise expressly provided, all of the definitions, provisions, terms and conditions of the Indenture shall be deemed to be incorporated in, and made a part of, this Twenty-Ninth Supplemental Indenture; and the Original Indenture as amended and supplemented by the First Supplemental Indenture, the Second Supplemental Indenture, the

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