<PAGE>

                                                                  Exhibit 4.6

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

                                PLEDGE AGREEMENT

                                      AMONG

                            SIERRA PACIFIC RESOURCES

                                       AND

      WELLS FARGO BANK MINNESOTA, NATIONAL ASSOCIATION, AS COLLATERAL AGENT

                                       AND

                WELLS FARGO BANK MINNESOTA, NATIONAL ASSOCIATION,
                           AS SECURITIES INTERMEDIARY

                                       AND

                THE BANK OF NEW YORK, AS PURCHASE CONTRACT AGENT

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

                          DATED AS OF NOVEMBER 16, 2001


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

<PAGE>

                                TABLE OF CONTENTS

<TABLE>
<CAPTION>
                                                                                                                PAGE
<S>                                                                                                             <C>
Section 1.        Definitions.....................................................................................2

Section 2.        Pledge..........................................................................................6
         Section 2.1       Pledge.................................................................................6
         Section 2.2       Control; Financing Statement...........................................................7
         Section 2.3       Termination............................................................................7

Section 3.        Distributions on Pledged Collateral.............................................................7
         Section 3.1       Income Distributions...................................................................7
         Section 3.2       Principal Payments Following Termination Event.........................................7
         Section 3.3       Principal Payments Prior to or On Purchase Contract Settlement Date....................8
         Section 3.4       Payments to Purchase Contract Agent....................................................8
         Section 3.5       Assets Not Properly Released...........................................................9

Section 4.        Control.........................................................................................9
         Section 4.1       Establishment of Collateral Account....................................................9
         Section 4.2       Treatment as Financial Assets..........................................................9
         Section 4.3       Sole Control by Collateral Agent......................................................10
         Section 4.4       Securities Intermediary's Location....................................................10
         Section 4.5       No Other Claims.......................................................................10
         Section 4.6       Investment and Release................................................................10
         Section 4.7       Statements and Confirmations..........................................................10
         Section 4.8       Tax Allocations.......................................................................10
         Section 4.9       No Other Agreements...................................................................11
         Section 4.10      Powers Coupled With An Interest.......................................................11

Section 5.        Initial Deposit; Creation of Treasury PIES; and Recreation of Corporate PIES; Other............11
         Section 5.1       Initial Deposit of Senior Notes.......................................................11
         Section 5.2       Creation of Treasury PIES by Substitution of Treasury Securities......................11
         Section 5.3       Recreation of Corporate PIES..........................................................13
         Section 5.4       Termination Event.....................................................................14
         Section 5.5       Cash Settlement.......................................................................15
         Section 5.6       Early Settlement; Merger Early Settlement.............................................16
         Section 5.7       Optional Remarketing..................................................................17
         Section 5.8       Application of Proceeds in Settlement; Remarketing....................................17

Section 6.        Voting Rights..................................................................................21

Section 7.        Rights and Remedies............................................................................21
         Section 7.1       Rights and Remedies of the Collateral Agent...........................................21
         Section 7.2       Substitutions.........................................................................22

                                       i

<PAGE>
<S>                                                                                                           <C>
                                                                                                              PAGE
Section 8.        Representations and Warranties; Covenants......................................................23
         Section 8.1       Representations and Warranties........................................................23
         Section 8.2       Covenants.............................................................................23

Section 9.        The Collateral Agent and the Securities Intermediary...........................................24
         Section 9.1       Appointment, Powers and Immunities....................................................24
         Section 9.2       Instructions of the Company...........................................................25
         Section 9.3       Reliance by Collateral Agent and Securities Intermediary..............................25
         Section 9.4       Rights in Other Capacities............................................................26
         Section 9.5       Non-Reliance on Collateral Agent and Securities Intermediary..........................26
         Section 9.6       Compensation and Indemnity............................................................26
         Section 9.7       Failure to Act........................................................................27
         Section 9.8       Resignation of Collateral Agent and Securities Intermediary...........................27
         Section 9.9       Right to Appoint Agent or Advisor.....................................................29
         Section 9.10      Survival .............................................................................29
         Section 9.11      Exculpation...........................................................................29

Section 10.       Amendment......................................................................................29
         Section 10.1      Amendment Without Consent of Holders..................................................29
         Section 10.2      Amendment with Consent of Holders.....................................................30
         Section 10.3      Execution of Amendments...............................................................31
         Section 10.4      Effect of Amendments..................................................................31
         Section 10.5      Reference to Amendments...............................................................31

Section 11.       Merger, Consolidation, Sale or Conveyance......................................................31
         Section 11.1      When Company May Merge, Etc...........................................................31
         Section 11.2      Successor Corporation Substituted.....................................................32
         Section 11.3      Limitation............................................................................32

Section 12.       Miscellaneous..................................................................................33
         Section 12.1      No Waiver.............................................................................33
         Section 12.2      Governing Law; Jurisdiction and Venue.................................................33
         Section 12.3      Notices...............................................................................33
         Section 12.4      Successors and Assigns................................................................34
         Section 12.5      Counterparts..........................................................................34
         Section 12.6      Effect of Headings and Table of Contents..............................................34
         Section 12.7      Severability..........................................................................35
         Section 12.8      Expenses, etc.........................................................................35
         Section 12.9      Security Interest Absolute............................................................35
</TABLE>

                                    EXHIBITS

<TABLE>
<S>                        <C>                                                                                 <C>
EXHIBIT A                  Instruction from Purchase Contract Agent to Collateral Agent
                           (Creation of Treasury PIES)..........................................................A-1
EXHIBIT B                  Instruction from Collateral Agent to Securities Intermediary
                           (Creation of Treasury PIES)..........................................................B-1

                                      -ii-

<PAGE>

<S>                        <C>                                                                                  <C>
EXHIBIT C                  Instruction from Purchase Contract Agent to Collateral Agent
                           (Recreation of Corporate PIES).......................................................C-1
EXHIBIT D                  Instruction from Collateral Agent to Securities Intermediary
                           (Recreation of Corporate PIES).......................................................D-1
EXHIBIT E                  Notice of Cash Settlement from the Securities Intermediary to the
                           Purchase Contract Agent..............................................................E-1
EXHIBIT F                  Instruction from Holder of Separated Senior Notes to Collateral
                              Agent Regarding Remarketing.......................................................F-1
EXHIBIT G                  Instruction from Purchase Contract Agent to Collateral Agent.........................G-1
EXHIBIT H                  Agency and Custody Account Direction for Cash Balances...............................H-1
</TABLE>

                                      -iii-

<PAGE>

         PLEDGE AGREEMENT, dated as of November 16, 2001, among SIERRA PACIFIC
RESOURCES, a Nevada corporation (the "Company"), WELLS FARGO BANK MINNESOTA,
NATIONAL ASSOCIATION, a national banking association, not individually but
solely as collateral agent (in such capacity, together with its successors in
such capacity, the "Collateral Agent"), WELLS FARGO BANK MINNESOTA, NATIONAL
ASSOCIATION, not individually but solely in its capacity as "Securities
Intermediary" (in such capacity, together with its successors in such capacity,
the "Securities Intermediary") as defined in Section 8-102(a)(14) of the UCC (as
hereinafter defined) with respect to the Collateral Account (as hereinafter
defined), and THE BANK OF NEW YORK, a New York banking corporation, not
individually but solely as purchase contract agent and as attorney-in-fact of
the Holders from time to time of the PIES (in such capacity, together with its
successors in such capacity, the "Purchase Contract Agent") under the Purchase
Contract Agreement (as hereinafter defined).

                                    RECITALS

         The Company and the Purchase Contract Agent are parties to the Purchase
Contract Agreement dated as of the date hereof (as amended, modified or
supplemented from time to time in accordance with the terms thereof, the
"Purchase Contract Agreement"), pursuant to which there are being issued
6,000,000 PIES (or up to 6,900,000, if the Underwriters' over-allotment option
pursuant to the Underwriting Agreement is exercised in full) (the "PIES"), all
of which will initially be Corporate PIES.

         Each Corporate PIES consists of a unit comprised of (a) one stock
purchase contract (a "Purchase Contract") under which the Holder will purchase
from the Company and the Company will be required to sell to such Holder not
later than the Purchase Contract Settlement Date, for an amount equal to $50
(the "Stated Amount"), a number of shares of Common Stock of the Company equal
to the Settlement Rate or Early Settlement Rate, as the case may be, then in
effect and (b) either beneficial ownership of (1) a Senior Note or (2) following
the Remarketing of the Senior Note in accordance with the Purchase Contract
Agreement and the Remarketing Agreement, the Treasury Portfolio Interest,
subject to the termination or settlement of the Purchase Contracts.

         In accordance with the terms of the Purchase Contract Agreement, a
Holder of Corporate PIES may separate the Senior Notes from the related Purchase
Contracts by substituting on or before the Election Date, for such Senior Notes,
Treasury Securities that will pay on maturity in the aggregate an amount equal
to the aggregate Stated Amount of such Corporate PIES. Upon such substitution,
the Corporate PIES will become Treasury PIES in accordance with the terms of the
Purchase Contract Agreement. Each Treasury PIES will be comprised of (a) a
Purchase Contract under which the holder will purchase from the Company not
later than the Purchase Contract Settlement Date, for the Stated Amount, a
number of shares of Common Stock of the Company equal to the Settlement Rate or
Early Settlement Rate, as the case may be, then in effect, and (b) a 1/20
undivided beneficial interest in a Treasury Security, subject to the termination
or settlement of the Purchase Contracts.

         Pursuant to the terms of the Purchase Contract Agreement and the
Purchase Contracts, the Holders, from time to time, of the PIES have irrevocably
authorized the Purchase Contract Agent, as attorney-in-fact of such Holders,
among other things, to execute and deliver this

<PAGE>

                                                                               2

Agreement on behalf of such Holders and to grant the pledge provided herein of
the Collateral Account to secure the Obligations.

         Accordingly, the Company, the Collateral Agent, the Securities
Intermediary and the Purchase Contract Agent, on its own behalf and as
attorney-in-fact of the Holders from time to time of the PIES, agree as follows:

Section 1.        DEFINITIONS.

                  For all purposes of this Agreement, except as otherwise
expressly provided or unless the context otherwise requires:

                  (a) the terms defined in this Section have the meanings
assigned to them in this Section and include the plural as well as the singular;

                  (b) the words "herein," "hereof" and "hereunder" and other
words of similar import refer to this Agreement as a whole and not to any
particular Section, Exhibit or other section;

                  (c) the following terms which are defined in the UCC shall
have the meanings set forth therein: "certificated security," "control,"
"financial asset," "entitlement order," "securities account" and "security
entitlement";

                  (d) capitalized terms used and not defined in this Agreement
shall have the meanings set forth in the Purchase Contract Agreement; and

                  (e) the following terms have the meanings given to them in
this Section 1(e):

         "Account Direction" means the Agency and Custody Account Direction for
Cash Balances in the form of Exhibit H attached hereto, as executed and
delivered to the Collateral Agent by the Company from time to time.

         "Agreement" means this Pledge Agreement, as the same may be amended,
modified or supplemented from time to time in accordance with the terms thereof.

         "Cash" means any coin or currency of the United States as at the time
shall be legal tender for payment of public and private debts.

         "Collateral" means the collective reference to:

                  (1) the Collateral Account;

                  (2) all investment property and other financial assets and
         other property and credit balances from time to time credited to the
         Collateral Account, including, without limitation, (A) any Senior Notes
         or any Treasury Portfolio Interest which are then a component of the
         Corporate PIES and, in each case, security entitlements relating
         thereto, (B) any Treasury Securities and security entitlements relating
         thereto delivered from time to time upon establishment of Treasury PIES
         in accordance with Section 5.2 hereof and (C) payments made by Holders
         pursuant to Section 5.5 hereof;

<PAGE>
                                                                               3

                  (3) all Proceeds of any of the foregoing (whether such
         Proceeds arise before or after the commencement of any proceeding under
         any applicable bankruptcy, insolvency or other similar law, by or
         against the pledgor or with respect to the pledgor); and

                  (4) all powers and rights now owned or hereafter acquired
         under or with respect to the Collateral Account.

         "Collateral Account" means the Securities Account No. 11874500 entitled
"Wells Fargo Bank Minnesota, National Association, as Collateral Agent,
Securities Account (Sierra Pacific Resources)" maintained by the Securities
Intermediary for the Purchase Contract Agent on behalf of and as
attorney-in-fact for the Holders.

         "Collateral Agent" means the Person named as the "Collateral Agent" in
the first paragraph of this instrument until a successor shall have become such
in accordance with the terms of this Agreement, and thereafter "Collateral
Agent" shall mean such successor.

         "Collateral Substitution" means the substitution of Treasury Securities
for a Holder's Senior Notes, pursuant to Section 3.13 of the Purchase Contract
Agreement and Section 5.2 of this Agreement, and the substitution of a Holder's
Senior Notes for Treasury Securities, pursuant to Section 3.14 of the Purchase
Contract Agreement and Section 5.3 of this Agreement.

         "Company" means the Person named as the "Company" in the first
paragraph of this instrument until a successor shall have become such in
accordance with the terms of this Agreement, and thereafter "Company" shall mean
such successor.

         "Custodian" has the meaning set forth in Section 5.2(c).

         "Final Remarketing" has the meaning set forth in the Remarketing
Agreement.

         "Final Remarketing Date" has the meaning set forth in the Remarketing
Agreement.

         "Initial Remarketing" has the meaning set forth in the Remarketing
Agreement.

         "Initial Remarketing Date" has the meaning set forth in Remarketing
Agreement.

         "Obligations" means, with respect to each Holder, the collective
reference to all obligations and liabilities of such Holder under such Holder's
Purchase Contract and this Agreement or any other document made, delivered or
given in connection herewith or therewith, in each case whether on account of
principal, interest (including, without limitation, interest accruing before and
after the filing of any petition in bankruptcy, or the commencement of any
insolvency, reorganization or like proceeding, relating to such Holder, whether
or not a claim for post-filing or post-petition interest is allowed in such
proceeding), fees, indemnities, costs, expenses or otherwise (including, without
limitation, all fees and disbursements of counsel to the Company or the
Collateral Agent or the Securities Intermediary that are required to be paid by
the Holder pursuant to the terms of any of the foregoing agreements).

         "Permitted Investments" means any one of the following which shall
mature not later than the Purchase Contract Settlement Date:

                  (1) any evidence of indebtedness with an original maturity of
         365 days or less issued, or directly and fully guaranteed or insured,
         by the United States of America or

<PAGE>
                                                                               4

         any agency or instrumentality thereof (provided that the full faith and
         credit of the United States of America is pledged in support of the
         timely payment thereof or such indebtedness constitutes a general
         obligation of it);

                  (2) deposits, certificates of deposit or acceptances with an
         original maturity of 365 days or less of any institution which is a
         member of the Federal Reserve System having combined capital and
         surplus and undivided profits of not less than $200,000,000 at the time
         of deposit, which may include the Collateral Agent or any of its
         affiliates;

                  (3) investments with an original maturity of 365 days or less
         of any Person that are fully and unconditionally guaranteed by a bank
         referred to in clause (2);

                  (4) repurchase agreements and reverse repurchase agreements
         relating to marketable direct obligations issued or unconditionally
         guaranteed by the United States Government or issued by any agency
         thereof and backed as to timely payment by the full faith and credit of
         the United States Government;

                  (5) investments in commercial paper, other than commercial
         paper issued by the Company or its affiliates, of any corporation
         incorporated under the laws of the United States or any State thereof,
         which commercial paper has a rating at the time of purchase at least
         equal to "A-1" by Standard & Poor's Ratings Services, Inc. ("S&P") or
         at least equal to "P-1" by Moody's Investors Service, Inc. ("Moody's");
         and

                  (6) investments in money market funds registered under the
         Investment Company Act of 1940, as amended, rated in the highest
         applicable rating category by S&P or Moody's, which may include such
         money market funds offered, administered or serviced by the Collateral
         Agent or any of its affiliates.

         "PIES" has the meaning specified in the paragraph preceding the
recitals of this Agreement.

         "Pledge" means the lien and security interest created by this
Agreement.

         "Pledged Senior Notes" means the Senior Notes, which shall be in
certificated form, and security entitlements with respect thereto from time to
time credited to the Collateral Account and not then released from the Pledge.

         "Pledged Treasury Portfolio Interest" means the Treasury Portfolio
Interest and security entitlements with respect thereto from time to time
credited to the Collateral Account and not then released from the Pledge.

         "Pledged Treasury Securities" means Treasury Securities and security
entitlements with respect thereto from time to time credited to the Collateral
Account and not then released from the Pledge.

         "Proceeds" has the meaning ascribed thereto in the UCC and includes,
without limitation, all interest, dividends, Cash, instruments, securities,
financial assets (as defined in ss. 8-102(a)(9) of the UCC) and other property
received, receivable or otherwise distributed upon the sale,

<PAGE>
                                                                               5

exchange, collection or disposition of any financial assets from time to time
held in the Collateral Account.

         "Purchase Contract Agent" means the Person named as the "Purchase
Contract Agent" in the first paragraph of this instrument until a successor
shall have become such in accordance with the terms of the Purchase Contract
Agreement, and thereafter "Purchase Contract Agent" shall mean such successor.

         "Purchase Contract Agreement" has the meaning specified in the
paragraph preceding the recitals of this Agreement.

         "Purchase Contract Settlement Date" means November 15, 2005.

         "Remarketing" means the remarketing of the Remarketing Senior Notes
pursuant to the Remarketing Procedures.

         "Remarketing Date" has the meaning set forth in the Purchase Contract
Agreement.

         "Remarketing Fee" has the meaning set forth in Section 5.8(a).

         "Remarketing Procedures" means, collectively, the procedures and
requirements relating to the Remarketing and the determination of the Reset Rate
as set forth in the Indenture, the Purchase Contract Agreement, this Agreement
and the Remarketing Agreement.

         "Remarketing Senior Notes" has the meaning set forth in Section 5.8(a).

         "Remarketing Settlement Date" has the meaning set forth in Section
5.8(a).

         "Reset Rate" has the meaning set forth in the Indenture.

         "Securities Intermediary" means the Person named as the "Securities
Intermediary" in the first paragraph of this instrument until a successor shall
have become such in accordance with the terms of this Agreement, and thereafter
"Securities Intermediary" shall mean such successor.

         "Separated Senior Notes" means any Senior Notes that are not Pledged
Senior Notes.

         "Stated Amount" has the meaning specified in the second paragraph of
the recitals of this Agreement.

         "Subsequent Remarketing" has the meaning specified in the Remarketing
Agreement.

         "Subsequent Remarketing Date" has the meaning specified in the
Remarketing Agreement.

          "Successful Final Remarketing" has the meaning set forth in Section
5.8(b).

         "Successful Initial Remarketing" has the meaning set forth in Section
5.8(a).

         "Successful Remarketing" has the meaning specified in the Remarketing
Agreement.

<PAGE>
                                                                               6

         "Successful Subsequent Remarketing" has the meaning set forth in
Section 5.8(a).

         "TRADES" means the Treasury/Reserve Automated Debt Entry System
maintained by the Federal Reserve Bank of New York pursuant to the TRADES
Regulations.

         "TRADES Regulations" means the regulations of the United States
Department of the Treasury, published at 31 C.F.R. Part 357, an amended from
time to time. Unless otherwise defined herein, all terms defined in the TRADES
Regulations are used herein as therein defined.

         "Transfer" means:

                  (1) in the case of certificated securities in registered form,
         delivery as provided in ss. 8-301(a) of the UCC, indorsed to the
         transferee or in blank by an effective indorsement

                  (2) in the case of Treasury Securities, registration of the
         transferee as the owner of such Treasury Securities on TRADES; and

                  (3) in the case of security entitlements, including, without
         limitation, security entitlements with respect to Treasury Securities,
         a securities intermediary indicating by book entry that such security
         entitlement has been credited to the transferee's securities account.

         "Treasury Security" means a zero-coupon U.S. Treasury Security that has
a principal amount at maturity of $1,000 and matures on or prior to the Business
Day prior to the Purchase Contract Settlement Date.

         "UCC" means the Uniform Commercial Code as in effect in the State of
New York from time to time.

         "Value" means, with respect to any item of Collateral on any date, as
to (i) Cash, the face amount thereof, (ii) Senior Notes, the aggregate principal
amount thereof due at maturity and (iii) Treasury Securities, the aggregate
principal amount thereof due at maturity and (iv) Treasury Portfolio Interest,
the aggregate principal amount thereof due at maturity.

Section 2.   PLEDGE.

         SECTION   2.1 PLEDGE.

                  Each Holder, acting through the Purchase Contract Agent as
such Holder's attorney-in-fact, hereby pledges and grants to the Collateral
Agent, as agent of and for the benefit of the Company, a continuing first
priority security interest in and to, and a lien upon and right of set off
against, all of such Holder's right, title and interest in and to the Collateral
to secure the prompt and complete payment and performance when due (whether at
stated maturity, by acceleration or otherwise) of the Obligations. The
Collateral Agent shall have all of the rights, remedies and recourses with
respect to the Collateral afforded a secured party by the UCC, in addition to,
and not in limitation of, the other rights, remedies and recourses afforded to
the Collateral Agent by this Agreement.

<PAGE>

                                                                               7

         SECTION 2.2   CONTROL; FINANCING STATEMENT.

                  (a) The Collateral Agent shall have control of the Collateral
Account pursuant to the provisions of Section 4.3 of this Agreement.

                  (b) On the date of initial issuance of the PIES, the Company
shall file in the Office of the Secretary of State of the State of New York, a
financing statement identifying the Purchase Contract Agent, as attorney-in-fact
for the Holders, as debtors, and the Collateral Agent, as the secured party, and
describing the Collateral.

         SECTION 2.3   TERMINATION.

                  As to each Holder, this Agreement and the Pledge created
hereby shall terminate upon the satisfaction in full, discharge or termination
of such Holder's Obligations. Upon satisfaction in full, discharge or
termination of such Holder's Obligations and written notice thereof from the
Company, the Purchase Contract Agent or holders of at least 10% of the
outstanding PIES to the Securities Intermediary, the Securities Intermediary
shall, Transfer any remaining Collateral to the Purchase Contract Agent for
distribution to such Holder in accordance with its interest, free and clear of
any lien, pledge or security interest created hereby.

Section 3. DISTRIBUTIONS ON PLEDGED COLLATERAL.

         SECTION 3.1   INCOME DISTRIBUTIONS.

                  All income distributions, including interest payments received
by the Securities Intermediary or the Collateral Agent on account of the Pledged
Senior Notes, the Pledged Treasury Portfolio Interest or Permitted Investments
from time to time held in the Collateral Account, if any, shall be distributed
to the Purchase Contract Agent for the benefit of the applicable Holders in
whose names the Corporate PIES or Treasury PIES are registered at the close of
business on the Record Date (as specified in the Purchase Contract Agreement)
preceding the date of such distribution as provided in the Purchase Contract
Agreement. Notwithstanding the foregoing, income distributions, including
interest payments received by the Securities Intermediary or the Collateral
Agent on account of the Treasury Portfolio Interest shall not exceed the
Treasury Portfolio Return.

         SECTION 3.2   PRINCIPAL PAYMENTS FOLLOWING TERMINATION EVENT.

                  All payments received by the Collateral Agent or the
Securities Intermediary following a Termination Event with respect to (1) the
Pledged Senior Notes or security entitlement with respect thereto, (2) the
Pledged Treasury Portfolio Interest or security entitlement with respect thereto
or (3) the Pledged Treasury Securities or security entitlement with respect
thereto shall, in each case, be distributed to the Purchase Contract Agent for
the benefit of the applicable Holders in whose names the Corporate PIES or
Treasury PIES are registered at the close of business on the Record Date (as
specified in the Purchase Contract Agreement) preceding the date of such
distribution for distribution to such Holders in accordance with their
respective interests.

<PAGE>

                                                                               8

         SECTION 3.3   PRINCIPAL PAYMENTS PRIOR TO OR ON PURCHASE CONTRACT
SETTLEMENT DATE.

                  (a) Except as provided in clause 3.3(b) below, if the
Securities Intermediary and Collateral Agent have not received notice of a
Termination Event, all payments received by the Collateral Agent or the
Securities Intermediary of (1) the principal amount with respect to the Pledged
Senior Notes or security entitlement with respect thereto (2) the principal
amount with respect to the Pledged Treasury Portfolio Interest or security
entitlement with respect thereto or (3) the principal amount with respect to
Pledged Treasury Securities or security entitlement with respect thereto, shall
be held and invested at the written direction of the Company in Permitted
Investments until the Purchase Contract Settlement Date and on the Purchase
Contract Settlement Date distributed to the Company as provided in Section 5.8
hereof. Any balance remaining in the Collateral Account shall be distributed to
the Purchase Contract Agent for the benefit of the applicable Holders for
distribution to such Holders in whose names the Corporate PIES or Treasury PIES
are registered at the close of business on the Record Date (as specified in the
Purchase Contract Agreement) immediately preceding the date of such distribution
in accordance with their respective interests. Upon the request of the
Securities Intermediary or the Collateral Agent, as applicable, the Company
shall instruct the Securities Intermediary or the Collateral Agent, as
applicable, as to the type of Permitted Investments in which any payments made
under this Section shall be invested, PROVIDED, HOWEVER, that if the Company
fails to deliver such instructions by 10:30 a.m. (New York City time), the
Securities Intermediary or the Collateral Agent, as applicable, shall invest
such payments in the Permitted Investments described in clause 6 of the
definition of Permitted Investments and identified by the Company in the Account
Direction..

                  (b) All payments received by the Collateral Agent or the
Securities Intermediary of (1) the principal amount with respect to the Pledged
Senior Notes or security entitlement with respect thereto (2) the principal
amount with respect to the Pledged Treasury Portfolio Interest or security
entitlement with respect thereto or (3) the principal amount of Pledged Treasury
Securities or security entitlement with respect thereto that, in each case, have
been released from the Pledge shall be distributed to the Purchase Contract
Agent, for the benefit of the Holders, to be distributed to such Holders in
whose names the Corporate PIES or Treasury PIES are registered at the close of
business on the Record Date (as specified in the Purchase Contract Agreement)
immediately preceding the date of such distribution in accordance with their
respective interests.

         SECTION 3.4   PAYMENTS TO PURCHASE CONTRACT AGENT.

                  Payments to the Purchase Contract Agent hereunder shall be
made to the account designated by the Purchase Contract Agent for such purpose
(which shall be: The Bank of New York, ABA 021 000 018; 88K-Attn: Corporate
Trust Agency/GLA 111-565; Account Name: Sierra Pacific Resources; Account No.
334151, unless and until otherwise advised by the Purchase Contract Agent) not
later than 12:00 p.m. (New York City time), on the Business Day such payment is
received by the Collateral Agent or the Securities Intermediary; PROVIDED,
HOWEVER, that if such payment is received by the Collateral Agent or the
Securities Intermediary on a day that is not a Business Day or after 11:00 a.m.
(New York City time) on a Business Day, then such payment shall be made no later
than 10:30 a.m. (New York City time), on the next succeeding Business Day.

<PAGE>

                                                                               9

         SECTION 3.5   ASSETS NOT PROPERLY RELEASED.

                  If the Purchase Contract Agent or any Holder shall receive any
payments on account of financial assets credited to the Collateral Account and
not released therefrom in accordance with this Agreement, the Purchase Contract
Agent or such Holder shall hold the same as trustee of an express trust for the
benefit of the Company and, upon receipt of an Officers' Certificate so
directing, promptly deliver the same to the Securities Intermediary for credit
to the Collateral Account or to the Company for application to the obligations
of the Holders under the related Purchase Contracts, and the Purchase Contract
Agent and Holders shall acquire no right, title or interest in any such payments
of amounts so received.

Section 4.   CONTROL.

         SECTION 4.1   ESTABLISHMENT OF COLLATERAL ACCOUNT.

                  The Securities Intermediary hereby confirms that:

                  (1) the Securities Intermediary has established the Collateral
         Account;

                  (2) the Collateral Account is a securities account;

                  (3) subject to the terms of this Agreement, the Securities
         Intermediary shall treat the Purchase Contract Agent as entitled to
         exercise the rights that comprise any financial asset credited to the
         Collateral Account;

                  (4) upon delivery to the Securities Intermediary of any
         property, including Cash, pursuant to this Agreement, the Purchase
         Contract Agreement or the Indenture, the Securities Intermediary will
         promptly indicate by book-entry that such property has been credited
         to the Collateral Account; and

                  (5) except with respect to the Pledged Senior Notes, which
         shall be registered in the name of the Purchase Contract Agent, all
         securities, securities entitlements or other property underlying any
         financial assets credited to the Collateral Account shall be
         registered in the name of the Securities Intermediary, indorsed to
         the Securities Intermediary, or in blank or credited to another
         securities account maintained in the name of the Securities
         Intermediary, and in no case will any financial asset or other
         property credited to the Collateral Account be registered in the name
         of the Purchase Contract Agent or any Holder, payable to the order of
         the Purchase Contract Agent or any Holder or specially indorsed to
         the Purchase Contract Agent or any Holder.

         SECTION 4.2   TREATMENT AS FINANCIAL ASSETS.

                  Each item of property (whether investment property,
financial asset, security, securities entitlements, instrument or Cash)
credited to the Collateral Account shall be treated as a financial asset
under Article 8 of the UCC.

         SECTION 4.3   SOLE CONTROL BY COLLATERAL AGENT.

                  Except as provided in Section 6, at all times prior to the
termination of the Pledge, the Collateral Agent shall have sole control of the
Collateral Account, and the Securities Intermediary shall take instructions and
directions with respect to the Collateral Account solely

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                                                                              10

from the Collateral Agent. If at any time the Securities Intermediary shall
receive an entitlement order issued by the Collateral Agent and relating to the
Collateral Account, the Securities Intermediary shall comply with such
entitlement order without further consent by the Purchase Contract Agent or any
Holder or any other Person. Until termination of the Pledge, the Securities
Intermediary will not comply with any entitlement orders issued by the Purchase
Contract Agent or any Holder.

         SECTION 4.4   SECURITIES INTERMEDIARY'S LOCATION.

                  The Collateral Account and the rights and obligations of the
Securities Intermediary, the Collateral Agent, the Purchase Contract Agent and
the Holders with respect thereto shall be governed by the laws of the State of
New York. Regardless of any provision in any other agreement, for purposes of
the UCC, New York shall be deemed to be the Securities Intermediary's location.

         SECTION 4.5   NO OTHER CLAIMS.

                  Except for the claims and interest of the Collateral Agent,
the Company, the Purchase Contract Agent and the Holders in the Collateral
Account, the Securities Intermediary does not know of any claim to, or interest
in, the Collateral Account or in any financial asset credited thereto. If any
Person asserts any lien, encumbrance or adverse claim (including any writ,
garnishment, judgment, warrant of attachment, execution or similar process)
against the Collateral Account or in any financial asset carried therein, the
Securities Intermediary, upon receiving written notice thereof, will promptly
notify the Collateral Agent, the Purchase Contract Agent and the Company.

         SECTION 4.6   INVESTMENT AND RELEASE.

                  All proceeds of financial assets from time to time deposited
in the Collateral Account shall be invested and reinvested as provided in this
Agreement. At all times prior to termination of the Pledge, no property shall be
released from the Collateral Account except in accordance with this Agreement
or upon written instructions of the Collateral Agent.

         SECTION 4.7   STATEMENTS AND CONFIRMATIONS.

                  The Securities Intermediary will promptly send copies of all
statements, confirmations and other correspondence concerning the Collateral
Account and any financial assets credited thereto simultaneously to each of the
Collateral Agent, the Purchase Contract Agent and the Company at their addresses
for notices under this Agreement.

         SECTION 4.8   TAX ALLOCATIONS.

                  The Company shall report all items of income, gain, expense
and loss recognized in the Collateral Account to the Internal Revenue Service
and all state and local taxing authorities under the names and taxpayer
identification numbers of the Holders that are the beneficial owners thereof.
None of the Collateral Agent, the Securities Intermediary or the Purchase
Contract Agent shall have any responsibility for such tax reporting.

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                                                                              11

         SECTION   4.9 NO OTHER AGREEMENTS.

                  The Securities Intermediary has not entered into, and prior to
the termination of the Pledge will not enter into, any agreement with any other
Person relating to the Collateral Account or any financial assets credited
thereto, including, without limitation, any agreement to comply with entitlement
orders of any Person other than the Collateral Agent.

         SECTION 4.10   POWERS COUPLED WITH AN INTEREST.

                  The rights and powers granted in this Section 4 to the
Collateral Agent have been granted in order to perfect its security interests in
the Collateral Account, are powers coupled with an interest and will be affected
neither by the bankruptcy of the Purchase Contract Agent or any Holder nor by
the lapse of time. The obligations of the Securities Intermediary under this
Section 4 shall continue in effect until the termination of the Pledge.

Section 5.   INITIAL DEPOSIT; CREATION OF TREASURY PIES; AND RECREATION OF
             CORPORATE PIES; OTHER.

         SECTION 5.1 INITIAL DEPOSIT OF SENIOR NOTES.

                  Prior to or concurrently with the execution and delivery of
this Agreement, the Purchase Contract Agent, on behalf of the initial Holders
of the Corporate PIES, shall Transfer to the Securities Intermediary, and the
Securities Intermediary shall accept, for credit to the Collateral Account,
the Senior Notes or security entitlements relating to such Senior Notes, the
Securities Intermediary shall indicate by book entry that a security
entitlement with respect to such Senior Notes has been credited to the
Collateral Account.

         SECTION 5.2   CREATION OF TREASURY PIES BY SUBSTITUTION OF TREASURY
SECURITIES.

                  (a) A Holder of Corporate PIES may separate the Senior Notes
from the related Purchase Contracts in respect of such Holder's Corporate PIES
by substituting for such Senior Notes Treasury Securities or security
entitlements thereto in an aggregate principal amount equal to the aggregate
principal amount of such Senior Notes, at any time from and after the date of
this Agreement until 5:00 p.m. (New York City time), on the Election Date by:

                  (1) providing notice to the Purchase Contract Agent,
         substantially in the form of Exhibit C to the Purchase Contract
         Agreement, of such Holder's intention to create Treasury PIES;

                  (2) for each group of 20 Corporate PIES from which such Holder
         wishes to create Treasury PIES, transferring a Treasury Security to the
         Securities Intermediary which shall then (y) deposit the Treasury
         Security with the Collateral Agent in the Collateral Account under this
         Agreement and instruct the Collateral Agent to hold such Treasury
         Security as Collateral under this Agreement and (z) instruct the
         Collateral Agent to release to the Purchase Contract Agent, on behalf
         of such Holder, $1,000 principal amount of Senior Notes formerly
         subject to the Pledge;

                  (3) transferring the related Corporate PIES to the Purchase
         Contract Agent accompanied by a notice to the Purchase Contract Agent,
         substantially in the form of

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                                                                              12

         Exhibit D to the Purchase Contract Agreement, stating that the Holder
         has transferred the relevant amount of Treasury Securities to the
         Securities Intermediary and requesting that the Purchase Contract Agent
         instruct the Collateral Agent to release the Senior Notes underlying
         such Corporate PIES, whereupon the Purchase Contract Agent shall
         promptly give such instruction to the Collateral Agent, substantially
         in the form of Exhibit A hereto; and

                  (4) paying to the Collateral Agent any fees or expenses
         incurred in connection with the Collateral Substitution;

PROVIDED that, Holders may make Collateral Substitutions only in integral
multiples of 20 Corporate PIES. Under no circumstances may a Holder of Corporate
PIES create Treasury PIES after 5:00 p.m. (New York City time) on the Election
Date.

                  Upon receipt from the Purchase Contract Agent of a notice
substantially in the form of Exhibit A hereto, confirmation from the Securities
Intermediary that Treasury Securities have been credited to the Collateral
Account and receipt of payment for any fees or expenses incurred in connection
with the Collateral Substitution, the Collateral Agent shall instruct the
Securities Intermediary by a notice, substantially in the form of Exhibit B
hereto, to release such Pledged Senior Notes from the Pledge by Transfer the
Purchase Contract Agent for distribution to such Holder thereof, free and clear
of any lien, pledge or security interest created hereby.

                  (b) Upon credit to the Collateral Account of Treasury
Securities or security entitlements thereto delivered by a Holder of Corporate
PIES and receipt of the related instruction from the Collateral Agent, the
Securities Intermediary shall release the Senior Notes specified in such
instruction and shall promptly Transfer the same to the Purchase Contract Agent
for distribution to such Holder, free and clear of any lien, pledge or security
interest created hereby.

                  A Holder may elect not to participate in the Remarketing by
creating Treasury PIES as specified in this Section and Section 5.3(e) of the
Purchase Contract Agreement at any time until 5:00 p.m. (New York City time) on
the Election Date.

                  (c) Notwithstanding any provision herein to the contrary,
the release and Transfer of the Pledged Senior Notes in connection with the
Collateral Substitution pursuant to this Section 5.2 shall be evidenced by an
endorsement by the Collateral Agent on the Pledged Senior Note held by the
Collateral Agent reflecting a reduction in the principal amount of such
Pledged Senior Note equal in amount to the principal amount of such Separated
Senior Note. The Collateral Agent shall confirm any such reduced principal
amount by telecopying or otherwise delivering a photocopy of such endorsement
made on the Pledged Senior Note evidencing such reduced principal amount to
the Trustee. Upon receipt of such confirmation, the Trustee shall instruct
the Custodian (as defined in the Indenture Officers' Certificate) to increase
the principal amount of the Senior Notes issued in global form held by the
Custodian in an amount equal to the reduced principal amount by an
endorsement made the Custodian on such global Senior Note to reflect such
increase.

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                                                                              13

         SECTION 5.3   RECREATION OF CORPORATE PIES.

                  (a) A Holder of a Treasury PIES may recreate Corporate PIES at
any time until 5:00 p.m. (New York City time) on the Election Date by:

                  (1) providing notice to the Purchase Contract Agent,
         substantially in the form of Exhibit C of the Purchase Contract
         Agreement, of such Holder's intention to create Corporate PIES;

                  (2) for each Treasury PIES such Holder wishes to substitute,
         transferring 20 Senior Notes to the Securities Intermediary which shall
         then (y) deposit such Senior Notes in the Collateral Account under this
         Agreement and instruct the Collateral Agent to hold such Senior Notes
         as Collateral and (z) instruct the Collateral Agent to release to such
         Holder one (1) Treasury Security formerly subject to the Pledge;

                  (3) transferring the related Treasury PIES to the Purchase
         Contract Agent accompanied by a notice to the Purchase Contract Agent,
         substantially in the form of Exhibit D of the Purchase Contract
         Agreement, (i) stating that the Holder has transferred the relevant
         amount of Senior Notes to the Securities Intermediary and (ii)
         requesting that the Purchase Contract Agent instruct the Collateral
         Agent to release the Treasury Securities underlying such Treasury PIES,
         whereupon the Purchase Contract Agent shall promptly give such
         instruction to the Collateral Agent, substantially in the form of
         Exhibit C hereto; and

                  (4) paying to the Collateral Agent any fees or expenses
         incurred in connection with the recreation of Corporate PIES;

PROVIDED that, Holders of Treasury PIES may recreate Corporate PIES in integral
multiples of 20 Treasury PIES for 20 Corporate PIES. Under no circumstance may a
Holder of Treasury PIES recreate Corporate PIES after 5:00 p.m. (New York City
time) on the Election Date.

                  Upon receipt from the Purchase Contract Agent of a notice
substantially in the form of Exhibit C hereto, confirmation that Senior Notes or
security entitlements thereto have been credited to the Collateral Account as
described in such notice and receipt of payment for any fees or expenses
incurred in connection with the recreation of Corporate PIES, the Collateral
Agent shall instruct the Securities Intermediary by a notice, substantially in
the form provided in Exhibit D hereto, to release such Pledged Treasury
Securities from the Pledge by Transfer to the Holder thereof.

                  (b) Upon credit to the Collateral Account of Senior Notes or
security entitlements thereto and receipt of the related instruction from the
Collateral Agent, the Securities Intermediary shall release the applicable
Treasury Securities specified in such instruction and shall promptly Transfer
the same to such Holder, free and clear of any lien, pledge or security interest
created hereby.

<PAGE>

                                                                              14

                  (c) Notwithstanding any provision herein to the contrary,
the Transfer of the Senior Notes in connection with the recreation of
Corporate PIES pursuant to this Section 5.3 shall be evidenced by an
endorsement by the Collateral Agent on the Pledged Senior Note held by the
Collateral Agent reflecting an increase in the principal amount of such
Pledged Senior Note equal in amount to the principal amount of such Senior
Note. The Collateral Agent shall confirm any such increased principal amount
by telecopying or otherwise delivering a photocopy of such endorsement made
on the Pledged Senior Note evidencing such increased principal amount to the
Trustee. Upon receipt of such confirmation, the Trustee shall instruct the
Custodian (as defined in the Indenture Officers' Certificate) to decrease the
principal amount of Senior Notes issued in global form held by the Custodian
in an amount equal to the increased principal amount by an endorsement made
by the Custodian on such global Senior Note to reflect such decrease.

         SECTION 5.4   TERMINATION EVENT.

                  (a) Upon receipt by the Collateral Agent of written notice
from the Company or the Purchase Contract Agent that a Termination Event has
occurred, the Collateral Agent shall release all Collateral from the Pledge and
shall promptly Transfer any Pledged Senior Notes or security entitlement with
respect thereto, any Pledged Treasury Portfolio Interest or security entitlement
with respect thereto and any Pledged Treasury Securities or security entitlement
with respect thereto to the Purchase Contract Agent for the benefit of the
Holders, for distribution to such Holders in accordance with their respective
interests, free and clear of any lien, pledge or security interest or other
interest created hereby.

                  (b) If such Termination Event shall result from the Company's
becoming a debtor under the Bankruptcy Code, and if the Collateral Agent shall
for any reason fail promptly to effectuate the release and Transfer of all
Pledged Senior Notes, the Pledged Treasury Portfolio Interest or the Pledged
Treasury Securities or security entitlements with respect thereto, as the case
may be, as provided by this Section 5.4, the Purchase Contract Agent shall:

                  (1) request an opinion letter of a nationally recognized law
         firm reasonably acceptable to the Collateral Agent to the effect that,
         as a result of the Company's being the debtor in such a bankruptcy
         case, the Collateral Agent will not be prohibited from releasing or
         Transferring the Collateral as provided in this Section 5.4, and shall
         deliver such opinion to the Collateral Agent within ten days after the
         occurrence of such Termination Event, and if (A) the Purchase Contract
         Agent shall be unable to obtain such opinion within ten days after the
         occurrence of such Termination Event or (B) the Collateral Agent shall
         continue, after delivery of such opinion, to refuse to effectuate the
         release and Transfer of all Pledged Senior Notes, all Pledged Treasury
         Portfolio Interest, all Pledged Treasury Securities or the Proceeds of
         any of the foregoing, as the case may be, as provided in this Section
         5.4, then the Purchase Contract Agent shall within thirty days after
         the occurrence of such Termination Event commence an action or
         proceeding in the court having jurisdiction of the Company's case under
         the Bankruptcy Code seeking an order requiring the Collateral Agent to
         effectuate the release and transfer of all Pledged Senior Notes, all
         Pledged Treasury Portfolio Interest or all the Pledged Treasury
         Securities or security entitlements with respect thereto, as the case
         may be, as provided by this Section 5.4; or

<PAGE>

                                                                              15

                  (2) commence an action or proceeding like that described in
         Section 5.4(b)(1)(B) hereof within ten days after the occurrence of
         such Termination Event.

The Purchase Contract Agent shall be deemed to have complied with Section
5.4(b)(1), and shall not be required to commence any action or proceeding
referred to therein, if it shall have either obtained such an opinion letter or
requested such an opinion from three such nationally recognized law firms
reasonably acceptable to the Collateral Agent.

         SECTION   5.5 CASH SETTLEMENT.

                  (a) Unless a Holder has effected an Early Settlement or a
Merger Early Settlement or a Successful Remarketing has occurred, in the case
of Corporate PIES, and unless a Termination Event has occurred prior to dates
required for notice to elect the Cash Settlement right specified in the
Purchase Contract Agreement and the Collateral Agent has received written
notice from the Company, the Purchase Contract Agent or, in the case of a
Termination Event, from the holders of at least 10% of the outstanding PIES
of such Early Settlement, Merger Early Settlement, Successful Remarketing or
Termination Event, as the case may be, upon receipt by the Collateral Agent
of (1) a notice from the Purchase Contract Agent (including a copy of such
notice received from the Holder substantially in the form of Exhibit F to the
Purchase Contract Agreement) promptly after the receipt by the Purchase
Contract Agent of a notice from a Holder of a Corporate PIES or a Treasury
PIES that it has elected, in accordance with the procedures specified in
Section 5.8(a)(i) or (b)(i) of the Purchase Contract Agreement, respectively,
to effect a Cash Settlement and (2) payment by such Holder by deposit in the
Collateral Account on or prior to 11:00 a.m. (New York City time), on the
fifth Business Day immediately preceding the Purchase Contract Settlement
Date in the case of Corporate PIES, and the Business Day immediately
preceding the Purchase Contract Settlement Date in the case of the Treasury
PIES, of the Purchase Price in lawful money of the United States by certified
or cashiers' check or wire transfer, in each case of immediately available
funds payable to or upon the order of the Securities Intermediary, then the
Collateral Agent shall upon receipt of written directions from the Company:

                  (1) instruct the Securities Intermediary promptly to invest
         any such Cash in Permitted Investments;

                  (2) release from the Pledge (i) in the case of a Holder of
         Corporate PIES, the related Pledged Senior Notes, or (ii) in the case
         of a Holder of Treasury PIES, the related Pledged Treasury Securities,
         with a principal amount or principal amount at maturity, as the case
         may be, equal to the product of (x) the Stated Amount times (y) the
         number of Purchase Contracts as to which such Holder has elected to
         effect a Cash Settlement; and

                  (3) instruct the Securities Intermediary to Transfer all such
         Pledged Senior Notes or Pledged Treasury Securities, as the case may
         be, to the Purchase Contract Agent for the benefit of such Holders, in
         each case free and clear of the Pledge created hereby, for distribution
         to such Holder.

                  The Company shall instruct the Securities Intermediary as to
the type of Permitted Investments in which any such Cash shall be invested;
PROVIDED, HOWEVER, that if the Company fails to deliver such instructions by
10:00 a.m. (New York City time), the Securities Intermediary shall invest such
Cash in the Permitted Investments described in clause 6 of the definition of

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                                                                              16

Permitted Investments and identified by the Company in the Account Direction.
Upon receipt of the proceeds upon the maturity of the Permitted Investments on
the Purchase Contract Settlement Date, the Collateral Agent shall (A) instruct
the Securities Intermediary to pay the portion of such proceeds and deliver any
certified or cashier's checks received, in an aggregate amount equal to the
Purchase Price, to the Company on the Purchase Contract Settlement Date, and (B)
instruct the Securities Intermediary to release any amounts in respect of the
interest earned from such Permitted Investments to the Purchase Contract Agent
for distribution to such Holder.

                  (b) If a Holder of a Corporate PIES notifies the Purchase
Contract Agent as provided in Section 5.8(a)(i) of the Purchase Contract
Agreement of its intention to pay the Purchase Price in cash, but fails to make
such payment as required by Section 5.8(a)(ii) of the Purchase Contract
Agreement, such Holder shall be deemed to have consented to (A) to the
disposition of the Pledged Senior Notes on the third Business Day prior to the
Purchase Contract Settlement Date in connection with the Final Remarketing in
accordance with Section 5.3 of the Purchase Contract Agreement or, (B) if a
Failed Remarketing occurs, the Collateral Agent, for the benefit of the Company,
and upon written direction of the Company as provided in this Agreement,
exercising all of its rights as a secured party with respect to any Pledged
Senior Notes under this Agreement and, subject to applicable law, by either (i)
retaining such Senior Notes in full satisfaction of such Holder's obligations
under the related Purchase Contracts or (ii) selling such Senior Notes in one or
more public or private sales.

                  (c) If a Holder of a Treasury PIES notifies the Purchase
Contract Agent as provided in Section 5.8(b)(i) of the Purchase Contract
Agreement of its intention to pay the Purchase Price in cash, but fails to make
such payment as required by Section 5.8(b)(ii) of the Purchase Contract
Agreement, such Holder shall be deemed to have elected to pay the Purchase Price
in accordance with Section 5.8(b) hereof.

                  (d) Prior to 3:00 p.m. (New York City time), on the fourth
Business Day immediately preceding the Purchase Contract Settlement Date, the
Securities Intermediary shall deliver to the Purchase Contract Agent a notice,
substantially in the form of Exhibit E hereto, stating the amount of cash that
it has received with respect to the Cash Settlement of Corporate PIES.

                  (e) Prior to 3:00 p.m. (New York City time), on the Business
Day immediately preceding the Purchase Contract Settlement Date, the Securities
Intermediary shall deliver to the Purchase Contract Agent a notice,
substantially in the form of Exhibit E hereto, stating the amount of cash that
it has received with respect to the Cash Settlement of Treasury PIES.

         SECTION 5.6   EARLY SETTLEMENT; MERGER EARLY SETTLEMENT.

                  Unless a Termination Event has occurred and the Collateral
Agent has received from the Company or the Purchase Contract Agent or holders of
at least 10% of the outstanding PIES written notice of such Termination Event,
upon receipt by the Collateral Agent of a notice from the Purchase Contract
Agent that a Holder of PIES has elected to effect Early Settlement or Merger
Early Settlement of its obligations under the Purchase Contracts forming a part
of such PIES in accordance with the terms of the Purchase Contracts and the
Purchase Contract Agreement (which notice shall set forth the number of such
Purchase Contracts as to which such Holder has elected to effect Early
Settlement or Merger Early Settlement), and that the Purchase

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                                                                              17

Contract Agent has received from such Holder, and paid to the Company as
confirmed in writing by the Company, the related Early Settlement Amounts or
Merger Early Settlement Amounts, as applicable, pursuant to the terms of the
Purchase Contract Agreement and all conditions to such Early Settlement or
Merger Early Settlement, as applicable, have been satisfied, then the Collateral
Agent shall release from the Pledge, (1) Pledged Senior Notes, or Pledged
Treasury Portfolio Interest, as the case may be, in the case of a Holder of
Corporate PIES, or (2) Pledged Treasury Securities, in the case of a Holder of
Treasury PIES, with a Value equal to the product of (i) the Stated Amount times
(ii) the number of Purchase Contracts as to which such Holder has elected to
effect Early Settlement or Merger Early Settlement, as applicable, and shall
instruct the Securities Intermediary to Transfer all such Pledged Senior Notes,
Pledged Treasury Portfolio Interest or Pledged Treasury Securities, as the case
may be, to the Purchase Contract Agent for the benefit of such Holder, in each
case free and clear of the Pledge created hereby, for distribution to such
Holder.

                  Notwithstanding anything to the contrary contained herein,
Holders may not effect Early Settlement after 5:00 p.m. (New York City time) on
the Election Date and Holders may effect Merger Early Settlement of PIES only in
integral multiples of 20 Corporate PIES or 20 Treasury PIES.

         SECTION 5.7   OPTIONAL REMARKETING.

                  Pursuant to the Indenture and the Remarketing Agreement, on or
prior to 5:00 p.m. (New York City time) on the Election Date, registered holders
of Separated Senior Notes may elect to have their Separated Senior Notes
remarketed by Transferring their Separated Senior Notes, together with a notice
of such election, substantially in the form of Exhibit F hereto and Exhibit B to
the Indenture Officers' Certificate, to the Collateral Agent and the Trustee,
respectively, whereupon, the Collateral Agent shall hold such Separated Senior
Notes in an account separate from the Collateral Account and cause such
Separated Senior Notes to be included in any Remarketing pursuant to the
Indenture and the Remarketing Procedures. Once such holder of such Separated
Senior Notes delivers such notice and Separated Senior Notes as specified in the
preceding sentence, such election may not be withdrawn and may not be
conditioned upon the level at which the Reset Rate is established in the
Remarketing; PROVIDED, HOWEVER, that if such a holder delivers only such a
notice but not the Separated Senior Notes subject to the notice, then none of
such holders' Separated Senior Notes shall be included in the Remarketing.

                  If a Failed Remarketing occurs, the Remarketing Agent shall
notify by telephone the Company, the Depositary, the Purchase Contract Agent,
the Collateral Agent and the Trustee that a Failed Remarketing has occurred and
shall Transfer to the Collateral Agent, by the third Business Day following the
Failed Remarketing, such Separated Senior Notes, whereupon the Collateral Agent
shall promptly Transfer such Separated Senior Notes to the holders entitled
thereto.

         SECTION 5.8   APPLICATION OF PROCEEDS IN SETTLEMENT; REMARKETING.

                  (a) Unless a Termination Event has occurred or a Holder has
effected an Early Settlement or a Merger Early Settlement, Early Settlement or
Merger Early Settlement and the Collateral Agent has received written notice of
such Termination Event, Early Settlement, or

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                                                                              18

Merger Early settlement from the Company or the Purchase Contract Agent or, in
the case of a Termination, Holders of at least 10% of the Outstanding PIES, (i)
the Purchase Contract Agent shall provide notice, substantially in the form of
Exhibit G to the Purchase Contract Agreement by 11:00 a.m. (New York City time),
on the Business Day immediately preceding the Initial Remarketing Date, to the
Remarketing Agent, the Collateral Agent, the Trustee and the Company of the
aggregate principal amount of Pledged Senior Notes comprising part of Corporate
PIES to be remarketed, other than those Pledged Senior Notes of Holders that
have elected not to participate in the Remarketing pursuant to paragraph
19(i)(B) of the Indenture Officers' Certificate and Section 5.3(e) of the
Purchase Contract Agreement (of which the Purchase Contract Agent has delivered
written notice thereof to the Collateral Agent, substantially in the form of
Exhibit G hereto), and (ii) the Collateral Agent shall notify, by 11:00 a.m.
(New York City time), on the Business Day immediately preceding the Initial
Remarketing Date, the Remarketing Agent, the Trustee and the Company of the
aggregate principal amount of Separated Senior Notes of holders of Separated
Senior Notes that have elected to participate in the Remarketing (the Senior
Notes described in clauses (i) and (ii) collectively being referred to as the
"Remarketing Senior Notes") and, concurrently therewith, the Collateral Agent
shall, without any further instruction from any holder of the Remarketing Senior
Notes, present all Remarketing Senior Notes to the Remarketing Agent for
Remarketing.

                  If there has been a successful Initial Remarketing (a
"Successful Initial Remarketing") or a successful Subsequent Remarketing (a
"Successful Subsequent Remarketing"), the Remarketing Agent will on the
Remarketing Date of such Remarketing (i) deduct and retain for itself as a
remarketing fee an amount not exceeding 25 basis points (0.25%) of the principal
amount of each remarketed Remarketing Senior Note (the "Remarketing Fee"), (ii)
use the remaining Proceeds with respect to the Pledged Senior Notes from such
Successful Remarketing to purchase the Treasury Portfolio and, on or prior to
the third Business Day following the Remarketing Date (such date of settlement
of the Remarketing, the "Remarketing Settlement Date"), and deliver such
Treasury Portfolio to the Collateral Agent, along with notification thereof,
which shall thereupon, for the benefit of the Company, apply such Treasury
Portfolio, to secure the obligation of all Holders of Corporate PIES to purchase
Common Stock under the Purchase Contracts constituting a part of such Corporate
PIES, in substitution for the Pledged Senior Notes, (iii) if any Separated
Senior Notes were remarketed, remit to the Collateral Agent, along with
notification thereof, for payment to the holders of such Separated Senior Notes
sold in the Remarketing the remaining proceeds from such Successful Remarketing
equal to the amounts described in clauses (1)(ii) and (2)(ii) of the definition
of Remarketing Value and (iv) if there then remains any proceeds from such
Successful Remarketing, after the application of such proceeds as set forth in
clauses (i) through (iii) above, then remit, along with notification thereof,
any such remaining proceeds attributable to the remarketed Pledged Senior Notes
to the Purchase Contract Agent for the benefit of the holders of such Pledged
Senior Notes and to the Collateral Agent for benefit of the holders of any
remarketed Separate Senior Notes, on a pro rata basis, PROVIDED, HOWEVER, that
if such Successful Remarketing is consummated after 4:30 p.m. (New York City
time) on such Remarketing Date and, despite using its commercially reasonable
efforts, the Remarketing Agent cannot cause the applications of the proceeds
specified above to occur on such Remarketing Date, then the Remarketing Agent
may make such applications and remittances on the next succeeding Business Day.
Holders of the Remarketing Senior Notes that are so remarketed will not
otherwise be responsible for the payment of any remarketing fee or expenses in
connection with the Remarketing. Following the delivery of the

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                                                                              19

Treasury Portfolio to the Collateral Agent as set forth above in this paragraph,
the Collateral Agent shall have such security interests, rights and obligations
with respect to the Treasury Portfolio as it had in respect of the Pledged
Senior Notes, as provided herein.

                  In the event that any portion of the Pledged Treasury
Portfolio Interest matures before the Purchase Contract Settlement Date, the
Collateral Agent shall invest the Cash Proceeds therefrom in Permitted
Investments in clause 6 of the definition of Permitted Investments, and
identified by the Company in the Account Direction, unless the Company shall
otherwise instruct the Securities Intermediary and the Collateral Agent as to
the type of Permitted Investments in which any such Cash Proceeds shall be
invested. The Collateral Agent shall cause the Securities Intermediary to remit,
on the Purchase Contract Settlement Date, a portion of the Cash Proceeds of the
maturing Pledged Treasury Portfolio Interest and of the investment earnings from
the related investment in Permitted Investments, in an aggregate amount equal to
the Treasury Portfolio Return to the Purchase Contract Agent for the benefit of
the Holders of the related Corporate PIES when received. Without receiving any
instruction from any such Holder of Corporate PIES, the Collateral Agent shall
apply, on the Purchase Contract Settlement Date, the Cash Proceeds of the
maturing Pledged Treasury Portfolio Interest and of the investment earnings from
the related investment in Permitted Investments, in an aggregate amount equal to
the aggregate Purchase Price applicable to such Corporate PIES to satisfy in
full such Holder's obligations to pay the Purchase Price to purchase the shares
of Common Stock under the related Purchase Contracts on the Purchase Contract
Settlement Date. In the event the sum of the Proceeds from the related Pledged
Treasury Portfolio Interest and the investment earnings from the related
investment in Permitted Investments exceeds the sum of the related Treasury
Portfolio Return and the aggregate Purchase Price of the Purchase Contracts
being settled thereby, the Collateral Agent shall instruct the Securities
Intermediary to distribute such excess, when received, to the Purchase Contract
Agent for distribution to the Holders whose Purchase Contracts were settled with
such Proceeds, on a pro rata basis.

                  If, by 4:00 p.m. (New York City time), on the ninth Business
Day preceding the Purchase Contract Settlement Date, the Remarketing Agent,
despite using its commercially reasonable efforts, has been and is unable to
remarket all of the Remarketing Senior Notes tendered for purchase at a price
equal to at least the Remarketing Value, the Remarketing Agent shall Transfer to
the Collateral Agent, along with notification thereof, by the sixth Business Day
preceding the Purchase Contract Settlement Date, the Pledged Senior Notes that
were to be remarketed in the Initial or Subsequent Remarketing, whereupon the
Collateral Agent shall, for the benefit of the Company, apply such Pledged
Senior Notes, to secure the obligation of the related Holders of Corporate PIES
to purchase Common Stock under the related Purchase Contracts.

                  (b) Unless a Termination Event has occurred or a Holder has
effected a Cash Settlement, an Early Settlement or a Merger Early Settlement, or
a Successful Initial Remarketing or a Successful Subsequent Remarketing has
occurred, such Holder shall be deemed to have consented to the Remarketing of
its Pledged Senior Notes in the Final Remarketing on the Final Remarketing Date,
in a Remarketing in accordance with Section 5.3(c) of the Purchase Contract
Agreement. Upon notice of such event from the Purchase Contract Agent, the
Collateral Agent shall, by 11:00 a.m. (New York City time), on the Business Day
immediately preceding the Final Remarketing Date, without any instruction from
such Holders

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                                                                              20

of Corporate PIES, Transfer the Remarketing Senior Notes to the Remarketing
Agent for Remarketing. Upon receiving such Remarketing Senior Notes, the
Remarketing Agent, pursuant to the terms of the Remarketing Agreement, will use
its commercially reasonable efforts to remarket such Remarketing Senior Notes on
the Final Remarketing Date.

                  If the Final Remarketing is successful (a "Successful Final
Remarketing"), the Remarketing Agent will on the Remarketing Date (i) deduct and
retain for itself the Remarketing Fee pursuant to the Remarketing Agreement,
(ii) cause the remaining Proceeds of the Remarketing with respect to the Pledged
Senior Notes in an amount equal to the aggregate principal amount of such Senior
Notes to be delivered to the Purchase Contract Agent, on the Remarketing
Settlement Date, (iii), if any Separated Senior Notes were remarketed, remit to
the Collateral Agent, along with notification thereof, for payment to the
holders of such Separated Senior Notes sold in the Remarketing the remaining
proceeds from such Successful Remarketing attributable to the Separated Senior
Notes in an amount equal to the principal amount of such Senior Notes and (iv)
if there then remains any proceeds from such Successful Remarketing, after the
application of such proceeds as set forth in clauses (i) through (iii) above,
remit, along with notification thereof, any excess Proceeds of the Remarketing
to the Purchase Contract Agent for the benefit of the Holders of Corporate PIES
whose Pledged Senior Notes were remarketed and to the Collateral Agent for the
benefit of the holders of any remarketed Separated Senior Notes, on a pro rata
basis. Holders of the Remarketing Senior Notes that are so remarketed will not
otherwise be responsible for the payment of any remarketing fee or expenses in
connection with the Remarketing. The Purchase Contract Agent shall give written
directions to the Collateral Agent, and the Collateral Agent shall instruct the
Securities Intermediary, to apply a portion of the Proceeds with respect to the
Pledged Senior Notes from such Remarketing, on the Purchase Contract Settlement
Date, equal to the aggregate principal amount of such Pledged Senior Notes to
satisfy in full the obligations of such Holders of Corporate PIES to pay the
Purchase Price to purchase the shares of Common Stock under the related Purchase
Contracts.

                  If a Failed Remarketing occurs, the Collateral Agent, having
received notice of such Failed Remarketing from the Remarketing Agent pursuant
to the Remarketing Agreement, shall, on the written direction of the Company,
exercise for the benefit of the Company, its rights as a secured creditor with
respect to the Pledged Senior Notes related to this Corporate PIES Certificate
and, subject to applicable law, may (i) retain such Pledged Senior Notes in full
satisfaction of the Holders' obligations under the Purchase Contracts or (ii)
sell such Pledged Senior Notes in one or more public or private sales, the
proceeds, if any, of such sale to constitute full satisfaction of the Holders'
obligations under the Purchase Contracts.

                  (c) Unless a Termination Event has occurred or a Holder has
effected a Cash Settlement, an Early Settlement or a Merger Early Settlement, if
a Successful Initial Remarketing or a Successful Subsequent Remarketing has
occurred, a Holder shall be deemed to have elected to pay for the shares of
Common Stock to be issued under such Purchase Contracts from the Proceeds of the
Pledged Treasury Portfolio, in the case of Holders of Corporate PIES, and the
related Pledged Treasury Securities, in the case of Holders of Treasury PIES.

                  (d) In the event that all or any portion of the Pledged
Treasury Securities matures before the Purchase Contract Settlement Date, the
Collateral Agent shall invest the Cash Proceeds therefrom in Permitted
Investments in clause 6 of the definition of Permitted

<PAGE>

                                                                              21

Investments and identified by the Company in the Account Direction, unless the
Company shall otherwise instruct the Securities Intermediary and the Collateral
Agent as to the type of Permitted Investments in which any such Cash Proceeds
shall be invested.

                  (e) Without receiving any instruction from any such Holder of
Treasury PIES, the Collateral Agent shall apply, on the Purchase Contract
Settlement Date, the Cash Proceeds of the maturing Pledged Treasury Securities
and of the investment earnings from the related investment in Permitted
Investments, in each case, in an amount equal to the aggregate Purchase Price
applicable to such Treasury PIES to satisfy in full such Holder's obligations to
pay the Purchase Price to purchase the shares of Common Stock under the related
Purchase Contracts on the Purchase Contract Settlement Date. In the event the
sum of the Proceeds from the related Pledged Treasury Securities and the
investment earnings from the related investment in Permitted Investments exceeds
the aggregate Purchase Price of the Purchase Contracts being settled thereby,
the Collateral Agent shall instruct the Securities Intermediary to distribute
such excess, when received, to the Purchase Contract Agent for distribution to
the Holders whose Purchase Contracts were settled with such Proceeds, on a pro
rata basis.

                  (f) Notwithstanding the Pledge and, if applicable, the
delivery of Separated Senior Notes to the Collateral Agent for Remarketing, in
each case, as set forth herein, the Company's obligation to pay interest,
including any accrued and unpaid, on all outstanding Senior Notes (whether then
comprising a part of Corporate PIES or as Separated Senior Notes) pursuant to
the Indenture shall remain.

Section 6.   VOTING RIGHTS.

                  The Purchase Contract Agent may exercise, or refrain from
exercising, any and all voting and other consensual rights pertaining to the
Pledged Senior Notes or any part thereof in accordance with the terms of the
Purchase Contract Agreement. The Purchase Contract Agent shall give the Company
and the Collateral Agent at least five calendar days' prior written notice of
the manner in which it intends to exercise, or its reasons for refraining from
exercising, any such right. Upon receipt of any notices and other communications
in respect of any Pledged Senior Notes, including notice of any meeting at which
holders of the Senior Notes are entitled to vote or solicitation of consents,
waivers or proxies of holders of the Senior Notes, the Collateral Agent shall
use its reasonable efforts to send promptly to the Purchase Contract Agent such
notice or communication, and as soon as reasonably practicable after receipt of
a written request therefor from the Purchase Contract Agent, execute and deliver
to the Purchase Contract Agent such proxies and other instruments in respect of
such Pledged Senior Notes (in form and substance satisfactory to the Collateral
Agent) as are prepared by the Purchase Contract Agent with respect to the
Pledged Senior Notes.

Section 7.   RIGHTS AND REMEDIES.

         SECTION 7.1 RIGHTS AND REMEDIES OF THE COLLATERAL AGENT.

                  (a) In addition to the rights and remedies specified in
Section 5.5 hereof or otherwise available at law or in equity, after an event of
default (as specified in Section 7.1(b) below) hereunder, the Collateral Agent
shall have all of the rights and remedies with respect to the Collateral of a
secured party under the UCC (whether or not the UCC is in effect in the

<PAGE>

                                                                              22

jurisdiction where the rights and remedies are asserted) and the TRADES
Regulations and such additional rights and remedies to which a secured party is
entitled under the laws in effect in any jurisdiction where any rights and
remedies hereunder may be asserted. Without limiting the generality of the
foregoing, such remedies may include, to the extent permitted by applicable law,
(i) retention of the Pledged Senior Notes, Pledged Treasury Portfolio Interest
or Pledged Treasury Securities in full satisfaction of the Holders' obligations
under the Purchase Contracts or (ii) sale of the Pledged Senior Notes, Pledged
Treasury Portfolio Interest or Pledged Treasury Securities in one or more public
or private sales.

                  (b) Without limiting any rights or powers otherwise granted by
this Agreement to the Collateral Agent, in the event the Collateral Agent is
unable to make payments to the Company on account of principal payments of any
Pledged Treasury Securities or on account of any Pledged Treasury Portfolio
Interest as provided in Section 3 hereof, in satisfaction of the Obligations of
the Holder of the PIES of which such Pledged Treasury Securities or Pledged
Treasury Portfolio Interest are a part under the related Purchase Contracts, the
inability to make such payments shall constitute an event of default hereunder
and the Collateral Agent shall have and may exercise, with reference to such
Pledged Treasury Securities or Pledged Treasury Portfolio Interest, as
applicable, any and all of the rights and remedies available to a secured party
under the UCC and the TRADES Regulations after default by a debtor, and as
otherwise granted herein or under any other law.

                  (c) Without limiting any rights or powers otherwise granted by
this Agreement to the Collateral Agent, the Collateral Agent is hereby
irrevocably authorized to receive and collect all payments of (i) the principal
amount of the Pledged Senior Notes, (ii) the principal amount of the Pledged
Treasury Securities and (iii) the principal amount of the Pledged Treasury
Portfolio Interest, subject, in each case, to the provisions of Section 3
hereof, and as otherwise granted herein.

                  (d) Subject to Section 9.1, the Purchase Contract Agent and
each Holder of PIES agrees that, from time to time, upon the written request of
the Collateral Agent, the Purchase Contract Agent or such Holder shall execute
and deliver such further documents and do such other acts and things as the
Collateral Agent may reasonably request in order to maintain the Pledge, and the
perfection and priority thereof, and to confirm the rights of the Collateral
Agent hereunder. The Purchase Contract Agent shall have no liability to any
Holder for executing any documents or taking any such acts requested by the
Collateral Agent hereunder, except for liability for its own grossly negligent
acts, its own grossly negligent failure to act or its own willful misconduct.

         SECTION 7.2   SUBSTITUTIONS.

                  Whenever a Holder has the right to substitute Treasury
Securities, Senior Notes or security entitlements to either of them for
financial assets held in the Collateral Account, such substitution shall not
constitute a novation of the security interest created hereby.

<PAGE>

                                                                              23

Section 8.   REPRESENTATIONS AND WARRANTIES; COVENANTS.

         SECTION 8.1   REPRESENTATIONS AND WARRANTIES.

                  Each Holder from time to time, acting through the Purchase
Contract Agent as attorney-in-fact (it being understood that the Purchase
Contract Agent shall not be liable for any representation or warranty made by or
on behalf of a Holder), hereby represents and warrants to the Collateral Agent
(with respect to its interest in the Collateral), which representations and
warranties shall be deemed repeated on each day a Holder Transfers Collateral
that:

                  (1) such Holder has the power to grant a security interest in
         and lien on the Collateral;

                  (2) such Holder is the sole beneficial owner of the Collateral
         and, in the case of Collateral delivered in physical form, is the sole
         holder of such Collateral and is the sole beneficial owner of, or has
         the right to Transfer, the Collateral it Transfers to the Securities
         Intermediary for credit to the Collateral Account, free and clear of
         any security interest, lien, encumbrance, call, liability to pay money
         or other restriction other than the security interest and lien granted
         under Section 2 hereof;

                  (3) upon the Transfer of the Collateral to the Securities
         Intermediary for credit to the Collateral Account, the Collateral
         Agent, for the benefit of the Company, will have a valid and perfected
         first priority security interest therein (assuming that any central
         clearing operation or any Securities Intermediary or other entity not
         within the control of the Holder involved in the Transfer of the
         Collateral, including the Collateral Agent and the Securities
         Intermediary, gives the notices and takes the action required of it
         hereunder and under applicable law for perfection of that interest and
         assuming the establishment and exercise of control pursuant to Section
         4 hereof); and

                  (4) the execution and performance by the Holder of its
         obligations under this Agreement will not result in the creation of any
         security interest, lien or other encumbrance on the Collateral other
         than the security interest and lien granted under Section 2 hereof or
         violate any provision of any existing law or regulation applicable to
         it or of any mortgage, charge, pledge, indenture, contract or
         undertaking to which it is a party or which is binding on it or any of
         its assets.

         SECTION 8.2   COVENANTS.

                  The Purchase Contract Agent and the Holders from time to time,
acting through the Purchase Contract Agent as their attorney-in-fact (it being
understood that the Purchase Contract Agent shall not be liable for any covenant
made by or on behalf of a Holder), hereby covenant to the Collateral Agent that
for so long as the Collateral remains subject to the Pledge:

                  (1) neither the Purchase Contract Agent nor such Holders will
         create or purport to create or allow to subsist any mortgage, charge,
         lien, pledge or any other security interest whatsoever over the
         Collateral or any part of it other than pursuant to this Agreement; and

<PAGE>

                                                                              24

                  (2) neither the Purchase Contract Agent nor such Holders will
         sell or otherwise dispose (or attempt to dispose) of the Collateral or
         any part of it except for the beneficial interest therein, subject to
         the Pledge hereunder, transferred in connection with the Transfer of
         the PIES.

Section 9.   THE COLLATERAL AGENT AND THE SECURITIES INTERMEDIARY.

                  It is hereby agreed as follows:

         SECTION  9.1  APPOINTMENT, POWERS AND IMMUNITIES.

                  The Collateral Agent and the Securities Intermediary shall
each act solely as agent for the Company hereunder and not in its individual
capacity with such powers as are specifically vested in the Collateral Agent or
the Securities Intermediary, as the case may be, by the terms of this Agreement,
together with such other powers as are reasonably incidental thereto. The
Collateral Agent and the Securities Intermediary shall:

                  (1) have no duties or responsibilities except those expressly
         set forth in this Agreement and no implied covenants or obligations
         shall be inferred from this Agreement against the Collateral Agent or
         the Securities Intermediary, nor shall the Collateral Agent or the
         Securities Intermediary be bound by the provisions of any agreement by
         any party hereto beyond the specific terms hereof;

                  (2) not be responsible for, and neither the Collateral Agent
         nor the Securities Intermediary makes any representation or warranty
         with respect to, any recitals contained in this Agreement, or in any
         certificate or other document referred to or provided for in, or
         received by it under, this Agreement, the PIES or the Purchase Contract
         Agreement, or for the value, validity, effectiveness, genuineness,
         enforceability or sufficiency of this Agreement (other than as against
         the Collateral Agent or the Securities Intermediary, as the case may
         be), the PIES or the Purchase Contract Agreement or any other document
         referred to or provided for herein or therein or for any failure by the
         Company or any other Person (except the Collateral Agent or the
         Securities Intermediary, as the case may be) to perform any of its
         obligations hereunder or thereunder or for the due creation,
         perfection, priority or, except, in the case of the Collateral Agent,
         as expressly required hereby, maintenance of any security interest
         created hereunder;

                  (3) not be required to initiate or conduct any litigation or
         collection proceedings hereunder (except, in the case of the Collateral
         Agent, pursuant to directions furnished under Section 9.2 hereof,
         subject to Section 9.6 hereof);

                  (4) not be responsible for any action taken or omitted to be
         taken by it hereunder or under any other document or instrument
         referred to or provided for herein or in connection herewith or
         therewith, except for its own gross negligence or willful misconduct;
         and

                  (5) not be required to advise any party as to selling or
         retaining, or taking or refraining from taking any action with respect
         to, any securities or other property deposited hereunder.

<PAGE>

                                                                              25

Subject to the foregoing, during the term of this Agreement, the Collateral
Agent shall take all reasonable action in connection with the safekeeping and
preservation of the Collateral hereunder.

                  No provision of this Agreement shall require the Collateral
Agent to expend or risk its own funds or otherwise incur any financial liability
in the performance of any of its duties hereunder. Notwithstanding the
foregoing, each of the Collateral Agent and the Securities Intermediary in its
individual capacity hereby waives any right of setoff, bankers' lien, liens or
perfection rights as Securities Intermediary or any counterclaim with respect to
any of the Collateral.

         SECTION 9.2   INSTRUCTIONS OF THE COMPANY.

                  The Company shall have the right, by one or more instruments
in writing executed and delivered to the Collateral Agent, to direct the time,
method and place of conducting any proceeding for the realization of any right
or remedy available to the Collateral Agent, or of exercising any power
conferred on the Collateral Agent, or to direct the taking or refraining from
taking of any action authorized by this Agreement; PROVIDED, HOWEVER, that (i)
such direction shall not conflict with the provisions of any law or of this
Agreement and (ii) the Collateral Agent shall be adequately indemnified as
provided herein. Nothing contained in this Section 9.2 shall impair the right of
the Collateral Agent in its discretion to take any action or omit to take any
action which it deems proper and which is not inconsistent with such direction.

                  In the event the Collateral Agent or the Securities
Intermediary is uncertain as to the application of any provision in this
Agreement or any other agreement relating to the transactions contemplated
hereby, or such provision is ambiguous as to its application or is, or appears
to be, in conflict with any other applicable provision hereof, or in the event
this Agreement permits any determination by the Collateral Agent or the
Securities Intermediary or is silent or incomplete as to the course of action
the Collateral Agent or the Securities Intermediary is required to take with
respect to a particular set of facts, the Collateral Agent or the Securities
Intermediary may seek instructions from the Company and shall not be liable to
any Person to the extent that it acts in good faith in accordance with the
instructions of the Company; PROVIDED, that, if the Collateral Agent or the
Securities Intermediary shall not have received instructions from the Company
pursuant to its request within twenty (20) days after the date of such request,
until instructed otherwise by the Company, the Collateral Agent or the
Securities Intermediary may, but shall be under no duty to, take or refrain from
taking such action as it shall deem advisable in the best interests of the
Company.

         SECTION 9.3   RELIANCE BY COLLATERAL AGENT AND SECURITIES INTERMEDIARY.

                  Each of the Securities Intermediary and the Collateral Agent
shall be entitled to rely upon, and shall not incur any liability to anyone in
acting upon, any certification, order, judgment, opinion, notice, instructions
or other communication (including, without limitation, any thereof by telephone,
telecopy, telex or facsimile) believed by it to be genuine and correct and to
have been signed or sent by or on behalf of the proper Person or Persons
(without being required to determine the correctness of any fact or matter
stated therein) and upon advice and statements of legal counsel and other
experts selected by the Collateral Agent or the Securities

<PAGE>

                                                                              26

Intermediary, as the case may be. As to any matters not expressly provided for
by this Agreement, the Collateral Agent and the Securities Intermediary shall in
all cases be fully protected in acting, or in refraining from acting, hereunder
in accordance with instructions given by the Company in accordance with Section
9.2 of this Agreement.

         SECTION 9.4   RIGHTS IN OTHER CAPACITIES.

                  The Collateral Agent and the Securities Intermediary and their
affiliates may (without having to account therefor to the Company) accept
deposits from, lend money to, make their investments in and generally engage in
any kind of banking, trust or other business with the Purchase Contract Agent or
the Securities Intermediary, as the case may be, any other Person interested
herein and any Holder of PIES (and any of their respective subsidiaries or
affiliates) as if it were not acting as the Collateral Agent or the Securities
Intermediary, as the case may be, and the Collateral Agent, the Securities
Intermediary and their affiliates may accept fees and other consideration from
the Purchase Contract Agent and any Holder of PIES without having to account for
the same to the Company; PROVIDED that each of the Securities Intermediary and
the Collateral Agent covenants and agrees with the Company that it shall not
accept, receive or permit there to be created in favor of itself and shall take
no affirmative action to permit there to be created in favor of any other
Person, any security interest, lien or other encumbrance of any kind in or upon
the Collateral other than the lien created by the Pledge.

         SECTION   9.5 NON-RELIANCE ON COLLATERAL AGENT AND SECURITIES
INTERMEDIARY.

                  Neither the Securities Intermediary nor the Collateral Agent
shall be required to keep itself informed as to the performance or observance by
the Purchase Contract Agent or any Holder of PIES of this Agreement, the
Purchase Contract Agreement, the PIES or any other document referred to or
provided for herein or therein or to inspect the properties or books of the
Purchase Contract Agent or any Holder of PIES. Neither the Collateral Agent nor
the Securities Intermediary shall have any duty or responsibility to provide the
Company with any credit or other information concerning the affairs, financial
condition or business of the Purchase Contract Agent or any Holder of PIES (or
any of their respective affiliates) that may come into the possession of the
Collateral Agent or the Securities Intermediary or any of their respective
affiliates.

         SECTION 9.6   COMPENSATION AND INDEMNITY.

                  The Company agrees to:

                  (1) pay the Collateral Agent and the Securities Intermediary
         from time to time such compensation as shall be agreed in writing
         between the Company and the Collateral Agent or the Securities
         Intermediary, as the case may be, for all services rendered by them
         hereunder; and

                  (2) indemnify the Collateral Agent and the Securities
         Intermediary for, and to hold each of them harmless from and against,
         any loss, liability or reasonable out-of-pocket expense incurred
         without gross negligence, willful misconduct or bad faith on its part,
         arising out of or in connection with the acceptance or administration
         of its powers and duties under this Agreement, including the reasonable
         costs and expenses (including

<PAGE>

                                                                              27

         reasonable fees and expenses of counsel) of defending itself against
         any claim or liability in connection with the exercise or performance
         of such powers and duties.

         SECTION 9.7   FAILURE TO ACT.

                  Subject to Section 9.2 of this Agreement, in the event of any
dispute between or conflicting claims by or among the parties hereto or any
other Person with respect to any funds or property deposited hereunder, the
Collateral Agent and the Securities Intermediary shall be entitled, after prompt
notice to the Company and the Purchase Contract Agent, at its sole option, to
refuse to comply with any and all claims, demands or instructions with respect
to such property or funds so long as such dispute or conflict shall continue,
and the Collateral Agent and the Securities Intermediary shall not be or become
liable in any way to any of the parties hereto for its failure or refusal to
comply with such conflicting claims, demands or instructions. The Collateral
Agent and the Securities Intermediary shall be entitled to refuse to act until
either:

                  (1) such conflicting or adverse claims or demands shall have
         been finally determined by a court of competent jurisdiction or settled
         by agreement between the conflicting parties as evidenced in a writing
         satisfactory to the Collateral Agent or the Securities Intermediary; or

                  (2) the Collateral Agent or the Securities Intermediary shall
         have received security or an indemnity satisfactory to it sufficient to
         save it harmless from and against any and all loss, liability or
         reasonable out-of-pocket expense which it may incur by reason of its
         acting.

The Collateral Agent and the Securities Intermediary may in addition elect to
commence an interpleader action or seek other judicial relief or orders as the
Collateral Agent or the Securities Intermediary may deem necessary.
Notwithstanding anything contained herein to the contrary, neither the
Collateral Agent nor the Securities Intermediary shall be required to take any
action that is in its opinion contrary to law or to the terms of this Agreement,
or which would in its opinion subject it or any of its officers, employees or
directors to liability.

         SECTION   9.8 RESIGNATION OF COLLATERAL AGENT AND SECURITIES
INTERMEDIARY.

                  (a) Subject to the appointment and acceptance of a successor
Collateral Agent as provided below:

                  (1) the Collateral Agent may resign at any time by giving
         notice thereof to the Company, the Purchase Contract Agent as
         attorney-in-fact for the Holders of PIES and the Trustee;

                  (2) the Collateral Agent may be removed at any time by the
         Company; and

                  (3) if the Collateral Agent fails to perform any of its
         material obligations hereunder in any material respect for a period of
         not less than 20 days after receiving written notice of such failure by
         the Purchase Contract Agent and such failure shall be continuing, the
         Collateral Agent may be removed by the Purchase Contract Agent;
         PROVIDED, HOWEVER, that neither this provision nor any other provision
         of this Agreement or

<PAGE>

                                                                              28

         the Purchase Contract Agreement shall require the Purchase Contract
         Agent to keep itself informed as to or to monitor the performance or
         observance by the Collateral Agent or the Securities Intermediary of
         their obligations hereunder.

The Purchase Contract Agent shall promptly notify the Company of any removal
of the Collateral Agent pursuant to clause (3) of the immediately preceding
sentence. Upon any such resignation or removal, the Company shall have the
right to appoint a successor Collateral Agent. If no successor Collateral
Agent shall have been so appointed and shall have accepted such appointment
within 30 days after the retiring Collateral Agent's giving of notice of
resignation or such removal, then the retiring Collateral Agent may petition
any court of competent jurisdiction for the appointment of a successor
Collateral Agent. The Collateral Agent shall be a bank which has an office in
New York, New York or Minneapolis, Minnesota with a combined capital and
surplus of at least $50,000,000 and shall not be the Purchase Contract Agent
or any of its affiliates. Upon the acceptance of any appointment as
Collateral Agent hereunder by a successor Collateral Agent, such successor
Collateral Agent shall thereupon succeed to and become vested with all the
rights, powers, privileges and duties of the retiring Collateral Agent, and
the retiring Collateral Agent shall take all appropriate action to transfer
any money and property held by it hereunder (including the Collateral) to
such successor Collateral Agent. The retiring Collateral Agent shall, upon
such succession, be discharged from its duties and obligations as Collateral
Agent hereunder. After any retiring Collateral Agent's resignation hereunder
as Collateral Agent, the provisions of this Section 9 shall continue in
effect for its benefit in respect of any actions taken or omitted to be taken
by it while it was acting as the Collateral Agent. Any resignation or removal
of the Collateral Agent hereunder shall be deemed for all purposes of this
Agreement as the simultaneous resignation or removal, as the case may be, of
the Securities Intermediary.

                  (b) Subject to the appointment and acceptance of a successor
Securities Intermediary as provided below:

                  (1) the Securities Intermediary may resign at any time by
         giving notice thereof to the Company, the Purchase Contract Agent as
         attorney-in-fact for the Holders of PIES and the Trustee;

                  (2) the Securities Intermediary may be removed at any time by
         the Company; and

                  (3) if the Securities Intermediary fails to perform any of its
         material obligations hereunder in any material respect for a period of
         not less than 20 days after receiving written notice of such failure by
         the Purchase Contract Agent and such failure shall be continuing, the
         Securities Intermediary may be removed by the Purchase Contract Agent.

The Purchase Contract Agent shall promptly notify the Company of any removal of
the Securities Intermediary pursuant to clause (3) of the immediately preceding
sentence. Upon any such resignation or removal, the Company shall have the right
to appoint a successor Securities Intermediary. If no successor Securities
Intermediary shall have been so appointed and shall have accepted such
appointment within 30 days after the retiring Securities Intermediary's giving
of notice of resignation or such removal, then the retiring Securities
Intermediary may petition any court of competent jurisdiction for the
appointment of a successor Securities Intermediary. The Securities Intermediary
shall be a bank which has an office in New York, New York with a

<PAGE>

                                                                              29

combined capital and surplus of at least $50,000,000 and shall not be the
Purchase Contract Agent or any of its affiliates. Upon the acceptance of any
appointment as Securities Intermediary hereunder by a successor Securities
Intermediary, such successor Securities Intermediary shall thereupon succeed to
and become vested with all the rights, powers, privileges and duties of the
retiring Securities Intermediary, and the retiring Securities Intermediary shall
take all appropriate action to transfer any money and property held by it
hereunder (including the Collateral) to such successor Securities Intermediary.
The retiring Securities Intermediary shall, upon such succession, be discharged
from its duties and obligations as Securities Intermediary hereunder. After any
retiring Securities Intermediary's resignation hereunder as Securities
Intermediary, the provisions of this Section 9 shall continue in effect for its
benefit in respect of any actions taken or omitted to be taken by it while it
was acting as the Securities Intermediary.

         SECTION 9.9   RIGHT TO APPOINT AGENT OR ADVISOR.

                  The Collateral Agent shall have the right to appoint agents or
advisors in connection with any of its duties hereunder, and the Collateral
Agent shall not be liable for any action taken or omitted by, or in reliance
upon the advice of, such agents or advisors selected in good faith. The
appointment of agents pursuant to this Section 9.9 shall be subject to prior
consent of the Company, which consent shall not be unreasonably withheld.

         SECTION 9.10   SURVIVAL.

                  The provisions of this Section 9 shall survive termination of
this Agreement and the resignation or removal of the Collateral Agent or the
Securities Intermediary.

         SECTION 9.11   EXCULPATION.

                  Anything contained in this Agreement to the contrary
notwithstanding, in no event shall the Collateral Agent or the Securities
Intermediary or their officers, directors, employees or agents be liable under
this Agreement to any third party for indirect, special, punitive or
consequential loss or damage of any kind whatsoever, including lost profits,
whether or not the likelihood of such loss or damage was known to the Collateral
Agent or the Securities Intermediary, or any of them, incurred without any act
or deed that is found to be attributable to gross negligence or willful
misconduct on the part of the Collateral Agent or the Securities Intermediary.
Any and all exculpatory provisions, immunities and indemnities in favor of the
Collateral Agent or the Securities Intermediary under this Agreement shall inure
to the benefit of the Collateral Agent or the Securities Intermediary, as
applicable, in its individual capacity or as a party to any agreement referred
to herein or therein, whether or not expressly so provided.

Section 10.   AMENDMENT.

         SECTION 10.1   AMENDMENT WITHOUT CONSENT OF HOLDERS.

                  Without the consent of any Holders, the Company (when
authorized by a Board Resolution), the Collateral Agent, the Securities
Intermediary and the Purchase Contract Agent, at any time and from time to time,
may amend this Agreement, in form satisfactory to the Company, the Collateral
Agent, the Securities Intermediary and the Purchase Contract Agent, to:

<PAGE>

                                                                              30

                  (1) evidence the succession of another Person to the Company,
         and the assumption to by any such successor of the covenants of the
         Company;

                  (2) evidence and provide for the acceptance of appointment
         hereunder by a successor Collateral Agent, Securities Intermediary or
         Purchase Contract Agent;

                  (3) add to the covenants of the Company for the benefit of the
         Holders, or to surrender any right or power herein conferred upon the
         Company, PROVIDED such covenants or such surrender do not adversely
         affect the validity, perfection or priority of the Pledge created
         hereunder; or

                  (4) cure any ambiguity (or formal defect), to correct or
         supplement any provisions herein which may be inconsistent with any
         other such provisions herein, or to make any other provisions with
         respect to such matters or questions arising under this Agreement,
         PROVIDED such action shall not adversely affect the interests of the
         Holders.

         SECTION 10.2   AMENDMENT WITH CONSENT OF HOLDERS.

                  With the consent of the Holders of not less than a majority of
the Purchase Contracts at the time outstanding, by Act of said Holders delivered
to the Company, the Purchase Contract Agent, the Securities Intermediary and the
Collateral Agent, the Company, when duly authorized by a Board Resolution, the
Purchase Contract Agent, the Securities Intermediary and the Collateral Agent
may amend this Agreement for the purpose of modifying in any manner the
provisions of this Agreement or the rights of the Holders in respect of the
PIES; PROVIDED, HOWEVER, that no such supplemental agreement shall, without the
unanimous consent of the Holders of each Outstanding PIES adversely affected
thereby, other than as expressly contemplated by the Agreement,

                  (1) change the amount or type of Collateral underlying a PIES,
         impair the right of the Holder of any PIES to receive distributions on
         the underlying Collateral or otherwise adversely affect the Holder's
         rights in or to such Collateral;

                  (2) otherwise effect any action that would require the consent
         of the Holder of each Outstanding PIES affected thereby pursuant to the
         Purchase Contract Agreement if such action were effected by an
         agreement supplemental thereto; or

                  (3) reduce the percentage of Purchase Contracts the consent of
         whose Holders is required for any such amendment;

PROVIDED that if any amendment or proposal referred to above would adversely
affect only the Corporate PIES or only the Treasury PIES after PIES of such
class are created and remain Outstanding, then only the affected class of Holder
as of the record date for the Holders entitled to vote thereon will be entitled
to vote on such amendment or proposal, and such amendment or proposal shall not
be effective except with the consent of Holders of not less than a majority of
such class; PROVIDED, FURTHER, that the unanimous consent of the Holders of each
outstanding Purchase Contract of such class affected thereby shall be required
to approve any amendment or proposal specified in clauses (1) through (3) above.

<PAGE>

                                                                              31

                  It shall not be necessary for any Act of Holders under this
Section to approve the particular form of any proposed amendment, but it shall
be sufficient if such Act shall approve the substance thereof.

         SECTION 10.3   EXECUTION OF AMENDMENTS.

                  In executing any amendment permitted by this Section, the
Collateral Agent, the Securities Intermediary and the Purchase Contract Agent
shall be entitled to receive and (subject to Section 7.1 of the Purchase
Contract Agreement with respect to the Purchase Contract Agent) shall be fully
protected in relying upon, an Opinion of Counsel (as defined in the Purchase
Contract Agreement) stating that the execution of such amendment is authorized
or permitted by this Agreement and that all conditions precedent, if any, to the
execution and delivery of such amendment have been satisfied.

         SECTION 10.4   EFFECT OF AMENDMENTS.

                  Upon the execution of any amendment under this Section, this
Agreement shall be modified in accordance therewith, and such amendment shall
form a part of this Agreement for all purposes; and every Holder of Certificates
theretofore or thereafter authenticated, executed on behalf of the Holders and
delivered under the Purchase Contract Agreement shall be bound thereby.

         SECTION 10.5   REFERENCE TO AMENDMENTS.

                  Certificates authenticated, executed on behalf of the Holders
and delivered after the execution of any amendment pursuant to this Section may,
and shall if required by the Collateral Agent or the Purchase Contract Agent,
bear a notation in form approved by the Purchase Contract Agent and the
Collateral Agent as to any matter provided for in such amendment. If the Company
shall so determine, new Security Certificates so modified as to conform, in the
opinion of the Collateral Agent, the Purchase Contract Agent and the Company, to
any such amendment may be prepared and executed by the Company and
authenticated, executed on behalf of the Holders and delivered by the Purchase
Contract Agent in accordance with the Purchase Contract Agreement in exchange
for Outstanding PIES Certificates.

Section 11.   MERGER, CONSOLIDATION, SALE OR CONVEYANCE.

         SECTION 11.1   WHEN COMPANY MAY MERGE, ETC.

                  The Company shall not consolidate with or merge into, or sell,
lease (for a term extending beyond the last stated maturity of the PIES and the
Senior Notes then Outstanding) or convey all or substantially all of its assets
to, any Person or group of Affiliated Persons in one transaction or a series of
related transactions, unless the Company shall be the continuing corporation, or
the successor or transferee Person expressly assumes by one or more supplemental
agreements, in form satisfactory to the Collateral Agent, all the obligations of
the Company with respect to this Agreement, and the Company or the successor or
transferee Person, as the case may be, (i) shall be a Corporation organized and
existing under the laws of one of the states in the United States and (ii) shall
not, immediately after such consolidation or merger or sale, lease or
conveyance, be in default in the performance or any covenant or

<PAGE>

                                                                              32

condition hereunder. The Company shall deliver to the Collateral Agent an
Officers' Certificate (as defined in the Original Indenture) and an Opinion of
Counsel (as defined in the Original Indenture), each stating that such
consolidation, merger sale, lease or conveyance and such supplemental agreement
comply with this Agreement and that all conditions precedent to the consummation
of any such consolidation, or merger, or any sale, lease or conveyance have been
met.

         SECTION 11.2   SUCCESSOR CORPORATION SUBSTITUTED.

                  Upon any consolidation or merger, or any sale, lease or
conveyance of all or substantially all of the assets of the Company in
accordance with Section 11.1, the successor corporation or the transferee
corporation formed by such consolidation or into which the Company is merged or
to which such transfer is made shall succeed to, and be substituted for, and may
exercise every right and power of, the Company under this Agreement with the
same effect as if such successor corporation had been named as the Company
herein.

                  Such successor or transferee Person thereupon may cause to be
signed, and may issue either in its own name or in the name of Sierra Pacific
Resources, any or all of the Certificates evidencing PIES issuable hereunder
which theretofore shall not have been signed by the Company and delivered to the
Purchase Contract Agent; and, upon the order of such successor or such
transferee Person, instead of the Company, and subject to all the terms,
conditions and limitations in this Agreement prescribed, the Purchase Contract
Agent shall authenticate and execute on behalf of the Holders and deliver any
Certificates which previously shall have been signed and delivered by the
officers of the Company to the Purchase Contract Agent for authentication and
execution, and any Certificate evidencing PIES which such successor corporation
or transferee corporation thereafter shall cause to be signed and delivered to
the Purchase Contract Agent for that purpose. All the Certificates issued shall
in all respects have the same legal rank and benefit under this Agreement as the
Certificates theretofore or thereafter issued in accordance with the terms of
this Agreement as though all of such Certificates had been issued at the date of
the execution hereof.

                  In case of any such merger, consolidation, share exchange,
sale, assignment, transfer, lease or conveyance such change in phraseology and
form (but not in substance) may be made in the Certificates evidencing PIES
thereafter to be issued as may be appropriate.

         SECTION 11.3   LIMITATION.

                  Nothing in this Agreement shall be deemed to prevent or
restrict; (a) any consolidation or merger after the consummation of which the
Company would be the surviving or resulting entity or any conveyance or other
transfer or lease of any part of the properties of the Company which does not
constitute the entirety, or substantially the entirety, thereof; or (b) the
approval by the Company of, or the consent by the Company to, any consolidation
or merger to which any Restricted Subsidiary (as defined in the Original
Indenture) or any other subsidiary or affiliate of the Company may be a party or
any conveyance, transfer or lease by any Subsidiary (as defined in the Original
Indenture) or any such other subsidiary or affiliate of any of its assets.

<PAGE>

                                                                              33

Section 12.   MISCELLANEOUS.

         SECTION 12.1   NO WAIVER.

                  No failure on the part of the Collateral Agent or any of its
agents to exercise, and no course of dealing with respect to, and no delay in
exercising, any right, power or remedy hereunder shall operate as a waiver
thereof; nor shall any single or partial exercise by the Collateral Agent or any
of its agents of any right, power or remedy hereunder preclude any other or
further exercise thereof or the exercise of any other right, power or remedy.
The remedies herein are cumulative and are not exclusive of any remedies
provided by law.

         SECTION 12.2   GOVERNING LAW; JURISDICTION AND VENUE.

                  THIS AGREEMENT SHALL BE GOVERNED BY, AND CONSTRUED IN
ACCORDANCE WITH, THE LAWS OF THE STATE OF NEW YORK.

                  The Company, the Collateral Agent, the Securities
Intermediary, the Purchase Contract Agent and the Holders from time to time of
the PIES, acting through the Purchase Contract Agent as their attorney-in-fact,
hereby submit to the nonexclusive jurisdiction of the United States District
Court for the Southern District of New York and of any New York state court
sitting in New York City for the purposes of all legal proceedings arising out
of or relating to this Agreement or the transactions contemplated hereby. The
Company, the Collateral Agent, the Securities Intermediary and the Holders from
time to time of the PIES, acting through the Purchase Contract Agent as their
attorney-in-fact, irrevocably waive, to the fullest extent permitted by
applicable law, any objection which they may now or hereafter have to the laying
of the venue of any such proceeding brought in such a court and any claim that
any such proceeding brought in such a court has been brought in an inconvenient
forum.

         SECTION 12.3   NOTICES.

                  All notices, requests, consents and other communications
provided for herein (including, without limitation, any modifications of, or
waivers or consents under, this Agreement) shall be given or made in writing
(including, without limitation, by telecopy) delivered to the intended recipient
specified below. Except as otherwise provided in this Agreement, all such
communications shall be deemed to have been duly given when transmitted by
telecopier or personally delivered or, in the case of a mailed notice, upon
receipt, in each case given or addressed as aforesaid.

<PAGE>

                                                                              34

                  If to the Company:

                  Sierra Pacific Resources
                  6100 Neil Road
                  P.O. Box 30150
                  Reno, Nevada  89520-0400
                  Telecopier No.: (775) 834-5462
                  Attention: Treasurer

                  If to the Collateral Agent or the Securities Intermediary:

                  Wells Fargo Bank Minnesota, National Association
                  Sixth and Marquette
                  MAC N9303-120
                  Minneapolis, Minnesota  55479
                  Telecopier No.: (612) 667-9825
                  Attention: Jane Schweiger

                  If to the Purchase Contract Agent or the Trustee:

                  The Bank of New York
                  101 Barclay Street, Floor 21 West
                  New York, New York  10286
                  Telecopier No.: (212) 896-7298
                  Attention: Corporate Trust Administration

         SECTION 12.4   SUCCESSORS AND ASSIGNS.

                  This Agreement shall be binding upon and inure to the benefit
of the respective successors and assigns of the Company, the Collateral Agent,
the Securities Intermediary and the Purchase Contract Agent, and the Holders
from time to time of the PIES, by their acceptance of the same, shall be deemed
to have agreed to be bound by the provisions hereof and to have ratified the
agreements of, and the grant of the Pledge hereunder by, the Purchase Contract
Agent.

         SECTION 12.5   COUNTERPARTS.

                  This Agreement may be executed in any number of counterparts,
all of which taken together shall constitute one and the same instrument, and
any of the parties hereto may execute this Agreement by signing any such
counterpart.

<PAGE>

                                                                              35

         SECTION 12.6   EFFECT OF HEADINGS AND TABLE OF CONTENTS.

         The headings and table of contents contained in this Agreement shall
not constitute a part, or to effect the meaning or interpretation of, this
Agreement.

         SECTION 12.7   SEVERABILITY.

                  If any provision hereof is invalid and unenforceable in any
jurisdiction, then, to the fullest extent permitted by law, (i) the other
provisions hereof shall remain in full force and effect in such jurisdiction and
shall be liberally construed in order to carry out the intentions of the parties
hereto as nearly as may be possible and (ii) the invalidity or unenforceability
of any provision hereof in any jurisdiction shall not affect the validity or
enforceability of such provision in any other jurisdiction.

         SECTION 12.8   EXPENSES, ETC.

                  The Company agrees to reimburse the Collateral Agent and the
Securities Intermediary for:

                  (1) all reasonable costs and expenses of the Collateral Agent
         and the Securities Intermediary (including, without limitation, the
         reasonable fees and expenses of counsel to the Collateral Agent and the
         Securities Intermediary), in connection with (i) the negotiation,
         preparation, execution and delivery or performance of this Agreement
         and (ii) any modification, supplement or waiver of any of the terms of
         this Agreement;

                  (2) all reasonable costs and expenses of the Collateral Agent
         and the Securities Intermediary (including, without limitation,
         reasonable fees and expenses of counsel) in connection with (i) any
         enforcement or proceedings resulting or incurred in connection with
         causing any Holder of PIES to satisfy its obligations under the
         Purchase Contracts forming a part of the PIES and (ii) the enforcement
         of this Section 12.8; and

                  (3) all transfer, stamp, documentary or other similar taxes,
         assessments or charges levied by any governmental or revenue authority
         in respect of this Agreement or any other document referred to herein
         and all costs, expenses, taxes, assessments and other charges incurred
         in connection with any filing, registration, recording or perfection of
         any security interest contemplated hereby.

         SECTION 12.9   SECURITY INTEREST ABSOLUTE.

                  All rights of the Collateral Agent and security interests
hereunder, and all obligations of the Holders from time to time hereunder, shall
be absolute and unconditional irrespective of:

                  (1) any lack of validity or enforceability of any provision of
         the Purchase Contracts or the PIES or any other agreement or instrument
         relating thereto;

                  (2) any change in the time, manner or place of payment of, or
         any other term of, or any increase in the amount of, all or any of the
         obligations of Holders of the PIES under the related Purchase
         Contracts, or any other amendment or waiver of any term of,

<PAGE>

                                                                              36

         or any consent to any departure from any requirement of, the Purchase
         Contract Agreement or any Purchase Contract or any other agreement or
         instrument relating thereto; or

                  (3) any other circumstance which might otherwise constitute a
         defense available to, or discharge of, a borrower, a guarantor or a
         pledgor.

<PAGE>

         IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be
duly executed as of the day and year first above written.

                            SIERRA PACIFIC RESOURCES

                            By:
                               ------------------------------------------------
                               Name:
                               Title:

                            THE BANK OF NEW YORK, not individually but solely as
                            Purchase Contract Agent and as attorney-in-fact of
                            the Holders from time to time of the PIES

                            By:
                               ------------------------------------------------
                               Name:
                               Title:

                            WELLS FARGO BANK MINNESOTA,
                            NATIONAL ASSOCIATION, as Collateral Agent

                            By:
                               ------------------------------------------------
                               Name:
                               Title:

                            WELLS FARGO BANK MINNESOTA,
                            NATIONAL ASSOCIATION, as Securities Intermediary

                            By:
                               ------------------------------------------------
                               Name:
                               Title:

<PAGE>

                                                                      EXHIBIT A

                                     NOTICE
                FROM PURCHASE CONTRACT AGENT TO COLLATERAL AGENT
                           (Creation of Treasury PIES)

Wells Fargo Bank Minnesota, National Association, as Collateral Agent
Sixth and Marquette
MAC N9303-120
Minneapolis, Minnesota  55479
Attention: Jane Schweiger
Fax (612) 667-9825

                  Re: PIES OF SIERRA PACIFIC RESOURCES

         Reference is made to the Pledge Agreement dated as of November 16, 2001
(the "Pledge Agreement"), among Sierra Pacific Resources (the "Company"), you,
as Collateral Agent and as Securities Intermediary, and the undersigned, as
Purchase Contract Agent and as attorney-in-fact for the holders of PIES from
time to time. Capitalized terms used herein but not defined shall have the
meanings attributable to them in the Pledge Agreement.

         We hereby notify you that, in accordance with Section 5.2 of the Pledge
Agreement and Section 3.13 of the Purchase Contract Agreement, the holder of
securities named below (the "Holder") has elected to substitute $__________
Value of Treasury Securities (CUSIP No. ) in exchange for an equal Value of
Pledged Senior Notes and has delivered to the undersigned Purchase Contract
Agent a notice stating that the Holder has Transferred such Treasury Securities
to the Securities Intermediary, for credit to the Collateral Account.

         We hereby request that you instruct the Securities Intermediary, upon
confirmation that such Treasury Securities have been credited to the Collateral
Account, to release by Transfer to the undersigned Purchase Contract Agent, on
behalf of the undersigned Holder an equal Value of Pledged Senior Notes in
accordance with Section 5.2 of the Pledge Agreement.

                                     THE BANK OF NEW YORK,
                                     as Purchase Contract Agent

                                     By:
                                        ---------------------------------------
                                        Name:
                                        Title:
                                        Date:

         Please print name and address of Holder electing to substitute Treasury
Securities or security entitlements thereto for the Pledged Senior Notes:

-----------------------------------------------------
         Name of Holder

-----------------------------------------------------
         TRADES Account No.

-----------------------------------------------------
Social Security or Taxpayer Identification Number

-----------------------------------------------------
         Address

<PAGE>

                                                                      EXHIBIT B

                                     NOTICE
                FROM COLLATERAL AGENT TO SECURITIES INTERMEDIARY
                           (Creation of Treasury PIES)

Wells Fargo Bank Minnesota, National Association, as Securities Intermediary
Sixth and Marquette
MAC N9303-120
Minneapolis, Minnesota  55479
Attention: Jane Schweiger
Fax (612) 667-9825

                  Re: PIES OF SIERRA PACIFIC RESOURCES

                      Securities Account No. 11874500 entitled "Wells Fargo Bank
                      Minnesota, National Association, as Collateral Agent,
                      Securities Account (Sierra Pacific Resources)" (the
                      "Collateral Account")

         Reference is made to the Pledge Agreement, dated as of November 16,
2001 (the "Pledge Agreement"), among Sierra Pacific Resources (the "Company"),
you, as Securities Intermediary, The Bank of New York, as Purchase Contract
Agent and as attorney-in-fact for the holders of PIES from time to time, and the
undersigned, as Collateral Agent. Capitalized terms used herein but not defined
shall have the meanings attributable to them in the Pledge Agreement.

         When you have confirmed that $__________ Value of Treasury Securities
(CUSIP No. ) has been credited to the Collateral Account by or for the benefit
of _________, as Holder of PIES (the "Holder"), you are hereby instructed to
release from the Collateral Account an equal Value of Senior Notes by Transfer
to the Purchase Contract Agent in accordance with Section 5.2 of the Pledge
Agreement.

                                  WELLS FARGO BANK MINNESOTA, NATIONAL
                                  ASSOCIATION,
                                  as Collateral Agent

                                  By:
                                     ------------------------------------------
                                     Name:
                                     Title:
                                     Date:

         Please print name and address of Holder:

--------------------------------------------------------
         Name

--------------------------------------------------------
         TRADES Account No.

--------------------------------------------------------
Social Security or Taxpayer Identification Number

--------------------------------------------------------
         Address

<PAGE>

                                                                      EXHIBIT C

                                     NOTICE
                FROM PURCHASE CONTRACT AGENT TO COLLATERAL AGENT
                         (Recreation of Corporate PIES)

Wells Fargo Bank Minnesota, National Association, as Collateral Agent
Sixth and Marquette
MAC N9303-120
Minneapolis, Minnesota  55479
Attention: Jane Schweiger
Fax (612) 667-9825

                  Re: PIES OF SIERRA PACIFIC RESOURCES

         Reference is made to the Pledge Agreement, dated as of November 16,
2001 (the "Pledge Agreement"), among Sierra Pacific Company (the "Company"),
you, as Collateral Agent and as Securities Intermediary, and the undersigned, as
Purchase Contract Agent and as attorney-in-fact for the holders of PIES from
time to time. Capitalized terms used herein but not defined shall have the
meanings attributable to them in the Pledge Agreement.

         We hereby notify you that, in accordance with Section 5.3 of the Pledge
Agreement and Section 3.14 of the Purchase Contract Agreement, the holder of
securities listed below (the "Holder") has elected to substitute $__________
Value of Senior Notes in exchange for $__________ Value of Pledged Treasury
Securities and has delivered to the undersigned a notice stating that the Holder
has Transferred such Senior Notes or security entitlements thereto to the
Securities Intermediary, for credit to the Collateral Account.

         We hereby request that you instruct the Securities Intermediary, upon
confirmation that such Senior Notes have been credited to the Collateral
Account, to release to the undersigned Holder an equal Value of Treasury
Securities or security entitlements thereto related to _____ Treasury PIES of
such Holder in accordance with Section 5.3 of the Pledge Agreement and Section
3.14 of the Purchase Contract Agreement.

                           THE BANK OF NEW YORK,
                           as Purchase Contract Agent

                           By:
                              -------------------------------------------------
                              Name:
                              Title:
                              Date:

Please print name and address of Holder electing to substitute Pledged Senior
Notes or security entitlements thereto for Pledged Treasury Securities:

--------------------------------------------------------
          Name

--------------------------------------------------------
          DTC Participant No.

--------------------------------------------------------
Social Security or Taxpayer Identification Number

--------------------------------------------------------
          Address

<PAGE>

                                                                      EXHIBIT D

                                     NOTICE
                FROM COLLATERAL AGENT TO SECURITIES INTERMEDIARY
                         (Recreation of Corporate PIES)

Wells Fargo Bank Minnesota, National Association, as Securities Intermediary
Sixth and Marquette
MAC N9303-120
Minneapolis, Minnesota  55479
Attention: Jane Schweiger
Fax  (612) 667-9825

                  Re: PIES OF SIERRA PACIFIC RESOURCES

                      Securities Account No. 11874500 entitled "Wells Fargo Bank
                      Minnesota, National Association, as Collateral Agent,
                      Securities Account (Sierra Pacific Resources)"

         Reference is made to the Pledge Agreement, dated as of November 16,
2001 (the "Pledge Agreement"), among Sierra Pacific Resources (the "Company"),
you, as Securities Intermediary, The Bank of New York, as Purchase Contract
Agent and as attorney-in-fact for the holders of PIES from time to time, and the
undersigned, as Collateral Agent. Capitalized terms used herein but not defined
shall have the meanings attributable to them in the Pledge Agreement.

         When you have confirmed that $_________ Value of Senior Notes has been
credited to the Collateral Account by or for the benefit of _________, as Holder
of PIES (the "Holder"), you are hereby instructed to release from the Collateral
Account $__________ Value of Treasury Securities (CUSIP No. ) or security
entitlements thereto by Transfer to the undersigned Holder in accordance with
Section 5.3 of the Pledge Agreement.

                                       WELLS FARGO BANK MINNESOTA, NATIONAL
                                       ASSOCIATION, as Collateral Agent

                                       By:
                                          -------------------------------------
                                          Name:
                                          Title:
                                          Date:

Please print name and address of Holder:

--------------------------------------------------------
          Name

--------------------------------------------------------
DTC Participant No.

--------------------------------------------------------
Social Security or Taxpayer Identification Number

--------------------------------------------------------
          Address

<PAGE>

                                                                      EXHIBIT E

                            NOTICE OF CASH SETTLEMENT
             FROM SECURITIES INTERMEDIARY TO PURCHASE CONTRACT AGENT
                            (Cash Settlement Amounts)

The Bank of New York, as Purchase Contract Agent
101 Barclay Street, Floor 21 West
New York, New York  10286
Attention: Corporate Trust Administration
Fax: (212) 896-7298

                  Re: PIES OF SIERRA PACIFIC RESOURCES

         Reference is made to the Pledge Agreement, dated as of November 16,
2001 (the "Pledge Agreement"), among Sierra Pacific Resources (the "Company"),
you, as Purchase Contract Agent and as attorney-in-fact for the holders of PIES
from time to time, as Collateral Agent and the undersigned, as Securities
Intermediary. Capitalized terms used herein but not defined shall have the
meanings attributable to them in the Pledge Agreement.

         In accordance with Section [5.5(d)] [5.5(e)] of the Pledge Agreement,
we hereby notify you that as of 11:00 a.m. (New York City time), [on the fifth
Business Day immediately preceding the Purchase Contract Settlement Date] [on
the Business Day immediately preceding the Purchase Contract Settlement Date],
we have received [$_____ in immediately available funds paid in an aggregate
amount equal to the Purchase Price to the Company on the Purchase Contract
Settlement Date with respect to __________ Corporate PIES] [$_________ in
immediately available funds paid in an aggregate amount equal to the Purchase
Price to the Company on the Purchase Contract Settlement Date with respect to
______ Treasury PIES.]

                                             WELLS FARGO BANK MINNESOTA,
                                             NATIONAL ASSOCIATION,
                                             as Securities Intermediary

                                             By:
                                                -------------------------------
                                                Name:
                                                Title:
                                                Date:

<PAGE>

                                                                     EXHIBIT F

                 NOTICE FROM HOLDER OF SEPARATED SENIOR NOTES TO
                     COLLATERAL AGENT REGARDING REMARKETING

Wells Fargo Bank Minnesota, National Association, as Collateral Agent
Sixth and Marquette
MAC N9303-120
Minneapolis, Minnesota  55479
Attention:  Jane Schweiger
Fax  (612) 667-9825

                  Re: SENIOR NOTES OF SIERRA PACIFIC RESOURCES

         Reference is made to the Pledge Agreement, dated as of November 16,
2001 (the "Pledge Agreement"), among Sierra Pacific Resources (the "Company"),
you, as Collateral Agent, and as Securities Intermediary, and The Bank of New
York, as Purchase Contract Agent and as attorney-in-fact for the holders of PIES
from time to time. Capitalized terms used herein but not defined shall have the
meanings attributable to them in the Pledge Agreement.

         The undersigned hereby notifies you in accordance with Section 5.7 of
the Pledge Agreement, that the undersigned elects to have $_________ principal
amount of Senior Notes for delivery to the Remarketing Agent on the Business Day
immediately preceding the Initial Remarketing Date for such Senior Notes to be
included in any Remarketing. The undersigned will, upon request of the
Remarketing Agent, promptly execute and deliver any additional documents deemed
by the Remarketing Agent or by the Company to be necessary or desirable to
complete the sale, assignment and transfer of the Senior Notes which are the
subject of this notice.

         The undersigned hereby instructs the you, upon receipt of the Proceeds
of such Remarketing from the Remarketing Agent to deliver such Proceeds to the
undersigned in accordance with the instructions indicated below under "Payment
Instructions." The undersigned hereby instructs you, in the event of a
unsuccessful Remarketing, upon receipt of the Senior Notes tendered herewith
from the Remarketing Agent, to deliver the Senior Notes to the person(s) and at
the address(es) indicated below under "Delivery Instructions." The undersigned
acknowledges and agrees that the Collateral Agent and the Remarketing Agent may
withhold from the Proceeds such amounts as they may determine to be appropriate
in respect of taxes which may be applicable.

         With this notice, the undersigned hereby (i) represents and warrants
that the undersigned has full power and authority to tender, sell, assign and
transfer the Notes tendered hereby and that the undersigned is the record owner
of any Notes tendered herewith in physical form or a participant in The
Depository Trust Company ("DTC") and the beneficial owner of any Notes tendered
herewith by book-entry transfer to your account at DTC and (ii) agrees to be
bound by the terms and conditions of the Pledge Agreement.

Date:

                                        By:
                                           ------------------------------------
                                           Name:
                                           Title:
                                           Signature Guarantee:

<PAGE>

Please print name and address of Holder:

--------------------------------------------------------
          Name

--------------------------------------------------------
Social Security or Taxpayer Identification Number

--------------------------------------------------------
          Address

                              HOLDER'S INSTRUCTIONS

<TABLE>
<CAPTION>
------------------------------------------------------- --- -------------------------------------------------------
A.       PAYMENT INSTRUCTIONS                               B.       DELIVERY INSTRUCTIONS
-------------------------------------------------------------------------------------------------------------------
<S>                                                         <C>
Proceeds of the remarketing should be paid by check         In the event of a failed remarketing, Senior
in the name of the person(s) set forth below and            Notes which are in physical form should be
mailed to the address set forth below                       delivered to the person(s) set forth below and
                                                            mailed to the address set forth below.

                    Name(s)                                                      Name(s)
        ------------------------------------                     -------------------------------------
               (Please Print)                                                  (Please Print)

                  Address                                                          Address

        ------------------------------------                     -------------------------------------
              (Please Print)                                                   (Please Print)

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

        ------------------------------------                     -------------------------------------
               (Zip Code)                                                       (Zip Code)

        ------------------------------------                     -------------------------------------
   (Tax Identification or Social Security Number)           (Tax Identification or Social Security Number)

                                                            In the event of a Failed Remarketing, Senior
    If a DTC Participant, add wire transfer                 Notes which are in book-entry form should be
    instructions and DTC Account No.                        credited to the account at The Depositary Trust
                                                            Company set forth below.

        ------------------------------------                     -------------------------------------
             Wire transfer instructions                                     DTC Account Number

        ------------------------------------
                 DTC Account Number                                   Name of Account Party: ______________
-------------------------------------------------------------------------------------------------------------------
</TABLE>

<PAGE>

                                                                      EXHIBIT G

                       NOTICE FROM PURCHASE CONTRACT AGENT
                               TO COLLATERAL AGENT

Wells Fargo Bank Minnesota, National Association, as Collateral Agent
Sixth and Marquette
MAC N9303-120
Minneapolis, Minnesota  55479
Attention: Jane Schweiger
Fax (612) 667-9825

                  Re: SENIOR NOTES OF SIERRA PACIFIC RESOURCES

                  Reference is made to the Pledge Agreement, dated as of
November 16, 2001 (the "Pledge Agreement"), among Sierra Pacific Resources (the
"Company"), you, as Collateral Agent and Securities Intermediary, and the
undersigned, as Purchase Contract Agent and as attorney-in-fact for the holders
of PIES from time to time. Capitalized terms used herein but not defined shall
have the meanings attributable to them in the Pledge Agreement.

                  The undersigned hereby notifies you, in accordance with
paragraph 19(i)(B) of the Indenture Officers' Certificate and Section 5.8 of the
Pledge Agreement, that the undersigned has received notice from the Holder named
below (the "Holder") that the Holder has elected not to participate in the
Remarketing through compliance with the procedures for creating Treasury PIES
set forth in Section 3.13 of the Purchase Contract Agreement and Section 5.2 of
the Pledge Agreement.

                  Accordingly, the undersigned hereby notifies you in accordance
with Section 3.13 of the Purchase Contract Agreement and Section 5.2 of the
Pledge Agreement that the Holder has elected to substitute $______________ Value
of Treasury Securities in exchange for an equal Value of Pledged Senior Notes
and has delivered to the undersigned a notice stating that the Holder has
Transferred such Treasury Securities to the Securities Intermediary, for credit
to the Collateral Account.

                  The undersigned hereby requests that you as the Collateral
Agent, upon confirmation from the Securities Intermediary that such Treasury
Securities have been credited to the Collateral Account, release to us for
delivery to such Holder _________ principal amount of the Pledged Senior Note in
accordance with Section 5.2 of the Pledge Agreement.

                                 THE BANK OF NEW YORK,
                                 as Purchase Contract Agent

                                 By:
                                    -------------------------------------------
                                    Name:
                                    Title:
                                    Date:

<PAGE>

                                                                     EXHIBIT H

                      AGENCY AND CUSTODY ACCOUNT DIRECTION
                                FOR CASH BALANCES

Direction to use Wells Fargo Funds for Cash Balances for the following
account(s):

         Account Names:      WELLS FARGO BANK MINNESOTA, NATIONAL ASSOCIATION,
                             AS COLLATERAL AGENT, SECURITIES ACCOUNT (SIERRA
                             PACIFIC RESOURCES)

         Account Number(s):  11874500

You are hereby directed to invest, as indicated below or as I shall direct
further from time to time, all cash in the Account in the following money market
portfolio of Wells Fargo Funds (the "Fund") (Check One):

/ / Wells Fargo Government Money Market Service Class Fund
/ / Wells Fargo 100% Treasury Money Market Fund Service Class Fund
/ / Wells Fargo Treasury Plus Institutional Money Market Fund Service Class Fund
/ / Wells Fargo National Tax-Free Institutional Money Market Service Class Fund

I acknowledge that I have received, at my request, and reviewed the Fund's
prospectus and have determined that the Fund is an appropriate investment for
the Account.

I understand from reading the Fund's prospectus that Wells Fargo Bank Minnesota,
National Association, ("Wells Fargo Bank") serves as investment advisor,
custodian and transfer agent for the Fund; I also understand that Wells Fargo
Bank will be paid, and its bank affiliates may be paid, fees for services to the
Fund and that those fees may include Processing Organization fees as described
in the Fund's prospectus.

I understand that you will not exclude amounts invested in the Fund from Account
assets subject to fees under the Account agreement between us.

I understand that investments in the Fund are not obligations of, or endorsed or
guaranteed by, Wells Fargo Bank or its affiliates and are not insured by the
Federal Deposit Insurance Corporation.

I acknowledge that I have full power to direct investments of the Account.

I understand that I may change this direction at any time and that it shall
continue in effect until revoked or modified by me by written notice to you.

                                           ------------------------------------
                                           Signature

                                           ------------------------------------
                                           Date