<PAGE>

                                                                   EXHIBIT 10.13

                                                                  EXECUTION COPY

                                 THIRD AMENDMENT

                  THIRD AMENDMENT, dated as of June 16, 2003 (this "Amendment"),
to the Credit Agreement, dated as of March 8, 2002 (as amended, the "Credit
Agreement"), among CALPINE CORPORATION, a Delaware corporation (the "Borrower"),
the various financial institutions as are or may become parties thereto (the
"Lenders"), THE BANK OF NOVA SCOTIA, as joint administrative agent and funding
agent (in such capacity, the "Agent") and CITICORP USA, INC., as joint
administrative agent.

                  WHEREAS pursuant to the Credit Agreement, the Lenders have
made extensions of credit to the Borrower; and

                  WHEREAS the Borrower has requested that certain provisions of
the Credit Agreement be modified in the manner provided for in this Amendment,
and the Lenders are willing to agree to such modifications as provided for in
this Amendment.

                  NOW, THEREFORE, the parties hereto hereby agree as follows:

                  1. Defined Terms. Capitalized terms used and not defined
herein shall have the meanings given to them in the Credit Agreement, as amended
hereby.

                  2. Amendments to Credit Agreement. The definitions of
"Revolving Loan Commitment Termination Date" and "Stated Maturity Date" in
Section 1.1 of the Credit Agreement and Section 2.7(a) of the Credit Agreement
are hereby amended by deleting the reference to "June 16, 2003" in such
definitions and such Section 2.7(a) and by substituting in lieu thereof in each
case "July 16, 2003"; provided, that if, by 5:00 p.m. (New York time) on June
24, 2003, the Agent shall not have received a consent letter, in form and
substance satisfactory to the Agent, from the Borrower and each Revolving Lender
with respect to a new term sheet for the extension of the revolving credit
facilities (the date, if any, on which the Agent shall have received such
consent letters, the "Term Sheet Agreement Date"), the foregoing extension shall
automatically cease to be in effect and the reference to July 16, 2003 set forth
herein shall automatically become a reference to June 24, 2003.

                  3. Representations and Warranties. The Borrower hereby
represents and warrants to the Agent and the Lenders that, as of the date hereof
and after giving effect to the amendment contained herein:

                  (a) No Default or Event of Default has occurred and is
continuing.

                  (b) The execution, delivery and performance by the Borrower of
this Amendment has been duly authorized by all necessary corporate and other
action and does not and will not require any registration with, consent or
approval of, notice to or action by, any person in order to be effective and
enforceable. Each of this Amendment and the Credit Agreement as amended by this
Amendment constitutes the legal, valid and binding obligation of the Borrower,
enforceable against each in accordance with its terms, subject to applicable
bankruptcy, insolvency, fraudulent conveyance, reorganization, moratorium or
other laws affecting creditors'

<PAGE>

                                                                               2

rights generally and subject to general principles of equity, regardless of
whether considered in a proceeding in equity or at law.

                  (c) All representations and warranties of each Obligor set
forth in the Loan Documents as amended hereby are true and correct in all
material respects.

                  4. Covenants. The Borrower hereby agrees that during the
period commencing on the date hereof up to and including July 16, 2003 (the
"Extension Period"), the Borrower shall not take any action which could,
directly or indirectly, have a material adverse effect upon (i) the financial
condition, operations, assets (including power projects), business or prospects
of the Borrower and its Subsidiaries taken as a whole; or (ii) the ability of
the Borrower or any other Obligor to perform under any Loan Document. Without
prejudice to the foregoing, the Borrower shall ensure that, during the Extension
Period, (1) no Indebtedness is incurred, created, assumed or suffered to exist
by the Borrower or any of its Subsidiaries (except (A) Indebtedness under the
Loan Documents and the Loan Documents (as defined in the Existing Credit
Agreement), (B) unsecured Indebtedness incurred in the ordinary course of
business, other than Indebtedness of the type described in (1) clauses (a), (c)
or (f) of the definition of "Indebtedness" and (2) clauses (b) and (g) of the
definition of "Indebtedness" with respect to any Indebtedness described in
clause (1) above, (C) other unsecured Indebtedness or Non-Recourse Debt (as
defined in the Senior Note Indentures) incurred in the ordinary course of
business in connection with Indebtedness existing or contractually committed to
be made available as of the date hereof, and (D) Indebtedness outstanding on the
date hereof), and no guarantee, collateral or other credit support is provided,
and no Lien on the properties of the Borrower or any of its Subsidiaries is
created, incurred, assumed or granted, in each case in support of (x) any
Indebtedness (other than Indebtedness permitted above) or (y) any obligation
relating to any synthetic lease transaction of the Borrower or any Subsidiary of
the Borrower; (2) no amendment, modification or supplement is made to any
agreement or instrument evidencing any Indebtedness, other than amendments,
modifications or supplements entered into in the ordinary course of business in
respect of (A) the Credit Agreement or the Existing Credit Agreement, (B) any
agreement or instrument evidencing Non-Recourse Debt (as defined in the Senior
Note Indentures) of a Subsidiary of the Borrower, or (C) any agreement or
instrument evidencing Indebtedness other than Indebtedness of the type described
in (1) clauses (a), (c) or (f) of the definition of "Indebtedness" and (2)
clauses (b) and (g) of the definition of "Indebtedness" with respect to any
Indebtedness described in clause (1) above (the Indebtedness described in
clauses (B) and (C) being collectively referred to as "Excluded Indebtedness");
(3) no optional prepayment is made on, or purchase or optional redemption is
executed of, any Indebtedness other than Excluded Indebtedness (including,
without limitation, any buy-back or defeasance of any outstanding bonds,
puttable convertible bonds or other securities of the Borrower or any of its
Subsidiaries), it being understood and agreed that, during the Extension Period,
neither the Borrower or any of its Subsidiaries shall obtain or receive any such
Indebtedness (or instruments evidencing same) in consideration of the sale or
other transfer of any assets or properties thereof; provided, that
notwithstanding anything to the contrary contained herein or in the Credit
Agreement, at any time after the Term Sheet Agreement Date, the Borrower shall
be permitted to repurchase notes issued by Calpine Canada Energy Finance II, ULC
for an aggregate purchase amount not to exceed US$50,000,000; (4) no Investment
is made by the Borrower or any of its Subsidiaries in any other Person (except
(A) Investments by the Borrower in the ordinary course of business in
Subsidiaries the equity in which has been pledged to the Lenders, and each of
their respective Subsidiaries, (B)

<PAGE>

                                                                               3

Investments by the Borrower in other Persons pursuant to contractual commitments
existing as of the date hereof, and (C) Investments by the Borrower in CES in
support of transactions entered into by CES in the ordinary course of CES's
business, consistent with historical practices); and (5) all transactions
between any one or more of the Borrower and its Affiliates entered into during
the Extension Period are on terms that are fair and reasonable and similar to
those found in a comparable arm's length transaction with a Person that is not
an Affiliate of the Borrower. Notwithstanding the foregoing, it is agreed that
(x) the Borrower and its Subsidiaries may effectuate the transactions referred
to in Schedule I attached to the letter from the Borrower to the Lenders dated
May 20, 2003 and (y) none of the prohibitions contained in this Section 4 shall
be applicable insofar as they would otherwise constitute an encumbrance or
restriction in violation of Section 3.5 of the Pre-2000 Indentures. The
provisions of this Section 4 may be amended, modified or waived, if such
amendment, modification or waiver is in writing and consented to by the Borrower
and Lenders owed or holding at least 51% of the aggregate Revolving Loan
Commitments and Commitments under the Credit Agreement and the Existing Credit
Agreement, respectively (it being understood, however, that no such amendment,
modification or waiver shall amend, modify or waive the provisions of the Credit
Agreement unless such amendment, modification or waiver satisfies the
requirements of Section 11.1 of the Credit Agreement).

                  5. Conditions Precedent to Effectiveness. This Amendment shall
become effective as of the date hereof upon (i) the Agent having received
counterparts hereof duly executed and delivered by the Borrower, the Required
Lenders and each Revolving Lender and (ii) the Seventh Amendment, dated as of
the date hereof, to the Existing Credit Agreement becoming effective in
accordance with its terms.

                  6. No Other Amendments. Except as expressly amended hereby,
the provisions of the Credit Agreement are and shall remain in full force and
effect.

                  7. Expenses. The Borrower agrees to pay or reimburse the Agent
for its out-of-pocket expenses in connection with this Amendment, including the
reasonable fees, charges and disbursements of counsel to the Agent.

                  8. Governing Law; Counterparts. (a) This Amendment and the
rights and obligations of the parties hereto shall be governed by, and construed
and interpreted in accordance with, the laws of the State of New York.

                  (b) This Amendment may be executed by one or more of the
parties to this Amendment on any number of separate counterparts, and all of
said counterparts taken together shall be deemed to constitute one and the same
instrument. This Amendment may be delivered by facsimile transmission of the
relevant signature pages hereof.

<PAGE>

                  IN WITNESS WHEREOF, the Borrower and the Lenders have caused
this Amendment to be duly executed by their respective authorized officers as of
the day and year first above written.

                                    CALPINE CORPORATION

                                    By   /s/ ROBERT D. KELLY
                                       -----------------------------------------
                                       Name: Robert D. Kelly
                                       Title: Chief Financial Officer

<PAGE>

                                    THE BANK OF NOVA SCOTIA, as Agent and Lender

                                    By   /s/ DENIS P. O'MEARA
                                       -----------------------------------------
                                       Name: Denis P. O'Meara
                                       Title: Managing Director

<PAGE>

                                    Signature page to the Third Amendment, dated
                                    as of June 16, 2003, to the Credit
                                    Agreement, dated as of March 8, 2002, as
                                    amended, among Calpine Corporation, the
                                    various financial institutions as are or may
                                    become parties thereto, The Bank of Nova
                                    Scotia and Citicorp USA, Inc., as joint
                                    administrative agents.

                                    BANK OF AMERICA, NA

                                    By   /s/ THOMAS BIAGGI
                                       --------------------------------
                                       Name: Thomas Biaggi
                                       Title: Managing Director

<PAGE>

                                    Signature page to the Third Amendment, dated
                                    as of June 16, 2003, to the Credit
                                    Agreement, dated as of March 8, 2002, as
                                    amended, among Calpine Corporation, the
                                    various financial institutions as are or may
                                    become parties thereto, The Bank of Nova
                                    Scotia and Citicorp USA, Inc., as joint
                                    administrative agents.

                                    CREDIT SUISSE FIRST BOSTON

                                    By /s/ JAMES P. MORAN
                                       -----------------------------------------
                                       Name: James P. Moran
                                       Title: Director

                                    By /s/ JAY CHALL
                                       -----------------------------------------
                                       Name: Jay Chall
                                       Title: Director

<PAGE>

                                    Signature page to the Third Amendment, dated
                                    as of June 16, 2003, to the Credit
                                    Agreement, dated as of March 8, 2002, as
                                    amended, among Calpine Corporation, the
                                    various financial institutions as are or may
                                    become parties thereto, The Bank of Nova
                                    Scotia and Citicorp USA, Inc., as joint
                                    administrative agents.

                                    BAYERISCHE LANDESBANK
                                    Cayman Islands Branch

                                    By   /s/ DIETMAR RIEG
                                       -----------------------------------------
                                       Name: Dietmar Rieg
                                       Title: First Vice President

                                    By   /s/ JAMES H. BOYLE
                                       --------------------------------
                                       Name: James H. Boyle
                                       Title: Vice President

<PAGE>

                                    Signature page to the Third Amendment, dated
                                    as of June 16, 2003, to the Credit
                                    Agreement, dated as of March 8, 2002, as
                                    amended, among Calpine Corporation, the
                                    various financial institutions as are or may
                                    become parties thereto, The Bank of Nova
                                    Scotia and Citicorp USA, Inc., as joint
                                    administrative agents.

                                    CITICORP USA, INC.

                                    By   /s/ ANTHONY MURPHY
                                       -----------------------------------------
                                       Name: Anthony Murphy
                                       Title: Managing Director

<PAGE>

                                    Signature page to the Third Amendment, dated
                                    as of June 16, 2003, to the Credit
                                    Agreement, dated as of March 8, 2002, as
                                    amended, among Calpine Corporation, the
                                    various financial institutions as are or may
                                    become parties thereto, The Bank of Nova
                                    Scotia and Citicorp USA, Inc., as joint
                                    administrative agents.

                                    DEUTSCHE BANK TRUST COMPANY AMERICAS

                                    By   /s/ MARCUS TARKINGTON
                                       -----------------------------------------
                                       Name: Marcus Tarkington
                                       Title: Director

<PAGE>

                                    Signature page to the Third Amendment, dated
                                    as of June 16, 2003, to the Credit
                                    Agreement, dated as of March 8, 2002, as
                                    amended, among Calpine Corporation, the
                                    various financial institutions as are or may
                                    become parties thereto, The Bank of Nova
                                    Scotia and Citicorp USA, Inc., as joint
                                    administrative agents.

                                    ING CAPITAL LLC

                                    By   /s/ STEPHEN E. FISCHER
                                       -----------------------------------------
                                       Name: Stephen E. Fischer
                                       Title: Managing Director

                                    By   /s/ G.D. BELLAMY, JR.
                                       -----------------------------------------
                                       Name: G.D. Bellamy, Jr.
                                       Title: Director

<PAGE>

                                    Signature page to the Third Amendment, dated
                                    as of June 16, 2003, to the Credit
                                    Agreement, dated as of March 8, 2002, as
                                    amended, among Calpine Corporation, the
                                    various financial institutions as are or may
                                    become parties thereto, The Bank of Nova
                                    Scotia and Citicorp USA, Inc., as joint
                                    administrative agents.

                                    TORONTO DOMINION (TEXAS) INC.

                                    By   /s/ LYNN CHASIN
                                       --------------------------------
                                       Name: Lynn Chasin
                                       Title: Vice President

<PAGE>

                                    Signature page to the Third Amendment, dated
                                    as of June 16, 2003, to the Credit
                                    Agreement, dated as of March 8, 2002, as
                                    amended, among Calpine Corporation, the
                                    various financial institutions as are or may
                                    become parties thereto, The Bank of Nova
                                    Scotia and Citicorp USA, Inc., as joint
                                    administrative agents.

                                    LANDMARK CDO LIMITED
                                    By:  Aladdin Capital Management LLC,
                                         as Manager

                                    By   /s/ JOSEPH MORONEY
                                       -----------------------------------------
                                       Name: Joseph Moroney, CFA
                                       Title: Authorized Signatory

<PAGE>

                                    Signature page to the Third Amendment, dated
                                    as of June 16, 2003, to the Credit
                                    Agreement, dated as of March 8, 2002, as
                                    amended, among Calpine Corporation, the
                                    various financial institutions as are or may
                                    become parties thereto, The Bank of Nova
                                    Scotia and Citicorp USA, Inc., as joint
                                    administrative agents.

                                    LANDMARK II CDO LIMITED
                                    By:  Aladdin Capital Management LLC,
                                         as Manager

                                    By   /s/ JOSEPH MORONEY
                                       -----------------------------------------
                                       Name: Joseph Moroney, CFA
                                       Title: Authorized Signatory

<PAGE>

                                    Signature page to the Third Amendment, dated
                                    as of June 16, 2003, to the Credit
                                    Agreement, dated as of March 8, 2002, as
                                    amended, among Calpine Corporation, the
                                    various financial institutions as are or may
                                    become parties thereto, The Bank of Nova
                                    Scotia and Citicorp USA, Inc., as joint
                                    administrative agents.

                                    AMMC CDO I, LIMITED
                                    By:  American Money Management Corp.,
                                         as Collateral Manager

                                    By   /s/ DAVID P. MEYER
                                       -----------------------------------------
                                       Name: David P. Meyer
                                       Title: Vice President

<PAGE>

                                    Signature page to the Third Amendment, dated
                                    as of June 16, 2003, to the Credit
                                    Agreement, dated as of March 8, 2002, as
                                    amended, among Calpine Corporation, the
                                    various financial institutions as are or may
                                    become parties thereto, The Bank of Nova
                                    Scotia and Citicorp USA, Inc., as joint
                                    administrative agents.

                                    AMMC CDO II, LIMITED
                                    By:  American Money Management Corp.,
                                         as Collateral Manager

                                    By   /s/ DAVID P. MEYER
                                       -----------------------------------------
                                       Name: David P. Meyer
                                       Title: Vice President

<PAGE>

                                    Signature page to the Third Amendment, dated
                                    as of June 16, 2003, to the Credit
                                    Agreement, dated as of March 8, 2002, as
                                    amended, among Calpine Corporation, the
                                    various financial institutions as are or may
                                    become parties thereto, The Bank of Nova
                                    Scotia and Citicorp USA, Inc., as joint
                                    administrative agents.

                                    WINGED FOOT FUNDING TRUST

                                    By   /s/ DIANA M. HIMES
                                       -----------------------------------------
                                       Name: Diana M. Himes
                                       Title: Authorized Agent

<PAGE>

                                    Signature page to the Third Amendment, dated
                                    as of June 16, 2003, to the Credit
                                    Agreement, dated as of March 8, 2002, as
                                    amended, among Calpine Corporation, the
                                    various financial institutions as are or may
                                    become parties thereto, The Bank of Nova
                                    Scotia and Citicorp USA, Inc., as joint
                                    administrative agents.

                                    JUPITER FUNDING TRUST

                                    By   /s/ DIANA M. HIMES
                                       -----------------------------------------
                                       Name: Diana M. Himes
                                       Title: Authorized Agent

<PAGE>

                                    Signature page to the Third Amendment, dated
                                    as of June 16, 2003, to the Credit
                                    Agreement, dated as of March 8, 2002, as
                                    amended, among Calpine Corporation, the
                                    various financial institutions as are or may
                                    become parties thereto, The Bank of Nova
                                    Scotia and Citicorp USA, Inc., as joint
                                    administrative agents.

                                    SRF 2000, INC.

                                    By   /s/ DIANA M. HIMES
                                       -----------------------------------------
                                       Name: Diana M. Himes
                                       Title: Assistant Vice President

<PAGE>

                                    Signature page to the Third Amendment, dated
                                    as of June 16, 2003, to the Credit
                                    Agreement, dated as of March 8, 2002, as
                                    amended, among Calpine Corporation, the
                                    various financial institutions as are or may
                                    become parties thereto, The Bank of Nova
                                    Scotia and Citicorp USA, Inc., as joint
                                    administrative agents.

                                    SRF TRADING, INC.

                                    By   /s/ DIANA M. HIMES
                                       -----------------------------------------
                                       Name: Diana M. Himes
                                       Title: Assistant Vice President

<PAGE>

                                    Signature page to the Third Amendment, dated
                                    as of June 16, 2003, to the Credit
                                    Agreement, dated as of March 8, 2002, as
                                    amended, among Calpine Corporation, the
                                    various financial institutions as are or may
                                    become parties thereto, The Bank of Nova
                                    Scotia and Citicorp USA, Inc., as joint
                                    administrative agents.

                                    STANWICH LOAN FUNDING LLC

                                    By   /s/ DIANA M. HIMES
                                       -----------------------------------------
                                       Name: Diana M. Himes
                                       Title: Assistant Vice President

<PAGE>

                                    Signature page to the Third Amendment, dated
                                    as of June 16, 2003, to the Credit
                                    Agreement, dated as of March 8, 2002, as
                                    amended, among Calpine Corporation, the
                                    various financial institutions as are or may
                                    become parties thereto, The Bank of Nova
                                    Scotia and Citicorp USA, Inc., as joint
                                    administrative agents.

                                    RIVIERA FUNDING LLC

                                    By   /s/ DIANA M. HIMES
                                       -----------------------------------------
                                       Name: Diana M. Himes
                                       Title: Assistant Vice President

<PAGE>

                                    Signature page to the Third Amendment, dated
                                    as of June 16, 2003, to the Credit
                                    Agreement, dated as of March 8, 2002, as
                                    amended, among Calpine Corporation, the
                                    various financial institutions as are or may
                                    become parties thereto, The Bank of Nova
                                    Scotia and Citicorp USA, Inc., as joint
                                    administrative agents.

                                    BH FINANCE LLC

                                    By   /s/ MARK D. MILLARD
                                       -----------------------------------------
                                       Name: Mark D. Millard
                                       Title: Authorized Signatory

<PAGE>

                                    Signature page to the Third Amendment, dated
                                    as of June 16, 2003, to the Credit
                                    Agreement, dated as of March 8, 2002, as
                                    amended, among Calpine Corporation, the
                                    various financial institutions as are or may
                                    become parties thereto, The Bank of Nova
                                    Scotia and Citicorp USA, Inc., as joint
                                    administrative agents.

                                    FIRST DOMINION FUNDING I

                                    By   /s/ DAVID H. LERNER
                                       -----------------------------------------
                                       Name: David H. Lerner
                                       Title: Authorized Signatory

<PAGE>

                                    Signature page to the Third Amendment, dated
                                    as of June 16, 2003, to the Credit
                                    Agreement, dated as of March 8, 2002, as
                                    amended, among Calpine Corporation, the
                                    various financial institutions as are or may
                                    become parties thereto, The Bank of Nova
                                    Scotia and Citicorp USA, Inc., as joint
                                    administrative agents.

                                    FIRST DOMINION FUNDING II

                                    By   /s/ DAVID H. LERNER
                                       -----------------------------------------
                                       Name: David H. Lerner
                                       Title: Authorized Signatory

<PAGE>

                                    Signature page to the Third Amendment, dated
                                    as of June 16, 2003, to the Credit
                                    Agreement, dated as of March 8, 2002, as
                                    amended, among Calpine Corporation, the
                                    various financial institutions as are or may
                                    become parties thereto, The Bank of Nova
                                    Scotia and Citicorp USA, Inc., as joint
                                    administrative agents.

                                    FIRST DOMINION FUNDING III

                                    By   /s/ DAVID H. LERNER
                                       -----------------------------------------
                                       Name: David H. Lerner
                                       Title: Authorized Signatory

<PAGE>

                                    Signature page to the Third Amendment, dated
                                    as of June 16, 2003, to the Credit
                                    Agreement, dated as of March 8, 2002, as
                                    amended, among Calpine Corporation, the
                                    various financial institutions as are or may
                                    become parties thereto, The Bank of Nova
                                    Scotia and Citicorp USA, Inc., as joint
                                    administrative agents.

                                    CSAM FUNDING I

                                    By   /s/ DAVID H. LERNER
                                       -----------------------------------------
                                       Name: David H. Lerner
                                       Title: Authorized Signatory

<PAGE>

                                    Signature page to the Third Amendment, dated
                                    as of June 16, 2003, to the Credit
                                    Agreement, dated as of March 8, 2002, as
                                    amended, among Calpine Corporation, the
                                    various financial institutions as are or may
                                    become parties thereto, The Bank of Nova
                                    Scotia and Citicorp USA, Inc., as joint
                                    administrative agents.

                                    CSAM FUNDING II

                                    By   /s/ DAVID H. LERNER
                                       -----------------------------------------
                                       Name: David H. Lerner
                                       Title: Authorized Signatory

<PAGE>

                                    Signature page to the Third Amendment, dated
                                    as of June 16, 2003, to the Credit
                                    Agreement, dated as of March 8, 2002, as
                                    amended, among Calpine Corporation, the
                                    various financial institutions as are or may
                                    become parties thereto, The Bank of Nova
                                    Scotia and Citicorp USA, Inc., as joint
                                    administrative agents.

                                    ATRIUM CDO

                                    By   /s/ DAVID H. LERNER
                                       -----------------------------------------
                                       Name: David H. Lerner
                                       Title: Authorized Signatory

<PAGE>

                                    Signature page to the Third Amendment, dated
                                    as of June 16, 2003, to the Credit
                                    Agreement, dated as of March 8, 2002, as
                                    amended, among Calpine Corporation, the
                                    various financial institutions as are or may
                                    become parties thereto, The Bank of Nova
                                    Scotia and Citicorp USA, Inc., as joint
                                    administrative agents.

                                    CONNECTICUT GENERAL LIFE
                                    INSURANCE COMPANY
                                    By:  CIGNA Investments, Inc.

                                    By   /s/ JOHN P. CONNOR
                                       -----------------------------------------
                                       Name: John P. Connor
                                       Title: Managing Director

<PAGE>

                                    Signature page to the Third Amendment, dated
                                    as of June 16, 2003, to the Credit
                                    Agreement, dated as of March 8, 2002, as
                                    amended, among Calpine Corporation, the
                                    various financial institutions as are or may
                                    become parties thereto, The Bank of Nova
                                    Scotia and Citicorp USA, Inc., as joint
                                    administrative agents.

                                    GOLDMAN SACHS CREDIT
                                    PARTNERS, L.P.

                                    By   /s/ SANDRA STULBERGER
                                       --------------------------------
                                       Name: Sandra Stulberger
                                       Title: Authorized Signatory

<PAGE>

                                    Signature page to the Third Amendment, dated
                                    as of June 16, 2003, to the Credit
                                    Agreement, dated as of March 8, 2002, as
                                    amended, among Calpine Corporation, the
                                    various financial institutions as are or may
                                    become parties thereto, The Bank of Nova
                                    Scotia and Citicorp USA, Inc., as joint
                                    administrative agents.

                                    INDOSUEZ CAPITAL FUNDING VI, LIMITED
                                    By:  Indosuez Capital as Collateral Manager

                                    By   /s/ CHARLES KOBAYASHI
                                       -----------------------------------------
                                       Name: Charles Kobayashi
                                       Title: Principal and Portfolio Manager

<PAGE>

                                    Signature page to the Third Amendment, dated
                                    as of June 16, 2003, to the Credit
                                    Agreement, dated as of March 8, 2002, as
                                    amended, among Calpine Corporation, the
                                    various financial institutions as are or may
                                    become parties thereto, The Bank of Nova
                                    Scotia and Citicorp USA, Inc., as joint
                                    administrative agents.

                                    ENDURANCE CLO I, LTD.
                                    By:  ING Capital Advisors LLC,
                                         as Collateral Manager

                                    By   /s/ GORDON R. COOK
                                       -----------------------------------------
                                       Name: Gordon R. Cook
                                       Title: Managing Director

                                    ARCHIMEDES FUNDING III, LTD.
                                    By:  ING Capital Advisors LLC,
                                         as Collateral Manager

                                    By   /s/ GORDON R. COOK
                                       -----------------------------------------
                                       Name: Gordon R. Cook
                                       Title: Managing Director

                                    ARCHIMEDES FUNDING IV (CAYMAN)
                                    LTD.
                                    By:  ING Capital Advisors LLC,
                                         as Collateral Manager

                                    By   /s/ GORDON R. COOK
                                       -----------------------------------------
                                       Name: Gordon R. Cook
                                       Title: Managing Director

<PAGE>

                                    BALANCED HIGH-YIELD FUND II
                                    LTD.
                                    By:  ING Capital Advisors LLC,
                                         as Asset Manager

                                    By   /s/ GORDON R. COOK
                                       -----------------------------------------
                                       Name: Gordon R. Cook
                                       Title: Managing Director

                                    SEQUILS-ING I (HBDGM), LTD.
                                    By:  ING Capital Advisors LLC,
                                         as Collateral Manager

                                    By   /s/ GORDON R. COOK
                                       -----------------------------------------
                                       Name: Gordon R. Cook
                                       Title: Managing Director

                                    NEMEAN CLO, LTD.
                                    By:  ING Capital Advisors LLC,
                                         as Investment Manager

                                    By   /s/ GORDON R. COOK
                                       -----------------------------------------
                                       Name: Gordon R. Cook
                                       Title: Managing Director

                                    ING-ORYX CLO, LTD.
                                    By:  ING Capital Advisors LLC,
                                         as Collateral Manager

                                    By   /s/ GORDON R. COOK
                                       -----------------------------------------
                                       Name: Gordon R. Cook
                                       Title: Managing Director

<PAGE>

                                    Signature page to the Third Amendment, dated
                                    as of June 16, 2003, to the Credit
                                    Agreement, dated as of March 8, 2002, as
                                    amended, among Calpine Corporation, the
                                    various financial institutions as are or may
                                    become parties thereto, The Bank of Nova
                                    Scotia and Citicorp USA, Inc., as joint
                                    administrative agents.

                                    KZH CNC LLC

                                    By   /s/ DORIAN HERRERA
                                       -----------------------------------------
                                       Name: Dorian Herrera
                                       Title: Authorized Agent

<PAGE>

                                    Signature page to the Third Amendment, dated
                                    as of June 16, 2003, to the Credit
                                    Agreement, dated as of March 8, 2002, as
                                    amended, among Calpine Corporation, the
                                    various financial institutions as are or may
                                    become parties thereto, The Bank of Nova
                                    Scotia and Citicorp USA, Inc., as joint
                                    administrative agents.

                                    KZH PONDVIEW LLC

                                    By   /s/ DORIAN HERRERA
                                       -----------------------------------------
                                       Name: Dorian Herrera
                                       Title: Authorized Agent

<PAGE>

                                    Signature page to the Third Amendment, dated
                                    as of June 16, 2003, to the Credit
                                    Agreement, dated as of March 8, 2002, as
                                    amended, among Calpine Corporation, the
                                    various financial institutions as are or may
                                    become parties thereto, The Bank of Nova
                                    Scotia and Citicorp USA, Inc., as joint
                                    administrative agents.

                                    KZH RIVERSIDE LLC

                                    By   /s/ DORIAN HERRERA
                                       -----------------------------------------
                                       Name: Dorian Herrera
                                       Title: Authorized Agent

<PAGE>

                                    Signature page to the Third Amendment, dated
                                    as of June 16, 2003, to the Credit
                                    Agreement, dated as of March 8, 2002, as
                                    amended, among Calpine Corporation, the
                                    various financial institutions as are or may
                                    become parties thereto, The Bank of Nova
                                    Scotia and Citicorp USA, Inc., as joint
                                    administrative agents.

                                    KZH SOLEIL LLC

                                    By   /s/ DORIAN HERRERA
                                       -----------------------------------------
                                       Name: Dorian Herrera
                                       Title: Authorized Agent

<PAGE>

                                    Signature page to the Third Amendment, dated
                                    as of June 16, 2003, to the Credit
                                    Agreement, dated as of March 8, 2002, as
                                    amended, among Calpine Corporation, the
                                    various financial institutions as are or may
                                    become parties thereto, The Bank of Nova
                                    Scotia and Citicorp USA, Inc., as joint
                                    administrative agents.

                                    KZH SOLEIL-2 LLC

                                    By   /s/ DORIAN HERRERA
                                       -----------------------------------------
                                       Name: Dorian Herrera
                                       Title: Authorized Agent

<PAGE>

                                    Signature page to the Third Amendment, dated
                                    as of June 16, 2003, to the Credit
                                    Agreement, dated as of March 8, 2002, as
                                    amended, among Calpine Corporation, the
                                    various financial institutions as are or may
                                    become parties thereto, The Bank of Nova
                                    Scotia and Citicorp USA, Inc., as joint
                                    administrative agents.

                                    KZH WATERSIDE LLC

                                    By   /s/ DORIAN HERRERA
                                       -----------------------------------------
                                       Name: Dorian Herrera
                                       Title: Authorized Agent

<PAGE>

                                    Signature page to the Third Amendment, dated
                                    as of June 16, 2003, to the Credit
                                    Agreement, dated as of March 8, 2002, as
                                    amended, among Calpine Corporation, the
                                    various financial institutions as are or may
                                    become parties thereto, The Bank of Nova
                                    Scotia and Citicorp USA, Inc., as joint
                                    administrative agents.

                                    MASTER SENIOR FLOATING RATE TRUST

                                    By   /s/ JAIMIN PATEL
                                       -----------------------------------------
                                       Name: Jaimin Patel
                                       Title: Authorized Signatory

<PAGE>

                                    Signature page to the Third Amendment, dated
                                    as of June 16, 2003, to the Credit
                                    Agreement, dated as of March 8, 2002, as
                                    amended, among Calpine Corporation, the
                                    various financial institutions as are or may
                                    become parties thereto, The Bank of Nova
                                    Scotia and Citicorp USA, Inc., as joint
                                    administrative agents.

                                    SENIOR HIGH INCOME PORTFOLIO, INC.

                                    By   /s/ JAIMIN PATEL
                                       -----------------------------------------
                                       Name: Jaimin Patel
                                       Title: Authorized Signatory

<PAGE>

                                    Signature page to the Third Amendment, dated
                                    as of June 16, 2003, to the Credit
                                    Agreement, dated as of March 8, 2002, as
                                    amended, among Calpine Corporation, the
                                    various financial institutions as are or may
                                    become parties thereto, The Bank of Nova
                                    Scotia and Citicorp USA, Inc., as joint
                                    administrative agents.

                                    MERRILL LYNCH PRIME RATE PORTFOLIO
                                    By:  Merrill Lynch Investment Managers, L.P.
                                         as Investment Advisor

                                    By   /s/ JAIMIN PATEL
                                       -----------------------------------------
                                       Name: Jaimin Patel
                                       Title: Authorized Signatory

<PAGE>

                                    Signature page to the Third Amendment, dated
                                    as of June 16, 2003, to the Credit
                                    Agreement, dated as of March 8, 2002, as
                                    amended, among Calpine Corporation, the
                                    various financial institutions as are or may
                                    become parties thereto, The Bank of Nova
                                    Scotia and Citicorp USA, Inc., as joint
                                    administrative agents.

                                    DEBT STRATEGIES FUND, INC.

                                    By   /s/ JAIMIN PATEL
                                       -----------------------------------------
                                       Name: Jaimin Patel
                                       Title: Authorized Signatory

<PAGE>

                                    Signature page to the Third Amendment, dated
                                    as of June 16, 2003, to the Credit
                                    Agreement, dated as of March 8, 2002, as
                                    amended, among Calpine Corporation, the
                                    various financial institutions as are or may
                                    become parties thereto, The Bank of Nova
                                    Scotia and Citicorp USA, Inc., as joint
                                    administrative agents.

                                    LONGHORN CDO II, LTD.
                                    By:  Merrill Lynch Investment Managers, L.P.
                                         as Investment Manager

                                    By   /s/ JAIMIN PATEL
                                       -----------------------------------------
                                       Name: Jaimin Patel
                                       Title: Authorized Signatory

<PAGE>

                                    Signature page to the Third Amendment, dated
                                    as of June 16, 2003, to the Credit
                                    Agreement, dated as of March 8, 2002, as
                                    amended, among Calpine Corporation, the
                                    various financial institutions as are or may
                                    become parties thereto, The Bank of Nova
                                    Scotia and Citicorp USA, Inc., as joint
                                    administrative agents.

                                    LONGHORN CDO (Cayman) LTD
                                    By:  Merrill Lynch Investment Managers, L.P.
                                         as Investment Advisor

                                    By   /s/ JAIMIN PATEL
                                       -----------------------------------------
                                       Name: Jaimin Patel
                                       Title: Authorized Signatory

<PAGE>

                                    Signature page to the Third Amendment, dated
                                    as of June 16, 2003, to the Credit
                                    Agreement, dated as of March 8, 2002, as
                                    amended, among Calpine Corporation, the
                                    various financial institutions as are or may
                                    become parties thereto, The Bank of Nova
                                    Scotia and Citicorp USA, Inc., as joint
                                    administrative agents.

                                    LONGHORN CDO III, LTD.
                                    By:  Merrill Lynch Investment Managers, L.P.
                                         as Investment Advisor

                                    By   /s/ JAIMIN PATEL
                                       -----------------------------------------
                                       Name: Jaimin Patel
                                       Title: Authorized Signatory

<PAGE>

                                    Signature page to the Third Amendment, dated
                                    as of June 16, 2003, to the Credit
                                    Agreement, dated as of March 8, 2002, as
                                    amended, among Calpine Corporation, the
                                    various financial institutions as are or may
                                    become parties thereto, The Bank of Nova
                                    Scotia and Citicorp USA, Inc., as joint
                                    administrative agents.

                                    MERRILL LYNCH GLOBAL INVESTMENT SERIES:
                                    INCOME STRATEGIES PORTFOLIO
                                    By:  Merrill Lynch Investment Managers, L.P.
                                         as Investment Advisor

                                    By   /s/ JAIMIN PATEL
                                       -----------------------------------------
                                       Name: Jaimin Patel
                                       Title: Authorized Signatory

<PAGE>

                                    Signature page to the Third Amendment, dated
                                    as of June 16, 2003, to the Credit
                                    Agreement, dated as of March 8, 2002, as
                                    amended, among Calpine Corporation, the
                                    various financial institutions as are or may
                                    become parties thereto, The Bank of Nova
                                    Scotia and Citicorp USA, Inc., as joint
                                    administrative agents.

                                    MERRILL LYNCH GLOBAL INVESTMENT SERIES:
                                    BANK LOAN INCOME PORTFOLIO
                                    By:  Merrill Lynch Investment Managers, L.P.
                                         as Investment Advisor

                                    By   /s/ JAIMIN PATEL
                                       -----------------------------------------
                                       Name: Jaimin Patel
                                       Title: Authorized Signatory

<PAGE>

                                    Signature page to the Third Amendment, dated
                                    as of June 16, 2003, to the Credit
                                    Agreement, dated as of March 8, 2002, as
                                    amended, among Calpine Corporation, the
                                    various financial institutions as are or may
                                    become parties thereto, The Bank of Nova
                                    Scotia and Citicorp USA, Inc., as joint
                                    administrative agents.

                                    MORGAN STANLEY SENIOR FUNDING, INC.

                                    By   /s/ JAMES MORGAN
                                       -----------------------------------------
                                       Name: James Morgan
                                       Title: Vice President

<PAGE>

                                    Signature page to the Third Amendment, dated
                                    as of June 16, 2003, to the Credit
                                    Agreement, dated as of March 8, 2002, as
                                    amended, among Calpine Corporation, the
                                    various financial institutions as are or may
                                    become parties thereto, The Bank of Nova
                                    Scotia and Citicorp USA, Inc., as joint
                                    administrative agents.

                                    STEIN ROE FLOATING RATE
                                    LIMITED LIABILITY COMPANY
                                    By:  Columbia Management Advisors, Inc.
                                         (f/k/a Stein Roe & Farnham
                                         Incorporated), As Advisor

                                    By   /s/ JAMES R. FELLOWS
                                       -----------------------------------------
                                       Name: James R. Fellows
                                       Title: Sr. Vice President & Portfolio
                                              Manager

<PAGE>

                                    Signature page to the Third Amendment, dated
                                    as of June 16, 2003, to the Credit
                                    Agreement, dated as of March 8, 2002, as
                                    amended, among Calpine Corporation, the
                                    various financial institutions as are or may
                                    become parties thereto, The Bank of Nova
                                    Scotia and Citicorp USA, Inc., as joint
                                    administrative agents.

                                    LIBERTY FLOATING RATE
                                    ADVANTAGE FUND
                                    By:  Columbia Management Advisors, Inc.
                                         (f/k/a Stein Roe & Farnham
                                         Incorporated), As Advisor

                                    By   /s/ JAMES R. FELLOWS
                                       -----------------------------------------
                                       Name: James R. Fellows
                                       Title: Sr. Vice President & Portfolio
                                              Manager

<PAGE>

                                    Signature page to the Third Amendment, dated
                                    as of June 16, 2003, to the Credit
                                    Agreement, dated as of March 8, 2002, as
                                    amended, among Calpine Corporation, the
                                    various financial institutions as are or may
                                    become parties thereto, The Bank of Nova
                                    Scotia and Citicorp USA, Inc., as joint
                                    administrative agents.

                                    STEIN ROE & FARNHAM CLO I LTD.
                                    By:  Columbia Management Advisors, Inc.
                                         (f/k/a Stein Roe & Farnham
                                         Incorporated), As Advisor

                                    By   /s/ JAMES R. FELLOWS
                                       -----------------------------------------
                                       Name: James R. Fellows
                                       Title: Sr. Vice President & Portfolio
                                              Manager

<PAGE>

                                    Signature page to the Third Amendment, dated
                                    as of June 16, 2003, to the Credit
                                    Agreement, dated as of March 8, 2002, as
                                    amended, among Calpine Corporation, the
                                    various financial institutions as are or may
                                    become parties thereto, The Bank of Nova
                                    Scotia and Citicorp USA, Inc., as joint
                                    administrative agents.

                                    AURUM CLO 2002-1 LTD.
                                    By:  Columbia Management Advisors, Inc.
                                         (f/k/a Stein Roe & Farnham
                                         Incorporated), As Advisor

                                    By       /s/ JAMES R. FELLOWS
                                       -----------------------------------------
                                       Name: James R. Fellows
                                       Title: Sr. Vice President & Portfolio
                                              Manager

<PAGE>

                                    Signature page to the Third Amendment, dated
                                    as of June 16, 2003, to the Credit
                                    Agreement, dated as of March 8, 2002, as
                                    amended, among Calpine Corporation, the
                                    various financial institutions as are or may
                                    become parties thereto, The Bank of Nova
                                    Scotia and Citicorp USA, Inc., as joint
                                    administrative agents.

                                    GALAXY CLO 1999-1, LTD.

                                    By   /s/ W. JEFFREY BAXTER
                                       -----------------------------------------
                                       Name: W. Jeffrey Baxter
                                       Title: Vice President

<PAGE>

                                    Signature page to the Third Amendment, dated
                                    as of June 16, 2003, to the Credit
                                    Agreement, dated as of March 8, 2002, as
                                    amended, among Calpine Corporation, the
                                    various financial institutions as are or may
                                    become parties thereto, The Bank of Nova
                                    Scotia and Citicorp USA, Inc., as joint
                                    administrative agents.

                                    SUNAMERICA LIFE INSURANCE COMPANY

                                    By   /s/ W. JEFFREY BAXTER
                                       -----------------------------------------
                                       Name: W. Jeffrey Baxter
                                       Title: Vice President

<PAGE>

                                    Signature page to the Third Amendment, dated
                                    as of June 16, 2003, to the Credit
                                    Agreement, dated as of March 8, 2002, as
                                    amended, among Calpine Corporation, the
                                    various financial institutions as are or may
                                    become parties thereto, The Bank of Nova
                                    Scotia and Citicorp USA, Inc., as joint
                                    administrative agents.

                                    SUNTRUST BANK

                                    By   /s/ PETER C. VAKY
                                       --------------------------------
                                       Name: Peter C. Vaky
                                       Title: Managing Director

<PAGE>

                                    Signature page to the Third Amendment, dated
                                    as of June 16, 2003, to the Credit
                                    Agreement, dated as of March 8, 2002, as
                                    amended, among Calpine Corporation, the
                                    various financial institutions as are or may
                                    become parties thereto, The Bank of Nova
                                    Scotia and Citicorp USA, Inc., as joint
                                    administrative agents.

                                    TRUMBULL, THC, LTD.

                                    By   /s/ STACEY MALEK
                                       -----------------------------------------
                                       Name: Stacey Malek
                                       Title: Attorney in fact