<PAGE>

                                                                     EXHIBIT 4.3

                          SIERRA PACIFIC POWER COMPANY

                              OFFICER'S CERTIFICATE

                                   May 1, 2003

         I, the undersigned officer of Sierra Pacific Power Company (the
"Company"), do hereby certify that I am an Authorized Officer of the Company as
such term is defined in the Indenture (as defined herein). I am delivering this
certificate pursuant to the authority granted in the Board Resolutions of the
Company dated March 12, 2003, and Sections 1.04, 2.01, 3.01, 4.01(a) and
4.03(b)(i) of the General and Refunding Mortgage Indenture dated as of May 1,
2001, as heretofore supplemented to the date hereof (as heretofore supplemented,
the "Indenture"), between the Company and The Bank of New York, as Trustee (the
"Trustee"). Terms used herein and not otherwise defined herein shall have the
meanings assigned to them in the Indenture, unless the context clearly requires
otherwise. Based upon the foregoing, I hereby certify on behalf of the Company
as follows:

         1.       The terms and conditions of the Securities of the series
described in this Officer's Certificate are as follows (the lettered
subdivisions set forth in this Paragraph 1 corresponding to the lettered
subdivisions of Section 3.01 of the Indenture):

         (a)      The Securities of the fourth series to be issued under the
         Indenture shall be designated "General and Refunding Mortgage Notes,
         Series D, due 2004" (the "Series D Notes").

         (b)      The Series D Notes shall initially be authenticated and
         delivered in the aggregate principal amount of $80,000,000. Additional
         Series D Notes may be authenticated and delivered only in exchange for
         or in replacement of Series D Notes previously authenticated and
         delivered.

         (c)      Not applicable.

         (d)      The principal of the Series D Notes shall be payable by the
         Company in whole or in installments on such date or dates as the
         Company has any principal repayment or purchase price obligations under
         Sections 4.2(a) or (b) of the Financing Agreement dated as of March 1,
         2001 (the "Financing Agreement") between the Company and Washoe County,
         Nevada (the "Issuer") in respect of the Issuer's Water Facilities
         Refunding Revenue Bonds (Sierra Pacific Power Company Project) Series
         2001 (the "Series 2001 Bonds") issued under the Indenture of Trust
         dated as of March 1, 2001 (the "Series 2001 Indenture") between the
         Issuer and The Bank of New York, as trustee (the "Series 2001 Bond
         Trustee"), or in whole on the Stated Maturity of the Series D Notes (if
         not previously paid or deemed paid). The Stated Maturity of the Series
         D Notes shall be not later than May 3, 2004 and shall be as set forth
         in each of the Series D Notes presented to the Trustee for
         authentication.

<PAGE>

                  The obligation of the Company to make any payment of the
         principal on the Series D Notes shall be fully or partially, as the
         case may be, deemed to have been paid or otherwise satisfied and
         discharged to the extent that the Company has made a payment under
         Section 4.2(a) of the Financing Agreement in respect of the principal
         of the Series 2001 Bonds or has made a payment or is deemed to have
         made a payment under Section 4.2(b) of the Financing Agreement in
         respect of the purchase price of Series 2001 Bonds tendered for
         purchase on May 3, 2004. If the Company shall fail to make any such
         payment in respect of principal or purchase price in respect of the
         Series 2001 Bonds as required under Sections 4.2(a) or (b) of the
         Financing Agreement, it shall be deemed to be a default, for the
         purposes of Section 10.01(b) of the Indenture, in the payment of an
         amount of principal of the Series D Notes equal to the amount of such
         unpaid principal or purchase price in respect of the Series 2001 Bonds
         (but, in no event, shall such principal amount payable exceed the
         aggregate principal amount of the Series D Notes).

         (e)      The Series D Notes shall bear interest at such rate per annum
         as shall cause the amount of interest on the Series D Notes to be equal
         to the amount of interest payable by the Company pursuant to the
         Financing Agreement in respect of the Term Rate Period (as defined
         under the Series 2001 Indenture) effective on May 1, 2003 and ending on
         and including May 2, 2004 (the "Current Term Rate Period"). Such
         interest on the Series D Notes shall be payable on the same date or
         dates as payment in respect of such interest is payable by the Company
         from time to time under the Financing Agreement, until the maturity of
         the Series D Notes (whether at their Stated Maturity or upon redemption
         or acceleration), at which time an amount of interest equal to all
         unpaid interest due on the Series 2001 Bonds through the end of the
         Current Term Rate Period shall be paid.

                  The amounts payable by the Company from time to time under the
         Financing Agreement in respect of interest on the Series 2001 Bonds,
         the basis on which such interest is computed and the dates on which
         such interest is payable are set forth in the Financing Agreement and
         the Series 2001 Indenture. The obligation of the Company to make any
         payment of interest on the Series D Notes shall be fully or partially,
         as the case may be, deemed to have been paid or otherwise satisfied and
         discharged to the extent that the Company has made the payments in
         respect of interest on the Series 2001 Bonds required under Section
         4.2(a) of the Financing Agreement. If the Company shall fail to make
         any payment in respect of interest on the Series 2001 Bonds as required
         under Section 4.2(a) of the Financing Agreement, it shall be deemed to
         be a default, for purposes of Section 10.01(a) of the Indenture, in the
         payment of an amount of interest on the Series D Notes equal to the
         amount of such unpaid interest in respect of the Series 2001 Bonds.

                  The amount of interest that shall be payable upon a
         declaration of acceleration of the Maturity of the Series D Notes
         pursuant to Section 10.02 of the Indenture shall be the amount of
         accrued and unpaid interest on the Series 2001 Bonds to the date of
         such declaration plus the amount of interest that the Company would
         have been obligated to pay under the Financing Agreement in respect of
         interest on the Series 2001 Bonds from and after such date of
         declaration through the end of the Current Term Rate Period.

                                       2

<PAGE>

         (f)      The Corporate Trust Office of The Bank of New York in New
         York, New York shall be the place at which (i) the principal of and
         interest on the Series D Notes shall be payable, (ii) registration of
         transfer of the Series D Notes may be effected, (iii) exchanges of the
         Series D Notes may be effected and (iv) notices and demands to or upon
         the Company in respect of the Series D Notes and the Indenture may be
         served; and The Bank of New York shall be the Security Registrar for
         the Series D Notes; provided, however, that the Company reserves the
         right to change, by one or more Officer's Certificates, with the
         consent of the Series 2001 Bond Trustee, any such place or the Security
         Registrar; and provided, further, that the Company reserves the right
         to designate, by one or more Officer's Certificates, its principal
         office in Reno, Nevada as any such place or itself as the Security
         Registrar; provided, however, that there shall be only a single
         Security Registrar for the Series D Notes. The principal of the Series
         D Notes shall be payable without the presentment or surrender thereof.

         (g)      Not applicable.

         (h)      Not applicable.

         (i)      The Series D Notes are issuable only in denominations of
                  $80,000,000.

         (j)      Not applicable.

         (k)      Not applicable.

         (l)      Not applicable.

         (m)      See subsections (d) and (e) above.

         (n)      Not applicable.

         (o)      Not applicable.

         (p)      Not applicable.

         (q)      Each of the Series D Notes shall be evidenced by a registered
         Series D Note in the principal amount and denomination of Eighty
         Million Dollars ($80,000,000). The Series D Notes shall be dated no
         earlier than May 1, 2003, shall mature on May 3, 2004, or such earlier
         date as set forth as the Stated Maturity date in each of the Series D
         Notes presented to the Trustee for authentication, unless sooner paid,
         and shall bear interest at the rate specified in subsection (e) above.
         The Series D Notes may be executed by the Company and delivered to the
         Trustee for authentication and delivery. The principal of and interest
         on the Series D Notes shall be payable at the Corporate Trust Office of
         the Trustee in New York, New York.

                  The initial Series D Note shall be identified by the number
         D-1 and additional Series D Notes shall be numbered consecutively from
         D-2 upwards. The Series D Notes shall upon issuance be delivered by the
         Company to, and registered in the name of, the Series 2001 Bond
         Trustee, and shall be transferable only as required to effect an

                                       3

<PAGE>

         assignment thereof to a successor-in-interest of the Series 2001 Bond
         Trustee under the Series 2001 Indenture. The Series D Notes are to be
         delivered to the Series 2001 Bond Trustee as security for the payment
         by the Company of its obligations under the Financing Agreement. The
         Series D Notes shall be held by the Series 2001 Bond Trustee subject to
         the terms of such Delivery Agreements, as may be executed from time to
         time, between the Company and the Series 2001 Bond Trustee.

                  Series D Notes issued upon transfer or exchange shall be
         numbered consecutively from D-2 upwards and issued in the same
         $80,000,000 denomination but, to the extent that the aggregate
         outstanding principal amount of the Series 2001 Bonds shall have
         theretofore been reduced, the registered holder thereof shall duly note
         on the Series D Notes a like reduction in such amount in the principal
         in the Schedule of Prepayments to such Series D Note and upon any
         transfer of said Series D Note, such Schedule of Prepayments shall
         transfer to the subsequently issued Series D Note.

                  See also subsection (s) below.

         (r)      Not applicable.

         (s)      The holder of each Series D Note by acceptance of the Series D
         Note agrees to restrictions on transfer and to waivers of certain
         rights of exchange as set forth herein. In addition, the Series D Notes
         will not be registered under the Securities Act of 1933 and the Series
         D Notes may not be transferred without compliance with applicable
         securities laws. The Series D Notes are not transferable except to a
         successor to the Series 2001 Bond Trustee under the Series 2001
         Indenture.

         (t)      For purposes of the Series D Notes, "Business Day" shall mean
         any day that is not a Friday, Saturday, Sunday or other day on which
         commercial banks are open for business, including dealings in deposits
         in U.S. dollars, in New York.

         (u)      The Trustee may conclusively presume that the obligation of
         the Company to pay the principal of and interest on the Series D Notes,
         when such payment is required to be made as provided therein, shall
         have been fully satisfied and discharged unless and until it shall have
         received a written notice from the Series 2001 Bond Trustee, signed by
         an authorized officer of the Series 2001 Bond Trustee, stating that the
         payment in respect of principal or purchase price of or interest on the
         Series 2001 Bonds has not been fully paid or provided for when due
         under the terms of the Financing Agreement and specifying the amount of
         funds required to make such payment.

                  The Series D Notes shall have such other terms and provisions
          as are provided in the form thereof attached hereto as Exhibit A, and
          shall be issued in substantially such form.

         2.       The undersigned has read all of the covenants and conditions
contained in the Indenture, and the definitions in the Indenture relating
thereto, relating to the issuance of the Series D Notes and in respect of
compliance with which this certificate is made.

                                       4

<PAGE>

                  The statements contained in this certificate are based upon
the familiarity of the undersigned with the Indenture, the documents
accompanying this certificate, and upon discussions by the undersigned with
officers and employees of the Company familiar with the matters set forth
herein.

                  In the opinion of the undersigned, he has made such
examination or investigation as is necessary to enable him to express an
informed opinion as to whether or not such covenants and conditions have been
complied with.

                  In the opinion of the undersigned, such conditions and
covenants have been complied with.

                                       5

<PAGE>

         IN WITNESS WHEREOF, the undersigned has executed this Officer's
Certificate as of the date first written above.

                            By: _______________________________________________
                                Richard K. Atkinson
                                Vice President and Chief Financial Officer

Received on
May 1, 2003

THE BANK OF NEW YORK,
as Trustee

By:    __________________________________
Name:  Stacey B. Poindexter
Title: Assistant Treasurer

                                       6

<PAGE>

                                    EXHIBIT A

                             FORM OF SERIES D NOTES

         NOTE: THE HOLDER OF THIS NOTE BY ACCEPTANCE HEREOF AGREES TO
RESTRICTIONS ON TRANSFER AND TO WAIVERS OF CERTAIN RIGHTS OF EXCHANGE, AS SET
FORTH BELOW. IN ADDITION, THE NOTE REPRESENTED BY THIS CERTIFICATE HAS NOT BEEN
REGISTERED UNDER THE SECURITIES ACT OF 1933 AND SUCH NOTE MAY NOT BE TRANSFERRED
WITHOUT COMPLIANCE WITH APPLICABLE SECURITIES LAWS.

         THIS NOTE IS NOT TRANSFERABLE EXCEPT TO A SUCCESSOR TO THE SERIES 2001
BOND TRUSTEE UNDER THE SERIES 2001 INDENTURE REFERRED TO HEREIN.

                          SIERRA PACIFIC POWER COMPANY
             General and Refunding Mortgage Note, Series D, due 2004

<TABLE>
<S>                              <C>              <C>
Original Interest Accrual Date:  May 1, 2003      Redeemable by Company: Yes [ ] No [X]
Stated Maturity:                 April 30, 2004   Redemption Date:  N/A
Interest Rate:                   See below        Redemption Price: N/A
Interest Payment Dates:          See below
Regular Record Dates:            N/A
</TABLE>

                    This Security is not a Discount Security
              within the meaning of the within-mentioned Indenture.

Principal Amount
$80,000,000                                                              No. D-1

         SIERRA PACIFIC POWER COMPANY, a corporation duly organized and existing
under the laws of the State of Nevada (herein called the "Company," which term
includes any successor corporation under the Indenture referred to below), for
value received, hereby promises to pay to THE BANK OF NEW YORK, as trustee (the
"Series 2001 Bond Trustee") under the Indenture of Trust dated as of March 1,
2001 (the "Series 2001 Indenture") between the Series 2001 Bond Trustee and
Washoe County, Nevada (the "Issuer"), the principal sum of EIGHTY MILLION
DOLLARS, or such lesser amount as set forth herein.

         Capitalized terms used herein and not defined herein shall have the
meanings specified in the Indenture (as defined below), unless otherwise noted.
Section headings in this Note are for convenience only and shall not affect the
construction hereof.

<PAGE>

         1. Principal. The principal of this Note shall be payable by the
Company in whole or in installments on such date or dates as the Company has any
principal repayment or purchase price obligations under Sections 4.2(a) or (b)
of the Financing Agreement dated as of March 1, 2001 (the "Financing Agreement")
between the Company and the Issuer in respect of the Issuer's Water Facilities
Refunding Revenue Bonds (Sierra Pacific Power Company Project), Series 2001 (the
"Series 2001 Bonds"), or in whole on the Stated Maturity specified above (if not
previously paid or deemed paid).

         The obligation of the Company to make any payment of principal on this
Note shall be fully or partially, as the case may be, deemed to have been paid
or otherwise satisfied or discharged to the extent that the Company has made a
payment under Section 4.2(a) of the Financing Agreement in respect of the
principal of the Series 2001 Bonds or has made a payment or is deemed to have
made a payment under Section 4.2(b) of the Financing Agreement in respect of the
purchase price of Series 2001 Bonds tendered for purchase on May 3, 2004. If the
Company shall fail to make any payment in respect of principal or purchase price
of the Series 2001 Bonds as required under Sections 4.2(a) or (b) of the
Financing Agreement, it shall be deemed to be a default, for purposes of Section
10.01(b) of the Indenture, in the payment of an amount of principal of this Note
equal to the amount of such unpaid principal or purchase price in respect of the
Series 2001 Bonds (but, in no event, shall such principal amount payable exceed
the aggregate principal amount of this Note).

         2. Interest. This Note shall bear interest at such rate per annum as
shall cause the amount of interest on this Note to be equal to the amount in
respect of interest payable by the Company pursuant to the Financing Agreement
in respect of the Term Rate Period (as defined in the Series 2001 Indenture)
effective on May 1, 2003 and ending on and including May 2, 2004 (the "Current
Term Rate Period"). The interest on this Note shall be payable on the same date
or dates as payment in respect of such interest is payable by the Company from
time to time under the Financing Agreement, until the maturity of this Note
(whether at the Stated Maturity as specified above or upon redemption or
acceleration), at which time an amount of interest equal to all unpaid interest
due on the Series 2001 Bond through the end of the Current Term Rate Period
shall be paid.

         The amounts payable by the Company from time to time under the
Financing Agreement in respect of interest on the Series 2001 Bonds, the basis
on which the interest on this Note is computed and the dates on which such
interest is payable are set forth in the Financing Agreement and the Series 2001
Indenture. The obligation of the Company to make any payment of interest on this
Note shall be fully or partially, as the case may be, deemed to have been paid
or otherwise satisfied and discharged to the extent that the Company has made
the payments in respect of interest on the Series 2001 Bonds required under
Section 4.2(a) of the Financing Agreement. If the Company shall fail to make any
payment in respect of interest on the Series 2001 Bonds as required under
Section 4.2(a) of the Financing Agreement, it shall be deemed to be a default,
for purposes of Section 10.01(a) of the Indenture, in the payment of an amount
of interest on this Note equal to the amount of such unpaid interest in respect
of the Series 2001 Bonds.

         The amount of interest that shall be payable upon a declaration of
acceleration of the maturity of this Note pursuant to Section 10.02 of the
Indenture shall be the amount of accrued and unpaid interest on the Series 2001
Bonds to the date of such declaration plus the amount that the Company would
have been obligated to pay under the Financing Agreement in respect of interest
on the Series 2001 Bonds from and after the date of such declaration through the
end of the Current Term Rate Period.

                                       8

<PAGE>

         3. Terms of Issuance. This Note is issued to the Series 2001 Bond
Trustee by the Company to secure the Company's payment obligations pursuant to
Sections 4.2(a) and (b) of the Financing Agreement in respect of the Current
Term Rate Period, in connection with the remarketing of the Series 2001 Bonds on
May 1, 2003 and the purchase and reoffering thereof by Lehman Brothers, Inc.
("Lehman") pursuant to the Bond Purchase Agreement, dated as of April 25, 2003
(the "Bond Purchase Agreement") among the Company and Lehman, as remarketing
agent and as underwriter. This Note shall be held by the Series 2001 Bond
Trustee subject to the terms of the Delivery Agreement dated as of May 1, 2003
between the Company and the Series 2001 Bond Trustee.

         4. Paying Agent and Security Registrar. The Corporate Trust Office of
The Bank of New York in New York, New York shall be the place at which, with
respect to this Note and the Indenture, as applicable, (i) the principal of and
interest shall be payable, (ii) registration of transfer may be effected, (iii)
exchanges may be effected and (iv) notices and demands to or upon the Company
may be served; and The Bank of New York shall be the Security Registrar for this
Note; provided, however, that the Company reserves the right to change, by one
or more Officer's Certificates, with the consent of the Series 2001 Bond
Trustee, any such place or the Security Registrar; and provided, further, that
the Company reserves the right to designate, by one or more Officer's
Certificates, its principal office in Reno, Nevada as any such place or itself
as the Security Registrar; provided, however, that there shall be only a single
Security Registrar for this Note. The principal of this Note shall be payable
without the presentment or surrender thereof.

         5. Indenture; Security. This Note is one of a duly authorized issue of
securities of the Company (herein called the "Securities"), issued and issuable
in one or more series under and equally secured by a General and Refunding
Mortgage Indenture, dated as of May 1, 2001 (such Indenture as originally
executed and delivered and as supplemented or amended from time to time
thereafter, together with any constituent instruments establishing the terms of
particular Securities, being herein called the "Indenture"), between the Company
and The Bank of New York, as trustee (herein called the "Trustee," which term
includes any successor trustee under the Indenture), to which Indenture and all
indentures supplemental thereto reference is hereby made for a description of
the property mortgaged, pledged and held in trust, the nature and extent of the
security and the respective rights, limitations of rights, duties and immunities
of the Company, the Trustee and the Holders of the Securities thereunder and of
the terms and conditions upon which the Securities are, and are to be,
authenticated and delivered and secured. The acceptance of this Note shall be
deemed to constitute the consent and agreement by the Holder hereof to all of
the terms and provisions of the Indenture. This Note is one of the series
designated above.

         6. Sinking Fund; Optional Redemption. The Notes of this series will not
be entitled to the benefit of any sinking fund or optional redemption
provisions.

         7. Event of Default. If an Event of Default, as defined in the
Indenture, shall occur and be continuing, the principal of this Note may be
declared due and payable in the manner and with the effect provided in the
Indenture and herein.

         8. Supplemental Indentures. The Indenture permits, with certain
exceptions as therein provided, the Trustee to enter into one or more
supplemental indentures for the purpose of adding any provisions to, or changing
in any manner or eliminating any of the provisions of, the Indenture with the
consent of the Holders of not less than a majority in aggregate principal amount
of the Securities of all series then Outstanding under the Indenture, considered
as one class; provided, however, that if there shall be Securities of more than
one series Outstanding under the Indenture and if a proposed supplemental
indenture shall directly affect the rights of the Holders of Securities of one
or more, but less than all, of such series, then the consent only of the Holders
of a majority in aggregate principal amount of the Outstanding Securities of all
series so directly affected, considered as one class, shall be required; and

                                       9

<PAGE>

provided, further, that if the Securities of any series shall have been issued
in more than one Tranche and if the proposed supplemental indenture shall
directly affect the rights of the Holders of Securities of one or more, but less
than all, of such Tranches, then the consent only of the Holders of a majority
in aggregate principal amount of the Outstanding Securities of all Tranches so
directly affected, considered as one class, shall be required; and provided,
further, that the Indenture permits the Trustee to enter into one or more
supplemental indentures for limited purposes without the consent of any Holders
of Securities.

         9. Consents and Waivers. The Indenture also contains provisions
permitting the Holders of a majority in principal amount of the Securities then
Outstanding, on behalf of the Holders of all Securities, to waive compliance by
the Company with certain provisions of the Indenture and certain past defaults
under the Indenture and their consequences. Any such consent or waiver by the
Holder of this Note shall be conclusive and binding upon such Holder and upon
all future Holders of this Note and of any Security issued upon the registration
of transfer hereof or in exchange therefor or in lieu hereof, whether or not
notation of such consent or waiver is made upon this Note.

         10. Person Deemed Owners. The Company, the Trustee and any agent of the
Company or the Trustee may deem and treat the person in whose name this Note
shall be registered upon the Security Register for the Notes of this series as
the absolute owner of such Note for the purpose of receiving payment of or on
account of the principal of and interest on this Note and for all other
purposes, whether or not this Note be overdue, and neither the Company nor the
Trustee shall be affected by any notice to the contrary; and all such payments
so made to such registered owner or upon his order shall be valid and effectual
to satisfy and discharge the liability upon this Note to the extent of the sum
or sums paid.

         11. Satisfaction and Discharge. The Trustee may conclusively presume
that the obligation of the Company to pay the principal of and interest on this
Note, when such payment is required to be made as provided herein, shall have
been fully satisfied and discharged unless and until it shall have received a
written notice from the Series 2001 Bond Trustee, signed by an authorized
officer of the Series 2001 Bond Trustee, stating that the payment in respect of
principal or purchase price of or interest on the Series 2001 Bonds has not been
fully paid or provided for when due under the terms of the Financing Agreement
and specifying the amount of funds required to make such payment.

         12. Transfer. This Note is not transferable except to a successor to
the Series 2001 Bond Trustee under the Series 2001 Indenture. Before any
transfer of this Note by the registered holder or his or its legal
representative will be recognized or given effect by the Company or the Trustee,
the registered holder shall note the amounts of reductions, if any, in the
aggregate outstanding principal amount of the Series 2001 Bonds, and shall
notify the Company and the Trustee of the name and address of the transferee and
shall afford the Company and the Trustee the opportunity of verifying the
notation as to such reductions.

         13. No Recourse. No recourse under or upon any obligation, covenant or
agreement contained in the Indenture or in any indenture supplemental thereto,
or in any Note or coupon thereby secured, or because of any indebtedness thereby
secured, shall be had against any incorporator, or against any past, present or
future stockholder, officer or director, as such, of the Company or any
successor corporation, either directly or through the Company or of any
successor corporation under any rule of law, statute or constitutional provision
or by the enforcement of any assessment or by any legal or equitable proceeding
or otherwise; it being expressly agreed and understood that the Indenture, any
indenture supplemental thereto and the obligations thereby secured, are solely
corporate obligations, and that no personal liability whatsoever shall attach
to, or be incurred by, such incorporators, stockholders, officers or directors,
as such, of the Company or of any successor corporation, or any of them, because
of the incurring of the indebtedness thereby authorized, or under or by reason
of any of the obligations, covenants or agreements

                                       10

<PAGE>

contained in the Indenture or in any indenture supplemental thereto or in any of
the Notes or coupons thereby secured, or implied therefrom.

         14. Business Day. For the purposes of this Note, "Business Day" shall
mean any day that is not a Friday, Saturday, Sunday or other day on which
commercial banks are open for business, including dealings in deposits in U.S.
dollars, in New York.

         15. Governing Law. This Note shall be governed by and construed in
accordance with the laws of the State of New York.

         16. Certificate of Authentication. Unless the certificate of
authentication hereon has been executed by the Trustee or an Authenticating
Agent by manual signature, this Note shall not be entitled to any benefit under
the Indenture or be valid or obligatory for any purpose.

            [The remainder of this page is intentionally left blank.]

                                       11

<PAGE>

         IN WITNESS WHEREOF, the Company has caused this instrument to be duly
executed.

                          SIERRA PACIFIC POWER COMPANY

                          By: /s/ Richard K. Atkinson
                              --------------------------------------------
                              Name:  Richard K. Atkinson
                              Title: Vice President and Chief Financial Officer

                          CERTIFICATE OF AUTHENTICATION

         This is one of the Securities of the series designated therein referred
to in the within-mentioned Indenture.

Dated: May 1, 2003

                                   THE BANK OF NEW YORK, AS TRUSTEE

                                   By: /s/ Stacey B. Poindexter
                                       -----------------------------
                                       Authorized Signatory

                                       12