Exhibit 10.16
              FIRST AMENDMENT OF CREDIT AGREEMENT

          THIS FIRST AMENDMENT OF CREDIT AGREEMENT (this "Amendment"),  dated as
of December 29, 1997,  is by and among  AMERICAN  RIVERS OIL COMPANY,  a Wyoming
corporation,  KARLTON  TERRY,  individually,  and JUBAL S.  TERRY,  individually
(collectively,  "Borrower"),  and VECTRA  BANK DTC BRANCH  ("Vectra"),  formerly
known as Professional Bank.

                           RECITALS

          A.  Borrower and  Professional  Bank  entered into a letter  agreement
dated  September  13, 1996 (the "Credit  Agreement"),  in order to set forth the
terms upon which  Professional Bank would make available to Borrower a revolving
line of credit.  Capitalized terms used herein but not defined herein shall have
the same meanings as set forth in the Credit Agreement.

          B.  Borrower and Vectra wish to enter into this Amendment in
order to amend certain terms and provisions of the Credit Agreement.

                          AMENDMENT

          NOW, THEREFORE, in consideration of $10.00 and other good and valuable
consideration, the receipt and sufficiency of which are hereby acknowledged, the
parties hereby agree as follows:

          1.   Credit Agreement.  The Credit Agreement shall be, and
hereby is, amended as follows of the date hereof:

               (a) By changing all references therein to "Professional  Bank" to
refer to "Vectra Bank DTC Branch f/k/a  Professional  Bank",  and to incorporate
therein  the  definition  of Vectra  set forth in the  first  paragraph  of this
Amendment.

               (b) By  substituting  the  following  for  clause  (1) of Section
1.1(b) on page 1 of the Credit Agreement:

                    (1) make an Advance after  September 12, 1997,  except that,
               on or about December 29, 1997,  Vectra shall make a final Advance
               (the "Final  Advance") in the amount of  $22,525.00,  which shall
               bring  the   outstanding   principal   balance  of  the  Loan  to
               $540,000.00;

               (c)  By substituting the following for Section 1.3 on
page 1 of the Credit Agreement:

                    1.3.  Mandatory  principal  payments from Borrower to Vectra
          shall be  required  as set forth in  Section  2.2  below.  The  entire
          outstanding  principal balance of the Loan,  together with all accrued
          interest and other  amounts  payable to Vectra  hereunder or under the
          Note, shall be due

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          and payable, if not previously paid, on March 13,
          1998.

               (c)  By inserting the following at the end of Section
1.4 on page 2 of the Credit Agreement:

                    In no event shall the proceeds of the Final  Advance be used
          for any  purpose  other  than:  (a) the  payment  to Vectra of accrued
          interest on the Loan  through  January 1, 1998,  (b) the payment of an
          engineering  fee  currently  owing  to  Kent  Lina  in the  amount  of
          $2,540.00,  (c) the  payment  to Vectra of a loan fee in the amount of
          $2,700.00,  and (d) the  payment of legal fees due David G. Stolfa for
          past legal services and services in connection  with this Amendment in
          the amount of $1,000.00.

               (d)  By substituting the following for Section 4.2(b) on
page 8 of the Credit Agreement:

                    (b) Additional Debt. AROC will not create,  incur, assume or
          permit to exist any outstanding debt,  except: (1) the Loan, (2) trade
          debt owed to suppliers,  pumpers,  mechanics,  materialmen  and others
          furnishing  goods or services to AROC in the ordinary course of AROC's
          business,  (3) debt as to which the  obligee's  repayment  rights  are
          limited to specific  items of property  pledged by Borrower  and as to
          which the obligee has no recourse to the general  credit of  Borrower,
          and (4) existing debt of Borrower  shown on the  financial  statements
          heretofore submitted by Borrower to Professional Bank.

               (e) Exhibit B attached  hereto shall be substituted for Exhibit B
attached to the Credit Agreement.

          2.  The Note.  The Note shall be amended, such amendment to
be effected by an Allonge (the "Allonge"), between Borrower and Vectra,
to be attached to the Note and to be substantially in the form of
Exhibit A attached hereto and made a part hereof.

          3.  Loan Documents.  All references in any document to the
Credit Agreement shall refer to the Credit Agreement, as amended
pursuant to this Amendment.  All references in any document to the Note
shall refer to the Note, as amended pursuant to the Allonge.

          4.  Conditions Precedent.  The obligations of the parties
under this Amendment are subject, at the option of Vectra, to the prior
satisfaction of the condition that Borrower shall have delivered to
Vectra the following (all documents to be satisfactory in form and

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substance to Vectra and, if appropriate,  duly executed  and/or  acknowledged on
behalf of the parties other than Vectra):

               (a)  This Amendment.

               (b)  The Allonge.

               (c) A Consent of Guarantor  and Amendment of Guaranty in the form
     of Exhibit C attached hereto and made a part hereof.

               (d)  Any and all other loan documents required
     by the Bank.

          5. Representations and Warranties. Borrower hereby certifies to Vectra
that, as of the date of this Amendment,  all of Borrower's  representations  and
warranties  contained in the Credit Agreement are true, accurate and complete in
all  material  respects,  no Event of  Default  has  occurred  and no event  has
occurred  which,  with the giving of notice,  the lapse of time, or both,  would
constitute an Event of Default.

          6. Continuation of the Credit  Agreement.  Except as specified in this
Amendment, the provisions of the Credit Agreement shall remain in full force and
effect, and if there is a conflict between the terms of this Amendment and those
of the  Credit  Agreement  or any  other  document  executed  and  delivered  in
connection therewith, the terms of this Amendment shall control.

          7.  Expenses.  Borrower shall pay all reasonable expenses
incurred in connection with the transactions contemplated by this
Amendment, including without limitation all reasonable fees and
expenses of Vectra's attorney.

          8.  Miscellaneous.  This Amendment  shall be governed by and construed
under the laws of the State of Colorado  and shall be binding  upon and inure to
the  benefit  of the  parties  hereto and their  successors  and  assigns.  This
Amendment may be executed in any number of counterparts,  each of which shall be
an original, but all of which together shall constitute one instrument.

          EXECUTED as of the date first above written.

                              VECTRA BANK DTC BRANCH f/k/a
                               PROFESSIONAL BANK


                              By:  /s/ James B. Bills
                                   Vice President

                              AMERICAN RIVERS OIL COMPANY



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                              By:  /s/ Richard E. Westerberg
                                   President


                              By:  /s/ Jubal S. Terry
                                       Vice President


                              /s/ Karlton Terry
                                  KARLTON TERRY


                              /s/ Jubal S. Terry
                                  JUBAL S. TERRY


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                          EXHIBIT A

                           ALLONGE

          FOR  VALUE   RECEIVED,   AMERICAN   RIVERS  OIL  COMPANY,   a  Wyoming
corporation,  KARLTON TERRY, individually, and JUBAL S. TERRY, individually (all
of the foregoing being herein collectively  called "Borrower"),  and VECTRA BANK
DTC BRANCH f/k/a PROFESSIONAL BANK ("Vectra"),  hereby amend the Promissory Note
dated  September 13, 1996, in the face amount of  $1,000,000,  made by Borrower,
payable to the order of Professional Bank (the "Note"), as follows:

               1.  All references in the Note to "Professional Bank" or
"Payee" shall be deemed to refer to Vectra Bank DTC Branch formerly
known as Professional Bank; and

               2. By  substituting  "March 13, 1998" for "September 13, 1997" as
the maturity date of the Note in line 4 of the third  paragraph on page 1 of the
Note.

          This Allonge is to be governed by and construed  according to the laws
of the State of Colorado.

          DATED as of December 29, 1997.

                              VECTRA BANK DTC BRANCH f/k/a
                               PROFESSIONAL BANK

                              By:  /s/ James B. Bills
                                   James B. Bills,
                                   Vice President


                              AMERICAN RIVERS OIL COMPANY

                              By:  /s/ Richard E. Westerberg
                                   President

                              By:  /s/ Jubal S. Terry
                                   Vice President

                              /s/  Karlton Terry
                                   KARLTON TERRY

                              /s/  Jubal S. Terry
                                   JUBAL S. TERRY

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                          EXHIBIT B

                      COMMITMENT AMOUNT


     Time Period                             Commitment Amount

   09/13/96 - 09/30/96                         $1,000,000.00
   10/01/96 - 10/31/96                           $980,174.00
   11/01/96 - 11/30/96                           $960,405.00
   12/01/96 - 12/31/96                           $940,724.00
   01/01/97 - 01/31/97                           $921,130.00
   02/01/97 - 02/28/97                           $901,772.00
   03/01/97 - 03/31/97                           $882,347.00
   04/01/97 - 04/30/97                           $863,005.00
   05/01/97 - 05/31/97                           $843,743.00
   06/01/97 - 06/30/97                           $824,560.00
   07/01/97 - 07/31/97                           $805,455.00
   08/01/97 - 08/31/97                           $786,427.00
   09/01/97 - 12/28/97                           $767,475.00
   12/29/97 - 03/12/98                           $540,000.00
   From and after 03/13/98                             $0.00




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                          EXHIBIT C

                    CONSENT OF GUARANTOR
                  AND AMENDMENT OF GUARANTY

          For good and valuable  consideration,  the receipt and  sufficiency of
which are hereby acknowledged,  KARLTON TERRY OIL COMPANY ("Guarantor"),  as the
guarantor under a Guaranty dated September 13, 1996 (the  "Guaranty"),  given by
Guarantor  to  Professional  Bank,  now known as  Vectra  Bank DTC  Branch  (the
"Bank"), to guaranty certain obligations of American Rivers Oil Company, Karlton
Terry  and  Jubal S.  Terry  (collectively,  "Borrowers")  to the  Bank,  hereby
consents  to, and  agrees  with the Bank that the  Guaranty  shall be amended to
reflect,  the  transactions set forth in and contemplated by the First Amendment
of Credit Agreement dated as of December 29, 1997 (the "First Amendment"), among
Borrowers and the Bank, including without limitation: (1) the extension to March
13,  1998 of the final  maturity  date of the loan made  pursuant  to the Credit
Agreement (as defined in the First Amendment) at which time all then-outstanding
principal, interest, fees, expenses and other amounts payable in connection with
the Credit Agreement shall be due and payable in full, and (2) the provisions of
the First Amendment  permitting  Borrowers to receive,  on or about December 29,
1997, a final advance of the loan made pursuant to the Credit Agreement.

          The  Guaranty  shall be further  amended by  changing  all  references
therein  to  "Professional  Bank" to  refer to  "Vectra  Bank DTC  Branch  f/k/a
Professional Bank".

          This Instrument may be executed in any number of counterparts, each of
which  shall be an  original  and no one of which  need be  signed by all of the
parties, but all of which together shall constitute one and the same instrument.
Guarantor hereby ratifies the Guaranty, as amended hereby.

          DATED as of December 29, 1997.

                              KARLTON TERRY OIL COMPANY

                              By:  /s/ Karlton Terry
                                   President

                              VECTRA BANK DTC BRANCH f/k/a
                               PROFESSIONAL BANK

                              By:  /s/ James B. Bills
                                   Vice President

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