Document:

<PAGE>

                                                                    Exhibit 10.5

                              AMENDMENT AGREEMENT
                              -------------------

          This AMENDMENT AGREEMENT (this "Agreement"), is made and entered into
                                          ---------
as of August 1, 2001, among SIERRA PACIFIC POWER COMPANY (the "Company"), MELLON
                                                               -------
BANK, N.A. ("Mellon"), FIRST UNION NATIONAL BANK ("First Union"), WELLS FARGO
             ------                                -----------
BANK, N.A. ("Wells Fargo"), and the other parties set forth on the signatures
             -----------
pages hereto.

                                   RECITALS
                                   --------

          A.  The Company, Mellon, in its capacity as administrative agent (the
"Administrative Agent"), First Union and Wells Fargo, each in their capacity as
 --------------------
syndication agent, and the Lenders have entered into a Credit Agreement, dated
as of June 24, 1999 (as amended, modified and supplemented through the date
hereof, the "Credit Agreement").
             ----------------

          B.  The Company desires, and the Administrative Agent and the Required
Lenders are willing, to amend the Credit Agreement upon the terms set forth in
this Agreement.

          NOW, THEREFORE, in consideration of the foregoing, the premises and
mutual covenants contained herein and for other valuable consideration, the
receipt and sufficiency of which are hereby acknowledged, the parties hereto
hereby agree as follows:

          1.  Defined Terms.  Unless otherwise defined herein, capitalized terms
              -------------
used herein shall have the meanings given thereto in the Credit Agreement.

          2.  Effectiveness of this Agreement.  This Agreement shall become
              -------------------------------
effective and the amendments described in Section 3 below shall become effective
at the time (the "Effective Time") on the first date (the "Effective Date") on
                  --------------                           --------------
which each of the following conditions shall be satisfied or waived by the
Administrative Agent and the Required Lenders:

              (a) Execution of Agreement.  The Company and the Required Lenders
                  ----------------------
     shall have executed a copy of this Agreement (whether the same or different
     copies) and shall have delivered the same to the Administrative Agent.

               (b) No Litigation. The Administrative Agent and the Required
                   -------------
     Lenders shall be satisfied that, immediately prior to the Effective Time,
     no judgment, order, injunction or other restraint shall have been issued or
     filed which restrains, and no hearing seeking injunctive relief or other
     restraint is pending or has been noticed which seeks to restrain, the
     Company from consummating the transactions described in the Loan Documents
     or this Agreement.

               (c) No Default; Representations and Warranties. The
                   ------------------------------------------
     Administrative Agent and the Required Lenders shall be satisfied that,
     immediately prior to the Effective Time and after giving effect to this
     Agreement, (i) there shall exist no Default or Event of Default and (ii)
     the representations and warranties of the Company contained in the Loan
     Documents to which the Company is a party are true and correct in all
     material respects as of the Effective Time with the same effect as though
     such representations and warranties had been made on and as of the
     Effective Time (except for such
<PAGE>

     representations and warranties made as of a specified date, which shall be
     true and correct in all material respects as of such specified date).

         (d) Corporate Proceedings. All corporate and legal proceedings and all
             ---------------------
     instruments and agreements in connection with the transactions contemplated
     in this Agreement and the other Loan Documents shall be satisfactory in
     form and substance to the Administrative Agent and the Required Lenders,
     and the Administrative Agent shall have received all information and copies
     of all documents and papers, including records of corporate proceedings and
     governmental approvals, if any, which any Lender reasonably may have
     requested in connection therewith, such documents and papers where
     appropriate to be certified by proper corporate or governmental
     authorities.

         (e) Fee. For consenting to the amendments contained in this Agreement,
             ---
     each Lender that executes and delivers this Agreement prior to 5:00 p.m.,
     Pacific Time, on July 31, 2001 shall have received on or before the
     Effective Date a fee in immediately available funds equal to the product of
     (i) 0.25% and (ii) the aggregate amount of such Lender's Commitments.

         (f) Payments. The Administrative Agent and each Lender shall have
             --------
     received all amounts, if any, owing from the Company to such Person through
     and including the Effective Date.

All the certificates and other documents and papers referred to in this Section
2, unless otherwise specified, shall be delivered to the Administrative Agent's
counsel, White & Case LLP, at 633 West Fifth Street, 19/th/ Floor, Los Angeles,
CA 90071, facsimile (213) 687-0758, for the account of each of the Lenders and
in sufficient counterparts for each of the Lenders and shall be satisfactory in
form and substance to the Administrative Agent and the Required Lenders.

     3.  Amendments. At and from the Effective Time, the Credit Agreement shall
         ----------
be amended as follows:

         (a) The cover page to the Credit Agreement shall be amended by
     deleting the text "$150,000,000" and inserting the text "$120,000,000" in
     its place.

         (b) Section 1.01 of the Credit Agreement shall be amended as follows:

             (i)  The defined term "Commitment" shall be amended by deleting
                                    ----------
         the text "$150,000,000" in the last sentence thereof and inserting the
         text "$120,000,000" in its place.

             (ii) The defined term "Final Repayment Date" shall be deleted in
                                      --------------------
         its entirety and the following shall be substituted therefor:

                  ""Final Repayment Date" means the earliest to occur of (a) the
                    --------------------
             date that is one year after the Term Loan Conversion Date, (b)
             August 27, 2002 and (c) the date on which the Obligations under
             this Agreement terminate, whether by prepayment, cancellation,
             acceleration or otherwise."

                                      -2-
<PAGE>

             (iii)  The following defined term shall be inserted immediately
          after the definition of "GAAP":

                    ""General and Refunding Mortgage Indenture" means the
                      ----------------------------------------
               General and Refunding Mortgage Indenture, dated as of May 1,
               2001, between the Borrower and The Bank of New York, as trustee,
               as the same may be amended, modified or supplemented from time to
               time."

               (iv) The defined term "Revolving Termination Date" shall be
                                      --------------------------
          deleted in its entirety and the following shall be substituted
          therefor:

                    ""Revolving Termination Date" means the earlier of (i)
                      --------------------------
               November 30, 2001, or such date after November 30, 2001 to which
               the Commitments are extended in accordance with Section 2.06(e),
               and (ii) the date the Obligations and Commitments under this
               Agreement terminate, whether by prepayment, cancellation,
               acceleration or otherwise."

               (v)  The following defined term shall be inserted immediately
          after the definition of "Total Indebtedness":

                    ""Triggering Event" has the meaning assigned to such term in
                      ----------------
               Section 6.09(b)."

          (c)  Section 6.01(a) of the Credit Agreement shall be amended by
     deleting the text "0.58 to 1" and inserting the text "0.60 to 1" in its
     place.

          (d)  Section 6.02(b) of the Credit Agreement shall be deleted in its
     entirety and the following shall be substituted therefor:

               "(b)  Liens securing obligations issued under and pursuant to the
          terms and conditions of either (i) the First Mortgage Indenture or
          (ii) the General and Refunding Mortgage Indenture; provided that the
                                                             --------
          aggregate amount of Indebtedness issued by the Company under and
          pursuant to the terms and conditions of the First Mortgage Indenture
          and the General and Refunding Mortgage Indenture shall not exceed
          $983.82 million, except that such Indebtedness may exceed $983.82
          million to the extent, and only to the extent, required to secure
          Loans pursuant to Section 6.09(b) of this Agreement, and any similar
          provision of any future short-term credit facility in a principal
          amount not to exceed $175,000,000 among the Borrower, the
          Administrative Agent, as agent, and the other financial institutions
          party thereto."

          (e)  Section 6.04 of the Credit Agreement shall be amended by deleting
     it in its entirety and replacing it with the following:

               "SECTION 6.04  Dispositions of Properties.
                              --------------------------

                                      -3-
<PAGE>

               The Borrower shall not, and shall not permit any of its
          Subsidiaries to, sell, convey, assign, lease, sale-leaseback,
          transfer, abandon or otherwise dispose of, voluntarily or
          involuntarily (collectively, "Dispose"), any of its Properties, or
                                        -------
          agree, become or remain liable contingently or otherwise to do any of
          the foregoing, except that, so long as no Default or Event of Default
          shall have occurred and be continuing or shall exist at such time or
          after giving effect to such transaction, the Borrower and its
          Subsidiaries may Dispose of Property (a) in transactions in the
          ordinary course of business consistent with past practice, (b) that is
          obsolete, (c) comprising accounts receivable transferred to a
          commercial paper conduit, special purpose subsidiary or similar
          entity; provided that (i) the aggregate face amount of such accounts
                  --------
          receivable, when added to the aggregate face amount of all other
          accounts receivable Disposed of in reliance on this clause (c), does
          not exceed $125,000,000 and (ii) the net cash proceeds from the
          Disposition of such accounts receivable, (A) when added to the net
          cash proceeds of all other Dispositions of accounts receivable made in
          reliance on this clause (c), are not less than 80% of the aggregate
          face amount of all accounts receivable Disposed of in reliance on this
          clause (c) and (B) at the time of such Disposition, do not exceed the
          sum of (I) the balance of the Borrower's deferred energy accrual
          account at such time and (II) the Borrower's deferred energy costs
          actually incurred but not yet reflected in the Borrower's deferred
          energy accrual account, in each case as set forth in the Borrower's
          books and records; provided, further, that each Disposition made by
                             --------  -------
          the Borrower in reliance on this clause (c) shall constitute a
          representation and warranty of the Borrower, made at the time of such
          Disposition, that the conditions set forth in clauses (i) and (ii)
          above are satisfied at such time and (d) in transactions other than as
          provided in Section 6.04 (a), (b) and (c); provided that the aggregate
                                                     --------
          book value of all Property Disposed of pursuant to this Section
          6.04(d) from and after the date hereof shall not exceed $50,000,000."

          (f)  Section 6.09 of the Credit Agreement shall be amended by deleting
     it in its entirety and replacing it with the following:

               "SECTION 6.09  Equal and Ratable Lien; Grant of Security Interest
                              --------------------------------------------------
          in Certain Events.
          -----------------

               (a) If, notwithstanding the prohibition contained in Section
          6.02, the Borrower or any of its Subsidiaries is subjected to any Lien
          upon any of its Property, other than those permitted by the provisions
          of Section 6.02, the Borrower will, and will cause its Subsidiaries
          to, make or cause to be made effective provisions whereby the
          Borrowings will be secured equally and ratably with any and all other
          obligations thereby secured, such security to be pursuant to
          agreements reasonably satisfactory to the Administrative Agent and, in
          any such case, the Borrowings shall have the benefit, to the fullest
          extent that, and with such priority as, the Lenders may be entitled
          under applicable law, of an equitable Lien on such Property.  Such
          violation of Section 6.02 will constitute an Event of Default, whether
          or not provision is made for an equal and ratable Lien pursuant to
          this Section 6.09, and no such Lien or agreements with respect thereto
          shall be deemed

                                      -4-
<PAGE>

          to be a waiver of or consent to such Event of Default by the
          Administrative Agent or any Lender.

               (b)  If any of the following (each, a "Triggering Event") shall
          occur:

                    (x) Sierra Pacific Resources shall not complete an
               underwritten public offering of its common stock with minimum net
               proceeds to Sierra Pacific Resources of $200,000,000 by September
               30, 2001;

                    (y) Moody's shall rate (1) the Index Debt or the senior,
               unsecured, long-term indebtedness for borrowed money of NPC as
               Baa3 or lower, or (2) the commercial paper of the Borrower or NPC
               below Prime-2; or

                    (z) S&P shall rate (1) the Index Debt or the senior,
               unsecured, long-term indebtedness for borrowed money of NPC as
               BB+ or lower, or (2) the commercial paper of the Borrower or NPC
               below A-2;

               then,

          the Borrower shall issue or cause to be issued, not later than 5
          Business Days after the date on which the Triggering Event first
          occurs, for the ratable benefit of the Lenders, General and Refunding
          Mortgage Bonds (as defined in the General and Refunding Mortgage
          Indenture), to the full extent permitted under applicable orders of
          the Public Utilities Commission of Nevada and the General and
          Refunding Mortgage Indenture, in an aggregate principal amount not to
          exceed the amount of principal of the Loans then outstanding, with
          interest and other terms and conditions substantially similar to the
          Loans, and the Borrower shall perform or cause to be performed all
          acts, and execute or cause to be executed all resolutions, orders,
          instruments, certificates, agreements and other documents, required
          under the General and Refunding Mortgage Indenture (including the
          documents referred to in Section 6.09(c)) to give effect to the
          foregoing within such 5-Business Day period.

               (c)  On or before September 30, 2001, the Borrower shall deliver
          or cause to be delivered to the Administrative Agent substantially
          final versions of the following documents (all as defined in the
          General and Refunding Mortgage Indenture) which, upon execution,
          delivery and filing, shall be sufficient for the issuance of the
          General and Refunding Mortgage Bonds required by Section 6.09(b): a
          Supplemental Indenture, an Officer's Certificate setting forth the
          terms of the General and Refunding Mortgage Bonds, a Company Order
          requesting authentication of the General and Refunding Mortgage Bonds
          by the trustee under the General and Refunding Mortgage Indenture, a
          form of the General and Refunding Mortgage Bonds to be issued and
          forms of all legal opinions required to issue the General and
          Refunding Mortgage Bonds under the General and Refunding Mortgage
          Indenture.  The forms of such documents, prior to their delivery to
          the

                                      -5-
<PAGE>

          Administrative Agent, shall have been approved by the trustee under
          the General and Refunding Mortgage Indenture and its counsel, but
          shall not be executed and delivered unless and until execution and
          delivery is required by Section 6.09(b)."

          (g) Schedule I to the Credit Agreement shall be amended by deleting it
     in its entirety and replacing it with the following:

                                 "Commitments
                                  -----------

               [See definitions of "Commitment" in Section 1.01]

LENDER                                    COMMITMENT AMOUNT
------                                    -----------------
Mellon Bank, N.A.                           $  15,937,500
Wells Fargo Bank, N.A.                      $  16,875,000
First Union National Bank                   $  12,187,500
Bank One                                    $  11,250,000
BNP Paribas                                 $  11,250,000
Credit Suisse First Boston                  $  11,250,000
The Bank of New York                        $  11,250,000
Union Bank of California, N.A.              $  11,250,000
Bayerische Landesbank Girozentrale          $   9,375,000
The Industrial Bank of Japan                $   9,375,000
                       Total                $ 120,000,000"

     4.   Representations and Warranties. The Company makes, as of the Effective
          ------------------------------
Date, each of the representations and warranties set forth in Article V of the
Credit Agreement and such representations and warranties are, by this reference,
incorporated herein as if set forth herein in their entirety; provided that
                                                              --------
references to "Loan Documents" shall, for purposes of this paragraph, be deemed
to include this Agreement.

     5.   Miscellaneous.
          -------------

     (a)  Except as expressly modified by this Agreement, the Credit Agreement
shall continue to be and remain in full force and effect in accordance with its
terms.  Any future reference to the Credit Agreement shall, from and after the
Effective Time, be deemed to be a reference to the Credit Agreement as amended
by Section 3 of this Agreement.

     (b)  This Agreement may be executed in any number of counterparts, each of
which shall constitute an original, but all of which when taken together shall
constitute but one instrument.

                                      -6-
<PAGE>

     (c)  THIS AGREEMENT AND THE RIGHTS AND OBLIGATIONS OF THE PARTIES HEREUNDER
SHALL BE GOVERNED BY AND CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF
NEW YORK WITHOUT REFERENCE TO CONFLICTS OF LAW RULES.

     (d)  This Agreement may be executed by facsimile signature and each such
signature shall be treated in all respects as having the same effect as an
original signature.

     (e)  The rules of construction set forth in Section 1.03 of the Credit
Agreement are, by this reference, incorporated herein as if set forth in their
entirety, provided that references to "this Agreement" in such section shall
mean references to this Agreement.

                        *              *              *

                                      -7-
<PAGE>

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

                                        SIERRA PACIFIC POWER COMPANY

                                        By:_________________________________
                                           Name:
                                           Title:

                               -Signature Page-
                              Amendment Agreement
<PAGE>

                                        MELLON BANK, N.A., as Administrative
                                           Agent and as a Lender

                                        By:_________________________________
                                           Name:
                                           Title:

                               -Signature Page-
                              Amendment Agreement
<PAGE>

                                        WELLS FARGO BANK, N.A., as Syndication
                                           Agent and as a Lender

                                        By:___________________________________
                                           Name:
                                           Title:

                               -Signature Page-
                              Amendment Agreement
<PAGE>

                                        FIRST UNION NATIONAL BANK, as
                                           Syndication Agent and as a Lender

                                        By:_________________________________
                                           Name:
                                           Title:

                               -Signature Page-
                              Amendment Agreement
<PAGE>

                                        BANK ONE, N.A. (Main Office-Chicago)

                                        By:_________________________________
                                           Name:
                                           Title:

                               -Signature Page-
                              Amendment Agreement
<PAGE>

                                        BNP PARIBAS

                                        By:_________________________________
                                           Name:
                                           Title:

                                        By:_________________________________
                                           Name:
                                           Title:

                               -Signature Page-
                              Amendment Agreement
<PAGE>

                                        CREDIT SUISSE FIRST BOSTON

                                        By:_________________________________
                                           Name:
                                           Title:

                               -Signature Page-
                              Amendment Agreement
<PAGE>

                                        THE BANK OF NEW YORK

                                        By:_________________________________
                                           Name:
                                           Title:

                               -Signature Page-
                              Amendment Agreement
<PAGE>

                                        UNION BANK OF CALIFORNIA, N.A.

                                        By:_________________________________
                                           Name:
                                           Title:

                               -Signature Page-
                              Amendment Agreement
<PAGE>

                                        BAYERISCHE LANDESBANK GIROZENTRALE

                                        By:_________________________________
                                           Name:
                                           Title:

                                        By:_________________________________
                                           Name:
                                           Title:

                               -Signature Page-
                              Amendment Agreement
<PAGE>

                                        THE INDUSTRIAL BANK OF JAPAN, LTD.

                                        By:_________________________________
                                           Name:
                                           Title:

                               -Signature Page-
                              Amendment Agreement<PAGE>

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

                                 $130,000,000

                               CREDIT AGREEMENT

                                  dated as of

                                August 1, 2001

                                     among

                         SIERRA PACIFIC POWER COMPANY,

                              MELLON BANK, N.A.,

                           as Administrative Agent,

                                 BNP PARIBAS,

                           FIRST UNION NATIONAL BANK

                                      and

                            WELLS FARGO BANK, N.A.

                            as Syndication Agents,

                                      and

                  the LENDERS party hereto from time to time

                                  Arranged By

                               MELLON BANK, N.A.

================================================================================
<PAGE>

          CREDIT AGREEMENT, dated as of August 1, 2001, among SIERRA PACIFIC
POWER COMPANY, a Nevada corporation, MELLON BANK, N.A., as Administrative Agent,
BNP PARIBAS, FIRST UNION NATIONAL BANK and WELLS FARGO BANK, N.A., as
Syndication Agents, the LENDERS party hereto from time to time and MELLON BANK,
N.A., as Arranger.

                             W I T N E S S E T H:
                             -------------------

          WHEREAS, the Borrower (as defined below) has requested, and the
Lenders (as defined below) have agreed to make available, the credit facilities
described below upon the terms and conditions contained herein.

          NOW, THEREFORE, in consideration of the premises and of the mutual
covenants herein contained and intending to be legally bound hereby, the parties
hereto agree as follows:

                                   ARTICLE I
                           DEFINITIONS; CONSTRUCTION

          SECTION 1.01   Defined Terms.
                         -------------

          As used in this Agreement, the following terms have the following
meanings:

          "ABR", when used in reference to any Loan or Borrowing, refers to
           ---
whether such Loan, or the Loans comprising such Borrowing, are bearing interest
at a rate determined by reference to the Alternate Base Rate.

          "Acquisition" means any transaction, or any series of related
           -----------
transactions, consummated after the Effective Date, by which the Borrower and/or
any of its Subsidiaries directly or indirectly (a) acquires any ongoing business
or all or substantially all of the assets of any Person engaged in any ongoing
business, whether through purchase of assets, merger or otherwise, (b) acquires
control of securities of a Person engaged in an ongoing business representing
more than 50% of the ordinary voting power for the election of directors or
other governing position if the business affairs of such Person are managed by a
board of directors or other governing body or (c) acquires control of more than
50% of the ownership interest in any partnership, joint venture, limited
liability company, business trust or other Person engaged in an ongoing business
that is not managed by a board of directors or other governing body.

          "Adjusted LIBO Rate" means, with respect to any Eurodollar Revolving
           ------------------
Borrowing for any Interest Period, an interest rate per annum (rounded upwards,
if necessary, to the nearest 1/100 of 1%) equal to (a) the LIBO Rate for such
Interest Period multiplied by (b) the Statutory Reserve Rate.

          "Administrative Agent" means Mellon Bank, N.A., in its capacity as
           --------------------
administrative agent for the Lenders hereunder and any successor appointed
pursuant to Section 8.10.

                                      -1-
<PAGE>

          "Affiliate" means, any Person that directly or indirectly Controls, or
           ---------
is under common Control with, or is Controlled by, another Person, provided
that, in any event, any Person that owns directly or indirectly securities
having 20% or more of the voting power for the election of directors or other
governing body of a corporation or 20% or more of the partnership or other
ownership interests of any other Person (other than as a limited partner of such
other Person) will be deemed to Control such corporation or other Person.

          "AFUDC-Debt" means, for any period, the allowance for borrowed funds
           ----------
used during construction for such period as calculated in accordance with the
rules of the Public Utilities Commission of Nevada.

          "AFUDC-Equity" means, for any period, the allowance for funds other
           ------------
than borrowed funds used during construction for such period as calculated in
accordance with the rules of the Public Utilities Commission of Nevada.

          "Agents" means, collectively, the Administrative Agent, the Arranger
           ------
and the Syndication Agents.

          "Alternate Base Rate" means, for any day, a rate per annum equal to
           -------------------
the greater of (a) the Prime Rate in effect on such day and (b) the Federal
Funds Effective Rate in effect on such day plus 1/2 of 1%. Any change in the
Alternate Base Rate due to a change in the Prime Rate or the Federal Funds
Effective Rate shall be effective from and including the effective date of such
change in the Prime Rate or the Federal Funds Effective Rate, respectively.

          "Applicable Percentage" means, with respect to any Lender as of any
           ---------------------
date of determination, the percentage of the total Commitments as of such date
represented by such Lender's Commitment as of such date.  If the Commitments
have terminated or expired, the Applicable Percentages shall be determined, as
of any date of determination, based upon the percentage of the total Loans
outstanding as of such date represented by such Lender's Loans outstanding as of
such date.

          "Applicable Rate" means, for any day, with respect to the facility
           ---------------
fees payable hereunder or with respect to any Eurodollar Revolving Loan or ABR
Loan, as the case may be, the applicable rate per annum set forth below under
the caption "Facility Fee",  "Eurodollar Spread" or "ABR Spread", as the case
may be, based on the ratings by S&P and Moody's,

                                      -2-
<PAGE>

respectively, applicable on such day to the Index Debt of Borrower:

<TABLE>
<CAPTION>
                                                        Facility       Eurodollar         ABR
Index Debt of Borrower Rating:  S&P/Moody's                Fee           Spread         Spread
-------------------------------------------                ---           ------         ------
<S>                                                   <C>            <C>             <C>
Ratings greater than A-/A3..........................      .1500%         .4250%            0
Ratings equal to A-/A3..............................      .1500%         .4750%            0
Ratings equal to BBB+/Baa1..........................      .2000%         .6250%            0
Ratings equal to BBB/Baa2...........................      .2250%         .9000%            0
Ratings equal to BBB-/Baa3..........................      .2500%        1.1250%         .1250%
Ratings less than BBB-/Baa3.........................      .3750%        2.1250%         .8750%
</TABLE>

For purposes of the foregoing, (i) if either Moody's or S&P shall not have in
effect a rating for the Index Debt of Borrower (other than by reason of the
circumstances referred to in the last sentence of this definition), then such
rating agency shall be deemed to have established a rating in its lowest rating
category, (ii) if the ratings established or deemed to have been established by
Moody's and S&P for the Index Debt of Borrower shall be changed (other than as a
result of a change in the rating system of Moody's or S&P), such change shall be
effective as of two Business Days after it is first announced by the applicable
rating agency and (iii) if the rating assigned by Moody's and the rating
assigned by S&P shall differ (a) by one level (e.g., Moody's rating of A3 and
S&P rating of BBB+), then the higher rating level shall apply (i.e., A3) and (b)
by more than one level (e.g., Moody's rating of A3 and S&P rating of BBB-), then
the rating level above the lower rating level shall apply (i.e., BBB/Baa2). Each
change in the Applicable Rate shall apply during the period commencing two
Business Days after the effective date of such change and ending on the date
immediately preceding the effective date of the next such change. If the rating
system of Moody's or S&P shall change, or if either such rating agency shall
cease to be in the business of rating corporate debt obligations, the Borrower
and the Lenders shall negotiate in good faith to amend this definition to
reflect such changed rating system or the unavailability of ratings from such
rating agency and, pending the effectiveness of any such amendment, the
Applicable Rate shall be determined by reference to the rating most recently in
effect prior to such change or cessation.

          "Arranger" means Mellon Bank, N.A. in its capacity as arranger
           --------
hereunder.

          "Assignment and Acceptance" means an assignment and acceptance entered
           -------------------------
into by a Lender and an assignee (with the consent of any party whose consent is
required by Section 9.12), and accepted by the Administrative Agent, in the form
of Exhibit A or any other form approved by the Administrative Agent.

          "Availability Period" means the period from and including the
           -------------------
Effective Date to but excluding the Revolving Termination Date.

                                      -3-
<PAGE>

          "Bankruptcy Code" means Title 11 of the United States Code entitled
           ---------------
"Bankruptcy," as now or hereafter in effect, or any successor thereto.

          "Board" means the Board of Governors of the Federal Reserve System of
           -----
the United States of America.

          "Borrower" means Sierra Pacific Power Company, a Nevada corporation.
           --------

          "Borrowing" means Loans of the same Type, made, converted or continued
           ---------
on the same date and, in the case of Eurodollar Loans, as to which a single
Interest Period is in effect.

          "Borrowing Request" means a request by the Borrower for a Borrowing
           -----------------
made in accordance with Section 2.03.

          "Business Day" means any day that is not a Saturday, Sunday or other
           ------------
day on which commercial banks in Pittsburgh, Pennsylvania are authorized or
required by Law to remain closed; provided that, when used in connection with a
                                  --------
Eurodollar Loan, the term "Business Day" shall also exclude any day on which
banks are not open for dealings in dollar deposits in the London interbank
market.

          "Capital Lease Obligations" of any Person means all obligations of
           -------------------------
such Person to pay rent or other amounts under a lease of (or other agreement
conveying the right to use) Property to the extent such obligations are required
to be classified and accounted for as a capital lease on a balance sheet of such
Person under GAAP (including Statement of Financial Accounting Standards No. 13
of the Financial Accounting Standards Board), and, for purposes of this
Agreement, the amount of such obligations shall be the capitalized amount
thereof, determined in accordance with GAAP (including such Statement No. 13).

          "Change in Control" means (a) the failure of Sierra Pacific Resources
           -----------------
to own, legally and beneficially, 100% of the aggregate ordinary voting power
represented by the issued and outstanding capital stock of the Borrower; (b) the
acquisition of ownership, directly or indirectly, beneficially or of record, by
any Person or group (within the meaning of the Securities Exchange Act of 1934
and the rules of the Securities and Exchange Commission thereunder as in effect
on the date hereof) of shares representing more than 20% of the aggregate
ordinary voting power represented by the issued and outstanding capital stock of
Sierra Pacific Resources; or (c) for any period of 12 consecutive calendar
months, a majority of the Board of Directors of Sierra Pacific Resources shall
no longer be composed of individuals (i) who were members of said Board on the
first day of such period, (ii) whose election or nomination to said Board was
approved by individuals referred to in clause (i) above constituting at the time
of such election or nomination at least a majority of said Board or (iii) whose
election or nomination to said Board was approved by individuals referred to in
clauses (i) and (ii) above constituting at the time of such election or
nomination at least a majority of said Board.

          "Change in Law" means (a) the adoption of any Law after the date of
           -------------
this Agreement, (b) any change in any Law or in the interpretation or
application thereof by any Governmental Authority after the date of this
Agreement or (c) compliance by any Lender (or, for

                                      -4-
<PAGE>

purposes of Section 2.12(b), by any lending office of such Lender or by such
Lender's Parent, if any) with any request, guideline or directive (whether or
not having the force of Law) of any Governmental Authority made or issued after
the date of this Agreement.

          "Class", when used in reference to any Loan or Borrowing, refers to
           -----
such Loan, or the Loans comprising such Borrowing, as Revolving Loans.

          "Code" means the Internal Revenue Code of 1986 and the regulations
           ----
promulgated and rulings issued thereunder.  Section references to the Code are
to the Code, as in effect at the date of this Agreement and any subsequent
provisions of the Code, amendatory thereof, supplemental thereto or substituted
therefor.

          "Commitment" means, with respect to each Lender, the commitment of
           ----------
such Lender to make Revolving Loans hereunder, expressed as an amount
representing the maximum aggregate amount of such Lender's Revolving Credit
Exposure hereunder, as such commitment may be (a) reduced from time to time
pursuant to Section 2.06 and (b) reduced or increased from time to time pursuant
to assignments by or to such Lender pursuant to Section 9.12.  The initial
amount of each Lender's Commitment is set forth on Schedule I or in the
Assignment and Acceptance pursuant to which such Lender shall have assumed its
Commitment, as applicable.  The initial aggregate amount of the Lenders'
Commitments is $130,000,000.

          "Consolidated Earnings Available For Fixed Charges" means, for any
           -------------------------------------------------
period, Consolidated Net Income Available to Common less AFUDC-Debt less AFUDC-
Equity plus Consolidated Fixed Charges, in each case for the Borrower for such
period.

          "Consolidated Fixed Charges" means, for any period, the sum of (i) the
           --------------------------
total consolidated cash interest paid by the Borrower and its consolidated
Subsidiaries for such period, (ii) lease payments made or accrued by the
Borrower and its consolidated Subsidiaries, on a consolidated basis, for such
period and (iii) preferred dividends paid by the Borrower and its consolidated
Subsidiaries for such period.

          "Consolidated Net Income Available to Common" means, for any period,
           -------------------------------------------
the consolidated net income of the Borrower and its consolidated Subsidiaries
before giving effect to any extraordinary non-cash gains or non-cash losses less
consolidated preferred dividends accrued by the Borrower and its consolidated
Subsidiaries, in each case for such period.

          "Control" of a Person (including, with its correlative meanings,
           -------
"Controlled by" and "under common Control with") means possession, directly or
indirectly, of the power to direct or cause the direction of management or
policies (whether through ownership of securities or partnership or other
ownership interests, by contract or otherwise) of such Person.

          "Default" means any event, act or condition which upon notice, lapse
           -------
of time or both would, unless cured or waived, become an Event of Default.

          "Default Interest" has the meaning assigned to such term in Section
           ----------------
2.10(c).

                                      -5-
<PAGE>

          "Dollars" or "$" refers to freely transferable lawful money of the
           -------      -
United States of America.

          "Effective Date" means the date on which the conditions specified in
           --------------
Section 4.01 are satisfied (or waived in accordance with Section 9.01).

          "Environmental Claims" means any and all administrative, regulatory or
           --------------------
judicial actions, suits, demands, demand letters, directives, claims, liens,
notices of noncompliance or violation, investigations or proceedings relating in
any way to any Environmental Law or any permit issued, or any approval given,
under any such Environmental Law (hereafter, "Claims"), including, without
                                              ------
limitation, (a) any and all Claims by governmental or regulatory authorities for
enforcement, cleanup, removal, response, remedial or other actions or damages
pursuant to any applicable Environmental Law, and (b) any and all Claims by any
third party seeking damages, contribution, indemnification, cost recovery,
compensation or injunctive relief in connection with alleged injury or threat of
injury to health, safety or the environment due to the presence of Hazardous
Materials.

          "Environmental Law" means any Federal, state, foreign or local
           -----------------
statute, Law, rule, regulation, ordinance, code, guideline, written policy and
rule of common law now or hereafter in effect and in each case as amended, and
any judicial or administrative interpretation thereof, including any judicial or
administrative order, consent decree or judgment, relating to the environment,
employee health and safety or Hazardous Materials, including, without
limitation, CERCLA; RCRA; the Federal Water Pollution Control Act, 33 U.S.C. (S)
1251 et seq.; the Toxic Substances Control Act, 15 U.S.C. (S) 2601 et seq.; the
     -- ----                                                       -- ----
Clean Air Act, 42 U.S.C. (S) 7401 et seq.; the Safe Drinking Water Act, 42
                                  -- ----
U.S.C. (S) 3803 et seq.; the Oil Pollution Act of 1990, 33 U.S.C. (S) 2701 et
                -- ----                                                    --
seq.; the Emergency Planning and the Community Right-to-Know Act of 1986, 42
----
U.S.C. (S) 11001 et seq.; the Hazardous Material Transportation Act, 49 U.S.C.
                 -- ----
(S) 1801 et seq. and the Occupational Safety and Health Act, 29 U.S.C. (S) 651
         -- ----
et seq.; and any state and local or foreign counterparts or equivalents, in each
-- ----
case as amended from time to time.

          "ERISA" means the Employee Retirement Income Security Act of 1974 and
           -----
the regulations promulgated and rulings issued thereunder.  Section references
to ERISA are to ERISA, as in effect at the date of this Agreement, and to any
subsequent provisions of ERISA, amendatory thereof, supplemental thereto or
substituted therefor.

          "ERISA Affiliate" means any corporation or trade or business that is a
           ---------------
member of any group of organizations described in Section 414(b) or (c) of the
Code of which the Borrower is a member.

          "Eurodollar", when used in reference to any Loan or Borrowing, refers
           ----------
to whether such Loan, or the Loans comprising such Borrowing, are bearing
interest at a rate determined by reference to the Adjusted LIBO Rate.

          "Event of Default" has the meaning assigned to such term in Section
           ----------------
7.01.

                                      -6-
<PAGE>

          "Excluded Taxes" means, with respect to the Administrative Agent, any
           --------------
Lender or any other recipient of any payment to be made by or on account of any
obligation of the Borrower hereunder, (a) income or franchise taxes imposed on
(or measured by) its net income by the United States of America, or by the
jurisdiction under the Laws of which such recipient is organized or in which its
principal office is located or, in the case of any Lender, in which its
applicable lending office is located, (b) any branch profits taxes imposed by
the United States of America or any similar tax imposed by any other
jurisdiction in which the Borrower is located and (c) in the case of a Foreign
Lender (other than an assignee pursuant to a request by the Borrower under
Section 2.16(b)), any withholding tax that is imposed on amounts payable to such
Foreign Lender at the time such Foreign Lender becomes a party to this Agreement
or is attributable to such Foreign Lender's failure or inability to comply with
Section 2.14(e), except to the extent that such Foreign Lender's assignor (if
any) was entitled, at the time of assignment, to receive additional amounts from
the Borrower with respect to such withholding tax pursuant to Section 2.14(a).

          "Existing Facility" means the Credit Agreement, dated as of June 24,
           -----------------
1999, as amended by Amendment No. 1 to Credit Agreement, dated as of May 1,
2000; the Amendment of Credit Agreement, dated as of July 1, 2000; the Amended
and Restated Credit Agreement, dated as of August 28, 2000; the Amendment and
Waiver Agreement, dated as of March 1, 2001; the Amendment and Waiver Agreement
dated as of May 8, 2001; and the Amendment Agreement, dated as of August 1,
2001, all by and among the Borrower, the Agents and the financial institutions
from time to time party thereto.

          "Existing Indebtedness" has the meaning assigned to such term in
           ---------------------
Section 3.22.

          "Extension Request" has the meaning assigned to such term in Section
           -----------------
2.06(e).

          "Extension Request Notice" has the meaning assigned to such term in
           ------------------------
Section 2.06(e).

          "Extension Request Period" has the meaning assigned to such term in
           ------------------------
Section 2.06(e).

          "Federal Funds Effective Rate" means, for any day, the weighted
           ----------------------------
average (rounded upwards, if necessary, to the next 1/100 of 1%) of the rates on
overnight Federal funds transactions with members of the Federal Reserve System
arranged by Federal funds brokers, as published on the next succeeding Business
Day by the Federal Reserve Bank of New York, or, if such rate is not so
published for any day that is a Business Day, the average (rounded upwards, if
necessary, to the next 1/100 of 1%) of the quotations for such day for such
transactions received by the Administrative Agent from three Federal funds
brokers of recognized standing selected by it.

          "First Mortgage Bonds" means obligations issued from time to time
           --------------------
under, and secured by, the First Mortgage Indenture.

                                      -7-
<PAGE>

          "First Mortgage Indenture" means the Indenture of Mortgage, dated as
           ------------------------
of December 1, 1940, from the Borrower to State Street Bank and Trust Company
(successor to The New England Trust Company), as trustee, and Gerald R. Wheeler
(successor to Leo W. Huegle), as co-Trustee, as modified, amended or
supplemented at any time or from time to time by supplemental indentures.

          "Fixed Charge Coverage Ratio" means, as of the last day of a fiscal
           ---------------------------
quarter, the ratio of Consolidated Earnings Available For Fixed Charges to
Consolidated Fixed Charges, in each case, for such fiscal quarter or the
consecutive fiscal quarter period of the Borrower ended on such last day, as
applicable.

          "Foreign Lender" means any Lender that is organized under the Laws of
           --------------
a jurisdiction other than the United States of America, each State thereof and
the District of Columbia.

          "Foreign Pension Plan" means any plan, fund (including, without
           --------------------
limitation, any superannuation fund) or other similar program established or
maintained outside the United States of America by the Borrower or any one or
more of its Subsidiaries primarily for the benefit of employees of the Borrower
or such Subsidiaries residing outside the United States of America, which plan,
fund or other similar program provides, or results in, retirement income, a
deferral of income in contemplation of retirement or payments to be made upon
termination of employment, and which plan is not subject to ERISA or the Code.

          "GAAP" means generally accepted accounting principles in the United
           ----
States of America applied in a consistent manner.

          "General and Refunding Mortgage Bonds" means obligations issued from
           ------------------------------------
time to time under, and secured by, the General and Refunding Mortgage
Indenture.

          "General and Refunding Mortgage Indenture" means the General and
Refunding Mortgage Indenture, dated as of May 1, 2001, between the Borrower and
the Bank of New York, as trustee, as the same may be amended, modified or
supplemented from time to time.

          "Governmental Action" means any authorization, approval, order,
           -------------------
decree, ruling or other action by, or notice to or filing with, any Governmental
Authority.

          "Governmental Authority" means the government of the United States of
           ----------------------
America, any other nation or any political subdivision thereof, whether state or
local, and any agency, authority, bureau, instrumentality, regulatory body,
court, tribunal, central bank or other entity exercising executive, legislative,
judicial, taxing, regulatory or administrative powers or functions of or
pertaining to government.

          "Hazardous Materials" means (a) any petroleum or petroleum products,
           -------------------
radioactive materials, asbestos in any form that is friable, urea formaldehyde
foam insulation, transformers or other equipment that contain dielectric fluid
containing levels of polychlorinated biphenyls, and radon gas; (b) any
chemicals, materials or substances defined as or included in the definition of
"hazardous substances," "hazardous waste," "hazardous materials," "extremely

                                      -8-
<PAGE>

hazardous substances," "restricted hazardous waste," "toxic substances," "toxic
pollutants," "contaminants," or "pollutants," or words of similar import, under
any applicable Environmental Law; and (c) any other chemical, material or
substance, the Release of which is prohibited, limited or regulated by any
governmental authority.

          "Indebtedness" of any Person means, (a) obligations created, issued or
           ------------
incurred by such Person for borrowed money (whether by loan, the issuance and
sale of debt securities or the sale of Property to another Person subject to an
understanding or agreement, contingent or otherwise, to repurchase such Property
from such Person); (b) obligations of such Person to pay the deferred purchase
or acquisition price of Property or services, other than trade accounts payable
(other than for borrowed money) arising, and accrued expenses incurred, in the
ordinary course of business; (c) Indebtedness of others secured by a Lien on the
Property of such Person, whether or not the respective indebtedness so secured
has been assumed by such Person; (d) obligations of such Person in respect of
letters of credit or similar instruments issued or accepted by banks and other
financial institutions for account of such Person; (e) Capital Lease Obligations
of such Person; and (f) any guarantee or other arrangement by which such Person
guarantees or is otherwise liable for the Indebtedness of others; provided,
                                                                  --------
however, that "Indebtedness" shall not include Secured Nonrecourse Obligations.
-------

          "Indemnified Parties" means each Agent, the Lenders, their respective
           -------------------
Affiliates, and the directors, officers, employees, attorneys and agents of each
of the foregoing.

          "Indemnified Taxes" means all Taxes other than Excluded Taxes.
           -----------------

          "Index Debt of Borrower" means the senior, unsecured, long-term
           ----------------------
indebtedness for borrowed money of the Borrower that is not guaranteed by any
other Person or subject to any credit enhancement.

          "Index Debt of NPC" means the senior, unsecured, long-term
           -----------------
indebtedness for borrowed money of NPC that is not guaranteed by any other
Person or subject to any credit enhancement.

          "Interest Election Request" means a request by the Borrower to convert
           -------------------------
or continue a Borrowing in accordance with Section 2.05.

          "Interest Payment Date" means (a) with respect to any ABR Loan, each
           ---------------------
Quarterly Date, and (b) with respect to any Eurodollar Loan, the last day of the
Interest Period applicable to the Borrowing of which such Loan is a part and, in
the case of a Eurodollar Borrowing with an Interest Period of more than three
months' duration, each day prior to the last day of such Interest Period that
occurs at intervals of three months' duration after the first day of such
Interest Period.

          "Interest Period" means, with respect to any Eurodollar Borrowing, the
           ---------------
period commencing on the date of such Borrowing and ending on the numerically
corresponding day in the calendar month that is one, two, three or six months
thereafter, as the Borrower may elect; provided, that (a) if any Interest Period
                                       --------
would end on a day other than a Business Day, such Interest Period shall be
extended to the next succeeding Business Day unless such next

                                      -9-
<PAGE>

succeeding Business Day would fall in the next calendar month, in which case
such Interest Period shall end on the next preceding Business Day and (b) any
Interest Period that commences on the last Business Day of a calendar month (or
on a day for which there is no numerically corresponding day in the last
calendar month of such Interest Period) shall end on the last Business Day of
the last calendar month of such Interest Period. For purposes hereof, the date
of a Borrowing initially shall be the date on which such Borrowing is made and,
thereafter shall be the effective date of the most recent conversion or
continuation of such Borrowing.

          "Investment" means, when used in connection with any Person, any
           ----------
investment by or of that Person, whether by means of purchase or other
acquisition of stock or other securities of any other Person or by means of a
loan, advance creating a debt, capital contribution, guaranty or other debt or
equity participation or interest in any other Person, including any partnership
                                                      ---------
and joint venture interests of such Person but excluding  any Wholly-Owned
                                               ---------
Subsidiary of such Person.  The amount of any Investment shall be the amount
actually invested (minus any return of capital with respect to such Investment
                   -----
which has actually been received in cash or has been converted into cash),
without adjustment for subsequent increases or decreases in the value of such
Investment.

          "Law" shall mean any law (including common law), constitution,
           ---
statute, treaty, convention, regulation, rule, ordinance, order, injunction,
writ, decree or award of any Governmental Authority.

          "Lenders" means the Persons listed on Schedule I and any other Person
           -------
that shall have become a party hereto pursuant to an Assignment and Acceptance.

          "LIBO Rate" means, with respect to any Eurodollar Borrowing for any
           ---------
Interest Period, the average of the offered rates for Dollar deposits for the
applicable Interest Period which appear on the Telerate Page 3750, British
Bankers Association Interest Settlement Rates, with maturities comparable to the
Interest Period to be applicable to such Eurodollar Loan, determined as of 10:00
A.M. (Pittsburgh, Pennsylvania time) on the date which is two Business Days
prior to the commencement of such Interest Period.

          "Lien" means, with respect to any Property, any mortgage, lien,
           ----
pledge, charge, security interest or encumbrance of any kind in respect of such
Property.  For purposes of this Agreement, a Person shall be deemed to own
subject to a Lien any Property that it has acquired or holds subject to the
interest of a vendor or lessor under any conditional sale agreement, capital
lease or other title retention agreement (other than an operating lease)
relating to such Property.

          "Loan Documents" means this Agreement, each Borrowing Request, each
           --------------
Interest Election Request and each Note.

          "Loans" means Revolving Loans.
           -----

          "Material Adverse Effect" means (a) a material adverse effect on (i)
           -----------------------
the Property, business, operations, financial condition, prospects, liabilities
or capitalization of the Borrower and its Subsidiaries taken as a whole, (ii)
the ability of the Borrower to perform its obligations

                                      -10-
<PAGE>

hereunder or (v) the timely payment of the principal of or interest on the Loans
or other amounts payable in connection therewith and (b) a material adverse
change in the facts and information regarding the Borrower and its Subsidiaries
submitted in writing to the Administrative Agent and/or the Lenders by the
Borrower.

          "Moody's" means Moody's Investors Service, Inc.; provided that if such
           -------                                         --------
corporation (or its successors and assigns) shall for any reason no longer
perform the functions of a securities rating agency, "Moody's" shall be deemed
to refer to any other nationally recognized securities rating agency approved
for purposes hereof by the Required Lenders and the Borrower.

          "Multiemployer Plan" means a multiemployer plan defined as such in
           ------------------
Section 3(37) of ERISA to which contributions have been made by the Borrower or
any ERISA Affiliate and which is covered by Title IV of ERISA.

          "NPC" means Nevada Power Co., a Nevada corporation.
           ---

          "Note" has the meaning assigned to such term in Section 2.07(f).
           ----

          "Obligations" means all Indebtedness, obligations and liabilities of
           -----------
the Borrower to any Lender or any Agent from time to time arising under or in
connection with or related to or evidenced by or secured by this Agreement or
any other Loan Document, and all extensions, renewals or refinancings thereof,
whether such Indebtedness, obligations or liabilities are direct or indirect,
otherwise secured or unsecured, joint or several, absolute or contingent, due or
to become due, whether for payment or performance, now existing or hereafter
arising.  Without limitation of the foregoing, such Indebtedness, obligations
and liabilities shall include the principal amount of all Loans, all interest,
fees, indemnities or expenses under or in connection with this Agreement or any
other Loan Document, and all extensions, renewals and refinancings thereof,
whether or not such Loans were made in compliance with the terms and conditions
of this Agreement or in excess of the obligation of the Lenders to lend.
Obligations shall remain obligations notwithstanding any assignment or transfer
or any subsequent assignment or transfer of any of the Obligations or any
interest therein.

          "Other Taxes" means any and all present or future stamp or documentary
           -----------
taxes or any other excise or Property taxes, charges or similar levies arising
from any payment made hereunder or from the execution, delivery or enforcement
of, or otherwise with respect to, this Agreement.

          "Parent" means any Person that Controls a Lender.
           ------

          "Participant" has the meaning assigned to Section 9.12(b).
           -----------

          "PBGC" means the Pension Benefit Guaranty Corporation or any entity
           ----
succeeding to any or all of its functions under ERISA.

          "Permitted Liens" has the meaning assigned to such term in Section
           ---------------
6.02.

                                      -11-
<PAGE>

          "Person" means any natural person, corporation, limited liability
           ------
company, trust, joint venture, association, company, partnership, Governmental
Authority or other entity.

          "Plan" means an employee benefit or other plan established or
           ----
maintained by the Borrower or any ERISA Affiliate and that is covered by Title
IV of ERISA, other than a Multiemployer Plan.

          "Prime Rate" means the rate of interest per annum publicly announced
           ----------
from time to time by Mellon Bank, N.A. as its prime rate, the Prime Rate to
change when and as such prime rate changes.  The Prime Rate is a reference rate
and does not necessarily represent the lowest or best rate actually charged to
any customer.  Mellon Bank, N.A. may make commercial loans or other loans at
rates of interest at, above or below the Prime Rate.

          "Principal Office" means the principal office of Mellon Bank, N.A.,
           ----------------
located on the date hereof at One Mellon Bank Center, Pittsburgh, Pennsylvania
15258.

          "Projections" means forecasted (a) balance sheets, (b) income
           -----------
statements, and (c) cash flow statements, in each case, for the Borrower and its
Subsidiaries, on a consolidated basis, and prepared on a consistent basis with
the Borrower's historical financial statements, together with appropriate
supporting details and a statement of underlying assumptions.

          "Property" means any right or interest in or to property of any kind
           --------
whatsoever, whether real, personal or mixed and whether tangible or intangible.

          "Purchasing Lender" has the meaning assigned to Section 9.12(c).
           -----------------

          "Quarterly Dates" means the last day of March, June, September and
           ---------------
December in each year, the first of which shall be the first such day after the
date hereof; provided that if any such day is not a Business Day, then such
             --------
Quarterly Date shall be the next succeeding Business Day (unless such succeeding
Business Day falls in a subsequent calendar month, in which event such Quarterly
Date shall be the next preceding Business Day).

          "Register" has the meaning assigned to Section 9.12(d).
           --------

          "Related Parties" means, with respect to any specified Person, such
           ---------------
Person's Affiliates and the respective directors, officers, employees, agents
and advisors of such Person and such Person's Affiliates.

          "Release" means the disposing, discharging, injecting, spilling,
           -------
pumping, leaking, leaching, dumping, emitting, escaping, emptying, pouring or
migrating, into or upon any land or water or air, or otherwise entering into the
environment.

          "Reportable Event" means an event described in Section 4043(c) of
           ----------------
ERISA with respect to a Plan that is subject to Title IV of ERISA other than
those events as to which the 30-day notice period is waived under subsection
 .22, .23, .25, .27 or .28 of PBGC Regulation Section 4043 (provided that a
failure to meet the minimum funding standard of Section 412 of the Code or
Section 302 of ERISA, including, without limitation, the failure to make on or
before

                                      -12-
<PAGE>

its due date a required installment under Section 412(m) of the Code or Section
302(e) of ERISA, shall be a reportable event regardless of the issuance of any
waivers in accordance with Section 412(d) of the Code).

          "Required Lenders" means (a) so long as the Commitments remain in
           ----------------
effect, Lenders having Commitments representing 51% or more of the sum of the
total Commitments at such time, or (b) if the Commitments have terminated,
Lenders holding 51% or more of the aggregate principal amount of the Loans
outstanding at such time.

          "Responsible Officer" means the Treasurer, the Assistant Treasurer,
           -------------------
the Chief Financial Officer or the Controller.

          "Revolving Credit Exposure" means, with respect to any Lender at any
           -------------------------
time, the aggregate outstanding principal amount of such Lender's Revolving
Loans at such time.

          "Revolving Loan" has the meaning assigned to such term in Section
           --------------
2.01(a).

          "Revolving Termination Date" means the earlier to occur of (a)
           --------------------------
November 30, 2001, or such date after November 30, 2001 to which the Commitments
are extended in accordance with Section 2.06(e) and (b) the date the Obligations
and Commitments under this Agreement terminate, whether by prepayment,
cancellation, acceleration or otherwise.

          "Secured Nonrecourse Obligations" means and includes (a) secured
           -------------------------------
obligations of the Borrower taken on a consolidated basis where recourse of the
payee of such obligations is expressly limited to an assigned lease or loan
receivable and the Property related thereto and (b) liabilities of the Borrower
taken on a consolidated basis to manufacturers of leased equipment where such
liabilities are payable solely out of revenues derived from the leasing or sale
of such equipment.

          "Sierra Pacific Resources" means Sierra Pacific Resources, a Nevada
           ------------------------
corporation.

          "Shareholders' Equity" means, as of any date of determination, the
           --------------------
amount which is shown as "shareholders' equity" (which shall include both common
and preferred equity) in the consolidated balance sheet of the Borrower at such
date.

          "S&P" means Standard & Poor's Ratings Group, a division of The McGraw
           ---
Hill Companies, Inc., and its successor and assigns; provided that if such
                                                     --------
corporation (or its successors and assigns) shall for any reason no longer
perform the functions of a securities rating agency, "S&P" shall be deemed to
refer to any other nationally recognized securities rating agency approved for
purposes hereof by the Required Lenders and the Borrower.

          "Statutory Reserve Rate" means a fraction (expressed as a decimal),
           ----------------------
the numerator of which is the number one and the denominator of which is the
number one minus the aggregate of the maximum reserve percentages (including any
marginal, special, emergency or supplemental reserves) expressed as a decimal
established by the Board to which the Administrative Agent is subject  for
eurocurrency funding (currently referred to as "Eurocurrency liabilities" in
Regulation D of the Board).  Such reserve percentages shall include those
imposed

                                      -13-
<PAGE>

pursuant to such Regulation D. Eurodollar Loans shall be deemed to constitute
eurocurrency funding and to be subject to such statutory reserve rates without
benefit of or credit for proration, exemptions or offsets that may be available
from time to time to any Lender under such Regulation D or any comparable
regulation. The Statutory Reserve Rate shall be adjusted automatically on and as
of the effective date of any change in any reserve percentage.

          "Subsidiary" shall mean, as to any Person, (i) any corporation more
           ----------
than 50% of whose stock of any class or classes having by the terms thereof
ordinary voting power to elect a majority of the directors of such corporation
(irrespective of whether or not at the time stock of any class or classes of
such corporation shall have or might have voting power by reason of the
happening of any contingency) is at the time owned by such Person and/or one or
more Subsidiaries of such Person and (ii) any partnership, limited liability
company, association, joint venture or other entity in which such Person and/or
one or more Subsidiaries of such Person has more than a 50% equity interest at
the time.

          "Substitute Lender" has the meaning assigned to such term in Section
           -----------------
2.06(f).

          "Syndication Agents" means BNP Paribas, First Union National Bank and
           ------------------
Wells Fargo Bank, N.A.

          "Taxes" means any and all present or future taxes, levies, imposts,
           -----
duties, deductions, charges or withholdings imposed by any Governmental
Authority.

          "Total Indebtedness" means, as of any date of determination, the sum
           ------------------
of all Indebtedness of the Borrower and its consolidated Subsidiaries as of such
date.

          "Triggering Event" has the meaning assigned to such term in Section
           ----------------
6.09(b).

          "Type", when used in reference to any Loan or Borrowing, refers to
           ----
whether the rate of interest on such Loan, or on the Loans comprising such
Borrowing, is determined by reference to the Adjusted LIBO Rate or the Alternate
Base Rate.

          "Unfunded Current Liability" of any Plan means the amount, if any, by
           --------------------------
which the value of the accumulated plan benefits under the Plan determined on a
plan termination basis in accordance with actuarial assumptions at such time
consistent with those prescribed by the PBGC for purposes of Section 4044 of
ERISA, exceeds the fair market value of all plan assets allocable to such
liabilities under Title IV of ERISA (excluding any accrued but unpaid
contributions).

          "Wholly-Owned Subsidiary" shall mean, as to any Person, (i) any
           -----------------------
corporation 100% of whose stock of any class or classes having by the terms
thereof ordinary voting power to elect a majority of the directors of such
corporation (irrespective of whether or not at the time stock of any class or
classes of such corporation shall have or might have voting power by reason of
the happening of any contingency) is at the time owned by such Person and/or one
or more Subsidiaries of such Person and (ii) any partnership, limited liability
company, association, joint venture or other entity in which such Person and/or
one or more Subsidiaries of such Person has a 100% equity interest at the time.

                                      -14-
<PAGE>

          SECTION 1.02.  Classification of Loans and Borrowings.
                         --------------------------------------

          For purposes of this Agreement, Loans may be classified and referred
to by Class (e.g., a "Revolving Loan") or by Type (e.g., a "Eurodollar Loan" or
an "ABR Loan") or by Class and Type (e.g., a "Eurodollar Revolving Loan").
Borrowings also may be classified and referred to by Class (e.g., a "Revolving
Borrowing") or by Type (e.g., a "Eurodollar Borrowing") or by Class and Type
(e.g., a "Eurodollar Revolving Borrowing").

          SECTION 1.03   Terms Generally.
                         ---------------

          The definitions of terms herein shall apply equally to the singular
and plural forms of the terms defined.  Whenever the context may require, any
pronoun shall include the corresponding masculine, feminine and neuter forms.
The words "include", "includes" and "including" shall be deemed to be followed
by the phrase "without limitation". The word "will" shall be construed to have
the same meaning and effect as the word "shall".  Unless the context requires
otherwise (a) any definition of or reference to any agreement, instrument or
other document herein shall be construed as referring to such agreement,
instrument or other document as from time to time amended, supplemented or
otherwise modified (subject to any restrictions on such amendments, supplements
or modifications set forth herein), (b) any reference herein to any Person shall
be construed to include such Person's successors and assigns, (c) the words
"herein", "hereof" and "hereunder", and words of similar import, shall be
construed to refer to this Agreement in its entirety and not to any particular
provision hereof and (d) all references herein to Articles, Sections, Exhibits
and Schedules shall be construed to refer to Articles and Sections of, and
Exhibits and Schedules to, this Agreement.

          SECTION 1.04   Accounting Terms; GAAP.
                         ----------------------

          Except as otherwise expressly provided herein, all terms of an
accounting or financial nature shall be construed in accordance with GAAP, as in
effect from time to time.

                                  ARTICLE II
                                  THE CREDITS

          SECTION 2.01   The Commitments.
                         ---------------

          Subject to the terms and conditions set forth herein, each Lender
agrees to make loans (each such loan, a "Revolving Loan") to the Borrower from
                                         --------------
time to time on any Business Day during the Availability Period in an aggregate
principal amount that will not result in (i) such Lender's Revolving Credit
Exposure (after giving effect to such Revolving Loans) exceeding such Lender's
Commitment or (ii) the sum of the Revolving Credit Exposures of all Lenders
exceeding the total Commitments.  Within the foregoing limits and subject to the
terms and conditions set forth herein, the Borrower may borrow, prepay and
reborrow Revolving Loans.

                                      -15-
<PAGE>

          SECTION 2.02  Loans and Borrowings.
                        --------------------

          (a)  Obligations of Lenders.  Each Revolving Loan shall be made as
               ----------------------
part of a Borrowing consisting of Loans of the same Type made by the Lenders
ratably in accordance with their respective Commitments. The failure of any
Lender to make any Loan required to be made by it shall not relieve any other
Lender of its obligations hereunder. The Commitments of the Lenders are several
and no Lender shall be responsible for any other Lender's failure to make Loans
as required.

          (b)  Type of Loans.  Subject to Section 2.11, each Borrowing shall be
               -------------
comprised entirely of ABR Loans or Eurodollar Loans.  Each Lender may, at its
option, make any Eurodollar Loan by causing any domestic or foreign branch or
Affiliate of such Lender to make such Loan; provided that any exercise of such
                                            --------
option shall not affect the obligation of the Borrower to repay such Loan in
accordance with the terms of this Agreement.

          (c)  Minimum Amounts; Limitation on Number of Borrowings.  Each
               ---------------------------------------------------
Revolving Borrowing (whether an ABR Borrowing or a Eurodollar Borrowing) shall
be in an aggregate amount equal to $5,000,000 or a multiple of $1,000,000 in
excess thereof; provided that an ABR Borrowing may be made in an aggregate
                --------
amount that is equal to the entire unused balance of the total Commitments.  The
Borrower may thereafter, upon irrevocable notice to the Administrative Agent in
accordance with Section 2.05(b), (i) elect, as of any Business Day, in the case
of ABR Loans, to convert any such ABR Loans or any part thereof, in an aggregate
amount equal to $5,000,000 or a multiple of $1,000,000 in excess thereof, into
Eurodollar Loans, and (ii) elect, as of the last day of the applicable Interest
Period, to continue any Eurodollar Loans having Interest Periods expiring on
such day or any part thereof in an aggregate amount of $5,000,000 or a multiple
of $1,000,000 in excess thereof; provided that, if at any time the aggregate
                                 --------
amount of Eurodollar Loans in respect of any Borrowing is reduced by payment,
prepayment or conversion of part thereof to be less than $5,000,000, such
Eurodollar Loans shall automatically convert into ABR Loans.  Borrowings of more
than one Type may be outstanding at the same time; provided that there shall not
                                                   --------
at any time be more than a total of five Eurodollar Borrowings outstanding.

          (d)  Maximum Duration of Interest Periods.  Notwithstanding any other
               ------------------------------------
provision of this Agreement, the Borrower shall not be entitled to request, or
to elect to convert or continue, any Eurodollar Borrowing if the Interest Period
requested with respect thereto would end after the Revolving Termination Date.

          SECTION 2.03   Requests for Revolving Borrowings.
                         ---------------------------------

          To request a Revolving Borrowing, the Borrower shall notify the
Administrative Agent of such request by telephone (a) in the case of a
Eurodollar Revolving Borrowing, not later than 12:00 noon., Pittsburgh,
Pennsylvania time, three Business Days before the date of the proposed
Borrowing, or (b) in the case of an ABR Borrowing, not later than 12:00 noon,
Pittsburgh, Pennsylvania time, one Business Day before the date of the proposed
Borrowing.  Each such telephonic Borrowing Request shall be irrevocable and
shall be confirmed promptly by hand delivery or telecopy to the Administrative
Agent of a written Borrowing Request in the

                                      -16-
<PAGE>

form attached hereto as Exhibit B and signed by the Borrower. Each such
telephonic and written Borrowing Request shall specify the following information
in compliance with Section 2.02:

               (i)    the aggregate amount of the requested Borrowing;

               (ii)   the date of such Borrowing, which shall be a Business Day;

               (iii)  whether such Borrowing is to be an ABR Borrowing or a
     Eurodollar Borrowing;

               (iv)   in the case of a Eurodollar Borrowing, the initial
     Interest Period to be applicable thereto, which shall be a period
     contemplated by the definition of the term "Interest Period"; and

               (v)    the location and number of the Borrower's account to which
     funds are to be disbursed, which shall comply with the requirements of
     Section 2.04.

          If no election as to the Type of Revolving Borrowing is specified,
then the requested Revolving Borrowing shall be an ABR Borrowing.  If no
Interest Period is specified with respect to any Eurodollar Revolving Borrowing,
then the Borrower shall be deemed to have selected an Interest Period of one
month's duration.  Promptly following receipt of a Borrowing Request in
accordance with this Section, the Administrative Agent shall advise each Lender
of the details thereof and of the amount of such Lender's Loan to be made as
part of the requested Borrowing.

          SECTION 2.04   Funding of Borrowings.
                         ---------------------

          (a)  Funding by Lenders.  No later than 12:00 noon, Pittsburgh,
               ------------------
Pennsylvania time, on the date specified in each Borrowing Request, each Lender
will make available its Applicable Percentage of each Revolving Borrowing
requested to be made on such date, in Dollars and in immediately available funds
at the account of the Administrative Agent most recently designated by it for
such purpose by notice to the Lenders.  The Administrative Agent will make such
Loans available to the Borrower by promptly crediting the amounts so received,
in like funds, to an account of the Borrower maintained with Mellon Bank, N.A.
at the Principal Office and designated by the Borrower in the applicable
Borrowing Request.

          (b)  Presumption by the Administrative Agent.  Unless the
               ---------------------------------------
Administrative Agent shall have received notice from a Lender prior to the
proposed date of any Borrowing that such Lender will not make available to the
Administrative Agent such Lender's share of such Borrowing, the Administrative
Agent may assume that such Lender has made such share available on such date in
accordance with paragraph (a) of this Section and may, in reliance upon such
assumption, make available to the Borrower a corresponding amount.  In such
event, if a Lender has not in fact made its share of the applicable Borrowing
available to the Administrative Agent, then the applicable Lender and the
Borrower severally agree to pay to the Administrative Agent forthwith on demand
such corresponding amount with interest thereon, for each day from and including
the date such amount is made available to the Borrower to but excluding the date
of payment to the Administrative Agent, at (i) in the case of such Lender, the
Federal Funds

                                      -17-
<PAGE>

Effective Rate or (ii) in the case of the Borrower, the interest rate applicable
to the Loans of such Borrowing. If such Lender pays such amount to the
Administrative Agent, then such amount shall constitute such Lender's Loan
included in such Borrowing.

          SECTION 2.05   Interest Elections.
                         ------------------

          (a)  Elections by the Borrower for Borrowings.  Each Borrowing
               ----------------------------------------
initially shall be of the Type specified in the applicable Borrowing Request
and, in the case of a Eurodollar Borrowing, shall have an initial Interest
Period as specified in such Borrowing Request.  Thereafter, the Borrower may
elect to convert such Borrowing to a different Type or to continue such
Borrowing and, in the case of a Eurodollar Borrowing, may elect Interest Periods
therefor, all as provided in this Section but subject to Section 2.02.  Once
Loans have been made pursuant to a Borrowing, the Borrower may elect to convert
or continue different portions of such Borrowing, in which case each such
portion shall be allocated ratably among the Lenders holding the Loans
comprising such Borrowing, and the Loans comprising each such portion shall be
considered a separate Borrowing.

          (b)  Notice of Elections.  To make an election pursuant to this
               -------------------
Section, the Borrower shall notify the Administrative Agent of such election by
telephone by the time that a Borrowing Request would be required under Section
2.03 if the Borrower were requesting a Revolving Borrowing of the Type resulting
from such election to be made on the effective date of such election.  Each such
telephonic Interest Election Request shall be irrevocable and shall be confirmed
promptly by hand delivery or telecopy to the Administrative Agent of a written
Interest Election Request in a form approved by the Administrative Agent and
signed by the Borrower.

          (c)  Information in Interest Election Requests.  Each telephonic and
               -----------------------------------------
written Interest Election Request shall specify the following information in
compliance with Section 2.02:

               (i)    the Borrowing to which such Interest Election Request
     applies and, if different options are being elected with respect to
     different portions thereof, the portions thereof to be allocated to each
     resulting Borrowing (in which case the information to be specified pursuant
     to clauses (iii) and (iv) of this paragraph shall be specified for each
     resulting Borrowing);

               (ii)   the effective date of the election made pursuant to such
     Interest Election Request, which shall be a Business Day;

               (iii)  whether the resulting Borrowing is to be an ABR Borrowing,
     or a Eurodollar Borrowing; and

               (iv)   if the resulting Borrowing is a Eurodollar Borrowing, the
     Interest Period to be applicable thereto after giving effect to such
     election, which shall be a period contemplated by the definition of the
     term "Interest Period".

                                      -18-
<PAGE>

          If any such Interest Election Request requests a Eurodollar Borrowing
but does not specify an Interest Period, then the Borrower shall be deemed to
have selected an Interest Period of one month's duration.

          (d)  Notice by the Administrative Agent to Lenders.  Promptly
               ---------------------------------------------
following receipt of an Interest Election Request, the Administrative Agent
shall advise each Lender of the details thereof and of such Lender's portion of
each resulting Borrowing.

          (e)  Failure to Elect; Events of Default.  If the Borrower fails to
               -----------------------------------
deliver a timely Interest Election Request with respect to a Eurodollar
Borrowing prior to the end of the Interest Period applicable thereto, then,
unless such Borrowing is repaid as provided herein, at the end of such Interest
Period such Borrowing shall be converted to an ABR Borrowing.  Notwithstanding
any contrary provision hereof, if an Event of Default has occurred and is
continuing and the Administrative Agent, at the request of the Required Lenders,
so notifies the Borrower, then, so long as an Event of Default is continuing (i)
no outstanding Borrowing may be converted to or continued as a Eurodollar
Borrowing and (ii) unless repaid, each Eurodollar Borrowing shall be converted
to an ABR Borrowing at the end of the Interest Period applicable thereto.

          SECTION 2.06   Termination, Reduction and Extension of Commitments.
                         ---------------------------------------------------

          (a)  Scheduled Termination.  Unless previously terminated, the
               ---------------------
Commitments shall terminate on the Revolving Termination Date.

          (b)  Voluntary Termination or Reduction.  The Borrower may at any time
               ----------------------------------
prior to the Revolving Termination Date terminate, or from time to time reduce,
the Commitments; provided that each reduction of the Commitments shall be in an
                 --------
amount of $25,000,000 or a multiple of $1,000,000 in excess thereof and (ii) the
Borrower shall not terminate or reduce the Commitments if, after giving effect
to any concurrent prepayment of the Loans in accordance with Section 2.08, the
sum of the total Revolving Credit Exposures would exceed the total Commitments.

          (c)  Notice of Voluntary Termination or Reduction.  The Borrower shall
               --------------------------------------------
notify the Administrative Agent of any election to terminate or reduce the
Commitments under paragraph (b) of this Section at least three Business Days
prior to the effective date of such termination or reduction, specifying such
election and the effective date thereof.  Promptly following receipt of any such
notice, the Administrative Agent shall advise the Lenders of the contents
thereof. Each notice delivered by the Borrower pursuant to this Section shall be
irrevocable; provided that a notice of termination of the Commitments delivered
             --------
by the Borrower may state that such notice is conditioned upon the effectiveness
of other credit facilities, in which case such notice may be revoked by the
Borrower (by notice to the Administrative Agent on or prior to the specified
effective date) if such condition is not satisfied.

          (d)  Effect of Termination or Reduction.  Any termination or reduction
               ----------------------------------
of the Commitments shall be permanent.  Each reduction of the Commitments shall
be made ratably among the Lenders in accordance with their Applicable
Percentages.

                                      -19-
<PAGE>

          (e)  Extension of Commitments.
               ------------------------

               (i)    Not earlier than the date which is 60 days (but not later
than 30 days) prior to the then existing Revolving Termination Date (the
"Extension Request Notice Date"), the Borrower may deliver to the Administrative
 -----------------------------
Agent (which shall promptly transmit the same to each Lender) a notice (an
"Extension Request") requesting that the Revolving Termination Date be extended
 -----------------
for an additional 364 days commencing on the then existing Revolving Termination
Date. Not earlier than the date which is 30 days (but not later than 20 days)
prior to the then existing Revolving Termination Date (the period from the
Extension Request Notice Date to such date, the "Extension Request Period"),
                                                 ------------------------
each Lender (in its sole and absolute discretion and after conducting an
internal credit review of the Borrower) shall notify the Administrative Agent of
such Lender's willingness or unwillingness to so extend the Revolving
Termination Date. Any Lender which shall fail to so notify the Administrative
Agent within such period shall be deemed to have declined to extend the
Revolving Termination Date. If Lenders having Commitments totaling an amount
equal to at least 51% of the aggregate amount of the Commitments then in effect
agree to such extension by notice to the Administrative Agent, then (A) subject
to clause (iii) below, the Revolving Termination Date shall be extended for an
additional 364 days with respect to the Commitments of the Lenders so agreeing,
and (B) subject to Section 2.06(f) hereof, the Commitment of each Lender not so
agreeing shall expire on the then expiring Revolving Termination Date and the
Borrower shall pay or prepay on such day without premium or penalty all
principal of such Lender's Loans together with accrued interest thereon and all
accrued facility fees and other amounts payable to such Lender hereunder
(including, without limitation, amounts payable pursuant to Section 2.13 hereof
as a result of such payment or prepayment); provided, however, that
                                            --------

               (x)    if Lenders having Commitments totaling an amount equal to
          at least 51% of the aggregate amount of the Commitments then in effect
          do not agree as contemplated by Section 2.06(e)(i), then the Revolving
          Termination Date shall not be extended pursuant to this Section
          2.06(e) and the Commitments of all of the Lenders shall remain in
          effect until the Revolving Termination Date except as otherwise
          provided in this Agreement; and

               (y)    the Borrower may not request any extension of the
          Revolving Termination Date pursuant to this Section 2.06(e)(i) more
          frequently than once in any calendar year.

               (ii)    Any Loan by any Lender the Commitment of which is to
     terminate pursuant to Section 2.06(e)(i) hereof that would otherwise be
     made or converted by such Lender as a Eurodollar Loan having an Interest
     Period ending after the date such Commitment is to terminate shall be made
     or continued as an ABR Loan and all ABR Loans of such Lender that would
     otherwise be converted into Eurodollar Loans having such Interest Periods
     shall remain as ABR Loans.

               (iii)  It shall be a condition precedent to any extension of the
     Revolving Termination Date that: (a) on the date of such extension no
     Default or Event of Default shall have occurred and be continuing; (b) the
     representations and warranties made by the

                                      -20-
<PAGE>

     Borrower in Article III shall be true and complete on and as of the date of
     such extension (or if any such representation or warranty is expressly
     stated to have been made as of a specific date, as of such specific date);
     and (c) on the date of such extension there shall have been no material
     adverse change in the consolidated financial condition, operations,
     business or prospects taken as a whole of the Borrower and its Subsidiaries
     from that set forth in its financial statements as of December 31, 2000
     referred to in Section 3.06 hereof or, if the Borrower has delivered its
     financial statements for any fiscal year to the Lenders and the
     Administrative Agent pursuant to Section 5.01(a) hereof, as of the date of
     the most recent such financial statements. Each request for an extension of
     the Revolving Termination Date pursuant to Section 2.06(e) shall constitute
     a certification by the Borrower to the effect set forth in the preceding
     sentence (both as of the date of such request and, unless the Borrower
     notifies the Administrative Agent prior to the date of such extension, as
     of the date of such extension).

          (f)  Substitute Lenders.  In the event any Lender does not agree to
               ------------------
any extension by the date provided pursuant to Section 2.06(e) hereof, then,
unless a Default or an Event of Default shall have occurred and be continuing,
the Borrower may, not later than 10 days following the expiration of the
Extension Request Period, designate one or more other banks (each such bank
being herein called a "Substitute Lender"), which may include any of the
                       -----------------
Lenders, acceptable to the Administrative Agent (which acceptance will not be
unreasonably withheld), to assume such non-consenting Lender's Commitment
hereunder and to purchase, on or before the date such Lender's Loans would
otherwise be required to be paid or prepaid hereunder, the Loans and Notes of
such Lender and such Lender's rights hereunder in respect thereof, without
recourse to or representation or warranty by, or expense to, such Lender. In
such event, the purchase price shall be equal to the outstanding principal
amount of the Loans and Notes payable to such Lender plus any accrued but unpaid
interest on such Loans and Notes and accrued but unpaid facility fees in respect
of such Lender's Commitment. Upon such assumption and purchase and the receipt
by such Lender of any other amounts payable to it by the Borrower under this
Agreement, and subject to the execution and delivery to the Administrative Agent
and such Lender by the Substitute Lender of documentation reasonably
satisfactory to the Administrative Agent and such Lender pursuant to which such
Substitute Lender shall assume the obligations of such original Lender under
this Agreement in respect of its Loans, Notes and Commitment and agree to become
a "Lender" hereunder (if not already a Lender) to the extent of the Commitments,
Loans and Notes assumed and purchased, the Substitute Lender shall succeed to
the rights, obligations and benefits of such Lender hereunder in such respect
(except for such rights, obligations and benefits of the Lender as have accrued
(other than principal, accrued interest or facility fees ) or are required to be
performed by it on or prior to the date of such assumption and purchase) (and
such Lender shall be released from its Commitment except for any liability
arising or relating to any event occurring prior to the date of such assumption
and purchase) and the Substitute Lender shall be deemed to have agreed to the
relevant extension of the Revolving Termination Date and, anything in Section
2.06(e) to the contrary notwithstanding, whether such extension is effective
shall be determined accordingly; provided that following any such assumption and
                                 --------
purchase, the Commitments of each Substitute Lender (including any Commitments
theretofore held by it) shall be not less than $10,000,000.

                                      -21-
<PAGE>

          SECTION 2.07   Repayment of Loans; Evidence of Debt.
                         ------------------------------------

          (a)  Repayment. The Borrower hereby unconditionally promises to pay to
               ---------
the Administrative Agent for account of the Lenders the outstanding principal
amount of the Revolving Loans on the Revolving Termination Date.

          (b)  Manner of Payment.  Prior to any repayment or prepayment of any
               -----------------
Borrowings hereunder, the Borrower shall select the Borrowing or Borrowings to
be paid and shall notify the Administrative Agent by telephone (confirmed by
telecopy) of such selection not later than 12:00 noon, Pittsburgh, Pennsylvania
time, three Business Days before the scheduled date of such repayment or
prepayment; provided that each repayment or prepayment of Borrowings shall be
            --------
applied to repay or prepay any outstanding ABR Borrowings before any other
Borrowings. If the Borrower fails to make a timely selection of the Borrowing or
Borrowings to be repaid or prepaid, such payment shall be applied, first, to pay
any outstanding ABR Borrowings and, second, to other Borrowings in the order of
the remaining duration of their respective Interest Periods (the Borrowing with
the shortest remaining Interest Period to be repaid first).  Each payment of a
Revolving Borrowing shall be applied ratably to the Loans included in such
Borrowing.

          (c)  Maintenance of Loan Accounts by Lenders.  Each Lender shall
               ---------------------------------------
maintain in accordance with its usual practice an account or accounts evidencing
the indebtedness of the Borrower to such Lender resulting from each Loan made by
such Lender, including the amounts of principal and interest payable and paid to
such Lender from time to time hereunder.

          (d)  Maintenance of Loan Accounts by the Administrative Agent.  The
               --------------------------------------------------------
Administrative Agent shall maintain accounts in which it shall record (i) the
amount of each Loan made hereunder and the Type thereof and the Interest Period
applicable thereto, (ii) the amount of any principal or interest due and payable
or to become due and payable from the Borrower to each Lender hereunder and
(iii) the amount of any sum received by the Administrative Agent hereunder for
the account of the Lenders and each Lender's share thereof.

          (e)  Effect of Entries.  The entries made in the accounts maintained
               ------------------
pursuant to paragraph (c) and (d) of this Section shall be prima facie evidence
of the existence and amounts of the obligations recorded therein; provided that
                                                                  --------
the failure of any Lender or the Administrative Agent to maintain such accounts
or any error therein shall not in any manner affect the obligation of the
Borrower to repay the Loans in accordance with the terms of this Agreement.

          (f)  Notes.  Any Lender may request that Loans made by it be evidenced
               -----
by a promissory note (each a "Note") in substantially the form of Exhibit C.  In
                              ----
such event, the Borrower shall prepare, execute and deliver to such Lender a
Note payable to the order of such Lender (or, if requested by such Lender, to
such Lender and its registered assigns) and in the form of Exhibit C.
Thereafter, the Loans evidenced by such Note and interest thereon shall at all
times (including after assignment pursuant to Section 9.12) be represented by
one or more Notes in such form payable to the order of the payee named therein
(or, if such Note is a registered note, to such payee and its registered
assigns).

                                      -22-
<PAGE>

          SECTION 2.08   Prepayment of Loans.
                         -------------------

          (a)  Optional Prepayments Right to Prepay Borrowings.  The Borrower
               -----------------------------------------------
shall have the right at any time and from time to time to prepay any Borrowing
in whole or in part, subject to the requirements of this Section.

          (b)  Notices, Etc.  The Borrower shall notify the Administrative Agent
               -------------
by telephone (confirmed by telecopy) of any optional prepayment hereunder (i) in
the case of prepayment of a Eurodollar Borrowing, not later than 12:00 noon,
Pittsburgh, Pennsylvania time, three Business Days before the date of
prepayment, or (ii) in the case of prepayment of an ABR Borrowing, not later
than 12:00 noon, Pittsburgh, Pennsylvania time, one Business Day before the date
of prepayment.  Each such notice shall be irrevocable and shall specify the
prepayment date and the principal amount of each Borrowing or portion thereof to
be prepaid; provided that, if a notice of prepayment is given in connection with
            --------
a conditional notice of termination of the Commitments as contemplated by
Section 2.06(c), then such notice of prepayment may be revoked if such notice of
termination is revoked in accordance with Section 2.06(c).  Promptly following
receipt of any such notice relating to a Borrowing, the Administrative Agent
shall advise the Lenders of the contents thereof.  Each partial prepayment of
any Borrowing shall be in an aggregate principal amount equal to $5,000,000 and
a multiple of $1,000,000 in excess thereof; provided that if any prepayment of
                                            --------
Eurodollar Loans made pursuant to a single Borrowing shall reduce the
outstanding Revolving Loans made pursuant to such Borrowing to an amount less
than $5,000,000, such outstanding Loans shall immediately be converted into ABR
Loans.  Each prepayment of a Borrowing shall be applied ratably to the Loans
included in the prepaid Borrowing.  Prepayments shall be accompanied by accrued
interest to the extent required by Section 2.10 and shall be made in the manner
specified in this Section 2.08(b).

          SECTION 2.09   Fees.
                         ----

          (a)  Facility Fee.  The Borrower shall pay the Administrative Agent
               ------------
for the account of each Lender a facility fee for the period from and including
the Effective Date to but excluding the Revolving Termination Date (or such
earlier date on which the total Commitments shall have been terminated) computed
at a rate per annum equal to the Applicable Rate on each Lender's daily average
Commitment, such fee to be paid quarterly in arrears on each Quarterly Date and
on the Revolving Termination Date (or such earlier date on which the total
Commitments shall have been terminated). The facility fee shall be calculated on
the basis of the actual number of days elapsed in a year of 360 days.

          (b)  Payment of Fees.  All fees payable hereunder shall be paid on the
               ---------------
dates due, in immediately available funds, to the Administrative Agent for
distribution, in the case of facility fees, to the Lenders entitled thereto.

          SECTION 2.10   Interest.
                         --------

          (a)  ABR Loans.  The Loans comprising each ABR Revolving Borrowing
               ---------
shall bear interest at a rate per annum equal to the Alternate Base Rate plus
the Applicable Rate.

                                      -23-
<PAGE>

          (b)  Eurodollar Loans.  The Loans comprising each Eurodollar Borrowing
               ----------------
shall bear interest at a rate per annum equal to the Adjusted LIBO Rate for the
Interest Period in effect for such Borrowing plus the Applicable Rate.

          (c)  Default Interest.  Notwithstanding the foregoing, if any
               ----------------
principal of or interest on any Loan or any fee or other amount payable by the
Borrower hereunder is not paid when due, whether at stated maturity, upon
acceleration or otherwise, such overdue amount shall bear interest, after as
well as before judgment, at a rate per annum equal to (i) in the case of overdue
principal of any Loan, 2% plus the rate otherwise applicable to such Loan as
provided above or (ii) in the case of any other amount, 2% plus the rate
applicable to ABR Loans as provided in paragraph (a) of this Section.

          (d)  Payment of Interest.  Accrued interest on each Loan shall be
               -------------------
payable in arrears on each Interest Payment Date for such Loan and upon
termination of the Commitments; provided that (x) interest accrued pursuant to
                                --------
paragraph (c) of this Section shall be payable on demand, (y) in the event of
any repayment or prepayment of any Loan (other than a prepayment of an ABR
Revolving Loan prior to the Revolving Termination Date), accrued interest on the
principal amount repaid or prepaid shall be payable on the date of such
repayment or prepayment and (z) in the event of any conversion of any Eurodollar
Borrowing prior to the end of the current Interest Period therefor, accrued
interest on such Borrowing shall be payable on the effective date of such
conversion.

          (e)  Computation.  All interest hereunder shall be computed on the
               -----------
basis of a year of 360 days, except that interest computed by reference to the
Alternate Base Rate at times when the Alternate Base Rate is based on the Prime
Rate shall be computed on the basis of a year of 365 days (or 366 days in a leap
year), and in each case shall be payable for the actual number of days elapsed
(including the first day but excluding the last day).  The applicable Alternate
Base Rate, Adjusted LIBO Rate or LIBO Rate shall be determined by the
Administrative Agent, and such determination shall be conclusive, absent
manifest error.

          SECTION 2.11   Alternate Rate of Interest.  If prior to the
                         --------------------------
commencement of any Interest Period for a Eurodollar Borrowing:

          (a)  the Administrative Agent determines (which determination shall be
conclusive, absent manifest error) that adequate and reasonable means do not
exist for ascertaining the Adjusted LIBO Rate or the LIBO Rate, as applicable,
for such Interest Period; or

          (b)  the Administrative Agent is advised by the Required Lenders that
the Adjusted LIBO Rate or the LIBO Rate, as applicable, for such Interest Period
will not adequately and fairly reflect the cost to such Lenders (or Lender) of
making or maintaining their Loans (or its Loan) included in such Borrowing for
such Interest Period;

then the Administrative Agent shall give notice thereof to the Borrower and the
Lenders by telephone or telecopy as promptly as practicable thereafter and,
until the Administrative Agent notifies the Borrower and the Lenders that the
circumstances giving rise to such notice no longer exist, (i) any Interest
Election Request that requests the conversion of any Borrowing to, or

                                      -24-
<PAGE>

continuation of any Borrowing as, a Eurodollar Borrowing shall be ineffective,
and (ii) if any Borrowing Request requests a Eurodollar Revolving Borrowing,
such Borrowing shall be made as an ABR Revolving Borrowing.

          SECTION 2.12   Increased Costs.
                         ---------------

          (a)  Increased Costs Generally.  If any Change in Law shall:
               -------------------------

               (i)    impose, modify or deem applicable any reserve, special
     deposit or similar requirement against assets of, deposits with or for the
     account of, or credit extended by, any Lender or its Parent (except any
     such reserve requirement reflected in the Adjusted LIBO Rate); or

               (ii)   impose on any Lender or its Parent or the London interbank
     market any other condition affecting this Agreement or Eurodollar Loans
     made by such Lender;

and the result of any of the foregoing shall be to increase the cost to such
Lender or its Parent of making or maintaining any Eurodollar Loan (or of
maintaining its obligation to make any such Loan) or to reduce the amount of any
sum received or receivable by such Lender hereunder (whether of principal,
interest or otherwise), then the Borrower will pay to such Lender such
additional amount or amounts as will compensate such Lender or its Parent, as
the case may be, for such additional costs incurred or reduction suffered.

          (b)  Capital Requirements.  If any Lender determines that any Change
               --------------------
in Law regarding capital requirements has or would have the effect of reducing
the rate of return on such Lender's capital or on the capital of its Parent as a
consequence of this Agreement or the Loans made by such Lender to a level below
that which such Lender or its Parent could have achieved but for such Change in
Law (taking into consideration such Lender's policies and the policies of its
Parent with respect to capital adequacy), then from time to time the Borrower
will pay to such Lender such additional amount or amounts as will compensate
such Lender or its Parent for any such reduction suffered.

          (c)  Certificates from Lenders.  A certificate of a Lender setting
               -------------------------
forth the amount or amounts necessary to compensate such Lender or its Parent,
as the case may be, as specified in paragraph (a) or (b) of this Section shall
be delivered to the Borrower and shall be conclusive, absent manifest error.
The Borrower shall pay such Lender the amount shown as due on any such
certificate within 10 days after receipt thereof.

          (d)  Delay in Requests.  Failure or delay on the part of any Lender to
               -----------------
demand compensation pursuant to this Section shall not constitute a waiver of
such Lender's right to demand such compensation.

          SECTION 2.13   Break Funding Payments.
                         ----------------------

          In the event of (a) the payment of any principal of any Eurodollar
Loan other than on the last day of an Interest Period applicable thereto
(including as a result of an Event of Default), (b) the conversion of Eurodollar
Loan other than on the last day of the Interest Period

                                      -25-
<PAGE>

applicable thereto, (c) the failure to borrow, convert, continue or prepay any
Revolving Loan on the date specified in any notice delivered pursuant hereto
(regardless of whether such notice is permitted to be revocable under Section
2.08(b) and is revoked in accordance herewith), or (d) the assignment of any
Eurodollar Loan other than on the last day of the Interest Period applicable
thereto as a result of a request by the Borrower pursuant to Section 2.16, then,
in any such event, the Borrower shall compensate each Lender for the loss, cost
and expense attributable to such event. In the case of a Eurodollar Loan, the
loss to any Lender attributable to any such event shall be deemed to include an
amount determined by such Lender to be equal to the excess, if any, of (i) the
amount of interest that such Lender would pay for a deposit equal to the
principal amount of such Loan for the period from the date of such payment,
conversion, failure or assignment to the last day of the then current Interest
Period for such Loan (or, in the case of a failure to borrow, convert or
continue, the duration of the Interest Period that would have resulted from such
borrowing, conversion or continuation) if the interest rate payable on such
deposit were equal to the Adjusted LIBO Rate for such Interest Period, over (ii)
the amount of interest that such Lender would earn on such principal amount for
such period if such Lender were to invest such principal amount for such period
at the interest rate that would be bid by such Lender (or an Affiliate of such
Lender) for dollar deposits from other banks in the eurodollar market at the
commencement of such period. A certificate of any Lender setting forth any
amount or amounts that such Lender is entitled to receive pursuant to this
Section shall be delivered to the Borrower and shall be conclusive, absent
manifest error. The Borrower shall pay such Lender the amount shown as due on
any such certificate within 10 days after receipt thereof.

          SECTION 2.14   Taxes.
                         -----

          (a)  Payments Free of Taxes.  Any and all payments by or on account of
               ----------------------
any obligation of the Borrower hereunder shall be made free and clear of and
without deduction for any Indemnified Taxes or Other Taxes; provided that if the
                                                            --------
Borrower shall be required to deduct any Indemnified Taxes or Other Taxes from
such payments, then (i) the sum payable shall be increased as necessary so that
after making all required deductions (including deductions applicable to
additional sums payable under this Section) the Administrative Agent, Arranger,
Syndication Agent or Lender (as the case may be) receives an amount equal to the
sum it would have received had no such deductions been made, (ii) the Borrower
shall make such deductions and (iii) the Borrower shall pay the full amount
deducted to the relevant Governmental Authority in accordance with applicable
Law.

          (b)  Payment of Other Taxes by the Borrower.  In addition, the
               --------------------------------------
Borrower shall pay any Other Taxes to the relevant Governmental Authority in
accordance with applicable Law.

          (c)  Indemnification by the Borrower.  The Borrower shall indemnify
               -------------------------------
the Administrative Agent, the Arranger, each Syndication Agent and each Lender,
within 10 days after written demand therefor, for the full amount of any
Indemnified Taxes or Other Taxes (including Indemnified Taxes or Other Taxes
imposed or asserted on or attributable to amounts payable under this Section)
paid by the Administrative Agent, Arranger, such Syndication Agent or such
Lender, as the case may be, and any penalties, interest and reasonable expenses
arising therefrom or with respect thereto, whether or not such Indemnified Taxes
or Other Taxes were correctly or legally imposed or asserted by the relevant
Governmental Authority. A certificate as

                                      -26-
<PAGE>

to the amount of such payment or liability delivered to the Borrower by a
Lender, the Arranger, a Syndication Agent or by the Administrative Agent (on its
own behalf or on behalf of a Lender, the Arranger or a Syndication Agent) shall
be conclusive, absent manifest error.

          (d)  Evidence of Payments.  As soon as practicable after any payment
               ---------------------
of Indemnified Taxes or Other Taxes by the Borrower to a Governmental Authority,
the Borrower shall deliver to the Administrative Agent the original or a
certified copy of a receipt issued by such Governmental Authority evidencing
such payment, a copy of the return reporting such payment or other evidence of
such payment reasonably satisfactory to the Administrative Agent.

          (e)  Foreign Lenders. Any Foreign Lender that is entitled to an
               ----------------
exemption from or reduction of withholding tax under the Law of the jurisdiction
in which the Borrower is located, or any treaty to which such jurisdiction is a
party, with respect to payments under this Agreement shall deliver to the
Borrower (with a copy to the Administrative Agent), at the time or times
prescribed by applicable Law or reasonably requested by the Borrower, such
properly completed and executed documentation prescribed by applicable Law as
will permit such payments to be made without withholding or at a reduced rate.

          SECTION 2.15   Payments Generally; Pro Rata Treatment; Sharing of Set-
                         ------------------------------------------------------
offs.
----

          (a)  Payments by the Borrower.  The Borrower shall make each payment
               ------------------------
required to be made by it hereunder (whether of principal, interest or fees, or
under Section 2.12, 2.13 or 2.14, or otherwise) prior to 1:00 PM, Pittsburgh,
Pennsylvania time, on the date when due, in immediately available funds, without
set-off or counterclaim.  Any amounts received after such time on any such date
shall be deemed to have been received on the next succeeding Business Day for
purposes of calculating interest thereon. All such payments shall be made to the
Administrative Agent at its Principal Office and to such account at its
Principal Office as the Administrative Agent shall specify to the Borrower,
except that payments pursuant to Sections 2.12, 2.13, 2.14 and 9.04 shall be
made directly to the Persons entitled thereto. The Administrative Agent shall
distribute any such payments received by it for account of any other Person to
the appropriate recipient promptly following receipt thereof.  If any payment
hereunder shall be due on a day that is not a Business Day, the date for payment
shall be extended to the next succeeding Business Day and, in the case of any
payment accruing interest, interest thereon shall be payable for the period of
such extension. All payments hereunder shall be made in Dollars.

          (b)  Application of Insufficient Payments.  If at any time
               ------------------------------------
insufficient funds are received by and available to the Administrative Agent to
pay fully all amounts of principal, interest and fees then due hereunder, such
funds shall be applied (i) first, to pay interest and fees then due hereunder,
ratably among the parties entitled thereto in accordance with the amounts of
interest and fees then due to such parties, and (ii) second, to pay principal
then due hereunder, ratably among the parties entitled thereto in accordance
with the amounts of principal then due to such parties.

          (c)  Pro Rata Treatment.  Except to the extent otherwise provided
               ------------------
herein:  (i) each Revolving Borrowing shall be made from the Lenders, each
payment of facility fees under

                                      -27-
<PAGE>

Section 2.09 shall be made for account of the Lenders, and each termination or
reduction of the amount of the Commitments under Section 2.06 shall be applied
to the respective Commitments of the Lenders, pro rata according to the amounts
of their respective Commitments; (ii) each Borrowing shall be allocated pro rata
among the Lenders according to the amounts of their respective Commitments (in
the case of the making of Revolving Loans) or their respective Loans (in the
case of conversions and continuations of Loans); (iii) each payment or
prepayment of principal of Loans by the Borrower shall be made for account of
the Lenders pro rata in accordance with the respective unpaid principal amounts
of the Loans held by them; and (iv) each payment of interest on Loans by the
Borrower shall be made for account of the Lenders pro rata in accordance with
the amounts of interest on such Loans then due and payable to the respective
Lenders.

          (d)  Sharing of Payments by Lenders.  If any Lender shall, by
               ------------------------------
exercising any right of set-off or counterclaim or otherwise, obtain payment in
respect of any principal of or interest on any of its Loans resulting in such
Lender receiving payment of a greater proportion of the aggregate amount of its
Loans and accrued interest thereon then due than the proportion received by any
other Lender, then the Lender receiving such greater proportion shall purchase
(for cash at face value) participations in the Loans of other Lenders to the
extent necessary so that the benefit of all such payments shall be shared by the
Lenders ratably in accordance with the aggregate amount of principal of and
accrued interest on their respective Loans; provided that (i) if any such
                                            --------
participations are purchased and all or any portion of the payment giving rise
thereto is recovered, such participations shall be rescinded and the purchase
price restored to the extent of such recovery, without interest, and (ii) the
provisions of this paragraph shall not be construed to apply to any payment made
by the Borrower pursuant to and in accordance with the express terms of this
Agreement or any payment obtained by a Lender as consideration for the
assignment of or sale of a participation in any of its Loans to any assignee or
participant, other than to the Borrower or any Subsidiary or Affiliate thereof
(as to which the provisions of this paragraph shall apply).  The Borrower
consents to the foregoing and agrees, to the extent it may effectively do so
under applicable Law, that any Lender acquiring a participation pursuant to the
foregoing arrangements may exercise against the Borrower rights of set-off and
counterclaim with respect to such participation as fully as if such Lender were
a direct creditor of the Borrower in the amount of such participation.

          (e)  Presumptions of Payment.  Unless the Administrative Agent shall
               -----------------------
have received notice from the Borrower prior to the date on which any payment is
due to the Administrative Agent for account of the Lenders hereunder that the
Borrower will not make such payment, the Administrative Agent may assume that
the Borrower has made such payment on such date in accordance herewith and may,
in reliance upon such assumption, distribute to the Lenders the amount due.  In
such event, if the Borrower has not in fact made such payment, then each of the
Lenders severally agrees to repay to the Administrative Agent forthwith on
demand the amount so distributed to such Lender with interest thereon, for each
day from and including the date such amount is distributed to it to but
excluding the date of payment to the Administrative Agent, at the Federal Funds
Effective Rate.

          (f)  Certain Deductions by the Administrative Agent.  If any Lender
               ----------------------------------------------
shall fail to make any payment required to be made by it pursuant to Section
2.04(b) or 2.15(e), then the

                                      -28-
<PAGE>

Administrative Agent may, in its discretion (notwithstanding any contrary
provision hereof), apply any amounts thereafter received by the Administrative
Agent for account of such Lender to satisfy such Lender's obligations under such
Sections until all such unsatisfied obligations are fully paid.

          SECTION 2.16   Mitigation Obligations; Replacement of Lenders.
                         ----------------------------------------------

          (a)  Designation of a Different Lending Office.  If any Lender
               -----------------------------------------
requests compensation under Section 2.12, or if the Borrower is required to pay
any additional amount to any Lender or any Governmental Authority for account of
any Lender pursuant to Section 2.14, then such Lender shall use reasonable
efforts to designate a different lending office for funding or booking its Loans
hereunder or to assign its rights and obligations hereunder to another of its
offices, branches or affiliates, if, in the judgment of such Lender, such
designation or assignment (i) would eliminate or reduce amounts payable pursuant
to Section 2.12 or 2.14, as the case may be, in the future and (ii) would not
subject such Lender to any unreimbursed cost or expense and would not otherwise
be disadvantageous to such Lender. The Borrower hereby agrees to pay all
reasonable costs and expenses incurred by any Lender in connection with any such
designation or assignment.

          (b)  Replacement of Lenders.  If any Lender requests compensation
               ----------------------
under Section 2.12, or if the Borrower is required to pay any additional amount
to any Lender or any Governmental Authority for account of any Lender pursuant
to Section 2.14, or if any Lender defaults in its obligation to fund Loans
hereunder, then the Borrower may, at its sole expense and effort, upon notice to
such Lender and the Administrative Agent, require such Lender to assign and
delegate, without recourse (in accordance with and subject to the restrictions
contained in Section 9.12), all its interests, rights and obligations under this
Agreement to an assignee that shall assume such obligations (which assignee may
be another Lender, if a Lender accepts such assignment); provided that (i) the
                                                         --------
Borrower shall have received the prior consent of the Administrative Agent,
which consent shall not unreasonably be withheld, (ii) such Lender shall have
received payment of an amount equal to the outstanding principal of its Loans,
accrued interest thereon, accrued fees and all other amounts payable to it
hereunder, from the assignee (to the extent of such outstanding principal and
accrued interest and fees) or the Borrower (in the case of all other amounts)
and (iii) in the case of any such assignment resulting from a claim for
compensation under Section 2.12 or payments required to be made pursuant to
Section 2.14, such assignment will result in a reduction in such compensation or
payments. A Lender shall not be required to make any such assignment and
delegation if, prior thereto, as a result of a waiver by such Lender or
otherwise, the circumstances entitling the Borrower to require such assignment
and delegation cease to apply.

                                  ARTICLE III
                        REPRESENTATIONS AND WARRANTIES

          The Borrower hereby represents and warrants to the Administrative
Agent and each Lender as follows:

                                      -29-
<PAGE>

          SECTION 3.01   Corporate Status.
                         ----------------

          The Borrower and each Subsidiary of the Borrower is a corporation,
trust or limited liability company duly organized, validly existing and in good
standing under the Laws of its jurisdiction of organization.  The Borrower and
each Subsidiary of the Borrower has the corporate power and authority to own its
Property and to transact the business in which it is engaged or presently
proposes to engage.  The Borrower and each Subsidiary of the Borrower is duly
qualified to do business as a foreign corporation, trust or limited liability
company and is in good standing in all jurisdictions in which the ownership of
its properties or the nature of its activities or both makes such qualification
necessary or advisable.  Schedule II states as of the date hereof the
jurisdiction of organization of the Borrower and each Subsidiary of the
Borrower, and the jurisdictions in which the Borrower and each Subsidiary of the
Borrower is qualified to do business as a foreign corporation, trust or limited
liability company.

          SECTION 3.02   Corporate Power and Authorization.
                         ---------------------------------

          The Borrower has the corporate power and authority to execute,
deliver, perform, and take all actions contemplated by, each of the Loan
Documents to which it is a party, and all such action has been duly and validly
authorized by all necessary corporate proceedings on its part.  Without limiting
the foregoing, the Borrower has the corporate power and authority to borrow
pursuant to the Loan Documents to the fullest extent permitted hereby and
thereby from time to time, and has taken all necessary corporate action to
authorize such borrowings.

          SECTION 3.03   Execution and Binding Effect.
                         ----------------------------

          This Agreement and each of the other Loan Documents to which the
Borrower is a party and which is required to be delivered on or before the
Effective Date pursuant to Section 4.01 has been duly and validly executed and
delivered by the Borrower.  This Agreement and each such other Loan Document
constitutes, and when executed and delivered by the Borrower will constitute,
the legal, valid and binding obligation of the Borrower, enforceable against the
Borrower in accordance with its terms, except as the enforceability hereof or
thereof may be limited by bankruptcy, insolvency or other similar laws of
general application affecting the enforcement of creditors' rights or by general
principles of equity limiting the availability of equitable remedies.

          SECTION 3.04   Governmental Approvals and Filings.
                         ----------------------------------

          The Public Utilities Commission of Nevada and the California Public
Utilities Commission have each duly and validly issued orders authorizing the
Borrower to enter into this Agreement and the other Loan Documents to which it
is a party and to take all actions contemplated hereby or thereby or in
connection herewith or therewith, and such orders remain in full force and
effect in the form issued.  No other Governmental Action is required for the due
execution, delivery and performance by the Borrower of this Agreement or any of
the other Loan Documents to which it is a party.

                                      -30-
<PAGE>

          SECTION 3.05   Absence of Conflicts.
                         --------------------

          Neither the execution and delivery of any of the Loan Documents by the
Borrower, nor the consummation of the transactions herein or therein
contemplated by the Borrower, nor the performance of or the compliance with the
terms and conditions hereof or thereof by the Borrower, does or will:

          (a)  violate or conflict with any Law; or

          (b)  violate, conflict with or result in a breach of any term or
condition of, or constitute a default under, or result in (or give rise to any
              --                             --
right, contingent or otherwise, of any Person to cause) any termination,
cancellation, prepayment or acceleration of performance of, or result in the
                                                            --
creation or imposition of (or give rise to any obligation, contingent or
otherwise, to create or impose) any Lien upon any of the Property of the
Borrower or any Subsidiary of the Borrower pursuant to, or otherwise result in
                                                        --
(or give rise to any right, contingent or otherwise, of any Person to cause) any
change in any right, power, privilege, duty or obligation of the Borrower or any
Subsidiary of the Borrower under or in connection with,

               (i)    the articles of incorporation or by-laws (or other
     constituent documents) of the Borrower or any Subsidiary of the Borrower;

               (ii)   any agreement or instrument creating, evidencing or
     securing any Indebtedness to which the Borrower or any Subsidiary of the
     Borrower is a party or by which any of them or any of their respective
     properties (now owned or hereafter acquired) may be subject or bound; or

               (iii)  any other material agreement or instrument to which the
     Borrower or any Subsidiary of the Borrower is a party or by which any of
     them or any of their respective properties (now owned or hereafter
     acquired) may be subject or bound.

          SECTION 3.06   Audited Financial Statements.
                         ----------------------------

          The Borrower has heretofore furnished to each of the Agents and each
of the Lenders consolidated balance sheets of the Borrower and its consolidated
Subsidiaries as of December 31, 1998, 1999 and 2000 and the related consolidated
statements of income, retained earnings and changes in cash flows for the fiscal
years then ended, as examined and reported on by independent certified public
accountants for the Borrower, who delivered an unqualified opinion in respect
thereof.  Such financial statements (including the notes thereto) present fairly
the financial condition of the Borrower and its consolidated Subsidiaries as of
the end of each such fiscal year and the results of their operations and their
retained earnings and changes in cash flows for the fiscal years then ended, all
in conformity with GAAP.

          SECTION 3.07   Interim Financial Statements.
                         ----------------------------

          The Borrower has heretofore furnished to each of the Agents and each
of the Lenders an interim consolidated balance sheet of the Borrower and its
consolidated Subsidiaries as of the end of the first fiscal quarter of the
fiscal year beginning January 1, 2001, together with

                                      -31-
<PAGE>

the related consolidated statements of income, retained earnings and changes in
cash flows for the applicable fiscal period ending on such date. Such financial
statements (including the notes thereto) present fairly the financial condition
of the Borrower and its consolidated Subsidiaries as of the end of such fiscal
quarter and the results of their operations and their retained earnings and
changes in cash flows for the fiscal periods then ended, all in conformity with
GAAP, subject to normal and recurring year-end audit adjustments.

          SECTION 3.08   Absence of Undisclosed Liabilities.
                         ----------------------------------

          Neither the Borrower nor any Subsidiary of the Borrower has any
liability or obligation of any nature whatever (whether absolute, accrued,
contingent or otherwise, whether or not due), forward or long-term commitments
or unrealized or anticipated losses from unfavorable commitments, except (a) as
disclosed in the financial statements referred to in Sections 3.06 and 3.07, and
(b) liabilities, obligations, commitments and losses incurred after March 31,
2001, in the ordinary course of business and consistent with past practices.

          SECTION 3.09   Absence of Material Adverse Change  .
                         ------------------------------------

          Since March 31, 2001, there has been no material adverse change in the
business, operations, condition (financial or otherwise), or prospects of the
Borrower and its Subsidiaries taken as a whole.

          SECTION 3.10   Accurate and Complete Disclosure.
                         --------------------------------

          All information heretofore, contemporaneously or hereafter provided by
or on behalf of the Borrower to any Agent or any Lender pursuant to or in
connection with any Loan Document or any transaction contemplated hereby or
thereby is or will be (as the case may be) true and accurate in all material
respects on the date as of which such information is dated (or, if not dated,
when received by such Agent or such Lender) and does not or will not (as the
case may be) omit to state any material fact necessary to make such information
not misleading at such time in light of the circumstances in which it was
provided.  The Borrower has disclosed to each Agent and each Lender in writing
every fact or circumstance which has, or which so far as the Borrower can
reasonably foresee is reasonably likely and is reasonably likely to have, a
Material Adverse Effect.

          SECTION 3.11   Margin Regulations.
                         ------------------

          No part of the proceeds of any Loan hereunder will be used for the
purpose of buying or carrying any "margin stock", as such term is used in
Regulation U of the Board of Governors of the Federal Reserve System, as amended
from time to time, or to extend credit to others for the purpose of buying or
carrying any "margin stock".  Neither the Borrower nor any Subsidiary of the
Borrower is engaged in the business of extending credit to others for the
purpose of buying or carrying "margin stock".  Neither the Borrower nor any
Subsidiary of the Borrower owns any "margin stock".  Neither the making of any
Loan nor any use of proceeds of any such Loan will violate or conflict with the
provisions of Regulation T, U or X of the Board, as amended from time to time.

                                      -32-
<PAGE>

          SECTION 3.12   Litigation.
                         ----------

          There is no pending or (to the Borrower's knowledge after due inquiry)
threatened action, suit, proceeding or investigation (including any
Environmental Claim) by or before any Governmental Authority against or
affecting the Borrower or any Subsidiary of the Borrower which, if adversely
decided, individually or in the aggregate, would reasonably be expected to have
a Material Adverse Effect, except for (a) matters described in the financial
statements referred to in Section 3.06 and (b) matters set forth in Schedule
III.

          SECTION 3.13   Absence of Events of Default.
                         ----------------------------

          No event has occurred and is continuing and no condition exists which
constitutes a Default or an Event of Default.

          SECTION 3.14   Absence of Other Conflicts.
                         --------------------------

          Neither the Borrower nor any Subsidiary of the Borrower is in
violation of or conflict with, or is subject to any contingent liability on
account of any violation of or conflict with:

          (a)  any Law (including ERISA, the Code, any applicable occupational
     health, safety or welfare Law or any applicable Environmental Law);

          (b)  its articles of incorporation or by-laws (or other constituent
     documents); or

          (c)  any agreement or instrument to which it is party or by which it
     or any of its properties (now owned or hereafter acquired) may be subject
     or bound;

except for matters which, individually or in the aggregate, would not reasonably
be expected to have a Material Adverse Effect.

          SECTION 3.15   Insurance.
                         ---------

          The Borrower and each Subsidiary of the Borrower maintains with
financially sound and reputable insurers insurance with respect to its
properties and business and against at least such liabilities, casualties and
contingencies and in at least such types and amounts as is customary in the case
of corporations engaged in the same or a similar business or having similar
properties similarly situated.

          SECTION 3.16   Title to Property; No Liens.
                         ---------------------------

          The Borrower and each Subsidiary of the Borrower has good and
marketable title in fee simple to all real Property owned or purported to be
owned by it and good title to all other Property of whatever nature owned or
purported to be owned by it, including but not limited to all Property reflected
in the most recent audited balance sheet referred to in Section 3.06 or
submitted pursuant to Section 5.01(b), as the case may be (except as sold or
otherwise disposed of in the ordinary course of business after the date of such
balance sheet), subject to no Liens except for (i)

                                      -33-
<PAGE>

Liens reflected in the most recent audited balance sheet referred to in Section
3.06 or submitted pursuant to Section 5.01(b), as the case may be, (ii) Liens
consisting of zoning or planning restrictions, easements, permits and other
restrictions or limitations on the use of real Property or irregularities in
title thereto which do not materially detract from the value of, or impair the
use of, such Property by the Borrower or any Subsidiary of the Borrower in the
operation of its business, (iii) Liens for current Taxes not yet due and
delinquent and (iv) Liens set forth on Schedule IV.

          SECTION 3.17   Taxes.
                         -----

          All tax and information returns required to be filed by or on behalf
of the Borrower or any Subsidiary of the Borrower have been properly prepared,
executed and filed.  All Taxes upon the Borrower or any Subsidiary of the
Borrower or upon any of their respective Properties, incomes, sales or
franchises which are due and payable have been paid, other than those not yet
delinquent and payable without premium or penalty, and except for those being
diligently contested in good faith by appropriate proceedings, and in each case
adequate reserves and provisions for Taxes have been made on the books of the
Borrower and each Subsidiary of the Borrower.  The reserves and provisions for
Taxes on the books of the Borrower and each Subsidiary of the Borrower are
adequate for all open years and for its current fiscal period.  Neither the
Borrower nor any Subsidiary of the Borrower knows of any proposed additional
assessment or basis for any material assessment for additional Taxes (whether or
not reserved against).

          SECTION 3.18   Borrower Not An Investment Company.
                         ----------------------------------

          Neither the Borrower nor any Subsidiary of the Borrower is an
"investment company" or a company controlled by an "investment company" within
the meaning of the Investment Company Act of 1940.

          SECTION 3.19   Environmental Matters.
                         ---------------------

          (a)  The Borrower and each of its Subsidiaries have complied with and
are in compliance with, all applicable Environmental Laws and the requirements
of any permits issued under such Environmental Laws.  Except as disclosed on
Schedule V, there are no pending or threatened Environmental Claims against the
Borrower or any of its Subsidiaries (including any such claim arising out of the
ownership, lease or operation by the Borrower or any of its Subsidiaries of any
real Property no longer owned, leased or operated by the Borrower or any of its
Subsidiaries) or any real Property owned, leased or operated by the Borrower or
any of its Subsidiaries.  Except as disclosed on Schedule V, there are no facts,
circumstances, conditions or occurrences with respect to the business or
operations of the Borrower or any of its Subsidiaries, or any real Property
owned, leased or operated by the Borrower or any of its Subsidiaries (including
any real Property formerly owned, leased or operated by the Borrower or any of
its Subsidiaries but no longer owned, leased or operated by the Borrower or any
of its Subsidiaries) or any Property adjoining or adjacent to any such real
Property that could be expected (i) to form the basis of an Environmental Claim
against the Borrower or any of its Subsidiaries or any real Property owned,
leased or operated by the Borrower or any of its Subsidiaries or (ii) to cause
any real Property owned, leased or operated by the Borrower or any of its
Subsidiaries to be subject to any

                                      -34-
<PAGE>

restrictions on the ownership, occupancy or transferability of such real
Property by the Borrower or any of its Subsidiaries under any applicable
Environmental Law.

          (b)  Hazardous Materials have not at any time been generated, used,
treated or stored on, or transported to or from, any real Property owned, leased
or operated by the Borrower or any of its Subsidiaries where such generation,
use, treatment or storage has violated or could be expected to violate any
Environmental Law.  Hazardous Materials have not at any time been Released on or
from any real Property owned, leased or operated by Borrower or any of its
Subsidiaries where such Release has violated or would be expected to violate any
applicable Environmental Law.

          (c)  Notwithstanding anything to the contrary in this Section, the
representations made in this Section shall not be untrue unless the effect of
all violations, claims, restrictions, failures and noncompliances of the types
described in this Section would reasonably be expected to, individually or in
the aggregate, have a Material Adverse Effect on the Borrower.

          SECTION 3.20   ERISA.
                         -----

          (a)  Each Plan (and each related trust, insurance contract or fund) is
in substantial compliance with its terms and with all applicable Laws, including
without limitation ERISA and the Code; each Plan (and each related trust, if
any) which is intended to be qualified under Section 401(a) of the Code has
received a determination letter from the Internal Revenue Service to the effect
that it meets the requirements of Sections 401(a) and 501(a) of the Code; no
Reportable Event has occurred; no Multiemployer Plan is insolvent or in
reorganization; no Plan has an Unfunded Current Liability; no Plan which is
subject to Section 412 of the Code or Section 302 of ERISA has an accumulated
funding deficiency within the meaning of such sections of the Code or ERISA or
has applied for or received a waiver of an accumulated funding deficiency or an
extension of any amortization period within the meaning of Section 412 of the
Code or Section 303 or 304 of ERISA; all contributions required to be made with
respect to a Plan have been timely made; neither the Borrower nor any Subsidiary
of the Borrower nor any ERISA Affiliate has incurred any material liability
(including any indirect, contingent or secondary liability) to or on account of
a Plan pursuant to Section 409, 502(i), 502(l), 515, 4062, 4063, 4064, 4069,
4201, 4204 or 4212 of ERISA or Section 401(a)(29), 4971 or 4975 of the Code or
expects to incur any such liability under any of the foregoing sections with
respect to any Plan; no condition exists which presents a material risk to the
Borrower or any Subsidiary of the Borrower or any ERISA Affiliate of incurring a
liability to or on account of a Plan pursuant to the foregoing provisions of
ERISA and the Code; no proceedings have been instituted to terminate or appoint
a trustee to administer any Plan; no action, suit, proceeding, hearing, audit or
investigation with respect to the administration, operation or the investment of
assets of any Plan (other than routine claims for benefits) is pending, expected
or threatened; using actuarial assumptions and computation methods consistent
with Part 1 of subtitle E of Title IV of ERISA, the aggregate liabilities of the
Borrower and its Subsidiaries and its ERISA Affiliates to all Multiemployer
Plans in the event of a complete withdrawal therefrom, as of the close of the
most recent fiscal year of each such Plan ended prior to the date of the most
recent Borrowing, would not have a Material Adverse Effect; each group health
plan (as defined in Section 607(1) of ERISA or Section 4980B(g)(2) of the Code)
which covers or has covered employees or former employees of the Borrower, any
Subsidiary of the

                                      -35-
<PAGE>

Borrower, or any ERISA Affiliate has at all times been operated in compliance
with the provisions of Part 6 of subtitle B of Title I of ERISA and Section
4980B of the Code; no Lien imposed under the Code or ERISA on the assets of the
Borrower or any Subsidiary of the Borrower or any ERISA Affiliate exists or is
likely to arise on account of any Plan; and the Borrower and its Subsidiaries
may cease contributions to or terminate any Plan maintained by any of them
without incurring any material liability.

          (b)  Each Foreign Pension Plan, if any, has been maintained in
substantial compliance with its terms and with the requirements of any and all
applicable Laws, statutes, rules, regulations and orders and has been
maintained, where required, in good standing with applicable regulatory
authorities.  All contributions required to be made with respect to a Foreign
Pension Plan have been timely made.  Neither the Borrower nor any of its
Subsidiaries has incurred any obligation in connection with the termination of
or withdrawal from any Foreign Pension Plan.  The present value of the accrued
benefit liabilities (whether or not vested) under each Foreign Pension Plan,
determined as of the end of the Borrower's most recently ended Fiscal Year on
the basis of actuarial assumptions, each of which is reasonable, did not exceed
the current value of the assets of such Foreign Pension Plan allocable to such
benefit liabilities.

          SECTION 3.21   Pari Passu Status.
                         -----------------

          The claims and rights of the Lenders against the Borrower hereunder
are not subordinated to, and rank at least pari passu with, the claims and
rights of other holders of its unsecured indebtedness except to the extent
otherwise provided by Law (including without limitation the Bankruptcy Code and
the provisions of 31 U.S.C. (S)3713).

          SECTION 3.22   Indebtedness.
                         ------------

          Schedule VI contains a true and complete list of all Indebtedness of
the Borrower and its Subsidiaries that is, or will be, outstanding on the
Effective Date ("Existing Indebtedness").
                 ---------------------

                                  ARTICLE IV
                                  CONDITIONS

          SECTION 4.01   Effective Date.
                         --------------

          This Agreement and the other Loan Documents shall become effective as
against the Lenders and the Agents on the first date on which all of the
following conditions shall be satisfied or waived:

          (a)  Agreement; Notes.  The Administrative Agent shall have received
               ----------------
     an executed counterpart of this Agreement for each Lender, duly executed by
     the Borrower, and, to the extent any Lender has requested a Note pursuant
     to Section 2.07(f), a Note conforming to the requirements hereof, duly
     executed on behalf of the Borrower.

          (b)  Governmental Approvals and Filings.  The Administrative Agent
               ----------------------------------
     shall have received, with copies and executed counterparts for each Lender,
     true and correct copies (in

                                      -36-
<PAGE>

     each case certified as to authenticity on such date on behalf of the
     Borrower) of the orders entered by the Public Utilities Commission of
     Nevada and the California Public Utilities Commission as referred to in
     Section 3.04, and such orders shall be satisfactory in form and substance
     to the Administrative Agent and shall be in full force and effect.

          (c)  Corporate Proceedings.  The Administrative Agent shall have
               ---------------------
     received, with a counterpart for each Lender, certificates by the Secretary
     or Assistant Secretary of the Borrower dated as of the Effective Date as to
     (i) true copies of the articles of incorporation and by-laws (or other
     constituent documents) of the Borrower as in effect on such date (which, in
     the case of articles of incorporation or other constituent documents filed
     or required to be filed with the Secretary of State or other Governmental
     Authority in its jurisdiction of incorporation, shall be certified to be
     true, correct and complete by such Secretary of State or other Governmental
     Authority not more than 30 days before the date hereof), (ii) true copies
     of all corporate action taken by the Borrower relative to this Agreement
     and the other Loan Documents, and (iii) the incumbency and signatures of
     the respective officers of the Borrower executing this Agreement and the
     other Loan Documents to which the Borrower is a party, together with
     satisfactory evidence of the incumbency of such Secretary or Assistant
     Secretary.  The Administrative Agent shall have received, with a copy for
     each Lender, certificates from the Secretary of State of Nevada (or other
     applicable Governmental Authority) dated not more than 30 days before the
     Effective Date showing the good standing of the Borrower in Nevada and in
     each state in which the Borrower does business.

          (d)  Legal Opinion of Counsel to the Borrower.  The Administrative
               ----------------------------------------
     Agent shall have received, with an executed counterpart for each Lender, an
     opinion addressed to the Administrative Agent and each Lender, dated the
     Effective Date, of Choate, Hall & Stewart, counsel to the Borrower, as to
     such matters as may be requested by the Administrative Agent and in form
     and substance satisfactory to the Lenders.

          (e)  Financial Statements; Projections.  The Administrative Agent
               ---------------------------------
     shall have received for each Lender a true and correct copy of the (i)
     audited consolidated financial statements, including balance sheets, income
     statements and cash flow statements, for the Borrower and each of its
     consolidated Subsidiaries for the years ended December 31, 1998, 1999 and
     2000, (ii) unaudited interim consolidated financial statements, including a
     balance sheet, income statement and statement of cash flows, for the
     Borrower and its consolidated Subsidiaries for the three-month period ended
     March 31, 2001 and (iii) Projections for each quarterly period ending after
     the date hereof and on or before December 31, 2001.

          (f)  No Material Adverse Effect.  Nothing shall have occurred (and
               --------------------------
     neither the Administrative Agent nor the Lenders shall have become aware of
     any facts or conditions not previously known) which the Lenders shall
     determine (i) has had, or could reasonably be expected to have, a Material
     Adverse Effect. The Administrative Agent shall have received a certificate
     of a senior financial officer of the Borrower, dated the Effective Date, to
     the effect that, as of the Effective Date, there has been no Material
     Adverse Effect since March 31, 2001.

                                      -37-
<PAGE>

          (g)  Governmental Approvals.  All necessary and material Governmental
               ----------------------
     Actions (domestic and foreign) and third party approvals and/or consents in
     connection with the transactions contemplated in this Agreement shall have
     been obtained and remain in effect and all applicable waiting periods with
     respect thereto shall have expired without any action being taken by any
     competent authority which restrains, prevents or imposes materially adverse
     conditions upon, the consummation of the transactions contemplated hereby
     or otherwise referred to herein.  The Administrative Agent shall have
     received documentation reasonably acceptable to it that (i) the Public
     Utilities Commission of Nevada has duly approved the Borrowings hereunder
     and (ii) the California Public Utilities Commission has exempted the
     Borrower from the requirement to secure its approval of the Borrowings
     hereunder, including, without limitation, a copy of the docket of matters
     pending before the California Public Utilities Commission showing no
     indication of a change with respect to such exemptive order.

          (h)  No Injunctions.  There shall not exist any judgment, order,
               --------------
     injunction or other restraint issued or filed or a hearing seeking
     injunctive relief or other restraint pending or notified prohibiting or
     imposing materially adverse conditions upon the consummation of the
     transactions contemplated hereby or otherwise referred to herein.

          (i)  Litigation, Proceedings and Investigations.  There shall be no
               ------------------------------------------
     actions, arbitrations, suits, investigations or proceedings pending or
     threatened with respect to this Agreement or which the Administrative Agent
     shall determine could reasonably be expected to have a Material Adverse
     Effect.

          (j)  No Violation of Existing Agreements.  Neither the Borrower nor
               -----------------------------------
     any Subsidiary of the Borrower is in violation of any material agreement or
     instrument to which it is party or by which it or any of its properties
     (now owned or hereafter acquired) may be subject or bound;

          (k)  Ratings.  The Administrative Agent shall have received a
               -------
     certificate of a senior financial officer of the Borrower, dated the
     Effective Date, setting forth the then current ratings of the Index Debt of
     Borrower and the Index Debt of NPC.

          (l)  Officers' Certificates.  The Administrative Agent shall have
               ----------------------
     received, with an executed counterpart for each Lender, certificates from
     such officers of the Borrower as to such matters as the Administrative
     Agent may request.

          (m)  Fees, Expenses, etc.  All fees and other items required to be
               --------------------
     paid to the Agents and the Lenders on or before the Effective Date
     (including all fees referenced in fee letters and offer letters) shall have
     been paid or received.

          (n)  Section 4.02 Conditions.
               -----------------------

               (i)    Each of the representations and warranties made by the
          Borrower herein and in each other Loan Document shall be true and
          correct in all material

                                      -38-
<PAGE>

          respects on and as of the Effective Date as if made on and as of such
          date, both before and after giving effect to the Loans requested to be
          made on such date.

               (ii)   No Default or Event of Default shall have occurred and be
          continuing on the Effective Date.

          (o)  The Lenders shall be satisfied with the results of their due
     diligence review of the Borrower and its Subsidiaries.

          (p)  Additional Matters.  The Administrative Agent shall have
               ------------------
     received, with copies or executed counterparts for each Lender, such other
     certificates, opinions, documents and instruments as the Administrative
     Agent may have requested. All corporate and other proceedings, and all
     documents, instruments and other matters in connection with the
     transactions contemplated by this Agreement and the other Loan Documents
     shall be satisfactory in form and substance to the Administrative Agent.

          SECTION 4.02   Conditions to All Loans.
                         -----------------------

          The obligation of each Lender to make, convert or continue any Loan on
the occasion of any Borrowing is subject to satisfaction of the conditions
precedent set forth in Section 4.01 and satisfaction of the following further
conditions precedent:

          (a)  Notice.  The Borrower shall have executed and delivered to the
               ------
     Administrative Agent a Borrowing Request or Interest Election Request for
     such Borrowing in accordance with Section 2.03 or 2.05, as the case may be.

          (b)  Representations and Warranties.  Each of the representations and
               ------------------------------
     warranties made by the Borrower herein and in each other Loan Document
     shall be true and correct in all material respects on and as of such date
     as if made on and as of such date, both before and after giving effect to
     the making, conversion or continuation of Loans requested to be made,
     converted or continued on such date.

          (c)  No Defaults.  No Default or Event of Default shall have occurred
               -----------
     and be continuing on such date or after giving effect to the making,
     conversion or continuation of Loans requested to be made, converted or
     continued on such date.

          (d)  No Violations of Law, etc.  Neither the making, conversion or
               -------------------------
     continuation of nor use of the Loans shall cause any Lender to violate or
     be in conflict with any Law.

          (e)  No Material Adverse Change.  There shall not have occurred, or be
               --------------------------
     threatened, any other event, act or condition which would reasonably be
     expected to have a Material  Adverse Effect.

          Each request by the Borrower for any Loan or conversion or
continuation thereof shall constitute a representation and warranty by the
Borrower that the conditions set forth in this Section 4.02 have been satisfied
as of the date of such request.  Failure of the Administrative Agent to receive
notice from the Borrower to the contrary before such Loan is made shall
constitute a

                                      -39-
<PAGE>

further representation and warranty by the Borrower that the conditions referred
to in this Section 4.02 have been satisfied as of the date such Loan is made.

                                   ARTICLE V
                             AFFIRMATIVE COVENANTS

     The Borrower hereby covenants to the Administrative Agent and each Lender:

          SECTION 5.01   Basic Reporting Requirements.
                         ----------------------------

          (a)  Annual Audit Reports.  As soon as practicable, and in any event
               --------------------
within 90 days after the close of each fiscal year of the Borrower, the Borrower
shall furnish to the Administrative Agent, with a copy for each Lender,
consolidated statements of income, retained earnings and cash flows of the
Borrower and its consolidated Subsidiaries for such fiscal year and a
consolidated balance sheet of the Borrower and its consolidated Subsidiaries as
of the close of such fiscal year, and notes to each, all in reasonable detail,
setting forth in comparative form the corresponding figures for the preceding
fiscal year.  Such financial statements shall be accompanied by an opinion of
independent certified public accountants of recognized national standing
selected by the Borrower, which opinion shall not be subject to any
qualification as to scope of audit or as to any other matter which the Required
Lenders determine is adverse.  Such opinion in any event shall contain a written
statement of such accountants substantially to the effect that (i) such
accountants examined such financial statements in accordance with generally
accepted auditing standards and accordingly made such tests of accounting
records and such other auditing procedures as such accountants considered
necessary in the circumstances and (ii) in the opinion of such accountants such
financial statements present fairly the financial position of the Borrower and
its consolidated Subsidiaries as of the end of such fiscal year and the results
of their operations and their retained earnings and cash flows for such fiscal
year, in conformity with GAAP.

          (b)  Quarterly Consolidated Reports.  As soon as practicable, and in
               ------------------------------
any event within 45 days after the close of each of the first three fiscal
quarters of each fiscal year of the Borrower, the Borrower shall furnish to the
Administrative Agent, with a copy for each Lender, unaudited consolidated
statements of income, retained earnings and cash flows of the Borrower and its
consolidated Subsidiaries for the period from the beginning of such fiscal year
to the end of such fiscal quarter and an unaudited consolidated balance sheet of
the Borrower and its consolidated Subsidiaries as of the close of such fiscal
quarter, and notes to each, all in reasonable detail, setting forth in
comparative form the corresponding figures for the same periods or as of the
same date during the preceding fiscal year (except for the consolidated balance
sheet, which shall set forth in comparative form the corresponding balance sheet
as of the prior fiscal year end).  Such financial statements shall be certified
by a Responsible Officer of the Borrower as presenting fairly the financial
position of the Borrower and its consolidated Subsidiaries as of the end of such
fiscal quarter and the results of their operations and their retained earnings
and changes in cash flows for such fiscal year, in conformity with GAAP, subject
to normal and recurring year-end audit adjustments.

          (c)  Quarterly Compliance Certificates.  The Borrower shall deliver to
               ---------------------------------
the Administrative Agent, with a copy for each Lender, a Quarterly Compliance
Certificate in

                                      -40-
<PAGE>

substantially the form set forth as Exhibit D, duly completed and signed by a
Responsible Officer of the Borrower concurrently with the delivery of the
financial statements referred to in subsections (a) and (b) of this Section
5.01.

          (d)     Certain Other Reports and Information.  Promptly upon their
                  -------------------------------------
becoming available to the Borrower, the Borrower shall deliver to the
Administrative Agent, with a copy for each Lender, a copy of (i) all regular or
special reports, registration statements and amendments to the foregoing which
the Borrower or any Subsidiary of the Borrower shall file with the Securities
and Exchange Commission (or any successor thereto) or any securities exchange,
and (ii) all reports, proxy statements, financial statements and other
information distributed by the Borrower to its stockbrokers, bondholders or the
financial community generally.

          (e)     Further Information.  The Borrower shall promptly furnish to
                  -------------------
the Administrative Agent, with a copy for each Lender, such other information
and in such form as the Administrative Agent or any Lender may reasonably
request from time to time.

          (f)     Notice of Certain Events.  Promptly (and, in the case of
                  ------------------------
clause (i) below, no later than two Business Days) upon becoming aware of any of
the following, the Borrower shall give the Administrative Agent notice thereof,
together with a written statement of a Responsible Officer of the Borrower
setting forth the details thereof and any action with respect thereto taken or
proposed to be taken by the Borrower:

          (i)     Any Default or Event of Default.

          (ii)    The occurrence or existence of any event or condition
     (including (A) the violation or alleged violation of any Environmental Law
     by the Borrower or any Subsidiary of the Borrower or the assertion of any
     Environmental Claim against the Borrower or any Subsidiary of the Borrower,
     (B) the commencement of any other action, suit, proceeding or investigation
     by or before any Governmental Authority against or affecting the Borrower
     or any Subsidiary of the Borrower, or (C) the violation, breach or default
     or alleged violation, breach or default by the Borrower or any Subsidiary
     of the Borrower or any other Person under any agreement or instrument
     material to the business, operations, condition (financial or otherwise) or
     prospects of the Borrower and its Subsidiaries taken as a whole) which
     event or condition, either individually or in the aggregate, has, or would
     reasonably be expected to have, a Material Adverse Effect.

          (iii)   Any change in the rating of the Index Debt of Borrower or the
     Index Debt of NPC.

          (g)     Visitation; Verification.  The Borrower shall permit such
                  ------------------------
Persons as the Administrative Agent or any Lender may designate from time to
time to visit and inspect any of the properties of the Borrower and of any
Subsidiary, to examine their respective books and records and take copies and
extracts therefrom and to discuss their respective affairs with their respective
officers, employees and independent accountants at such times and as often as
the Administrative Agent or any Lender may reasonably request; provided,
                                                               --------
however, that the Borrower reserves the right to restrict access to any of its
generating facilities in accordance with reasonably adopted

                                      -41-
<PAGE>

practices relating to safety and security. The Borrower hereby authorizes such
officers, employees and independent accountants to discuss with the
Administrative Agent or any Lender the affairs of the Borrower and its
Subsidiaries.

          (h)  ERISA.  Within 30 days after the Borrower knows that any of the
               -----
events or conditions specified below with respect to any Plan or Multiemployer
Plan has occurred or exists, a statement signed by a Responsible Officer of the
Borrower setting forth details respecting such event or condition and the
action, if any, that the Borrower or its ERISA Affiliate proposes to take with
respect thereto (and a copy of any report or notice required to be filed with or
given to PBGC by the Borrower or an ERISA Affiliate with respect to such event
or condition):

               (i)    any Reportable Event and any request for a waiver under
     Section 412(d) of the Code for any Plan;

               (ii)   the distribution under Section 4041 of ERISA of a notice
     of intent to terminate any Plan or any action taken by the Borrower or an
     ERISA Affiliate to terminate any Plan, in each case with respect to which
     there are insufficient assets to pay benefits as they become due;

               (iii)  the institution by PBGC of proceedings under Section 4042
     of ERISA for the termination of, or the appointment of a trustee to
     administer, any Plan, or the receipt by the Borrower or any ERISA Affiliate
     of a notice from a Multiemployer Plan that such action has been taken by
     PBGC with respect to such Multiemployer Plan;

               (iv)   the complete or partial withdrawal from a Multiemployer
     Plan by the Borrower or any ERISA Affiliate that results in liability under
     Section 4201 or 4204 of ERISA (including the obligation to satisfy
     secondary liability as a result of a purchaser default) or the receipt by
     the Borrower or any ERISA Affiliate of notice from a Multiemployer Plan
     that it is in reorganization or insolvency pursuant to Section 4241 or 4245
     of ERISA or that it intends to terminate or has terminated under Section
     4041A of ERISA; and

               (v)    the adoption of an amendment to any Plan that, pursuant to
     Section 401(a)(29) of the Code or Section 307 of ERISA, would result in the
     loss of tax-exempt status of the trust of which such Plan is a part if the
     Borrower or an ERISA Affiliate fails to timely provide security to the Plan
     in accordance with the provisions of said Sections.

          (i)  Satisfaction of Certain Reporting Requirements.   Notwithstanding
               ----------------------------------------------
any other provision of this Section 5.01, the Borrower shall be deemed to have
satisfied its obligations pursuant to Sections 5.01(a) and (b) if and to the
extent that it shall have provided to the Administrative Agent and each Lender,
pursuant to Section 5.01(d), copies of its periodic reports (on Form 10-K or 10-
Q, as the case may be) as required to be filed with the Securities and Exchange
Commission (or any successor thereto) pursuant to the Securities and Exchange
Act of 1934, as amended (or any successor statute of similar import), for the
annual and quarterly periods described in such Sections.

                                      -42-
<PAGE>

          (j)  Delivery to Lenders.  The Administrative Agent shall promptly
               -------------------
deliver to each Lender each of the reports, statements, certificates or other
documents delivered to the Administrative Agent by the Borrower pursuant to this
Section 5.01.

          SECTION 5.02   Insurance.
                         ---------

          The Borrower shall, and shall cause each of its Subsidiaries to,
maintain with financially sound and reputable insurers insurance with respect to
its properties and business and against such liabilities, casualties and
contingencies and of such types and in such amounts as is customary in the case
of corporations engaged in the same or similar businesses or having similar
properties similarly situated and as is satisfactory from time to time to the
Required Lenders in their reasonable discretion.

          SECTION 5.03   Payment of Taxes and Other Potential Charges and
                         ------------------------------------------------
Priority Claims.
---------------

          The Borrower shall, and shall cause each of its Subsidiaries to, pay
or discharge

          (a)  on or prior to the date on which penalties or Liens attach
     thereto, all Taxes imposed upon it or any of its properties;

          (b)  on or prior to the date when due, all lawful claims of
     materialmen, mechanics, carriers, warehousemen, landlords and other like
     Persons which, if unpaid, might result in the creation of a Lien upon any
     such Property; and

          (c)  on or prior to the date when due, all other lawful claims which,
     if unpaid, might result in the creation of a Lien upon any such Property or
     which, if unpaid, might give rise to a claim entitled to priority over
     general creditors of the Borrower or such Subsidiary in a case under the
     Bankruptcy Code;

provided, that, unless and until foreclosure, distraint, levy, sale or similar
--------
proceedings shall have been commenced, the Borrower or such Subsidiary need not
pay or discharge any such Tax, assessment, charge or claim so long as (x) the
validity thereof is contested in good faith and by appropriate proceedings
diligently conducted, and (y) such reserves or other appropriate provisions as
may be required by GAAP shall have been made therefor.

          SECTION 5.04   Preservation of Corporate Status and Franchises.
                         -----------------------------------------------

          The Borrower shall, and shall cause each of its Subsidiaries to,
maintain its status as a corporation, trust or limited liability company duly
organized, validly existing and in good standing under the Laws of its
jurisdiction of organization, and to be duly qualified to do business as a
foreign corporation, trust or limited liability company and in good standing in
all jurisdictions in which the ownership of its properties or the nature of its
business or both make such qualification necessary or advisable; provided,
                                                                 --------
however, that nothing in this Section 5.04 shall prevent the withdrawal by the
-------
Borrower or any of its Subsidiaries of its qualification as a foreign
corporation in any jurisdiction where such withdrawal could not have a Material
Adverse Effect.  The Borrower shall, and shall cause each of its Subsidiaries
to, do or cause to be done, all things

                                      -43-
<PAGE>

necessary to preserve and keep in full force and effect its material rights,
franchises, licenses and patents.

          SECTION 5.05   Governmental Approvals and Filings.
                         ----------------------------------

          The Borrower shall keep and maintain in full force and effect all
Governmental Actions necessary or advisable in connection with execution and
delivery of any Loan Document, consummation of the transactions herein or
therein contemplated, performance of or compliance with the terms and conditions
hereof or thereof or to ensure the legality, validity, binding effect or
enforceability hereof or thereof.

          SECTION 5.06   Maintenance of Properties.
                         -------------------------

          The Borrower shall, and shall cause each of its Subsidiaries to,
maintain or cause to be maintained in good repair, working order and condition
the properties now or hereafter owned, leased or otherwise possessed by it and
shall make or cause to be made all needful and proper repairs, renewals,
replacements and improvements thereto so that the business carried on in
connection therewith may be properly and advantageously conducted at all times.

          SECTION 5.07   Avoidance of Other Conflicts.
                         ----------------------------

          The Borrower shall not, and shall not permit any of its Subsidiaries
to, violate or conflict with, be in violation of or in conflict with, or be or
remain subject to any liability (contingent or otherwise) on account of any
violation or conflict with

          (a)  any Law;

          (b)  its articles of incorporation or by-laws; or

          (c)  any agreement or instrument to which it is party or by which any
     of them or any of their respective Subsidiaries is a party or by which any
     of them or any of their respective properties (now owned or hereafter
     acquired) may be subject or bound,

except for matters which would not reasonably be expected, either individually
or in the aggregate, to have a Material Adverse Effect.

          SECTION 5.08   Financial Accounting Practices.
                         ------------------------------

          The Borrower shall, and shall cause each of its Subsidiaries to, make
and keep books, records and accounts which, in reasonable detail, accurately and
fairly reflect its transactions and dispositions of its assets and maintain a
system of internal accounting controls sufficient to provide reasonable
assurances that (a) transactions are executed in accordance with management's
general or specific authorization, (b) transactions are recorded as necessary
(i) to permit preparation of financial statements in conformity with GAAP and
(ii) to maintain accountability for assets, (c) access to assets is permitted
only in accordance with management's general or specific authorization and (d)
the recorded accountability for assets is compared with the

                                      -44-
<PAGE>

existing assets at reasonable intervals and appropriate action is taken with
respect to any differences.

          SECTION 5.09   Use of Proceeds.
                         ---------------

          The Borrower shall apply the proceeds of all Loans hereunder only for
working capital and general corporate purposes of the Borrower, including
commercial paper backup.  The Borrower shall not use the proceeds of any Loans
hereunder directly or indirectly for any unlawful purpose, in any manner
inconsistent with Section 3.11, or inconsistent with any other provision of any
Loan Document.

          SECTION 5.10   End of Fiscal Periods.
                         ---------------------

          The Borrower shall cause (a) each of its, and each of its
Subsidiary's, fiscal years to end on December 31 and (b) each of its, and each
of its Subsidiary's, fiscal quarters to end on March 31, June 30, September 30
and December 31.

                                  ARTICLE VI
                              NEGATIVE COVENANTS

          The Borrower hereby covenants to the Administrative Agent and each
Lender as follows:

          SECTION 6.01   Financial Covenants.
                         -------------------

          (a)  Maximum Leverage.  The Borrower shall not permit the ratio of (a)
               ----------------
Total Indebtedness  to (b) the sum of Total Indebtedness and Shareholders'
Equity, determined as of the last day of each fiscal quarter, to exceed 0.60 to
1.

          (b)  Fixed Charge Coverage Ratio.  The Borrower shall not permit the
               ---------------------------
Fixed Charge Coverage Ratio, determined as of the last day of each fiscal
quarter set forth below for the period set forth below, to be less than 1.5 to
1:

<TABLE>
<CAPTION>
     Fiscal Quarter Ended               Period
     --------------------               ------
<S>                                     <C>
     September 30, 2001                 the two consecutive fiscal quarters ended as of the
                                        last day of such fiscal quarter
     December 31, 2001                  the three consecutive fiscal quarters ended as of
                                        the last day of such fiscal quarter
     March 31, 2002 and each            the four consecutive fiscal quarters ended as of the
     fiscal quarter ended thereafter    last day of such fiscal quarter
</TABLE>

                                      -45-
<PAGE>

          SECTION 6.02   Liens.
                         -----

          The Borrower shall not, and shall not permit any of its Subsidiaries
to, at any time create, incur, assume or suffer to exist any Lien on any of its
Property (now owned or hereafter acquired), or agree, become or remain liable
(contingently or otherwise) to do any of the foregoing, except for the following
("Permitted Liens"):
  ---------------

          (a)  Liens existing on the date hereof and securing obligations
     existing on the date hereof, as such Liens and obligations are listed on
     Schedule IV;

          (b)  Liens securing obligations issued under and pursuant to the terms
     and conditions of either (i) the First Mortgage Indenture or (ii) the
     General and Refunding Mortgage Indenture; provided that the aggregate
                                               --------
     amount of Indebtedness issued by the Company under and pursuant to the
     terms and conditions of the First Mortgage Indenture and the General and
     Refunding Mortgage Indenture shall not exceed $983.82 million, except that
     such Indebtedness may exceed $983.82 million to the extent, and only to the
     extent, required to secure (x) Loans pursuant to Section 6.09(b) of this
     Agreement, and (y) loans pursuant to Section 6.09(b) of the Existing
     Facility;

          (c)  Liens on First Mortgage Bonds issued as collateral for pollution
     control or gas or water facility revenue bonds issued for the benefit of
     the Borrower or its Subsidiaries (and related rights and interests) to
     secure obligations of the Borrower or such Subsidiaries for the benefit of
     the holders of such bonds, provided that such bonds are not secured by any
     other assets or Properties of the Borrower or its Subsidiaries;

          (d)  Liens on "transition property" arising pursuant to Section 843 of
     the California Public Utility Code for the benefit of holders of rate
     reduction bonds issued pursuant to a valid financing order of the
     California Public Utilities Commission;

          (e)  Liens arising from taxes, assessments, charges or claims
     described in Section 5.03 that are not yet due or that remain payable
     without penalty or to the extent permitted to remain unpaid under the
     proviso to such Section 5.03;

          (f)  Deposits or pledges of cash or securities in the ordinary course
     of business to secure (i) worker's compensation, unemployment insurance or
     other social security obligations, (ii) performance of bids, tenders, trade
     contracts (other than for payment of money) or leases, (iii) stay, surety
     or appeal bonds, or (iv) other obligations of a like nature incurred in the
     ordinary course of business;

          (g)  Zoning restrictions, easements, minor restrictions on the use of
     real Property, minor irregularities in title thereto and other minor Liens
     that do not secure the payment of money or the performance of an obligation
     and that do not in the aggregate materially detract from the value of an
     asset to, or materially impair its use in the business of, the Borrower or
     such Subsidiary; and

          (h)  Liens on Property securing all or part of the purchase price
     thereof and Liens (whether or not assumed) existing in Property at the time
     of purchase thereof, provided

                                      -46-
<PAGE>

     that: (i) such Lien is created before or substantially simultaneously with
     the purchase of such Property by the Borrower or such Subsidiary, (ii) such
     Lien is confined solely to the Property so purchased, improvements thereto
     and proceeds thereof, (iii) the aggregate amount secured by such Liens on
     any particular Property at the time purchased by the Borrower or such
     Subsidiary, as the case may be, shall not exceed the lesser of the purchase
     price of such Property and the fair market value of such Property at the
     time of purchase thereof by the Borrower or such Subsidiary, and (iv) the
     aggregate amount secured by all Liens described in this Section 6.02(h)
     shall not at any time exceed $50,000,000.

"Permitted Liens" shall in no event include any Lien imposed by, or required to
be granted pursuant to, ERISA or any Environmental Law.

          SECTION 6.03   Mergers.
                         -------

          The Borrower shall not, and shall not permit any of its Subsidiaries
to, (a) merge with or into or consolidate with any other Person, (b) liquidate,
wind-up, dissolve or divide, or (c) agree, become or remain liable (contingently
or otherwise) to do any of the foregoing, except:

          (i)     A Person may merge with or into or consolidate with any
     Subsidiary of the Borrower; provided that (x) the surviving Person shall be
                                 --------
     a Subsidiary of the Borrower, (y) no Default or Event of Default shall have
     occurred and be continuing or shall exist at such time or after giving
     effect to such transaction and (z) the Borrower shall deliver to the
     Administrative Agent (A) a certificate, in a form reasonably satisfactory
     to the Administrative Agent, certifying that no Default or Event of Default
     exists or will result from such merger and (B) pro forma financial
     statements in support of such certification; and

          (ii)    A Person may merge with or into or consolidate with the
     Borrower, provided that (x) the Borrower shall be the surviving Person, (y)
     no Default or Event of Default shall have occurred and be continuing or
     shall exist at such time or after giving effect to such transaction and (z)
     the Borrower shall deliver to the Administrative Agent (A) a certificate,
     in a form reasonably satisfactory to the Administrative Agent, certifying
     that no Default or Event of Default exists or will result from such merger
     and (B) pro forma financial statements in support of such certification.

          SECTION 6.04   Dispositions of Properties.
                         --------------------------

          The Borrower shall not, and shall not permit any of its Subsidiaries
to, sell, convey, assign, lease, sale-leaseback, transfer, abandon or otherwise
dispose of, voluntarily or involuntarily (collectively, "Dispose"), any of its
                                                         -------
Properties, or agree, become or remain liable contingently or otherwise to do
any of the foregoing, except that, so long as no Default or Event of Default
shall have occurred and be continuing or shall exist at such time or after
giving effect to such transaction, the Borrower and its Subsidiaries may Dispose
of Property (a) in transactions in the ordinary course of business consistent
with past practice, (b) that is obsolete, (c) comprising accounts receivable
transferred to a commercial paper conduit, special purpose subsidiary or similar
entity; provided that (i) the aggregate face amount of such accounts receivable,
        --------
when added

                                      -47-
<PAGE>

to the aggregate face amount of all other accounts receivable Disposed of in
reliance on this clause (c), does not exceed $125,000,000 and (ii) the net cash
proceeds from the Disposition of such accounts receivable, (A) when added to the
net cash proceeds of all other Dispositions of accounts receivable made in
reliance on this clause (c), are not less than 80% of the aggregate face amount
of all accounts receivable Disposed of in reliance on this clause (c) and (B) at
the time of such Disposition, do not exceed the sum of (I) the balance of the
Borrower's deferred energy accrual account at such time and (II) the Borrower's
deferred energy costs actually incurred but not yet reflected in the Borrower's
deferred energy accrual account, in each case as set forth in the Borrower's
books and records; provided, further, that each Disposition made by the Borrower
                   --------  -------
in reliance on this clause (c) shall constitute a representation and warranty of
the Borrower, made at the time of such Disposition, that the conditions set
forth in clauses (i) and (ii) above are satisfied at such time and (d) in
transactions other than as provided in Section 6.04 (a), (b) and (c); provided
                                                                      --------
that the aggregate book value of all Property Disposed of pursuant to this
Section 6.04(d) from and after the date hereof shall not exceed $50,000,000.

          SECTION 6.05   Investments and Acquisitions.
                         ----------------------------

          Prior to the making of any Investment or the consummation of any
Acquisition by the Borrower or any of its Subsidiaries, the amount or purchase
price of which, as the case may be, when aggregated with the amounts and
purchase prices of other Investments and Acquisitions made by the Borrower and
its Subsidiaries, would exceed $10,000,000 in the aggregate at any time, the
Borrower shall deliver to the Administrative Agent (i) a certificate, in a form
reasonably satisfactory to the Administrative Agent, certifying that no Default
or Event of Default exists or will result from such Acquisition and (ii) pro
forma financial statements in support of such certification.

          SECTION 6.06  Dividends and Stock Repurchases.
                        -------------------------------

          The Borrower shall not declare or pay any dividend on its capital
stock (except for dividends in the form of capital stock), or redeem or
repurchase any of its capital stock, if a Default or Event of Default shall have
occurred and be continuing or shall exist at such time or after giving effect to
such transaction.

          SECTION 6.07  Transactions with Affiliates.
                        ----------------------------

          The Borrower shall not enter into any transaction of any kind with any
Person that Controls the Borrower or is controlled by the Borrower or is under
common control with the Borrower other than (a) salary, bonus, employee stock
option and other compensation arrangements with directors or officers in the
ordinary course of business, (b) transactions that are fully disclosed to the
board of directors (or executive committee thereof) of the Borrower and
expressly authorized by a resolution of the board of directors (or executive
committee) of the Borrower which is approved by a majority of the directors (or
executive committee) not having an interest in the transaction, (c) transactions
between or among the Borrower and its Wholly-Owned Subsidiaries, (d)
transactions between the Borrower and its Subsidiaries, on the one hand, and NPC
and its Subsidiaries, on the other hand, and (e) transactions on overall terms
at least as favorable to

                                      -48-
<PAGE>

the Borrower as would be the case in an arm's-length transaction between
unrelated parties of equal bargaining power.

          SECTION 6.08   Change of Business.
                         ------------------

          The Borrower shall not engage in any business other than the
businesses of (a) the generation or purchase of electrical power and (b) the
purchase of natural gas, and in each case the transmission and distribution
thereof to industrial, commercial and residential customers.  In addition to,
and not by way of limitation of, the previous sentence, the Borrower shall
maintain ongoing business segments (as defined in FASB Statement 131 -
Disclosure about Segments of an Enterprise and Related Information) consisting
of electricity and gas assets (exclusive of cash and readily marketable
securities) and operating income reflected in the financial statements of the
Borrower as being directly attributable to the generation, transmission and/or
distribution of electricity or gas, which segments and operating income shall,
in the aggregate, comprise not less than 80% of the consolidated assets
(exclusive of cash and readily marketable securities) of the Borrower and its
Subsidiaries.

          SECTION 6.09   Equal and Ratable Lien; Grant of Security Interest in
                         -----------------------------------------------------
Certain Events.
--------------

          (a)  If, notwithstanding the prohibition contained in Section 6.02,
the Borrower or any of its Subsidiaries is subjected to any Lien upon any of its
Property, other than those permitted by the provisions of Section 6.02, the
Borrower will, and will cause its Subsidiaries to, make or cause to be made
effective provisions whereby the Borrowings will be secured equally and ratably
with any and all other obligations thereby secured, such security to be pursuant
to agreements reasonably satisfactory to the Administrative Agent and, in any
such case, the Borrowings shall have the benefit, to the fullest extent that,
and with such priority as, the Lenders may be entitled under applicable law, of
an equitable Lien on such Property. Such violation of Section 6.02 will
constitute an Event of Default, whether or not provision is made for an equal
and ratable Lien pursuant to this Section 6.09, and no such Lien or agreements
with respect thereto shall be deemed to be a waiver of or consent to such Event
of Default by the Administrative Agent or any Lender.

          (b)  If any of the following (each, a "Triggering Event") shall occur:

               (x)    Sierra Pacific Resources shall not complete an
     underwritten public offering of its common stock with minimum net proceeds
     to Sierra Pacific Resources of $200,000,000 by September 30, 2001;

               (y)    Moody's shall rate (1) the Index Debt of Borrower or the
     Index Debt of NPC as Baa3 or lower, or (2) the commercial paper of the
     Borrower or NPC below Prime-2; or

               (z)    S&P shall rate (1) the Index Debt of Borrower or the Index
     Debt of NPC as BB+ or lower, or (2) the commercial paper of the Borrower or
     NPC below A-2;

          then,

                                      -49-
<PAGE>

the Borrower shall issue or cause to be issued, not later than 5 Business Days
after the date on which the Triggering Event first occurs, for the ratable
benefit of the Lenders, General and Refunding Mortgage Bonds, to the full extent
permitted under applicable orders of the Public Utilities Commission of Nevada
and the General and Refunding Mortgage Indenture, in an aggregate principal
amount not to exceed the amount of principal of the Loans then outstanding, with
interest and other terms and conditions substantially similar to the Loans, and
the Borrower shall perform or cause to be performed all acts, and execute or
cause to be executed all resolutions, orders, instruments, certificates,
agreements and other documents required under the General and Refunding Mortgage
Indenture (including the documents referred to in Section 6.09(c)) to give
effect to the foregoing within such 5-Business Day period.

          (c)  On or before September 30, 2001, the Borrower shall deliver or
cause to be delivered to the Administrative Agent substantially final versions
of the following documents (all as defined in the General and Refunding Mortgage
Indenture) which, upon execution, delivery and filing, shall be sufficient for
the issuance of the General and Refunding Mortgage Bonds required by Section
6.09(b): a Supplemental Indenture, an Officer's Certificate setting forth the
terms of the General and Refunding Mortgage Bonds, a Company Order requesting
authentication of the General and Refunding Mortgage Bonds by the trustee under
the General and Refunding Mortgage Indenture, a form of the General and
Refunding Mortgage Bonds to be issued and forms of all legal opinions required
to issue the General and Refunding Mortgage Bonds under the General and
Refunding Mortgage Indenture.  The forms of such documents, prior to their
delivery to the Administrative Agent, shall have been approved by the trustee
under the General and Refunding Mortgage Indenture and its counsel, but shall
not be executed and delivered unless and until execution and delivery is
required by Section 6.09(b).

          SECTION 6.10   Restrictive Agreements.
                         -----------------------

          Except as otherwise permitted under Article VI hereunder, the Borrower
will not, and will not permit any of its Subsidiaries to, directly or
indirectly, enter into, incur or permit to exist any agreement or other
arrangement that prohibits, restricts or imposes any condition upon (a) the
ability of the Borrower or any Subsidiary to create, incur or permit to exist
any Lien upon any of its Property or assets, or (b) the ability of any
Subsidiary to pay dividends or other distributions with respect to any shares of
its capital stock or to make or repay loans or advances to the Borrower or any
other Subsidiary or to guarantee Indebtedness of the Borrower or any other
Subsidiary.

                                  ARTICLE VII
                                    DEFAULTS

          SECTION 7.01   Events of Default.
                         -----------------

          An "Event of Default" shall mean the occurrence or existence of one or
              ----------------
more of the following events or conditions (for any reason, whether voluntary,
involuntary or effected or required by Law):

          (a)  The Borrower shall fail to pay when due principal of any Loan.

                                      -50-
<PAGE>

          (b)  The Borrower shall fail to pay when due interest on any Loan, any
     fees, indemnity or expenses, or any other amount due hereunder or under any
     other Loan Document and such failure shall have continued for a period of
     three business days.

          (c)  Any representation or warranty made or deemed made by the
     Borrower in or pursuant to or in connection with any Loan Document, or any
     statement made by the Borrower in any financial statement, certificate,
     report, exhibit or document furnished by the Borrower to the Administrative
     Agent or any Lender pursuant to or in connection with any Loan Document,
     shall prove to have been false or misleading in any material respect as of
     the time when made or deemed made (including by omission of material
     information necessary to make such representation, warranty or statement
     not misleading).

          (d)  The Borrower shall default in the performance or observance of
     any covenant contained in Article VI or any of the covenants contained in
     Sections 5.01(f)(i) or 5.09 or 5.10.

          (e)  The Borrower shall default in the performance or observance of
     any other covenant, agreement or duty under this Agreement or any other
     Loan Document and (i) in the case of a default under Section 5.01 (other
     than as referred to in subsection (f)(i) thereof) such default shall have
     continued for a period of ten Business Days and (ii) in the case of any
     other default such default shall have continued for a period of 30 days
     after notice from the Administrative Agent to the Borrower.

          (f)  The Borrower or any Subsidiary of the Borrower shall (i) fail to
     make any payment (x) on account of any Indebtedness aggregating $10,000,000
     or more in principal amount or (y) aggregating $10,000,000 or more, on any
     Indebtedness, or any interest or premium thereon, in each case, when due
     (whether by scheduled maturity, required prepayment, acceleration, demand
     or otherwise), and, in each case, such failure shall have continued beyond
     any applicable grace period specified in any agreement or instrument
     relating to such Indebtedness, or (ii) fail to perform or observe any other
     term, covenant or condition on its part to be performed or observed under
     any agreement or instrument relating to any Indebtedness when required to
     be performed or observed, and such failure shall have continued beyond any
     applicable grace period specified in any agreement or instrument relating
     to such Indebtedness, if the effect of such failure to perform or observe
     is to accelerate, or to permit the acceleration of, the maturity of such
     Indebtedness, the unpaid principal amount of which then aggregates
     $10,000,000.

          (g)  One or more final judgments or orders for the payment of money
     shall have been entered against the Borrower or any Subsidiary of the
     Borrower, which judgments or orders exceed $10,000,000 in the aggregate,
     and such judgments or orders shall have remained undischarged and unstayed
     for a period of thirty consecutive days.

          (h) One or more writs or warrants of attachment, garnishment,
     execution, distraint or similar process exceeding in value the aggregate
     amount of $10,000,000 shall have been issued against the Borrower or any
     Subsidiary of the Borrower or any of their

                                      -51-
<PAGE>

     respective properties and shall have remained undischarged and unstayed for
     a period of thirty consecutive days.

          (i)  Any Governmental Action now or hereafter made by or with any
     Governmental Authority in connection with any Loan Document is not obtained
     or shall have ceased to be in full force and effect or shall have been
     modified or amended or shall have been held to be illegal or invalid, and
     the Required Lenders shall have determined (which determination shall be
     conclusive provided it is reached in good faith) that the consequence of
     any of the foregoing events would reasonably be expected to have,
     individually or in the aggregate, a Material Adverse Effect.

          (j)  Any Loan Document or any material term or provision thereof shall
     have ceased to be in full force and effect, or the Borrower or any
     Governmental Authority with jurisdiction over the Borrower shall, or shall
     purport to, terminate, repudiate, declare voidable or void or otherwise
     contest, any Loan Document or any material term or provision thereof or any
     obligation or liability of the Borrower thereunder.

          (k)  An event or condition specified in Section 5.01(h) hereof shall
     occur or exist with respect to any Plan or Multiemployer Plan or any Lien
     arises pursuant to ERISA and, as a result of such event or condition or
     Liens, together with all other such events or conditions or Liens, the
     Borrower or any ERISA Affiliate shall incur or shall be reasonably likely
     to incur a liability to a Plan, a Multiemployer Plan or PBGC or suffer an
     encumbrance to exist in favor of any thereof (or any combination of the
     foregoing) which would constitute a Material Adverse Effect.

          (l)  The Borrower or any Subsidiary of the Borrower shall have
     violated any Environmental Law or become subject to any Environmental Claim
     and, in either case, the Required Lenders shall have determined (which
     determination shall be conclusive provided it is reached in good faith)
     that such event would reasonably be expected, either individually or in the
     aggregate, to have a Material Adverse Effect.

          (m)  A proceeding shall have been instituted in respect of the
     Borrower or any Subsidiary of the Borrower:

               (i)    seeking to have an order for relief entered in respect of
          such Person, or seeking a declaration or entailing a finding that such
          Person is insolvent or a similar declaration or finding, or seeking
          dissolution, winding-up, charter revocation or forfeiture,
          liquidation, reorganization, arrangement, adjustment, composition or
          other similar relief with respect to such Person, its assets or its
          debts under any Law relating to bankruptcy, insolvency, relief of
          debtors or protection of creditors, termination of legal entities or
          any other similar Law now or hereafter in effect, or

               (ii)   seeking appointment of a receiver, trustee, liquidator,
          assignee, sequestrator or other custodian for such Person or for all
          or any substantial part of its Property,

                                      -52-
<PAGE>

     and such proceeding shall result in the entry, making or grant of any such
     order for relief, declaration, finding, relief or appointment, or such
     proceeding shall remain undismissed and unstayed for a period of thirty
     consecutive days.

          (n)     The Borrower or any Subsidiary of the Borrower shall become
     insolvent; shall fail to pay, become unable to pay, or state that it is or
     will be unable to pay, its debts as they become due; shall voluntarily
     suspend transaction of its business; shall make a general assignment for
     the benefit of creditors; shall institute (or fail to controvert in a
     timely and appropriate manner) a proceeding described in Section
     7.01(m)(i), or (whether or not any such proceeding has been instituted)
     shall consent to or acquiesce in any such order for relief, declaration,
     finding or relief described therein; shall institute (or fail to controvert
     in a timely and appropriate manner) a proceeding described in Section
     7.01(m)(ii), or (whether or not any such proceeding has been instituted)
     shall consent to or acquiesce in any such appointment or to the taking of
     possession by any such custodian of all or any substantial part of its
     Property; shall dissolve, wind-up, revoke or forfeit its charter (or other
     constituent documents) or liquidate itself or any substantial part of its
     Property; or shall take any action in furtherance of any of the foregoing.

          (o)     A Change in Control shall occur.

          (p)     The Borrower shall cease to maintain a first mortgage bond
     rating of at least Baa3 by Moody's and BBB- by S&P.

          SECTION 7.02   Consequences of an Event of Default.
                         -----------------------------------

          (a)     If an Event of Default specified in subsections (a) through
(l), (o), (p) or (q) of Section 7.01 shall occur and, be continuing or shall
exist, then, in addition to all other rights and remedies which the
Administrative Agent or any Lender may have hereunder or under any other Loan
Document, at law, in equity or otherwise, the Lenders shall be under no further
obligation to make Loans hereunder, and the Administrative Agent may, and, upon
the written request of the Required Lenders shall, by notice to the Borrower,
from time to time do any or all of the following:

          (i)     Declare the Commitments terminated, whereupon the Commitments
     will terminate and any fees hereunder shall be immediately due and payable
     without presentment, demand, protest or further notice of any kind, all of
     which are hereby waived, and an action therefor shall immediately accrue.

          (ii)     Declare the unpaid principal amount of the Loans, interest
     accrued thereon and all other obligations to be immediately due and payable
     without presentment, demand, protest or further notice of any kind, all of
     which are hereby waived, and an action therefor shall immediately accrue.

          (b)     If an Event of Default specified in subsection (m) or (n) of
Section 7.01 shall occur or exist, then, in addition to all other rights and
remedies which the Administrative Agent or any Lender may have hereunder or
under any other Loan Document, at law, in equity or otherwise, the Commitments
shall automatically terminate and the Lenders shall be under no further

                                      -53-
<PAGE>

obligation to make Loans, and the unpaid principal amount of the Loans, interest
accrued thereon and all other obligations shall become immediately due and
payable without presentment, demand, protest or notice of any kind, all of which
are hereby waived, and an action therefor shall immediately accrue.

                                 ARTICLE VIII
                                  THE AGENTS

          SECTION 8.01   Appointment.
                         -----------

          Each Lender hereby irrevocably appoints Mellon Bank, N.A. to act as
Administrative Agent for such Lender under this Agreement and the other Loan
Documents.  Each Lender hereby irrevocably authorizes the Administrative Agent
to take such action on behalf of such Lender under the provisions of this
Agreement and the other Loan Documents, and to exercise such powers and to
perform such duties, as are expressly delegated to or required of the
Administrative Agent by the terms hereof or thereof, together with such powers
as are reasonably incidental thereto.  Mellon Bank, N.A. hereby agrees to act as
Administrative Agent on behalf of the Lenders on the terms and conditions set
forth in this Agreement and the other Loan Documents, subject to its right to
resign as provided in Section 8.10. Each Lender hereby irrevocably authorizes
the Administrative Agent to execute and deliver each of the Loan Documents
executed after the date hereof and to accept delivery of such of the other Loan
Documents delivered after the date hereof as may not require execution by the
Administrative Agent (with such consents of the Lenders as required pursuant to
Section 9.01).  Each Lender agrees that the rights and remedies granted to the
Administrative Agent under the Loan Documents shall be exercised exclusively by
the Administrative Agent, and that no Lender shall have any right individually
to exercise any such right or remedy, except to the extent expressly provided
herein or therein.

          SECTION 8.02   General Nature of Administrative Agent's Duties.
                         -----------------------------------------------

          Notwithstanding anything to the contrary elsewhere in this Agreement
or in any other Loan Document:

          (a)  The Administrative Agent shall have no duties or responsibilities
     except those expressly set forth in this Agreement and the other Loan
     Documents, and no implied duties or responsibilities on the part of the
     Administrative Agent shall be read into this Agreement or any other Loan
     Document or shall otherwise exist.

          (b)  The duties and responsibilities of the Administrative Agent under
     this Agreement and the other Loan Documents shall be mechanical and
     administrative in nature, and the Administrative Agent shall not have a
     fiduciary relationship in respect of any Lender.

          (c)  The Administrative Agent is and shall be solely the agent of the
     Lenders.  The Administrative Agent does not assume, and shall not at any
     time be deemed to have, any relationship of agency or trust with or for, or
     any other duty or responsibility to, the Borrower or any other Person
     (except only for its relationship as agent for, and its express

                                      -54-
<PAGE>

     duties and responsibilities to, the Lenders as provided in this Agreement
     and the other Loan Documents).

          (d)  The Administrative Agent shall be under no obligation to take any
     action hereunder or under any other Loan Document if the Administrative
     Agent believes in good faith that taking such action may conflict with any
     Law or any provision of this Agreement or any other Loan Document, or may
     require the Administrative Agent to qualify to do business in any
     jurisdiction where it is not then so qualified.

          SECTION 8.03   Exercise of Powers.
                         ------------------

          The Administrative Agent shall take any action of the type specified
in this Agreement or any other Loan Document as being within the Administrative
Agent's rights, powers or discretion in accordance with directions from the
Required Lenders (or, to the extent this Agreement or such Loan Document
expressly requires the direction or consent of some other Person or set of
Persons, then instead in accordance with the directions of such other Person or
set of Persons).  In the absence of such directions, the Administrative Agent
shall have the authority (but under no circumstances shall be obligated), in its
sole discretion, to take any such action, except to the extent that this
Agreement or such Loan Document expressly requires the direction or consent of
the Required Lenders (or some other Person or set of Persons), in which case the
Administrative Agent shall not take such action absent such direction or
consent.  Any action or inaction pursuant to such direction, discretion or
consent shall be binding on all the Lenders.  The Administrative Agent shall not
have any liability to any Person as a result of (a) the Administrative Agent
acting or refraining from acting in accordance with the directions of the
Required Lenders (or other applicable Person or set of Persons), (b) the
Administrative Agent refraining from acting in the absence of instructions to
act from the Required Lenders (or other applicable Person or set of Persons),
whether or not the Administrative Agent has discretionary power to take such
action, or (c) the Administrative Agent taking discretionary action it is
authorized to take under this Section (subject, in the case of clauses (b) and
(c), to the provisions of Section 8.04(a)).

          SECTION 8.04   General Exculpatory Provisions.
                         ------------------------------

          Notwithstanding anything to the contrary elsewhere in this Agreement
or any other Loan Document:

          (a)  The Administrative Agent shall not be liable for any action taken
     or omitted to be taken by it under or in connection with this Agreement or
     any other Loan Document, unless caused by its own gross negligence or
     willful misconduct.

          (b)  The Administrative Agent shall not be responsible for (i) the
     execution, delivery, effectiveness, enforceability, genuineness, validity
     or adequacy of this Agreement or any other Loan Document, (ii) any recital,
     representation, warranty, document, certificate, report or statement in,
     provided for in, or received under or in connection with, this Agreement or
     any other Loan Document, (iii) any failure of the Borrower or any Lender to
     perform any of their respective obligations under this Agreement or any
     other Loan Document, or (iv) the existence, validity, enforceability,
     perfection, recordation,

                                      -55-
<PAGE>

     priority, adequacy or value, now or hereafter, of any Lien or other direct
     or indirect security afforded or purported to be afforded by any of the
     Loan Documents or otherwise from time to time.

          (c)  The Administrative Agent shall not be under any obligation to
     ascertain, inquire or give any notice relating to (i) the performance or
     observance of any of the terms or conditions of this Agreement or any other
     Loan Document on the part of the Borrower, (ii) the business, operations,
     condition (financial or otherwise) or prospects of the Borrower or any
     other Person, or (iii) except to the extent set forth in Section 8.05(f),
     the existence of any Default or Event of Default.

          (d)  The Administrative Agent shall not be under any obligation,
     either initially or on a continuing basis, to provide any Lender with any
     notices, reports or information of any nature, whether in its possession
     presently or hereafter, except for such notices, reports and other
     information expressly required by this Agreement or any other Loan Document
     to be furnished by the Administrative Agent to such Lender.

          SECTION 8.05   Administration by the Administrative Agent.
                         ------------------------------------------

          (a)  The Administrative Agent may rely upon any notice or other
communication of any nature (written or oral, including but not limited to
telephone conversations, whether or not such notice or other communication is
made in a manner permitted or required by this Agreement or any other Loan
Document) purportedly made by or on behalf of the proper party or parties, and
the Administrative Agent shall not have any duty to verify the identity or
authority of any Person giving such notice or other communication.

          (b)  The Administrative Agent may consult with legal counsel
(including, without limitation, in-house counsel for the Administrative Agent or
in-house or other counsel for the Borrower), independent public accountants and
any other experts selected by it from time to time, and the Administrative Agent
shall not be liable for any action taken or omitted to be taken in good faith by
it in accordance with the advice of such counsel, accountants or experts.

          (c)  The Administrative Agent may conclusively rely upon the truth of
the statements and the correctness of the opinions expressed in any certificates
or opinions furnished to the Administrative Agent in accordance with the
requirements of this Agreement or any other Loan Document.  Whenever the
Administrative Agent shall deem it necessary or desirable that a matter be
proved or established with respect to the Borrower or any Lender, such matter
may be established by a certificate of the Borrower or such Lender, as the case
may be, and the Administrative Agent may conclusively rely upon such certificate
(unless other evidence with respect to such matter is specifically prescribed in
this Agreement or another Loan Document).

          (d)  The Administrative Agent may fail or refuse to take any action
unless it shall be indemnified to its satisfaction from time to time against any
and all amounts, liabilities, obligations, losses, damages, penalties, actions,
judgments, suits, costs, expenses or disbursements of any kind or nature which
may be imposed on, incurred by or asserted against the Administrative Agent by
reason of taking or continuing to take any such action.

                                      -56-
<PAGE>

          (e)  The Administrative Agent may perform any of its duties under this
Agreement or any other Loan Document by or through agents or attorneys-in-fact.
The Administrative Agent shall not be responsible for the negligence or
misconduct of any agents or attorneys-in-fact selected by it with reasonable
care.

          (f)  The Administrative Agent shall not be deemed to have any
knowledge or notice of the occurrence of any Default or Event of Default unless
the Administrative Agent has received notice from a Lender or the Borrower
referring to this Agreement, describing such Default or Event of Default, and
stating that such notice is a "notice of default". If the Administrative Agent
receives such a notice, the Administrative Agent shall give prompt notice
thereof to each Lender.

          SECTION 8.06   Lenders Not Relying on Administrative Agent or Other
                         ----------------------------------------------------
Lenders.
-------

          Each Lender acknowledges as follows:

          (a)  Neither the Administrative Agent nor any other Lender has made
     any representations or warranties to it, and no act taken hereafter by the
     Administrative Agent or any other Lender shall be deemed to constitute any
     representation or warranty by the Administrative Agent or such other Lender
     to it.

          (b)  It has, independently and without reliance upon the
     Administrative Agent or any other Lender, and based upon such documents and
     information as it has deemed appropriate, made its own credit and legal
     analysis and decision to enter into this Agreement and the other Loan
     Documents.

          (c)  It will, independently and without reliance upon the
     Administrative Agent or any other Lender, and based upon such documents and
     information as it shall deem appropriate at the time, make its own
     decisions to take or not take action under or in connection with this
     Agreement and the other Loan Documents.

          SECTION 8.07   Indemnification.
                         ---------------

          Each Lender agrees to reimburse and indemnify the Administrative Agent
and its directors, officers, employees and agents (to the extent not reimbursed
by the Borrower and without limitation of the obligations of the Borrower to do
so, in each case pursuant to the terms of this Agreement and the other Loan
Documents), based on its Applicable Percentage, from and against any and all
amounts, losses, liabilities, claims, damages, expenses, obligations, penalties,
actions, judgments, suits, costs or disbursements of any kind or nature
(including, without limitation, the fees and disbursements of counsel for the
Administrative Agent or such other Person in connection with any investigative,
administrative or judicial proceeding commenced or threatened, whether or not
the Administrative Agent or such other Person shall be designated a party
thereto) that may at any time be imposed on, incurred by or asserted against the
Administrative Agent or such other Person as a result of, or arising out of, or
in any way related to or by reason of, this Agreement, any other Loan Document,
any transaction from time to time contemplated hereby or thereby, or any
transaction financed in whole or in part or directly or

                                      -57-
<PAGE>

indirectly with the proceeds of any Loan, provided that no Lender shall be
                                          --------
liable for any portion of such amounts, losses, liabilities, claims, damages,
expenses, obligations, penalties, actions, judgments, suits, costs or
disbursements resulting solely from the gross negligence or willful misconduct
of the Administrative Agent or such other Person, as finally determined by a
court of competent jurisdiction. Payments under this Section 8.07 shall be due
and payable on demand, and to the extent that any Lender fails to pay any such
amount on demand, such amount shall bear interest for each day from the date of
demand until paid (before and after judgment) at a rate per annum (calculated on
the basis of a year of 360 days and actual days elapsed) which for each day
shall be equal to the Federal Funds Effective Rate for such day.

          SECTION 8.08   Administrative Agent in its Individual Capacity.
                         -----------------------------------------------

          With respect to its Commitment and the Obligations owing to it, the
Administrative Agent shall have the same rights and powers under this Agreement
and each other Loan Document as any other Lender and may exercise the same as
though it were not the Administrative Agent, and the terms "Lenders," "holders
of Notes" and like terms shall include the Administrative Agent in its
individual capacity as such.  The Administrative Agent and its affiliates may,
without liability to account, make loans to, accept deposits from, acquire debt
or equity interests in, act as trustee under indentures of, and engage in any
other business with, the Borrower and any stockholder, subsidiary or affiliate
of the Borrower, as though the Administrative Agent were not the Administrative
Agent hereunder.

          SECTION 8.09   Holders of Notes.
                         ----------------

          The Administrative Agent may deem and treat the Lender which is payee
of a Note as the owner and holder of such Note for all purposes hereof unless
and until an Assignment and Acceptance with respect to the assignment or
transfer thereof shall have been filed with the Administrative Agent in
accordance with Section 9.12.  Any authority, direction or consent of any Person
who at the time of giving such authority, direction or consent is shown in the
Register as being a Lender shall be conclusive and binding on each present and
subsequent holder, transferee or assignee of any Note or Notes payable to such
Lender or of any Note or Notes issued in exchange therefor.

          SECTION 8.10   Successor Administrative Agent.
                         ------------------------------

          The Administrative Agent may resign at any time by giving 10 days'
prior written notice thereof to the Lenders and the Borrower.  The
Administrative Agent may be removed by the Required Lenders at any time with or
without cause by giving 10 days, prior written notice thereof to the
Administrative Agent, the other Lenders and the Borrower.  Upon any such
resignation or removal, the Required Lenders shall have the right to appoint a
successor Administrative Agent. If no successor Administrative Agent shall have
been so appointed and consented to, and shall have accepted such appointment,
within 30 days after such notice of resignation or removal, then the retiring
Administrative Agent, on behalf of the Lenders, may appoint a successor
Administrative Agent. Each successor Administrative Agent shall be a commercial
bank or trust company organized under the Laws of the United States of America
or any State thereof and having a combined capital and surplus of at least
$1,000,000,000. The appointment of any successor

                                      -58-
<PAGE>

Administrative Agent at any time pursuant to this Section 8.10 shall be subject
to the approval of the Borrower, provided that at such time there shall not have
occurred and be continuing any Default or Event of Default, and provided further
that the Borrower's consent to any such appointment shall not be unreasonably
withheld. Upon the acceptance by a successor Administrative Agent of its
appointment as Administrative Agent hereunder, such successor Administrative
Agent shall thereupon succeed to and become vested with all the properties,
rights, powers, privileges and duties of the former Administrative Agent without
further act, deed or conveyance. Upon the effective date of resignation or
removal of a retiring Administrative Agent, the Administrative Agent shall be
discharged from its duties under this Agreement and the other Loan Documents,
but the provisions of this Agreement shall inure to its benefit as to any
actions taken or omitted by it while it was Administrative Agent under this
Agreement. If and for so long as no successor Administrative Agent shall have
been appointed, then any notice or other communication required or permitted to
be given by the Administrative Agent shall be sufficiently given if given by the
Required Lenders, all notices or other communications required or permitted to
be given to the Administrative Agent shall be given to each Lender, and all
payments to be made to the Administrative Agent shall be made directly to the
Borrower or Lender for whose account such payment is made.

          SECTION 8.11   Additional Administrative Agents.
                         --------------------------------

          If the Administrative Agent shall from time to time deem it necessary
or advisable, for its own protection in the performance of its duties hereunder
or in the interest of the Lenders, the Administrative Agent and the Borrower
shall execute and deliver a supplemental agreement and all other instruments and
agreements necessary or advisable in the opinion of the Administrative Agent to
constitute another commercial bank or trust company, or one or more other
Persons approved by the Administrative Agent, to act as co-Administrative Agent,
with such powers of the Administrative Agent as may be provided in such
supplemental agreement, and to vest in such bank, trust company or Person, as
such co-Administrative Agent, any properties, rights, powers, privileges and
duties of the Administrative Agent under this Agreement or any other Loan
Document.  The appointment of any co-Administrative Agent at any time pursuant
to this Section 8.11 shall be subject to the approval of the Borrower, provided
that at such time there shall not have occurred and be continuing any Default or
Event of Default, and provided further that the Borrower's consent to any such
appointment shall not be unreasonably withheld.

          SECTION 8.12   Calculations.
                         ------------

          The Administrative Agent shall not be liable for any calculation,
apportionment or distribution of payments made by it in good faith, in the
absence of its own gross negligence or willful misconduct.  If such calculation,
apportionment or distribution is subsequently determined to have been made in
error, the sole recourse of any Lender to whom payment was due but not made
(except as provided in the preceding sentence) shall be to recover from the
other Lenders any payment in excess of the amount to which they are determined
to be entitled or, if the amount due was not paid by the Borrower, to recover
such amount from the Borrower.

                                      -59-
<PAGE>

          SECTION 8.13   Syndication Agents.
                         ------------------

          As Syndication Agents, none of BNP Paribas, First Union National Bank
or Wells Fargo Bank, N.A. shall have any right, power, obligation, liability,
responsibility or duty under this Agreement other than those applicable to all
Lenders as such.  Without limiting the foregoing, none of BNP Paribas, First
Union National Bank or Wells Fargo Bank, N.A. shall have any or be deemed to
have any fiduciary relationship with any Lender.  Each Lender acknowledges that
it has not relied, and will not rely, on BNP Paribas, First Union National Bank
or Wells Fargo Bank, N.A. in deciding to enter into this Agreement or in not
taking action hereunder or under the Loan Documents.

                                  ARTICLE IX
                                 MISCELLANEOUS

          SECTION 9.01   Amendments and Waivers.
                         ----------------------

          Neither this Agreement nor any other Loan Document may be amended,
modified or supplemented except in accordance with the provisions of this
Section 9.01. The Administrative Agent and the Borrower may from time to time
amend, modify or supplement the provisions of this Agreement or any other Loan
Document for the purpose of amending, adding to or waiving any provision, or
changing in any manner the rights and duties of the Borrower, the Administrative
Agent or any Lender.  Any such amendment, modification or supplement made by the
Borrower and the Administrative Agent in accordance with the provisions of this
Section 9.01 shall be binding upon the Borrower, each Lender and the
Administrative Agent.  The Administrative Agent shall enter into such
amendments, modifications or supplements from time to time as directed by the
Required Lenders, and only as so directed, provided, that no such amendment,
                                           --------
modification or supplement may be made which will:

          (a)  Increase the Commitment of any Lender  over the amount thereof
     then in effect, without the written consent of each Lender affected
     thereby;

          (b)  Extend the Revolving Termination Date, without the written
     consent of all the Lenders;

          (c)  Reduce the principal amount of or extend the time for any payment
     of principal of any Loan, or reduce the rate of interest or extend the time
     for payment of any interest borne by any Loan, or extend the time for
     payment of or reduce the amount of any fees, or reduce or postpone the date
     for payment of any other obligation, without the written consent of each
     Lender affected thereby;

          (d)  Change the definition of "Required Lenders" or amend this Section
     9.01 or Section 9.12(a) or any other provision of this Agreement that
     requires the consent of all Lenders to the taking or failure to take action
     hereunder, without the written consent of all the Lenders; or

          (e)  Amend or waive any of the provisions of Article VIII, or impose
     additional duties upon the Administrative Agent or otherwise adversely
     affect the rights, interests or

                                      -60-
<PAGE>

     obligations of the Administrative Agent, without the written consent of the
     Administrative Agent;

and provided, further, that Assignment and Acceptances may be entered into in
    --------
the manner provided in Section 9.12. Any such amendment, modification or
supplement must be in writing and shall be effective only to the extent set
forth in such writing.  Any Default or Event of Default waived or consented to
in any such amendment, modification or supplement shall be deemed to be cured
and not continuing to the extent and for the period set forth in such waiver or
consent, but no such waiver or consent shall extend to any other or subsequent
Default or Event of Default or impair any right consequent thereto.

          SECTION 9.02  No Implied Waiver; Cumulative Remedies.
                        --------------------------------------

          No course of dealing and no delay or failure of the Administrative
Agent or any Lender in exercising any right, power or privilege under this
Agreement or any other Loan Document shall affect any other or future exercise
thereof or the exercise of any other right, power or privilege; nor shall any
single or partial exercise of any such right, power or privilege or any
abandonment or discontinuance of steps to enforce such a right, power or
privilege preclude any further exercise thereof or of any other right, power or
privilege.  The rights and remedies of the Administrative Agent and the Lenders
under this Agreement and any other Loan Document are cumulative and not
exclusive of any rights or remedies which the Administrative Agent or any Lender
would otherwise have hereunder or thereunder, at law, in equity or otherwise.

          SECTION 9.03  Notices.
                        -------

          (a)  Except to the extent otherwise expressly permitted hereunder or
thereunder, all notices, requests, demands, directions and other communications
(collectively "notices") under this Agreement or any other Loan Document shall
               -------
be in writing (including telecopied communication) and shall be sent by first-
class mail, or by nationally-recognized overnight courier, or by telecopier
(with confirmation in writing mailed first-class or sent by such an overnight
courier), or by personal delivery.  All notices shall be sent to the applicable
party at the address stated on the signature pages hereof or in accordance with
the last unrevoked written direction from such party to the other parties hereto
in all cases with postage or other charges prepaid.  Any such properly given
notice shall be effective on the earliest to occur of receipt, telephone
confirmation of receipt of telecopy communication, one Business Day after
delivery to a nationally-recognized overnight courier, or three Business Days
after deposit in the mail.

          (b)  Any Lender giving any notice to the Borrower or any other party
to a Loan Document shall simultaneously send a copy thereof to the
Administrative Agent, and the Administrative Agent shall promptly notify the
other Lenders of the receipt by it of any such notice.

          (c)  The Administrative Agent and each Lender may rely on any notice
(whether or not such notice is made in a manner permitted or required by this
Agreement or any other Loan Document) purportedly made by or on behalf of the
Borrower, and neither the Administrative

                                      -61-
<PAGE>

Agent nor any Lender shall have any duty to verify the identity or authority of
any Person giving such notice.

          SECTION 9.04  Expenses; Taxes; Indemnity.
                        --------------------------

          (a)  The Borrower agrees to pay or cause to be paid and to save the
Administrative Agent and each of the Lenders harmless against liability for the
payment of all reasonable out-of-pocket costs and expenses (including but not
limited to reasonable fees and expenses of counsel) incurred by the
Administrative Agent or any Lender from time to time arising from or relating to
(i) in the case of the Administrative Agent, the negotiation, syndication,
preparation, execution, delivery, administration and performance of this
Agreement and the other Loan Documents, (ii) in the case of the Syndication
Agents, the syndication of this Agreement and the other Loan Documents, (iii) in
the case of the Administrative Agent, any amendments, modifications,
supplements, waivers or consents to this Agreement or any other Loan Document
(whether or not ultimately entered into or granted), and (iv) in the case of the
Administrative Agent or any Lender, the enforcement or preservation of rights
under this Agreement or any other Loan Document (including but not limited to
any such costs or expenses arising from or relating to (A) collection or
enforcement of an outstanding Loan or any other amount owing hereunder or
thereunder by the Administrative Agent or such Lender, and (B) any litigation,
proceeding, dispute, work-out, restructuring or rescheduling related in any way
to this Agreement or the Loan Documents).

          (b)  The Borrower hereby agrees to pay all stamp, document, transfer,
recording, filing, registration, search, sales and excise fees and taxes and all
similar impositions now or hereafter determined by the Administrative Agent or
any Lender to be payable in connection with this Agreement or any other Loan
Documents or any other documents, instruments or transactions pursuant to or in
connection herewith or therewith (which determination shall be conclusive
provided it is reached in good faith), and the Borrower agrees to save the
Administrative Agent and each Lender harmless from and against any and all
present or future claims, liabilities or losses with respect to or resulting
from any omission to pay or delay in paying any such fees, taxes or impositions.

          (c)  The Borrower hereby agrees to reimburse and indemnify each of the
Indemnified Parties from and against any and all losses, liabilities, claims,
damages, expenses, obligations, penalties, actions, judgments, suits, costs or
disbursements of any kind or nature whatsoever (including, without limitation,
the reasonable fees and disbursements of counsel for such Indemnified Party in
connection with any investigative, administrative or judicial proceeding
commenced or threatened, whether or not such Indemnified Party shall be
designated a party thereto) that may at any time be imposed on, asserted against
or incurred by such Indemnified Party as a result of, or arising out of, or in
any way related to or by reason of, this Agreement or any other Loan Document,
any transaction from time to time contemplated hereby or thereby, or any
transaction financed in whole or in part or directly or indirectly with the
proceeds of any Loan (and without in any way limiting the generality of the
foregoing, including any violation or breach of any Environmental Law or any
other Law by the Borrower or any Subsidiary of the Borrower; any Environmental
Claim arising out of the management, use, control, ownership or operation of
Property by any of such Persons, including all onsite and off-site activities
involving Hazardous

                                      -62-
<PAGE>

Materials; or any exercise by the Administrative Agent or any Lender of any of
its rights or remedies under this Agreement or any other Loan Document); but
excluding any such losses, liabilities, claims, damages, expenses, obligations,
penalties, actions, judgments, suits, costs or disbursements resulting solely
from the gross negligence or willful misconduct of such Indemnified Party, as
finally determined by a court of competent jurisdiction. If and to the extent
that the foregoing obligations of the Borrower under this subsection (c), or any
other indemnification obligation of the Borrower hereunder or under any other
Loan Document, are unenforceable for any reason, the Borrower hereby agrees to
make the maximum contribution to the payment and satisfaction of such
obligations which is permissible under applicable Law.

          SECTION 9.05  Severability.
                        ------------

          The provisions of this Agreement are intended to be severable.  If any
provision of this Agreement shall be held invalid or unenforceable in whole or
in part in any jurisdiction such provision shall, as to such jurisdiction, be
ineffective to the extent of such invalidity or unenforceability without in any
manner affecting the validity or enforceability thereof in any other
jurisdiction or the remaining provisions hereof in any jurisdiction.

          SECTION 9.06  Prior Understandings.
                        --------------------

          This Agreement, the other Loan Documents and that certain letter
agreement regarding fees dated June 18, 2001 among Mellon Bank, N.A., Sierra
Pacific Resources and the Borrower, as such agreements shall be amended from
time to time, supersede all prior and contemporaneous understandings and
agreements, whether written or oral, among the parties hereto relating to the
transactions provided for herein and therein.

          SECTION 9.07  Duration; Survival.
                        ------------------

          All representations and warranties of the Borrower contained herein or
in any other Loan Document or made in connection herewith or therewith shall
survive the making, and shall not be waived by the execution and delivery, of
this Agreement or any other Loan Document, any investigation by or knowledge of
the Administrative Agent or any Lender, the making of any Loan, or any other
event or condition whatever.  All covenants and agreements of the Borrower
contained herein or in any other Loan Document shall continue in full force and
effect from and after the date hereof so long as the Borrower may borrow
hereunder and until payment in full of all Obligations.  Without limitation, all
obligations of the Borrower hereunder or under any other Loan Document to make
payments to or indemnify the Administrative Agent or any Lender shall survive
the payment in full of all other Obligations, termination of the Borrower's
right to borrow hereunder, and all other events and conditions whatever.  In
addition, all obligations of each Lender to make payments to or indemnify the
Administrative Agent shall survive the payment in full by the Borrower of all
Obligations, termination of the Borrower's right to borrow hereunder, and all
other events or conditions whatever.

                                      -63-
<PAGE>

          SECTION 9.08  Counterparts.
                        ------------

          This Agreement may be executed in any number of counterparts and by
the different parties hereto on separate counterparts each of which, when so
executed, shall be deemed an original, but all such counterparts shall
constitute but one and the same instrument.

          SECTION 9.09  Limitation on Payments.
                        ----------------------

          The parties hereto intend to conform to all applicable Laws in effect
from time to time limiting the maximum rate of interest that may be charged or
collected.  Accordingly, notwithstanding any other provision hereof or of any
other Loan Document, the Borrower shall not be required to make any payment to
or for the account of any Lender, and each Lender shall refund any payment made
by the Borrower, to the extent that such requirement or such failure to refund
would violate or conflict with nonwaivable provisions of applicable Laws
limiting the maximum amount of interest which may be charged or collected by
such Lender.

          SECTION 9.10  Set-Off.
                        -------

          The Borrower hereby agrees that, to the fullest extent permitted by
Law, if any Obligation of the Borrower shall be due and payable (by acceleration
or otherwise), each Lender shall have the right, without notice to the Borrower,
to set-off against and to appropriate and apply to such Obligation any
indebtedness, liability or obligation of any nature owing to the Borrower by
such Lender, including but not limited to all deposits (whether time or demand,
general or special, provisionally credited or finally credited, whether or not
evidenced by a certificate of deposit) now or hereafter maintained by the
Borrower with such Lender.  Such right shall be absolute and unconditional in
all circumstances and, without limitation shall exist whether or not such Lender
or any other Person shall have given notice or made a demand to the Borrower or
any other Person, whether such indebtedness, obligation or liability owed to the
Borrower is contingent, absolute, matured or unmatured (it being agreed that
such Lender may deem such indebtedness, obligation or liability to be then due
and payable at the time of such setoff), and regardless of the existence or
adequacy of any collateral, guaranty or any other security, right or remedy
available to any Lender or any other Person.  The Borrower hereby agrees that,
to the fullest extent permitted by Law, any Participant and any branch,
subsidiary or affiliate of any Lender or any Participant shall have the same
rights of set-off as a Lender as provided in this Section (regardless of whether
such Participant, branch, subsidiary or affiliate would otherwise be deemed in
privity with or a direct creditor of the Borrower).  The rights provided by this
Section are in addition to all other rights of set-off and banker's lien and all
other rights and remedies which any Lender (or any such Participant, branch,
subsidiary or affiliate) may otherwise have under this Agreement, any other Loan
Document, at law or in equity, or otherwise, and nothing in this Agreement or
any other Loan Document shall be deemed a waiver or prohibition of or
restriction on the rights of set-off or bankers' lien of any such Person.

          SECTION 9.11  Sharing of Collections.
                        ----------------------

          The Lenders hereby agree among themselves that if any Lender shall
receive (by voluntary payment, realization upon security, set-off or from any
other source) any amount on

                                      -64-
<PAGE>

account of the Loans, interest thereon, or any other Obligation contemplated by
this Agreement or the other Loan Documents to be made by the Borrower pro rata
to all Lenders (or pro rata to holders of Notes) in greater proportion than any
such amount received by any other applicable Lender, then the Lender receiving
such proportionately greater payment shall notify each other Lender and the
Administrative Agent of such receipt, and equitable adjustment will be made in
the manner stated in this Section 9.11 so that, in effect, all such excess
amounts will be shared ratably among all of the applicable Lenders. The Lender
receiving such excess amount shall purchase (which it shall be deemed to have
done simultaneously upon the receipt of such excess amount) for cash from the
other applicable Lenders a participation in the applicable Obligations owed to
such other Lenders in such amount as shall result in a ratable sharing by all
applicable Lenders of such excess amount (and to such extent the receiving
Lender shall be a Participant). If all or any portion of such excess amount is
thereafter recovered from the Lender making such purchase, such purchase shall
be rescinded and the purchase price restored to the extent of such recovery,
together with interest or other amounts, if any, required by Law to be paid by
the Lender making such purchase. The Borrower hereby consents to and confirms
the foregoing arrangements. Each Participant shall be bound by this Section as
fully as if it were a Lender hereunder.

          SECTION 9.12  Successors and Assigns; Participations; Assignments.
                        ---------------------------------------------------

          (a)  Successors and Assigns.  This Agreement shall be binding upon and
               ----------------------
inure to the benefit of the Borrower, the Lenders, all future holders of the
Notes, the Agents and their respective successors and assigns, except that the
Borrower may not assign or transfer any of its rights hereunder or interests
herein without the prior written consent of all the Lenders and the
Administrative Agent, and any purported assignment without such consent shall be
void.

          (b)  Participations.  Any Lender may, in the ordinary course of its
               --------------
commercial banking business and in accordance with applicable Law, at any time
sell participations to one or more commercial banks or other Persons (each a
"Participant") in all or a portion of its rights and obligations under this
 -----------
Agreement and the other Loan Documents (including, without limitation, all or a
portion of its Commitment and the Loans owing to it and any Note held by it);
provided, that
--------

          (i)   any such Lender's obligations under this Agreement and the other
     Loan Documents shall remain unchanged,

          (ii)  such Lender shall remain solely responsible to the other parties
     hereto for the performance of such obligations,

          (iii) the parties hereto shall continue to deal solely and directly
     with such Lender in connection with such Lender's rights and obligations
     under this Agreement and each of the other Loan Documents,

          (iv)  such Participant shall be bound by the provisions of Section
     9.11, and

          (v)   no Participant (unless such Participant is an Affiliate of such
     Lender, or is itself a Lender) shall be entitled to require such Lender to
     take or refrain from taking action under this Agreement or under any other
     Loan Document, except that such Lender may

                                      -65-
<PAGE>

     agree with such Participant that such Lender will not, without such
     Participant's consent, take any action, or consent to the taking of any
     action, of the type described in Section 9.01(a), (b) or (c).

The Borrower agrees that any such Participant shall be entitled to the benefits
of Sections 2.12, 2.13, 2.14 and 9.04 with respect to its participation in the
Commitments and the Loans outstanding from time to time; provided, that no such
                                                         --------
Participant shall be entitled to receive any greater amount pursuant to such
Sections than the transferor Lender would have been entitled to receive in
respect of the amount of the participation transferred to such Participant had
no such transfer occurred.

          (c)   Assignments.  Any Lender may, in the ordinary course of its
                -----------
commercial banking business and in accordance with applicable Law, at any time
assign all or a portion of its rights and obligations under this Agreement and
the other Loan Documents (including, without limitation, all or any portion of
its Commitment and Loans owing to it and any Note held by it) to any Lender, any
Affiliate of a Lender or to one or more additional commercial banks or other
Persons (each a "Purchasing Lender"); provided, that
                 -----------------    --------

          (i)   any such assignment to a Purchasing Lender which is not a Lender
     or an affiliate of a Lender shall be made only with the consent (which in
     each case shall not be unreasonably withheld) of the Borrower (so long as
     no Default or Event of Default shall have occurred and be continuing) and
     the Administrative Agent;

          (ii)  if a Lender makes such an assignment of less than all of its
     then remaining rights and obligations under this Agreement and the other
     Loan Documents, such transferor Lender shall retain, after such assignment,
     a minimum principal amount of $10,000,000 of the Commitments and Loans then
     outstanding, and such assignment, unless made to an assignee who is a
     Lender hereunder prior to such assignment, shall be in a minimum principal
     amount of $10,000,000 of the Commitments and Loans then outstanding;

          (iii) each such assignment shall be of a constant, and not a varying,
     percentage of the Commitment of the transferor Lender and of all of the
     transferor Lender's rights and obligations under this Agreement and the
     other Loan Documents; and

          (iv)  each such assignment shall be made pursuant to an Assignment and
     Acceptance.

In order to effect any such assignment, the transferor Lender and the Purchasing
Lender shall execute and deliver to the Administrative Agent a duly completed
Assignment and Acceptance (including the consents required by clause (i) of the
preceding sentence) with respect to such assignment, together with any Note or
Notes subject to such assignment and a processing and recording fee of $3,500;
and, upon receipt thereof, the Administrative Agent shall accept such Assignment
and Acceptance.  Upon receipt of notice from the transferor Lender that it has
received the consideration described in the Assignment and Acceptance, the
Administrative Agent shall record such acceptance in the Register.  Upon such
execution, delivery, acceptance and recording, from and after the close of
business at the Administrative Agent's Office on the settlement date specified
in such Assignment and Acceptance:

                                      -66-
<PAGE>

          (x)  the Purchasing Lender shall be a party hereto and, to the extent
     provided in such Assignment and Acceptance, shall have the rights and
     obligations of a Lender hereunder, and

          (y)  the transferor Lender thereunder shall be released from its
     obligations under this Agreement to the extent so transferred (and, in the
     case of an Assignment and Acceptance covering all or the remaining portion
     of a transferor Lender's rights and obligations under this Agreement, such
     transferor Lender shall cease to be a party to this Agreement) from and
     after the settlement date.

On or prior to the settlement date specified in an Assignment and Acceptance,
the Borrower, at its expense, shall execute and deliver to the Administrative
Agent (for delivery to the Purchasing Lender) new Notes evidencing such
Purchasing Lender's assigned Commitment or Loans and (for delivery to the
transferor Lender) replacement Notes in the principal amount of the Loans or
Commitment retained by the transferor Lender (such Notes to be in exchange for,
but not in payment of, those Notes then held by such transferor Lender).  Each
such Note shall be dated the date and be substantially in the form of the
predecessor Note.  The Administrative Agent shall mark the predecessor Notes
"exchanged" and deliver them to the Borrower.  Accrued interest and accrued fees
shall be paid to the Purchasing Lender at the same time or times provided in the
predecessor Notes and this Agreement.

          (d)  Register. The Administrative Agent shall maintain at its office a
               --------
copy of each Assignment and Acceptance delivered to it and a register (the
"Register") for the recordation of the names and addresses of the Lenders and
 --------
the Commitment of, and principal amount of the Loans owing to, each Lender from
time to time.  The entries in the Register shall be conclusive absent manifest
error and the Borrower, the Administrative Agent and the Lenders may treat each
Person whose name is recorded in the Register as a Lender hereunder for all
purposes of the Agreement.  The Register shall be available for inspection by
the Borrower or any Lender at any reasonable time and from time to time upon
reasonable prior notice.

          (e)  Financial and Other Information.  The Borrower authorizes the
               -------------------------------
Administrative Agent and each Lender to disclose to any Participant or
Purchasing Lender (each, a "transferee") and any prospective transferee any and
                            ----------
all financial and other information in such Person's possession concerning the
Borrower and its Subsidiaries and Affiliates which has been or may be delivered
to such Person by or on behalf of the Borrower in connection with this Agreement
or any other Loan Document or such Person's credit evaluation of the Borrower
and its Subsidiaries and Affiliates.

          (f)  Assignments to Federal Reserve Bank.  Any Lender may at any time
               -----------------------------------
assign all or any portion of its rights under this Agreement, including without
limitation any Loans owing to it, and any Note held by it, to a Federal Reserve
Bank.  No such assignment shall relieve the transferor Lender from its
obligations hereunder.

          (g)  Special Purpose Funding Vehicles.  Notwithstanding anything to
               --------------------------------
the contrary contained herein, any Lender (a "Granting Lender") may grant to a
special purpose funding vehicle (an "SPC") the option to fund all or any part of
any Loan that such Granting

                                      -67-
<PAGE>

Lender would otherwise be obligated to fund pursuant to this Agreement; provided
                                                                        --------
that (i) nothing herein shall constitute a commitment by any SPC to fund any
Loan, and (ii) if an SPC elects not to exercise such option or otherwise fails
to fund all or any part of such Loan, the Granting Lender shall be obligated to
fund such Loan pursuant to the terms hereof. The funding of a Loan by an SPC
hereunder shall utilize the Revolving Credit Commitment of the Granting Lender
to the same extent, and as if, such Loan were funded by such Granting Lender.
Each party hereto hereby agrees that no SPC shall be liable for any indemnity or
payment under this Agreement for which a Lender would otherwise be liable for so
long as, and to the extent, the Granting Lender provides such indemnity or makes
such payment. Notwithstanding anything to the contrary contained in this
Agreement, any SPC may disclose on a confidential basis any non-public
information relating to its funding of Loans to any rating agency, commercial
paper dealer or provider of any surety or guarantee to such SPC. This Section
may not be amended without the prior written consent of each Granting Lender,
all or any part of whose Loan is being funded by an SPC at the time of such
amendment.

          SECTION 9.13  Governing Law; Submission to Jurisdiction Waiver of Jury
                        --------------------------------------------------------
Trial; Limitation of Liability.
------------------------------

          (a)  Governing Law.  THIS AGREEMENT AND ALL OTHER LOAN DOCUMENTS
               -------------
(EXCEPT TO THE EXTENT, IF ANY, OTHERWISE EXPRESSLY STATED IN SUCH OTHER LOAN
DOCUMENTS) SHALL BE GOVERNED BY, AND CONSTRUED AND ENFORCED IN ACCORDANCE WITH,
THE LAWS OF THE STATE OF NEW YORK, WITHOUT REGARD TO CHOICE OF LAW PRINCIPLES.

          (b)  Certain Waivers.  EACH PARTY TO THIS AGREEMENT HEREBY IRREVOCABLY
               ---------------
AND UNCONDITIONALLY:

          (i)  AGREES THAT ANY ACTION, SUIT OR PROCEEDING BY ANY PERSON ARISING
     FROM OR RELATING TO THIS AGREEMENT OR ANY OTHER LOAN DOCUMENT OR ANY
     STATEMENT, COURSE OF CONDUCT, ACT, OMISSION, OR EVENT OCCURRING IN
     CONNECTION HEREWITH OR THEREWITH (COLLECTIVELY, "RELATED LITIGATION") MAY
                                                      ------------------
     BE BROUGHT IN ANY STATE OR FEDERAL COURT OF COMPETENT JURISDICTION SITTING
     IN NEW YORK, NEW YORK AND SUBMITS TO THE JURISDICTION OF SUCH COURTS (AND,
     TO THE FULLEST EXTENT PERMITTED BY LAW, THE BORROWER AGREES THAT IT WILL
     NOT BRING ANY RELATED LITIGATION IN ANY OTHER FORUM, BUT NOTHING HEREIN
     SHALL AFFECT THE RIGHT OF THE ADMINISTRATIVE AGENT OR ANY LENDER TO BRING
     ANY ACTION, SUIT OR PROCEEDING IN ANY OTHER FORUM IN WHICH THE BORROWER OR
     ANY OF ITS ASSETS MAY BE LOCATED OR IN WHICH THE BORROWER MAY BE DOING
     BUSINESS OR THE RIGHT OF THE BORROWER TO ASSERT ANY DEFENSE OR COUNTERCLAIM
     TO ANY ACTION BROUGHT BY THE ADMINISTRATIVE AGENT OR ANY LENDER IN ANY
     FORUM);

          (ii) WAIVES ANY OBJECTION WHICH IT MAY HAVE AT ANY TIME TO THE LAYING
     OF VENUE OF ANY RELATED LITIGATION BROUGHT IN ANY

                                      -68-
<PAGE>

     SUCH COURT, WAIVES ANY CLAIM THAT ANY SUCH RELATED LITIGATION HAS BEEN
     BROUGHT IN AN INCONVENIENT FORUM, AND WAIVES ANY RIGHT TO OBJECT, WITH
     RESPECT TO ANY RELATED LITIGATION BROUGHT IN ANY SUCH COURT, THAT SUCH
     COURT DOES NOT HAVE JURISDICTION OVER IT;

          (iii) CONSENTS AND AGREES TO SERVICE OF ANY SUMMONS, COMPLAINT OR
     OTHER LEGAL PROCESS IN ANY RELATED LITIGATION BY REGISTERED OR CERTIFIED
     U.S. MAIL, POSTAGE PREPAID, TO IT AT THE ADDRESS FOR NOTICES DESCRIBED IN
     SECTION 9.03, AND CONSENTS AND AGREES THAT SUCH SERVICE SHALL CONSTITUTE IN
     EVERY RESPECT VALID AND EFFECTIVE SERVICE (BUT NOTHING HEREIN SHALL AFFECT
     THE VALIDITY OR EFFECTIVENESS OF PROCESS SERVED IN ANY OTHER MANNER
     PERMITTED BY LAW); AND

          (iv)  WAIVES THE RIGHT TO TRIAL BY JURY IN ANY RELATED LITIGATION.

          (c)   Limitation of Liability. TO THE FULLEST EXTENT PERMITTED BY LAW,
                -----------------------
NO CLAIM MAY BE MADE BY ANY PARTY TO THIS AGREEMENT AGAINST ANY OTHER PARTY TO
THIS AGREEMENT OR ANY AFFILIATE, DIRECTOR, OFFICER, EMPLOYEE, ATTORNEY OR AGENT
OF ANY OF THEM FOR ANY SPECIAL, INCIDENTAL, INDIRECT, CONSEQUENTIAL OR PUNITIVE
DAMAGES IN RESPECT OF ANY CLAIM ARISING FROM OR RELATING TO THIS AGREEMENT OR
ANY OTHER LOAN DOCUMENT OR ANY STATEMENT, COURSE OF CONDUCT, ACT, OMISSION, OR
EVENT OCCURRING IN CONNECTION HEREWITH OR THEREWITH (WHETHER FOR BREACH OF
CONTRACT, TORT OR ANY OTHER THEORY OF LIABILITY).  EACH PARTY TO THIS AGREEMENT
HEREBY WAIVES, RELEASES AND AGREES NOT TO SUE UPON ANY CLAIM FOR ANY SUCH
DAMAGES, WHETHER SUCH CLAIM PRESENTLY EXISTS OR ARISES HEREAFTER AND WHETHER OR
NOT SUCH CLAIM IS KNOWN OR SUSPECTED TO EXIST IN ITS FAVOR.

                             *         *         *

                                      -69-
<PAGE>

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

Address                                   SIERRA PACIFIC POWER COMPANY
-------                                   ----------------------------

Sierra Pacific Resources
6100 Neil Road
P.O. Box 30150                            By_______________________________
Reno, Nevada 89520                          Name:
Attn: Richard K. Atkinson                   Title:

                               -Signature Page-
                         Sierra Pacific Power Company
                               Credit Agreement
<PAGE>

Address                                MELLON BANK, N.A., as Administrative
-------                                  Agent, Arranger and as a Lender

Mellon Bank
One Mellon Center
Pittsburgh, Pennsylvania 15258
Attn: Richard A. Matthews              By______________________________
                                         Name:  Richard A. Matthews
                                         Title: First Vice President

                               -Signature Page-
                         Sierra Pacific Power Company
                               Credit Agreement
<PAGE>

Address                               BNP PARIBAS, as Syndication Agent
-------                                  and as a Lender

BNP Paribas
787 7/th/ Avenue
New York, New York 10019
Attn: Thomas Beaumont                 By_______________________________
                                        Name:
                                        Title:

                                      By_______________________________
                                        Name:
                                        Title:

                               -Signature Page-
                         Sierra Pacific Power Company
                               Credit Agreement
<PAGE>

Address                                     FIRST UNION NATIONAL BANK, as
-------                                       Syndication Agent and as a Lender

First Union National Bank
One First Union Center
201 South College Street, 17/th/ floor
Charlotte, North Carolina 28288-1183        By_______________________________
Attn: Chanue Michael                          Name:  Joe K. Dancy
                                              Title: Vice President

                               -Signature Page-
                         Sierra Pacific Power Company
                               Credit Agreement
<PAGE>

Address                                     WELLS FARGO BANK, N.A., as
-------                                       Syndication Agent and as a Lender

Wells Fargo Bank
201 Third Street
8/th/ Floor
San Francisco, California 94103             By_______________________________
Attn: Maria Cindy Dunn                        Name:
                                              Title:

                               -Signature Page-
                         Sierra Pacific Power Company
                               Credit Agreement
<PAGE>

Address
-------                                        LEHMAN COMMERCIAL PAPER INC.

3 World Financial Center 11/th/ Floor
New York, New York 10285
Attn:   Operations - Jennifer Laino           By_______________________________
        Credit - Michele Swanson                Name:
                                                Title:

                               -Signature Page-
                         Sierra Pacific Power Company
                               Credit Agreement
<PAGE>

Address                                 MERRILL LYNCH CAPITAL
-------                                   CORPORATION

4 World Financial Center
7/th/ Floor
New York, New York 10080
Attn:                                   By_______________________________
                                          Name:
                                          Title:

                               -Signature Page-
                         Sierra Pacific Power Company
                               Credit Agreement
<PAGE>

Address                                BANK ONE, N.A. (Main Office-Chicago)
-------

Bank One
One First National Plaza
Suite 0573
Chicago, Illinois                      By_______________________________
Attn:                                    Name:
                                         Title:

                               -Signature Page-
                         Sierra Pacific Power Company
                               Credit Agreement
<PAGE>

Address                                   BAYERISCHE LANDESBANK
-------                                     GIROZENTRALE

Bayerische Landesbank Girozentrale
560 Lexington Avenue
New York, New York 10022
Attn: Patricia Sanchez                    By_______________________________
                                            Name:
                                            Title:

                                          By________________________
                                            Name:
                                            Title:

                               -Signature Page-
                         Sierra Pacific Power Company
                               Credit Agreement
<PAGE>

Address                                      UNION BANK OF CALIFORNIA, N.A.
-------

Union Bank of California
Energy Capital Services - LA Office
445 South Figueroa Street                    By_______________________________
15/th/ Floor                                   Name:
Los Angeles, California 90071                  Title:
Attn Patricia A. Gonzales

                               -Signature Page-
                         Sierra Pacific Power Company
                               Credit Agreement
<PAGE>

                                                                      SCHEDULE I
                                                                      ----------

                                  Commitments
                                  -----------

               [See definitions of "Commitment" in Section 1.01]

LENDER                                  COMMITMENT AMOUNT
------                                  -----------------

Mellon Bank, N.A.                          $ 15,000,000

BNP Paribas                                $ 14,750,000

First Union National Bank                  $ 14,750,000

Wells Fargo Bank, N.A.                     $ 14,750,000

Lehman Commercial Paper Inc.               $ 14,750,000

Merrill Lynch                              $ 14,750,000

Bank One                                   $ 13,750,000

Bayerische Landesbank Girozentrale         $ 13,750,000

Union Bank of California, N.A.             $ 13,750,000

                     Total:                $130,000,000
<PAGE>

<TABLE>
<CAPTION>
                                                     TABLE OF CONTENTS
                                                     -----------------

                                                                                                                        Page
                                                                                                                        ----
<S>                                                                                                                     <C>
ARTICLE I              DEFINITIONS; CONSTRUCTION..............................................................             1

     SECTION 1.01  Defined Terms..............................................................................             1
     SECTION 1.02  Classification of Loans and Borrowings.....................................................            15
     SECTION 1.03  Terms Generally............................................................................            15
     SECTION 1.04  Accounting Terms; GAAP.....................................................................            15

ARTICLE II             THE CREDITS............................................................................            15

     SECTION 2.01  The Commitments............................................................................            15
     SECTION 2.02  Loans and Borrowings.......................................................................            15
     SECTION 2.03  Requests for Revolving Borrowings..........................................................            16
     SECTION 2.04  Funding of Borrowings......................................................................            17
     SECTION 2.05  Interest Elections.........................................................................            18
     SECTION 2.06  Termination, Reduction and Extension of Commitments........................................            19
     SECTION 2.07  Repayment of Loans; Evidence of Debt.......................................................            21
     SECTION 2.08  Prepayment of Loans........................................................................            22
     SECTION 2.09  Fees.......................................................................................            23
     SECTION 2.10  Interest...................................................................................            23
     SECTION 2.11  Alternate Rate of Interest.................................................................            24
     SECTION 2.12  Increased Costs............................................................................            24
     SECTION 2.13  Break Funding Payments.....................................................................            25
     SECTION 2.14  Taxes......................................................................................            26
     SECTION 2.15  Payments Generally; Pro Rata Treatment; Sharing of Set-offs................................            27
     SECTION 2.16  Mitigation Obligations; Replacement of Lenders.............................................            28

ARTICLE III            REPRESENTATIONS AND WARRANTIES.........................................................            29

     SECTION 3.01  Corporate Status...........................................................................            29
     SECTION 3.02  Corporate Power and Authorization..........................................................            30
     SECTION 3.03  Execution and Binding Effect...............................................................            30
     SECTION 3.04  Governmental Approvals and Filings.........................................................            30
     SECTION 3.05  Absence of Conflicts.......................................................................            30
     SECTION 3.06  Audited Financial Statements...............................................................            31
     SECTION 3.07  Interim Financial Statements...............................................................            31
     SECTION 3.08  Absence of Undisclosed Liabilities.........................................................            31
     SECTION 3.09  Absence of Material Adverse Change.........................................................            32
     SECTION 3.10  Accurate and Complete Disclosure...........................................................            32
     SECTION 3.11  Margin Regulations.........................................................................            32
     SECTION 3.12  Litigation.................................................................................            32
     SECTION 3.13  Absence of Events of Default...............................................................            32
</TABLE>

                                      (i)
<PAGE>

<TABLE>
                                                                                                                        Page
                                                                                                                        ----
<S>                                                                                                                     <C>
     SECTION 3.14  Absence of Other Conflicts.................................................................            33
     SECTION 3.15  Insurance..................................................................................            33
     SECTION 3.16  Title to Property; No Liens................................................................            33
     SECTION 3.17  Taxes......................................................................................            33
     SECTION 3.18  Borrower Not An Investment Company.........................................................            34
     SECTION 3.19  Environmental Matters......................................................................            34
     SECTION 3.20  ERISA......................................................................................            35
     SECTION 3.21  Pari Passu Status..........................................................................            36
     SECTION 3.22  Indebtedness...............................................................................            36

ARTICLE IV             CONDITIONS.............................................................................            36

     SECTION 4.01  Effective Date.............................................................................            36
     SECTION 4.02  Conditions to All Loans....................................................................            39

ARTICLE V              AFFIRMATIVE COVENANTS..................................................................            39

     SECTION 5.01  Basic Reporting Requirements...............................................................            39
     SECTION 5.02  Insurance..................................................................................            42
     SECTION 5.03  Payment of Taxes and Other Potential Charges and Priority Claims...........................            42
     SECTION 5.04  Preservation of Corporate Status and Franchises............................................            43
     SECTION 5.05  Governmental Approvals and Filings.........................................................            43
     SECTION 5.06  Maintenance of Properties..................................................................            43
     SECTION 5.07  Avoidance of Other Conflicts...............................................................            44
     SECTION 5.08  Financial Accounting Practices.............................................................            44
     SECTION 5.09  Use of Proceeds............................................................................            44
     SECTION 5.10  End of Fiscal Periods......................................................................            44

ARTICLE VI             NEGATIVE COVENANTS.....................................................................            45

     SECTION 6.01  Financial Covenants........................................................................            45
     SECTION 6.02  Liens......................................................................................            45
     SECTION 6.03  Mergers....................................................................................            46
     SECTION 6.04  Dispositions of Properties.................................................................            47
     SECTION 6.05  Investments and Acquisitions...............................................................            48
     SECTION 6.06  Dividends and Stock Repurchases............................................................            48
     SECTION 6.07  Transactions with Affiliates...............................................................            48
     SECTION 6.08  Change of Business.........................................................................            48
     SECTION 6.09  Equal and Ratable Lien; Grant of Security Interest in Certain Events.......................            49
     SECTION 6.10  Restrictive Agreements.....................................................................            50

ARTICLE VII            DEFAULTS...............................................................................            50

     SECTION 7.01  Events of Default..........................................................................            50
     SECTION 7.02  Consequences of an Event of Default........................................................            53

ARTICLE VIII           THE AGENTS.............................................................................            53
</TABLE>
                                     (ii)
<PAGE>

<TABLE>
                                                                                                                        Page
                                                                                                                        ----
<S>                                                                                                                     <C>
     SECTION 8.01  Appointment................................................................................            53
     SECTION 8.02  General Nature of Administrative Agent's Duties............................................            54
     SECTION 8.03  Exercise of Powers.........................................................................            54
     SECTION 8.04  General Exculpatory Provisions.............................................................            55
     SECTION 8.05  Administration by the Administrative Agent.................................................            55
     SECTION 8.06  Lenders Not Relying on Administrative Agent or Other Lenders...............................            56
     SECTION 8.07  Indemnification............................................................................            57
     SECTION 8.08  Administrative Agent in its Individual Capacity............................................            57
     SECTION 8.09  Holders of Notes...........................................................................            58
     SECTION 8.10  Successor Administrative Agent.............................................................            58
     SECTION 8.11  Additional Administrative Agents...........................................................            58
     SECTION 8.12  Calculations...............................................................................            59
     SECTION 8.13  Syndication Agents.........................................................................            59

ARTICLE IX    MISCELLANEOUS...................................................................................            59

     SECTION 9.01  Amendments and Waivers.....................................................................            59
     SECTION 9.02  No Implied Waiver; Cumulative Remedies.....................................................            60
     SECTION 9.03  Notices....................................................................................            61
     SECTION 9.04  Expenses; Taxes; Indemnity.................................................................            61
     SECTION 9.05  Severability...............................................................................            62
     SECTION 9.06  Prior Understandings.......................................................................            62
     SECTION 9.07  Duration; Survival.........................................................................            63
     SECTION 9.08  Counterparts...............................................................................            63
     SECTION 9.09  Limitation on Payments.....................................................................            63
     SECTION 9.10  Set-Off....................................................................................            63
     SECTION 9.11  Sharing of Collections.....................................................................            64
     SECTION 9.12  Successors and Assigns; Participations; Assignments........................................            64
     SECTION 9.13  Governing Law; Submission to Jurisdiction Waiver of Jury Trial; Limitation of Liability....            67

                                   SCHEDULES
                                   ---------

     Schedule I..........................COMMITMENTS
     Schedule II.........................JURISDICTIONS
     Schedule III........................LITIGATION
     Schedule IV.........................LIENS
     Schedule V..........................ENVIRONMENTAL CLAIMS
     Schedule VI.........................EXISTING INDEBTEDNESS

                                   EXHIBITS
                                   --------

     Exhibit A...........................FORM OF ASSIGNMENT AND ACCEPTANCE
</TABLE>
                                     (iii)
<PAGE>

<TABLE>
                                                                                   Page
                                                                                   ----
<S>                                                                                <C>
     Exhibit B...........................FORM OF BORROWING REQUEST
     Exhibit C...........................FORM OF PROMISSORY NOTE
     Exhibit D...........................FORM OF QUARTERLY COMPLIANCE CERTIFICATE
</TABLE>

                                     (iv)

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