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                                                                   EXHIBIT 10(Q)


                              FOURTH AMENDMENT TO
                  FOURTH AMENDED AND RESTATED CREDIT AGREEMENT

     THIS FOURTH AMENDMENT TO FOURTH AMENDED AND RESTATED CREDIT AGREEMENT (this
"Amendment") dated as of the 15/th/ day of September, 1999, by and among PLAINS
RESOURCES INC., a Delaware corporation (the "Company"), FIRST UNION NATIONAL
BANK (assignee of ING (U.S.) Capital LLC, successor in interest to ING (U.S.)
Capital Corporation), as Agent ("Agent"), and the Lenders under the Original
Agreement (as defined herein).

                              W I T N E S S E T H:

     WHEREAS,  the Company, Agent and Lenders entered into that certain Fourth
Amended and Restated Credit Agreement dated as of May 22, 1998, as amended by a
First Amendment to Fourth Amended and Restated Credit Agreement dated November
17, 1998, a Second Amendment to Fourth Amended and Restated Credit Agreement
dated March 15, 1999 and a Third Amendment to Fourth Amended and Restated Credit
Agreement dated June 21, 1999 (as amended, the "Original Agreement") for the
purposes and consideration therein expressed, pursuant to which Lenders became
obligated to make and made loans to the Company as therein provided; and

     WHEREAS, the Company, Agent and Lenders desire to amend the Original
Agreement for the purposes described herein;

     NOW, THEREFORE, in consideration of the premises and the mutual covenants
and agreements contained herein and in the Original Agreement, in consideration
of the loans which may hereafter be made by Lenders to the Company, and for
other good and valuable consideration, the receipt and sufficiency of which are
hereby acknowledged, the parties hereto do hereby agree as follows:

                    ARTICLE I. -- Definitions and References

     (S) 1.1.  Terms Defined in the Original Agreement.  Unless the context
otherwise requires or unless otherwise expressly defined herein, the terms
defined in the Original Agreement shall have the same meanings whenever used in
this Amendment.

     (S) 1.2.  Other Defined Terms.  Unless the context otherwise requires, the
following terms when used in this Amendment shall have the meanings assigned to
them in this (S) 1.2.

          "Amendment" means this Fourth Amendment to Fourth Amended and Restated
     Credit Agreement.

          "Amendment Documents" means this Amendment.

          "Credit Agreement" means the Original Agreement as amended hereby.

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                           ARTICLE II. -- Amendments

     (S) 2.1.  Definitions.  The definitions of "Senior Subordinated Indenture"
and "Senior Subordinated Notes" set forth in Section 1.01 of the Original
Agreement are hereby amended in their entirety to read as follows:

          "Senior Subordinated Indenture" shall mean (i) that certain Indenture
     dated as of March 15, 1996 among the Company, "Subsidiary Guarantors" (as
     defined therein) and Chase Bank of Texas, National Association (f/k/a Texas
     Commerce Bank National Association), as Trustee, (ii) that certain
     Indenture dated as of  July 21, 1997 among the Company, "Subsidiary
     Guarantors" (as defined therein) and Chase Bank of Texas, National
     Association (f/k/a Texas Commerce Bank National Association), as Trustee,
     and (iii) that certain Indenture dated as of September 15, 1999 among the
     Company, "Subsidiary Guarantors" (as defined therein) and Chase Bank of
     Texas, National Association, as Trustee, in each case as amended or
     modified from time to time in compliance with Section 8.23

          "Senior Subordinated Notes" shall mean (i) the 10 1/4% senior
     subordinated notes due 2006 in the aggregate principal amount of
     $150,000,000 issued by the Company pursuant to the Senior Subordinated
     Indenture dated as of March 15, 1996, (ii) the 10 1/4% senior subordinated
     notes due 2006 in the aggregate principal amount of $50,000,000 issued by
     the Company pursuant to the Senior Subordinated Indenture dated as of July
     21, 1997, and (iii) the 10 1/4% senior subordinated notes due 2006 in the
     aggregate principal amount of $75,000,000 to be dated on or about September
     22, 1999 issued by the Company pursuant to the Senior Subordinated
     Indenture dated as of September 15, 1999.

     (S) 2.2.  Subordinated Indebtedness.  Section 8.14(b) of the Original
Agreement are hereby amended in its entirety to read as follows:

          (b) The Company may offer to purchase and redeem Senior Subordinated
     Notes in the amount and under the circumstances described in Section
     4.12(iii)(c) of the Senior Subordinated Indenture dated as of March 15,
     1996, Section 4.12(iv) of the Senior Subordinated Indenture dated as of
     July 21, 1997, and Section 4.12(iv) of the Senior Subordinated Indenture
     dated as of September 15, 1999, provided that: (i) the Company shall have
     given Agent and each Lender written notice of its intent to so purchase and
     redeem (collectively "redeem") the Senior Subordinated Notes at least 25
     days prior to the date (the "Net Proceeds Payment Date") that it will
     become obligated to so redeem such Senior Subordinated Notes pursuant to
     such Section 4.12(iii)(c), Section 4.12(iv) or Section 4.12(iv), as
     appropriate, such notice to specify the Net Proceeds Payment Date and,
     based upon the proceeds available for such redemption, the maximum amount
     of Senior Subordinated Notes that may be so redeemed, (ii) the Company
     shall have provided to Agent and each Lender such information as Agent
     shall have reasonably requested with regard to such redemption, (iii) no
     Default or Event of Default shall have occurred and be continuing at the
     time of any such redemption, and (iv) if elected by Majority Lenders, by
     written notice to the Company during the 25 day period after such notice is
     given, a new Borrowing Base shall have been determined by Majority Lenders
     in

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     the manner specified by Section 2.08 hereof and the outstanding aggregate
     principal balance of the Notes shall not exceed such Adjusted Borrowing
     Base as so redetermined.

     (S) 2.3.  Waiver and Consent - Issuance of Senior Subordinated Notes.  The
Company proposes to issue its Senior Subordinated Notes due 2006 (as more
particularly described in clause (iii) of the definition of "Senior Subordinated
Notes") in the aggregate principal amount of $75,000,000, as set forth in an
Offering Circular relating thereto substantially in the form previously
furnished to Agent and Lenders, which are to be guaranteed by Subsidiary
Guarantors. The Company intends to use the proceeds of such Senior Subordinated
Notes to prepay the Loans.  Lenders hereby consent to, and waive any Default or
Event of Default occurring as a result of, the issuance of such new Senior
Subordinated Notes and the guarantee of such new Senior Subordinated Notes by
Subsidiary Guarantors; provided the subordination provisions of the Senior
Subordinated Indenture dated as of September 15, 1999 pursuant to which such new
Senior Subordinated Notes are to be issued and the guaranties of such new Senior
Subordinated Notes by Subsidiary Guarantors are to be made shall be identical in
all material respects to those provisions set forth in Articles Ten, Eleven and
Twelve of the Senior Subordinated Indenture dated as of March 15, 1996 and the
Senior Subordinated Indenture dated as of July 21, 1997.

     (S) 2.4.  Waiver and Consent - Prepayment of Eurodollar Loans.  The Company
proposes to use the proceeds of the new Senior Subordinated Notes to prepay the
Loans, which may include Eurodollar Loans.  Such proposed prepayment may violate
Section 2.07(a)(ii) of the Credit Agreement, which permits the prepayment of a
Eurodollar Loan only on the last day of an Interest Period for such Eurodollar
Loan.  Lenders hereby consent to, and waive any Default or Event of Default
under Section 2.07 of the Credit Agreement occurring as a result of, the
prepayment of such Loans; provided the Company shall, pursuant to Section 5.05
of the Credit Agreement, promptly pay to each Lender any breakage costs
associated with the prepayment of any Eurodollar Loans.

                  ARTICLE III. -- Conditions of Effectiveness

     (S) 3.1.  Effective Date.  This Amendment shall become effective as of the
date first above written when and only when (i) Agent shall have received, at
Agent's office, a counterpart of this Amendment executed and delivered by the
Company and Majority Lenders, and (ii) Agent shall have additionally received
all of the following documents, each document (unless otherwise indicated) being
dated the date of receipt thereof by Agent, duly authorized, executed and
delivered, and in form and substance satisfactory to Agent:

          (A) Officer's Certificate.  A certificate of a duly authorized officer
     of the Company to the effect that all of the representations and warranties
     set forth in Article IV hereof are true and correct at and as of the date
     thereof.

          (B) Supporting Documents.  Such supporting documents as Agent may
     reasonably request.

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                 ARTICLE IV. -- Representations and Warranties

     (S) 4.1.  Representations and Warranties of the Company.  In order to
induce Agent and Lenders to enter into this Amendment, the Company represents
and warrants to Agent and Lenders that:

          (a) The representations and warranties contained in Section 7 of the
     Original Agreement, are true and correct at and as of the time of the
     effectiveness hereof, subject to the amendment of certain of the Schedules
     to the Credit Agreement as attached hereto. No Default has occurred and is
     continuing.

          (b) The Company and the Subsidiaries are duly authorized to execute
     and deliver this Amendment and the other Amendment Documents to the extent
     a party thereto, and the Company is and will continue to be duly authorized
     to borrow and perform its obligations under the Credit Agreement.  The
     Company and the Subsidiaries have duly taken all corporate action necessary
     to authorize the execution and delivery of this Amendment and the other
     Amendment Documents, to the extent a party thereto, and to authorize the
     performance of their respective obligations thereunder.

          (c) The execution and delivery by the Company and the Subsidiaries of
     this Amendment and the other Amendment Documents, to the extent a party
     thereto, the performance by the Company and the Subsidiaries of their
     respective obligations hereunder and thereunder, and the consummation of
     the transactions contemplated hereby and thereby, do not and will not
     conflict with any provision of law, statute, rule or regulation or of the
     certificate or articles of incorporation and bylaws of the Company or any
     Subsidiary, or of any material agreement, judgment, license, order or
     permit applicable to or binding upon the Company or any Subsidiary, or
     result in the creation of any lien, charge or encumbrance upon any assets
     or properties of the Company or any Subsidiary, except in favor of Agent
     for the benefit of Lenders.  Except for those which have been duly
     obtained, no consent, approval, authorization or order of any court or
     governmental authority or third party is required in connection with the
     execution and delivery by the Company or any Subsidiary of this Amendment
     or any other Amendment Document, to the extent a party thereto, or to
     consummate the transactions contemplated hereby and thereby.

          (d) When this Amendment and the other Amendment Documents have been
     duly executed and delivered, each of the Basic Documents, as amended by
     this Amendment and the other Amendment Documents, will be a legal and
     binding instrument and agreement of the Company and the Subsidiaries, to
     the extent a party thereto, enforceable in accordance with its terms,
     (subject, as to enforcement of remedies, to applicable bankruptcy,
     insolvency and similar laws applicable to creditors' rights generally and
     to general principles of equity).

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                          ARTICLE V. -- Miscellaneous

     (S) 5.1.  Ratification of Agreements.  The Original Agreement, as hereby
amended, is hereby ratified and confirmed in all respects.  The Basic Documents,
as they may be amended or affected by this Amendment and/or the other Amendment
Documents, are hereby ratified and confirmed in all respects.  Any reference to
the Credit Agreement in any Basic Document shall be deemed to refer to this
Amendment also.  The execution, delivery and effectiveness of this Amendment and
the other Amendment Documents shall not, except as expressly provided herein or
therein, operate as a waiver of any right, power or remedy of Agent or any
Lender under the Credit Agreement or any other Basic Document nor constitute a
waiver of any provision of the Credit Agreement or any other Basic Document.

     (S) 5.2.  Ratification of Security Documents.  The Company, Agent and
Lenders each acknowledge and agree that any and all indebtedness, liabilities or
obligations arising under or in connection with the Notes are Obligations and is
secured indebtedness under, and is secured by, each and every Security Document
to which the Company is a party.  The Company hereby re-pledges, re-grants and
re-assigns a security interest in and lien on every asset of the Company
described as collateral in any Security Document.

     (S) 5.3.  Survival of Agreements.  All representations, warranties,
covenants and agreements of the Company herein and in the other Amendment
Documents shall survive the execution and delivery of this Amendment and the
other Amendment Documents and the performance hereof and thereof, including
without limitation the making or granting of each Loan, and shall further
survive until all of the Obligations are paid in full.  All statements and
agreements contained in any certificate or instrument delivered by the Company
or any Subsidiary hereunder, under the other Amendment Documents or under the
Credit Agreement to Agent or any Lender shall be deemed to constitute
representations and warranties by, or agreements and covenants of, the Company
under this Amendment and under the Credit Agreement.

     (S) 5.4.  Basic Documents.  This Amendment and each of the other Amendment
Documents is a Basic Document, and all provisions in the Credit Agreement
pertaining to Basic Documents apply hereto and thereto.

     (S) 5.5.  GOVERNING LAW.  THIS AMENDMENT AND THE OTHER AMENDMENT DOCUMENTS
SHALL BE GOVERNED BY AND CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF
NEW YORK AND ANY APPLICABLE LAWS OF THE UNITED STATES OF AMERICA IN ALL
RESPECTS, INCLUDING CONSTRUCTION, VALIDITY AND PERFORMANCE.

     (S) 5.6.  Counterparts.  This Amendment and each of the other Amendment
Documents may be separately executed in counterparts and by the different
parties hereto in separate counterparts, each of which when so executed shall be
deemed to constitute one and the same Amendment or Amendment Document, as the
case may be.

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     IN WITNESS WHEREOF, this Amendment is executed as of the date first above
written.

                              PLAINS RESOURCES INC.

                              By:   /s/ Michael R. Patterson
                                 -----------------------------------------------
                                 Name: Michael R. Patterson
                                 Title:   Vice President


                              FIRST UNION NATIONAL BANK,
                              as Agent, LC Issuer and a Lender

                              By:   /s/ Paul N. Riddle
                                 -----------------------------------------------
                                 Name: Paul N. Riddle
                                 Title:   Senior Vice President

                              BANKBOSTON, N.A., Lender

                              By:   /s/ Terrence Ronan
                                 -----------------------------------------------
                                 Terrence Ronan, Vice President

                              DEN NORSKE BANK ASA, Lender

                              By:   /s/ Byron L. Cooley
                                 -----------------------------------------------
                                 Name: Byron L. Cooley
                                 Title:   Senior Vice President

                              By:   /s/ Charles E. Hall
                                 -----------------------------------------------
                                 Name: Charles E. Hall
                                 Title:   Senior Vice President


                              WELLS FARGO BANK (TEXAS),
                              NATIONAL ASSOCIATION, Lender

                              By:   /s/ Ann Rhoads
                                 -----------------------------------------------
                                 Name: Ann Rhoads
                                 Title:   Vice President

                              CHASE BANK OF TEXAS, N.A., Lender

                              By:   /s/ Russell A. Johnson
                                 -----------------------------------------------
                                 Name: Russell A. Johnson
                                 Title:   Vice President

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                              COMERICA BANK-TEXAS, Lender

                              By:   /s/ Daniel G. Steele
                                 -----------------------------------------------
                                 Name: Daniel G. Steele
                                 Title:   Senior Vice President


                              MEESPIERSON CAPITAL CORP., Lender

                              By:   /s/ Darrell W. Holley
                                 -----------------------------------------------
                                 Name: Darrell W. Holley
                                 Title:   Senior Vice President

                              By:   /s/ Karel Louman
                                 -----------------------------------------------
                                 Name: Karel Louman
                                 Title:   Managing Director

                              BANK OF SCOTLAND, Lender

                              By:   /s/ Annie Glynn
                                 -----------------------------------------------
                                 Name: Annie Glynn
                                 Title:   Senior Vice President


                              U.S. BANK NATIONAL ASSOCIATION, Lender

                              By:   /s/ Monte E. Deckerd
                                 -----------------------------------------------
                                 Name: Monte E. Deckerd
                                 Title:   Vice President


                              HIBERNIA NATIONAL BANK

                              By:   /s/
                                 -----------------------------------------------
                                 Name:
                                 Title:


                              GENERAL ELECTRIC CAPITAL CORPORATION

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

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                             CONSENT AND AGREEMENT

     Each of the undersigned Subsidiary Guarantors hereby consents to the
provisions of this Amendment and the transactions contemplated herein and hereby
(i) acknowledges and agrees that any and all indebtedness, liabilities or
obligations arising under or in connection with the Notes are Obligations and
are secured indebtedness under, and are secured by, each and every Security
Document to which it is a party, (ii) re-pledges, re-grants and re-assigns a
security interest in and lien on all of its assets described as collateral in
any Security Document, (iii) ratifies and confirms its Amended and Restated
Guaranty dated May 22, 1998 made by it for the benefit of Agent and Lenders, and
(iv) expressly acknowledges and agrees that such Subsidiary Guarantor guarantees
all indebtedness, liabilities and obligations arising under or in connection
with the Notes pursuant to the terms of such Amended and Restated Guaranty, and
agrees that its obligations and covenants thereunder are unimpaired hereby and
shall remain in full force and effect.

                         PLAINS RESOURCES INTERNATIONAL INC.
                         STOCKER RESOURCES, INC.
                         CALUMET FLORIDA, INC.
                         PLAINS ILLINOIS INC.


                         By:   /s/ Michael R. Patterson
                            -----------------------------------------------
                            Name: Michael R. Patterson
                            Title:   Vice President


                         STOCKER RESOURCES, L.P.

                         By:  Stocker Resources, Inc.,
                               its General Partner


                              By:   /s/ Michael R. Patterson
                                 -----------------------------------------------
                                 Name: Michael R. Patterson
                                 Title:   Vice President

                                       8
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     The undersigned Subsidiary Guarantor hereby consents to the provisions of
this Agreement and the transactions contemplated herein and hereby (i)
acknowledges and agrees that any and all indebtedness, liabilities or
obligations arising under or in connection with the Notes are Obligations and
are secured indebtedness under, and are secured by, each and every Security
Document to which it is a party, (ii) re-pledges, re-grants and re-assigns a
security interest in and lien on all of its assets described as collateral in
any Security Document, (iii) ratifies and confirms its Guaranty dated July 1,
1999 made by it for the benefit of Agent and Lenders, and (iv) expressly
acknowledges and agrees that such Subsidiary Guarantor guarantees all
indebtedness, liabilities and obligations arising under or in connection with
the Notes pursuant to the terms of such Guaranty, and agrees that its
obligations and covenants thereunder are unimpaired hereby and shall remain in
full force and effect.

                         ARGUELLO, INC.


                         By:   /s/ Michael R. Patterson
                            -----------------------------------------------
                              Name: Michael R. Patterson
                              Title:   Vice President

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