Document:

<PAGE>
                                                                    EXHIBIT 10.8
                                                                  EXECUTION COPY

                FIRST AMENDMENT TO GUARANTY BY MIDSTREAM ENTITIES

         This First Amendment dated as of October 31, 2002 (this "Amendment") to
the Guaranty dated as of July 31, 2002 (as amended and modified from time to
time, the "Guaranty"), is executed by certain Midstream Subsidiaries (the
"Guarantors"), in favor of Citibank, N.A., as surety administrative agent
("Agent") for the benefit of the holders of the Secured Obligations. All
capitalized terms used herein and not otherwise defined shall have the meanings
ascribed to such terms in the Guaranty.

                                   WITNESSETH:

         WHEREAS, the parties hereto have agreed to amend certain provisions of
the Guaranty;

         NOW THEREFORE, in consideration of the mutual covenants contained
herein and for other good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, the parties hereto agree that the
Guaranty is hereby amended as follows:

1.       Amendments

         (a) Pursuant to the terms of those two certain Consent and Waivers each
         dated as of September 20, 2002, by and among the Company and the other
         signatories thereto, the Guaranty was amended to (i) remove Williams
         Field Services - Gulf Coast Company, L.P., as a Guarantor and (ii) add
         Williams Gulf Coast Gathering Company, LLC, as a Guarantor. Pursuant to
         this Amendment, the following additional parties are added as
         Guarantors: WFS - Pipeline Company; WFS Gathering Company, L.L.C.;
         Williams Field Services - Matagorda Offshore Company, LLC; Williams Gas
         Processing - Mid Continent Region Company; WFS-OCS Gathering Co.;
         HI-BOL Pipeline Company; Goebel Gathering Company, L.L.C.; Williams
         Petroleum Services, LLC; Longhorn Enterprises of Texas, Inc.; and
         Williams GP LLC.

         (b) The second sentence of Section 1 of the Guaranty is hereby amended
         by adding at the end of such sentence the following proviso: ";
         provided that Guaranteed Obligations shall not include any increases
         which occur after the date hereof in the principal amount of the
         obligations under the Credit Documents (other than increases in the
         principal amount of such obligations that are provided for as of the
         date of the execution of this Agreement but not yet funded) and/or the
         commitments to advance funds or letters of credit thereunder".

         (c) Section 8.01 of the Guaranty is hereby amended and restated in its
         entirety and replaced with the following:

                  "8.01. Amendments, Etc. Any amendment or waiver to this
                  Guaranty shall be effective only if approved by Financial
                  Institutions holding at least 51% of the principal amount of
                  the Guaranteed Obligations at the time thereof and only in the
                  specific instance and for the specific purpose for which
                  given. Provided,

<PAGE>

                  however, any amendment or waiver releasing any Guarantor from
                  any liability hereunder shall require the unanimous consent of
                  all Financial Institutions and be effective only in the
                  specific instance and for the specific purpose for which
                  given. Notwithstanding the foregoing, any release of a
                  Guarantor as permitted in Section 5.2(e) of the L/C Credit
                  Agreement and Section 5.02(l) of the Multiyear Williams Credit
                  Agreement (without giving effect to any amendment or waiver of
                  such Sections except such amendments or waivers that are
                  unanimously approved under the terms of Section 9.1 of the L/C
                  Credit Agreement and Section 8.01 of the Multiyear Williams
                  Credit Agreement) shall not require any consent beyond
                  compliance with the appropriate provisions set forth in such
                  credit agreements. No Financial Institution may be removed as
                  a beneficiary of this Guaranty without such Financial
                  Institution's prior written consent."

         (d) Section 8.06 of the Guaranty is hereby amended and restated in its
         entirety and replaced with the following:

                  "Section 8.06 Incorporated Definitions and Provisions. All
                  defined terms and other provisions that are incorporated into
                  this Guaranty by reference to other agreements shall
                  incorporate into this Guaranty the provisions of such other
                  agreements that exist as of the date hereof; however, such
                  provisions shall be automatically modified herein by any
                  amendment or modification that takes place after the date
                  hereof in such other referenced agreement(s)."

         (e) The following Section 8.08 is hereby added to the Guaranty:

                  "Section 8.08 Joinder. Pursuant to the terms of the Credit
                  Documents certain Subsidiaries (hereafter referred to as the
                  "Joining Subsidiaries") may desire to or be required to join
                  this Guaranty as Guarantors. In connection with any such
                  joinder the Joining Subsidiary shall execute and deliver (a) a
                  joinder agreement substantially in the form of the joinder
                  agreement attached hereto as Schedule I and (b) authorization
                  documentation, corporate documentation, perfection
                  documentation and opinion letters satisfactory to the Agent
                  reflecting the status of such Joining Subsidiary and the
                  enforceability of such agreements with respect to such Joining
                  Subsidiary and reasonable opinions with respect to such
                  Joining Subsidiary."

         (f) A new Schedule I to the Security Agreement is hereby added which is
         the document attached as Schedule I hereto.

2. Conditions to Effectiveness. This Amendment shall be deemed effective (the
"Effective Date") upon the satisfaction of the conditions precedent as set out
in Section 3.1 of that certain Amended and Restated Credit Agreement, dated as
of October 31, 2002, among Company and the Financial Institutions named therein,
without giving effect to the terms of Section 3.3.

3. Governing Law. This Amendment shall be governed by, and construed and
enforced in accordance with, the laws of the State of New York.

                                      -2-
<PAGE>

4. Reference to and Effect on the Guaranty. The amendments set forth herein are
limited precisely as written and shall not be deemed to be a consent or waiver
to, or modification of any other term or condition in the Guaranty or any of the
documents referred to therein. Except as expressly amended and consented hereby,
the terms and conditions of the Guaranty shall continue in full force and
effect, and as amended hereby, the Guaranty is ratified and confirmed in all
respects. On and after the Effective Date, the Guaranty shall be deemed to mean
the Guaranty as amended hereby.

5. Counterparts. This Amendment may be executed in several counterparts, each of
which shall be deemed an original, but all of which together shall constitute
one and the same agreement.

Schedule I:   Form of Joinder Agreement

                                      -3-
<PAGE>

         IN WITNESS WHEREOF, the parties hereto, acting through their duly
authorized representatives, have caused this amendment to be signed in their
respective names.

                                    AGENT:

                                    CITIBANK, N.A., as Agent (as defined in the
                                    Guaranty)

                                    By /s/ Todd J. Mogil
                                       -----------------------------------------
                                    Name: Todd J. Mogil
                                    Title: Vice President

                                    AGENT AND COLLATERAL AGENT:

                                    CITICORP USA, INC., as Agent and Collateral
                                    Agent

                                    By /s/ Todd J. Mogil
                                       -----------------------------------------
                                    Name: Todd J. Mogil
                                    Title: Vice President

                                    BANKS AND ISSUING BANKS:

                                    CITIBANK N.A., as Issuing Bank

                                    By /s/ Todd J. Mogil
                                       -----------------------------------------
                                    Name: Todd J. Mogil
                                    Title: Vice President

                                    CITICORP USA, INC.

                                    By /s/ Todd J. Mogil
                                       -----------------------------------------
                                    Name: Todd J. Mogil
                                    Title: Vice President

                                    THE BANK OF NOVA SCOTIA, as Canadian Issuing
                                    Bank and Bank

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

SIGNATURE PAGE TO
FIRST AMENDMENT TO MIDSTREAM GUARANTY
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                                    BANK OF AMERICA, N.A., as Issuing Bank and
                                    Bank

                                    By /s/ Claire M. Liu
                                       -----------------------------------------
                                    Name: Claire M. Liu
                                    Title: Managing Director

                                    JP MORGAN CHASE BANK

                                    By: /s/ Robert W. Traband
                                       -----------------------------------------
                                    Name: Robert W. Traband
                                    Title: Vice President

                                    TORONTO DOMINION (TEXAS), INC.

                                    By: /s/ Jill Hall
                                        ----------------------------------------
                                    Name: Jill Hall
                                    Title: Vice President

                                    CREDIT LYONNAIS NEW YORK BRANCH

                                    By: /s/ Olivier Audemard
                                        ----------------------------------------
                                    Name: Olivier Audemard
                                    Title: Senior Vice President

                                    MERRILL LYNCH CAPITAL CORP.

                                    By: /s/ Carol J. E. Feeley
                                        ----------------------------------------
                                    Name: Carol J. E. Feeley
                                    Title: Vice President

SIGNATURE PAGE TO
FIRST AMENDMENT TO MIDSTREAM GUARANTY
<PAGE>

                                    LEHMAN COMMERCIAL PAPER INC.

                                    By: /s/ Francis Chang
                                        ----------------------------------------
                                    Name: Francis Chang
                                    Title: Authorized Signatory

                                    CO-SYNDICATION AGENTS:

                                    JPMORGAN CHASE BANK
                                    (formerly known as
                                    THE CHASE MANHATTAN BANK),
                                    As Co-Syndication Agent

                                    By /s/ Robert W. Traband
                                       -----------------------------------------
                                    Name: Robert W. Traband
                                    Title: Vice President

                                    COMMERZBANK AG,
                                    as Co-Syndication Agent

                                    By /s/ Harry Yergey
                                       -----------------------------------------
                                    Name: Harry Yergey
                                    Title: Senior Vice Pres. and Manager

                                    By /s/ Brian Campbell
                                       -----------------------------------------
                                    Name: Brian Campbell
                                    Title: Senior Vice President

                                    DOCUMENTATION AGENT:

                                    CREDIT LYONNAIS NEW YORK BRANCH
                                    as Documentation Agent

                                    By: /s/ Olivier Audemard
                                        ----------------------------------------
                                    Name: Olivier Audemard
                                    Title: Senior Vice President

                                    BANKS:

                                    CITICORP, USA, INC.

                                    By /s/ Todd J. Mogil
                                       -----------------------------------------
                                    Name: Todd J. Mogil
                                    Title: Vice President

SIGNATURE PAGE TO
FIRST AMENDMENT TO MIDSTREAM GUARANTY
<PAGE>

                                    THE BANK OF NOVA SCOTIA

                                    By: /s/ N. Bell
                                       -----------------------------------------
                                    Name: N. Bell
                                    Title: Senior Manager

                                    BANK OF AMERICA, N.A.

                                    By /s/ Claire M. Liu
                                       -----------------------------------------
                                    Name: Claire M. Liu
                                    Title: Managing Director

                                    BANK ONE, N.A. (MAIN OFFICE - CHICAGO)

                                    By /s/ Jeanie C. Gonzalez
                                       -----------------------------------------
                                    Name: Jeanie C. Gonzalez
                                    Title: Director

                                    JPMORGAN CHASE BANK
                                    (formerly known as
                                    THE CHASE MANHATTAN BANK),

                                    By /s/ Robert W. Traband
                                       -----------------------------------------
                                    Name: Robert W. Traband
                                    Title: Vice President

                                    COMMERZBANK AG
                                    NEW YORK AND GRAND CAYMAN BRANCHES

                                    By /s/ Brian Campbell
                                       -----------------------------------------
                                    Name: Brian Campbell
                                    Title: Senior Vice President

                                    By /s/ W. David Suttles
                                       -----------------------------------------
                                    Name: W. David Suttles
                                    Title: Vice President

SIGNATURE PAGE TO
FIRST AMENDMENT TO MIDSTREAM GUARANTY
<PAGE>

                                    CREDIT LYONNAIS NEW YORK BRANCH

                                    By: /s/ Olivier Audemard
                                        ----------------------------------------
                                    Name: Olivier Audemard
                                    Title: Senior Vice President

                                    NATIONAL WESTMINSTER PLC

                                    By: /s/ Charles Greer
                                        ----------------------------------------
                                    Name: Charles Greer
                                    Title: Senior Vice President

                                    ABN AMRO BANK, N.V.

                                    By /s/ Frank R. Russo, Jr.
                                       -----------------------------------------
                                    Name: Frank R. Russo, Jr.
                                    Title: Group Vice President

                                    By /s/ Jeffrey G. White
                                       -----------------------------------------
                                    Name: Jeffrey G. White
                                    Title: Vice President

                                    BANK OF MONTREAL

                                    By /s/ Mary Lee Latta
                                       -----------------------------------------
                                    Name: Mary Lee Latta
                                    Title: Director

                                    THE BANK OF NEW YORK

                                    By /s/ Raymond J. Palmer
                                       -----------------------------------------
                                    Name: Raymond J. Palmer
                                    Title: Vice President

SIGNATURE PAGE TO
FIRST AMENDMENT TO MIDSTREAM GUARANTY
<PAGE>

                                    BARCLAYS BANK PLC

                                    By /s/ Nicholas A. Bell
                                       -----------------------------------------
                                    Name: Nicholas A. Bell
                                    Title: Director, Loan Transaction Management

                                    CIBC INC.

                                    By /s/ George Knight
                                       -----------------------------------------
                                    Name: George Knight
                                    Title: Managing Director

                                    CREDIT SUISSE FIRST BOSTON

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

                                    By /s/ Ian W. Nalitt
                                       -----------------------------------------
                                    Name: Ian W. Nalitt
                                    Title: Associate

                                    ROYAL BANK OF CANADA

                                    By /s/ Peter Barnes
                                       -----------------------------------------
                                    Name: Peter Barnes
                                    Title: Senior Manager

                                    THE BANK OF TOKYO-MITSUBISHI, LTD., HOUSTON
                                    AGENCY

                                    By /s/ Kelton Glassock
                                       -----------------------------------------
                                    Name: Kelton Glassock
                                    Title: Vice President and Manager

                                    By /s/ Jay Fort
                                       -----------------------------------------
                                    Name: Jay Fort
                                    Title: Vice President

SIGNATURE PAGE TO
FIRST AMENDMENT TO MIDSTREAM GUARANTY
<PAGE>

                                    FLEET NATIONAL BANK
                                    f/k/a Bank Boston, N.A.

                                    By /s/ Matthew W. Speh
                                       -----------------------------------------
                                    Name: Matthew W. Speh
                                    Title: Authorized Officer

                                    SOCIETE GENERALE, SOUTHWEST AGENCY

                                    By /s/ J. Douglas McMurrey, Jr.
                                       -----------------------------------------
                                    Name: J. Douglas McMurrey, Jr.
                                    Title: Managing Director

                                    TORONTO DOMINION (TEXAS), INC.

                                    By: /s/ Jill Hall
                                       -----------------------------------------
                                    Name: Jill Hall
                                    Title: Vice President

                                    UBS AG, STAMFORD BRANCH

                                    By /s/ Kelly Smith
                                       -----------------------------------------
                                    Name: Kelly Smith
                                    Title: Director - Recovery Management

                                    By David J. Kalal
                                       -----------------------------------------
                                    Name: David J. Kalal
                                    Title: Executive Director - Recovery
                                           Management

                                    WELLS FARGO BANK TEXAS, N.A.

                                    By /s/ J. Alan Alexander
                                       -----------------------------------------
                                    Name: J. Alan Alexander
                                    Title: Vice President

SIGNATURE PAGE TO
FIRST AMENDMENT TO MIDSTREAM GUARANTY
<PAGE>

                                    WESTLB AG, NEW YORK BRANCH

                                    By /s/ Duncan M. Robertson
                                       -----------------------------------------
                                    Name: Duncan M. Robertson
                                    Title: Director

                                    Name: Salvatore Battinelli
                                    Title: Managing Director - Credit Department

                                    CREDIT AGRICOLE INDOSUEZ

                                    By /s/ Larry Materi
                                       -----------------------------------------
                                    Name: Larry Materi
                                    Title: Vice President

                                    By /s/ Paul A. Dytrych
                                       -----------------------------------------
                                    Name: Paul A. Dytrych
                                    Title: Vice President, Senior Relationship
                                           Manager

                                    SUNTRUST BANK

                                    By /s/ Steven J. Newby
                                       -----------------------------------------
                                    Name: Steven J. Newby
                                    Title: Director

                                    ARAB BANKING CORPORATION (B.S.C.)

                                    By /s/ Robert J. Ivosevich
                                       -----------------------------------------
                                    Name: Robert J. Ivosevich
                                    Title: Deputy General Manager

                                    By /s/ Barbara C. Sanderson
                                       -----------------------------------------
                                    Name: Barbara C. Sanderson
                                    Title: Vice President Head of Credit

                                    BANK OF CHINA, NEW YORK BRANCH

                                    By
                                    Name:
                                    Title:

SIGNATURE PAGE TO
FIRST AMENDMENT TO MIDSTREAM GUARANTY
<PAGE>

                                    BANK OF OKLAHOMA, N.A.

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

                                    BNP PARIBAS, HOUSTON AGENCY

                                    By /s/ Larry Robinson
                                       -----------------------------------------
                                    Name: Larry Robinson
                                    Title: Vice President

                                    By /s/ Mark A. Cox
                                       -----------------------------------------
                                    Name: Mark A. Cox
                                    Title: Director

                                    DZ BANK AG DEUTSCHE
                                    ZENTRALGENOSSENSCHAFTSBANK, NEW YORK BRANCH

                                    By /s/ Mark Connelly
                                       -----------------------------------------
                                    Name: Mark Connelly
                                    Title: Senior V.P.

                                    By /s/ Richard W. Wilbert
                                       -----------------------------------------
                                    Name: Richard W. Wilbert
                                    Title: Vice President

                                    KBC BANK N.V.

                                    By /s/ Michael V. Curran
                                       -----------------------------------------
                                    Name: Michael V. Curran
                                    Title: First Vice President

                                    By /s/ Diane M. Grimmig
                                       -----------------------------------------
                                    Name: Diane M. Grimmig
                                    Title: First Vice President

                                    WACHOVIA BANK, N.A.

                                    By: /s/ David E. Humphreys
                                       -----------------------------------------
                                    Name: David E. Humphreys
                                    Title: Vice President

SIGNATURE PAGE TO
FIRST AMENDMENT TO MIDSTREAM GUARANTY
<PAGE>

                                    MIZUHO CORPORATE BANK, LTD

                                    By /s/ Jacques Azagury
                                       -----------------------------------------
                                    Name: Jacques Azagury
                                    Title: Senior Vice President and Manager

                                    SUMITOMO MITSUI BANKING CORPORATION

                                    By /s/ Leo E. Pagarigan
                                       -----------------------------------------
                                    Name: Leo E. Pagarigan
                                    Title: Senior Vice President

                                    COMMERCE BANK, N.A.

                                    By /s/ Dennis R. Block
                                       -----------------------------------------
                                    Name: Dennis R. Block
                                    Title: Senior Vice President

                                    ROYAL BANK OF SCOTLAND

                                    Name:
                                    Title:

                                    RZB FINANCE, LLC

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

SIGNATURE PAGE TO
FIRST AMENDMENT TO MIDSTREAM GUARANTY
<PAGE>

                                    WORTHINGTON GENERATION, L.L.C.

                                    By: /s/ William E. Hobbs
                                       -----------------------------------------
                                    Name: William E. Hobbs
                                    Title: President

                                    WILLIAMS REFINING & MARKETING, L.L.C.

                                    By: /s/ James G. Ivey
                                       -----------------------------------------
                                    Name: James G. Ivey
                                    Title: Assistant Treasurer

                                    WILLIAMS PETROLEUM SERVICES, LLC

                                    By: /s/ Ralph A. Hill
                                       -----------------------------------------
                                    Name: Ralph A. Hill
                                    Title: Senior Vice President

                                    WILLIAMS PETROLEUM PIPELINE SYSTEMS, INC.

                                    By: /s/ Ralph A. Hill
                                       -----------------------------------------
                                    Name: Ralph A. Hill
                                    Title: Senior Vice President

                                    WILLIAMS MID-SOUTH PIPELINES, LLC

                                    By: /s/ James G. Ivey
                                       -----------------------------------------
                                    Name: James G. Ivey
                                    Title: Assistant Treasurer

SIGNATURE PAGE TO
FIRST AMENDMENT TO MIDSTREAM GUARANTY
<PAGE>

                                    WILLIAMS GENERATION COMPANY-HAZLETON

                                    By: /s/ Ralph A. Hill
                                       -----------------------------------------
                                    Name: Ralph A. Hill
                                    Title: Vice President

                                    WILLIAMS OLEFINS, L.L.C.

                                    By: /s/ James G. Ivey
                                       -----------------------------------------
                                    Name: James G. Ivey
                                    Title: Assistant Treasurer

                                    WILLIAMS OLEFINS FEEDSTOCK PIPELINES, L.L.C.

                                    By: /s/ James G. Ivey
                                       -----------------------------------------
                                    Name: James G. Ivey
                                    Title: Assistant Treasurer

                                    WILLIAMS NATURAL GAS LIQUIDS, INC.

                                    By: /s/ Alan S. Armstrong
                                       -----------------------------------------
                                    Name: Alan S. Armstrong
                                    Title: Senior Vice President

                                    WILLIAMS MIDSTREAM NATURAL GAS LIQUIDS, INC.

                                    By: /s/ Alan S. Armstrong
                                       -----------------------------------------
                                    Name: Alan S. Armstrong
                                    Title: Senior Vice President

SIGNATURE PAGE TO
FIRST AMENDMENT TO MIDSTREAM GUARANTY
<PAGE>

                                    WILLIAMS MERCHANT SERVICES COMPANY, INC.

                                    By: /s/ William E. Hobbs
                                       -----------------------------------------
                                    Name: William E. Hobbs
                                    Title: President

                                    WILLIAMS MEMPHIS TERMINAL, INC.

                                    By: /s/ James G. Ivey
                                       -----------------------------------------
                                    Name: James G. Ivey
                                    Title: Assistant Treasurer

                                    WILLIAMS GULF COAST GATHERING COMPANY, LLC

                                    By: /s/ James G. Ivey
                                       -----------------------------------------
                                    Name: James G. Ivey
                                    Title: Assistant Treasurer

                                    WILLIAMS GP, LLC

                                    By: /s/ Don R. Wellendorf
                                       -----------------------------------------
                                    Name: Don R. Wellendorf
                                    Title: President and Chief Executive Officer

                                    WILLIAMS GENERATING MEMPHIS, LLC

                                    By: /s/ James G. Ivey
                                       -----------------------------------------
                                    Name: James G. Ivey
                                    Title: Assistant Treasurer

SIGNATURE PAGE TO
FIRST AMENDMENT TO MIDSTREAM GUARANTY
<PAGE>

                                    WILLIAMS GAS PROCESSING - WAMSUTTER COMPANY.

                                    By: /s/ Alan S. Armstrong
                                       -----------------------------------------
                                    Name: Alan S. Armstrong
                                    Title: Senior Vice President

                                    WILLIAMS GAS PROCESSING COMPANY

                                    By: /s/ Alan S. Armstrong
                                       -----------------------------------------
                                    Name: Alan S. Armstrong
                                    Title: Senior Vice President

                                    WILLIAMS GAS PROCESSING - MID-CONTINENT
                                    REGION COMPANY

                                    By: /s/ Alan S. Armstrong
                                       -----------------------------------------
                                    Name: Alan S. Armstrong
                                    Title: Senior Vice President

                                    WILLIAMS FIELD SERVICES GROUP, INC.

                                    By: /s/ Alan S. Armstrong
                                       -----------------------------------------
                                    Name: Alan S. Armstrong
                                    Title: Senior Vice President

                                    WILLIAMS FIELD SERVICES COMPANY

                                    By: /s/ Alan S. Armstrong
                                       -----------------------------------------
                                    Name: Alan S. Armstrong
                                    Title: Senior Vice President

SIGNATURE PAGE TO
FIRST AMENDMENT TO MIDSTREAM GUARANTY
<PAGE>

                                    WILLIAMS FIELD SERVICES - MATAGORDA OFFSHORE
                                    COMPANY, LLC

                                    By: /s/ James G. Ivey
                                       -----------------------------------------
                                    Name: James G. Ivey
                                    Title: Assistant Treasurer

                                    WILLIAMS EXPRESS, INC. (DE)

                                    By: /s/ Ralph A. Hill
                                       -----------------------------------------
                                    Name: Ralph A. Hill
                                    Title: Chief Executive Officer

                                    WILLIAMS EXPRESS INC. (AK)

                                    By: /s/ Ralph A. Hill
                                       -----------------------------------------
                                    Name: Ralph A. Hill
                                    Title: Chief Executive Officer

                                    WILLIAMS ETHANOL SERVICES, INC.

                                    By: /s/ Paul W. Nelson
                                       -----------------------------------------
                                    Name: Paul W. Nelson
                                    Title: Treasurer

                                    WILLIAMS ENERGY SERVICES, LLC

                                    By: /s/ Alan S. Armstrong
                                       -----------------------------------------
                                    Name: Alan S. Armstrong
                                    Title: Senior Vice President

SIGNATURE PAGE TO
FIRST AMENDMENT TO MIDSTREAM GUARANTY
<PAGE>

                                    WILLIAMS ENERGY MARKETING & TRADING COMPANY

                                    By: /s/ William E. Hobbs
                                       -----------------------------------------
                                    Name: William E. Hobbs
                                    Title: President

                                    WILLIAMS BIO-ENERGY, L.L.C.

                                    By: /s/ James G. Ivey
                                       -----------------------------------------
                                    Name: James G. Ivey
                                    Title: Assistant Treasurer

                                    WILLIAMS ALASKA PIPELINE COMPANY, L.L.C.

                                    By: /s/ Ralph A. Hill
                                       -----------------------------------------
                                    Name: Ralph A. Hill
                                    Title: Senior Vice President

                                    WILLIAMS ALASKA PETROLEUM, INC.

                                    By: /s/ Ralph A. Hill
                                       -----------------------------------------
                                    Name: Ralph A. Hill
                                    Title: Chief Executive Officer

                                    WILLIAMS ALASKA AIR CARGO PROPERTIES, L.L.C.

                                    By: /s/ Ralph A. Hill
                                       -----------------------------------------
                                    Name: Ralph A. Hill
                                    Title: Chief Executive Officer

SIGNATURE PAGE TO
FIRST AMENDMENT TO MIDSTREAM GUARANTY
<PAGE>

                                    WFS-OFFSHORE GATHERING COMPANY

                                    By: /s/ Alan S. Armstrong
                                       -----------------------------------------
                                    Name: Alan S. Armstrong
                                    Title: Senior Vice President

                                    WFS-NGL PIPELINE COMPANY, INC.

                                    By: /s/ Alan S. Armstrong
                                       -----------------------------------------
                                    Name: Alan S. Armstrong
                                    Title: Senior Vice President

                                    WFS-LIQUIDS COMPANY

                                    By: /s/ Alan S. Armstrong
                                       -----------------------------------------
                                    Name: Alan S. Armstrong
                                    Title: Senior Vice President

                                    WFS GATHERING COMPANY, L.L.C.

                                    By: /s/ James G. Ivey
                                       -----------------------------------------
                                    Name: James G. Ivey
                                    Title: Assistant Treasurer

                                    WFS ENTERPRISES, INC.

                                    By: /s/ Mary Jane Bittick
                                       -----------------------------------------
                                    Name: Mary Jane Bittick
                                    Title: Treasurer

SIGNATURE PAGE TO
FIRST AMENDMENT TO MIDSTREAM GUARANTY
<PAGE>

                                    WFS - PIPELINE COMPANY

                                    By: /s/ Alan S. Armstrong
                                       -----------------------------------------
                                    Name: Alan S. Armstrong
                                    Title: Senior Vice President

                                    WFS - OCS GATHERING CO.

                                    By: /s/ Alan S. Armstrong
                                       -----------------------------------------
                                    Name: Alan S. Armstrong
                                    Title: Senior Vice President

                                    NORTH PADRE ISLAND SPINDOWN, INC.

                                    By: /s/ Alan S. Armstrong
                                       -----------------------------------------
                                    Name: Alan S. Armstrong
                                    Title: Senior Vice President

                                    MEMPHIS GENERATION, L.L.C.

                                    By: /s/ William E. Hobbs
                                       -----------------------------------------
                                    Name: William E. Hobbs
                                    Title: President

                                    MAPL INVESTMENTS, INC.

                                    By: /s/ Alan S. Armstrong
                                       -----------------------------------------
                                    Name: Alan S. Armstrong
                                    Title: Senior Vice President

SIGNATURE PAGE TO
FIRST AMENDMENT TO MIDSTREAM GUARANTY
<PAGE>

                                    MAPCO INC.

                                    By: /s/ Alan S. Armstrong
                                       -----------------------------------------
                                    Name: Alan S. Armstrong
                                    Title: Senior Vice President

                                    LONGHORN ENTERPRISES OF TEXAS, INC.

                                    By: /s/ Ralph A. Hill
                                       -----------------------------------------
                                    Name: Ralph A. Hill
                                    Title: Senior Vice President

                                    JUAREZ PIPELINE COMPANY

                                    By: /s/ Alan S. Armstrong
                                       -----------------------------------------
                                    Name: Alan S. Armstrong
                                    Title: Senior Vice President

                                    HI-BOL PIPELINE COMPANY

                                    By: /s/ Alan S. Armstrong
                                       -----------------------------------------
                                    Name: Alan S. Armstrong
                                    Title: Senior Vice President

                                    GOEBEL GATHERING COMPANY, L.L.C.

                                    By: /s/ James G. Ivey
                                       -----------------------------------------
                                    Name: James G. Ivey
                                    Title: Assistant Treasurer

SIGNATURE PAGE TO
FIRST AMENDMENT TO MIDSTREAM GUARANTY
<PAGE>

                                    GAS SUPPLY, L.L.C.

                                    By: /s/ Ralph A. Hill
                                       -----------------------------------------
                                    Name: Ralph A. Hill
                                    Title: Senior Vice President

                                    BLACK MARLIN PIPELINE COMPANY

                                    By: /s/ Alan S. Armstrong
                                       -----------------------------------------
                                    Name: Alan S. Armstrong
                                    Title: Senior Vice President

SIGNATURE PAGE TO
FIRST AMENDMENT TO MIDSTREAM GUARANTY

<PAGE>

                                   SCHEDULE I
                                       TO
                                    GUARANTY

                            FORM OF JOINDER AGREEMENT

                                JOINDER AGREEMENT
                          (name of joining subsidiary)

                               [_________, _____]

         This Joinder Agreement is entered into to join [Joining Subsidiary] as
an additional guarantor to the Guaranty dated as of July 31, 2002 (as amended,
supplemented or otherwise modified from time to time, the "Midstream Guaranty"),
which was executed by THE WILLIAMS COMPANIES, INC. (the "Company"), a Delaware
corporation, and certain Midstream Subsidiaries.

         [Joining Subsidiary], a [_________ corporation] (the "Subsidiary"),
hereby agrees with CITIBANK, N.A., as surety administrative agent for the
Financial Institution (as such term is defined in the Midstream Guaranty) as
follows:

         All capitalized terms used herein and not defined herein shall have the
meanings ascribed to such terms in the Amended and Restated Credit Agreement,
dated as of October 31, 2002, by and among The Williams Companies, Inc., the
various lenders as are or may become parties thereto; the Issuing Banks, and
Citicorp USA, Inc., as Agent and Collateral Agent (as further amended, modified,
supplemented, renewed, extended or restated from time to time, the "Credit
Agreement").

         In accordance with the terms of the Credit Documents and the Midstream
Guaranty (collectively, the "Security Documents"), the Subsidiary hereby (a)
joins the Midstream Guaranty as a party thereto and assumes all the obligations
of a Guarantor thereunder, (b) agrees to be bound by the provisions of the
Midstream Guaranty as if the Subsidiary had been an original party to the
Midstream Guaranty, and (c) confirms that, after joining the Midstream Guaranty
as set forth above, the representations and warranties set forth in each of the
Credit Documents with respect to the Subsidiary are true and correct in all
material respects as of the date of this Joinder Agreement.

         For purposes of notices under the Security Documents, the notice
address for the Subsidiary may be given to the Subsidiary by providing notice
addressed to [Subsidiary' Name] c/o The Williams Companies, Inc., in any manner
that notice is permitted to be given to the Company pursuant to the terms of the
Credit Agreement.

         THIS WRITTEN AGREEMENT AND THE CREDIT DOCUMENTS REPRESENT THE FINAL
AGREEMENT AMONG THE PARTIES AND MAY NOT BE CONTRADICTED BY EVIDENCE OF PRIOR,
CONTEMPORANEOUS, OR SUBSEQUENT ORAL AGREEMENTS OF THE PARTIES.

         THERE ARE NO UNWRITTEN ORAL AGREEMENTS AMONG THE PARTIES.

                                      -4-
<PAGE>

         IN WITNESS WHEREOF this Joinder Agreement is executed and delivered as
of the ___ day of ____________, _____.

                                    [Joining Subsidiary]

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

Source: [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00044-of-00352.parquet"}]