American Rivers Oil Company
November 1, 1996
Page 1
                                                                    Exhibit 5.1



                            OPON DEVELOPMENT COMPANY
                            1675 Broadway, Suite 1050
                             Denver, Colorado 80202



                                November 1, 1996



American Rivers Oil Company
700 East 9th Avenue
Denver, Colorado 80203

Attention:  Karlton Terry
            Chief Executive Officer

Ladies and Gentlemen:

     This will confirm the mutual  intentions  of Opon  Development  Company,  a
Delaware  corporation  ("ODC"),  and  American  Rivers  Oil  Company,  a Wyoming
corporation ("AROC"), as follows:

     1. Transaction. Based upon the mutual investigations completed to date, ODC
and AROC,  with the  approval  of their  respective  Boards of  Directors,  have
determined that it is in the best interests of each company and their respective
common shareholders that ODC and AROC combine into a single business enterprise.
The parties will consider a holding company structure with separate subsidiaries
holding the domestic and international properties, respectively. The form of the
transaction  is  anticipated  to be a merger of ODC with the  successor  to AROC
(which will be reincorporated in Delaware as discussed below) ("AROC-Delaware"),
or a  wholly-owned  subsidiary  of  AROC-Delaware,  with  AROC-Delaware  as  the
surviving or ultimate parent corporation (the "Merger"). The transaction will be
structured to qualify as a tax-free reorganization. Prior to the Merger (i) AROC
will  distribute to the Class A common  shareholders  of AROC all of the capital
stock  of  its  subsidiary,  Bishop  Capital  Corporation  ("Bishop"),  the  tax
consequences of which will be addressed in the definitive  agreement,  (ii) AROC
will  pay in full  any  and all  indebtedness  owed  by  AROC to  Bishop  or its
affiliates,  and Bishop will release any  outstanding  lien on property of AROC,
(iii) AROC and Bishop will enter into a cross-indemnification agreement on terms
mutually  acceptable to AROC, Bishop and ODC, (iv) AROC will dispose of, without
ongoing  liability to AROC, that certain Louisiana  property Bayou Chauvin,  and
(v) AROC will be reincorporated in Delaware by merger into AROC-Delaware. In the
reincorporation  merger each  outstanding  share of AROC  Common  Stock and AROC
Class B Common Stock will be converted into the immediate  right to receive such
percentage of a share of AROC-Delaware  Common Stock as determined by the mutual
agreement of the parties.






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November 1, 1996
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     2.  Consideration.  The number of shares of AROC- Delaware Common Stock for
which each share of ODC Common  Stock shall be  exchanged  at the Closing of the
Merger shall be determined by dividing the number of ODC shares outstanding into
the  number of shares of  AROC-Delaware  representing  95% of the  fully-diluted
equity  capital  of  AROC-Delaware  at  the  time  of  the  Merger,   such  that
shareholders  of  AROC-Delaware  immediately  prior to the Merger will own 5% of
AROC-Delaware  immediately after the Merger, with the shareholders of ODC owning
the remaining 95%. Such ownership ratio could change from 5%:95% to 10%:90%,  or
a ratio in between, pursuant to an agreement between the parties.

     3. Post-Merger  Management.  It is intended that immediately  following the
Merger,  the Board of Directors of AROC-  Delaware  shall  consist of Douglas K.
Childs,  James D. Brownlie,  Orlyn Terry and John Alexander,  or their nominees.
Further,  the senior  management  of  AROC-Delaware  shall be Douglas K. Childs,
James D.  Brownlie and Orlyn Terry.  Karlton  Terry and Jubal Terry shall remain
employees of AROC-Delaware pursuant to employment agreements to be negotiated by
the parties.  As part of these  employment  agreements,  Karlton and Jubal Terry
shall waive any rights  arising under  existing  arrangements,  including  those
triggered by a change of control of AROC.

     4.  Shareholder  Matters.  Each of AROC and ODC shall  present  the  Merger
Agreement to, and,  subject to the  fiduciary  duties of the Board of Directors,
shall  recommend that their common  shareholders  vote in favor of the Merger at
meetings of shareholders to be held at the earliest  practicable  date after the
effectiveness of the registration statement discussed below. In that connection,
AROC shall, as soon as practicable  after the execution of the definitive Merger
Agreement,  prepare and file with the Securities and Exchange Commission a proxy
statement with respect to the Merger and the related  transactions.  AROC,  with
the  cooperation of ODC, shall use its best efforts to have the proxy  statement
cleared by the SEC, declared effective and mailed to the common  shareholders of
each of AROC and ODC as promptly as practicable. Promptly following the mailing,
each of AROC and ODC shall convene a meeting of shareholders with respect to the
foregoing.

     5.  Covenants  of AROC and ODC.  From and after the date  hereof  until the
termination of this Letter of Intent  pursuant to Section 13 or until  execution
of the Merger  Agreement which will contain similar terms,  each of AROC and ODC
will conduct its business  only in the normal and ordinary  course and,  without
the prior written consent of the other, it will not, among other things:








American Rivers Oil Company
November 1, 1996
Page 3


          (a) except for the issuance of shares of capital  stock upon  exercise
or conversion of presently  outstanding  stock  options,  rights or  convertible
securities  and, to the extent it does not adversely  affect the tax-free nature
of the Merger,  for the current private placement of AROC common stock for up to
$2,500,000  in the  aggregate  which shall be  consummated  prior to the Merger,
issue or sell, or contract to issue or sell,  any shares of capital stock or any
of its  subsidiaries  or any securities  convertible  into or  exchangeable  for
shares of capital  stock or any of its  subsidiaries  or  securities,  warrants,
options or rights to purchase any of the foregoing;

          (b) purchase or redeem any shares of capital stock;

          (c)  declare  or  pay  any  dividends  or  agree  to  make  any  other
distribution with respect to any shares of capital stock; or

          (d) amend its Articles of Incorporation or Bylaws.

     In addition, without the prior written consent of ODC, AROC will not:

          (a) incur any indebtedness in excess of $250,000 in the aggregate; or

          (b) make any expenditure in excess of $250,000 in the aggregate.

     In addition, without the prior written consent of AROC, ODC will not:

          (a) incur debt except  pursuant to the  Funding  Agreement  with Amoco
Corporation  or  debt  extended  to  ODC  by  current  ODC  shareholders,  their
successors or assigns in the amounts  necessary to keep all accounts current and
in good standing.

     6. Due  Diligence.  Each of AROC and ODC shall be  permitted to make a full
and complete  investigation of the other's business,  accounting,  financial and
legal affairs.  Each of AROC and ODC shall give the other,  and their authorized
representatives,   reasonable  access  during  regular  business  hours  to  its
employees,  officers,  assets  and  properties,  as from  time  to  time  may be
requested.  The parties  agree to use their best  efforts to  complete  such due
diligence investigations prior








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November 1, 1996
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to the execution of the definitive Merger Agreement and agree to promptly advise
the other of any concerns noted. All information  gained from such investigation
by either party concerning the business or affairs of the other shall be subject
to the Confidentiality  Agreement attached hereto, between them, which agreement
shall continue in effect in accordance with its terms.

     7.  Announcements.  Prior to execution of the definitive  Merger Agreement,
neither party shall issue any statement or communication to the public regarding
the transaction  without the consent of the other party, which consent shall not
be unreasonably  withheld,  and except that this restriction shall be subject to
AROC's  obligation to comply with  applicable  securities  laws.  AROC agrees to
consult  with ODC and its counsel  with  respect to any public  announcement  it
believes is required.

     8.  Definitive  Agreement.  The  transactions  contemplated  hereby will be
evidenced by a definitive  Merger Agreement to be executed by AROC, ODC and each
of the significant shareholders of each and containing customary representations
and  warranties  by AROC and  ODC,  including,  but not  limited  to,  financial
statements,  litigation,  tax  liabilities,  title  matters,  employee  matters,
environmental  liabilities  and any other  unknown  or  undisclosed  liabilities
relating to actions,  events or conditions  existing  prior to the Closing.  The
representations  and  warranties  contained  in the Merger  Agreement  shall not
survive  the  closing of the  Merger.  The Merger  Agreement  will also  contain
representations and warranties by AROC with respect to issuance of the shares to
the  shareholders  of ODC customary  for a public  company  issuing  shares in a
transaction of this nature and will contain the following conditions to closing:

          (a) ODC and AROC  shall be  satisfied  with the  results  of their due
diligence examination of the other;

          (b) There shall have been no material  adverse  change since March 31,
1995 in the  financial  condition,  operating  results,  customer  and  employee
relations, business, prospects, or financing arrangements of either party;

          (c) The parties shall have obtained all  governmental  and third party
consents, approvals and waivers, if any, necessary to permit the consummation of
the Merger and the related transactions; and





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November 1, 1996
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          (d)  The  parties  shall  have  arranged  for  debt  financing  by  NM
Rothschild & Sons Limited on terms and conditions acceptable to ODC.

     The  definitive  agreements  shall also  provide  for demand and  piggyback
registration rights for the former shareholders of ODC.

     9. Expenses.  Except as provided below, if the Closing is not  consummated,
all fees and  expenses  incurred  in  connection  with  the  negotiation  and/or
effectuation of the transactions  contemplated hereby shall be the obligation of
the  respective  party  incurring  such fees and  expenses.  If the  Closing  is
consummated,  AROC-Delaware,  as the surviving corporation, shall pay all legal,
accounting  and other  professional  services  and costs  incurred by ODC or its
shareholders  by reason of the  negotiation  and/or  effectuation of the several
transactions   contemplated  hereby.  ODC  and  its  affiliates  are  committing
significant  time  and  expense,   incurring  significant  disruption  of  their
organization  and  foregoing  other  opportunities,   in  order  to  pursue  the
transactions  contemplated  hereby.  Accordingly,  if this  letter  of intent is
terminated by written  notice by AROC pursuant to Section 13 hereof,  AROC shall
pay  ODC,  immediately  upon  such  termination,   its  out-of-pocket  expenses,
including  attorney's fees. If AROC shall fail to make such payment when due, it
shall also pay to ODC all costs and expenses  (including  reasonable  attorney's
fees) incurred by ODC in connection with the collection  thereof,  plus interest
at a rate of 10% per annum.  If this letter of intent is  terminated  by written
notice by ODC  pursuant  to Section 13 hereof,  ODC shall pay AROC,  immediately
upon such termination,  its out-of-pocket  expenses,  including attorney's fees,
except those fees and expenses charged by Rothschild Natural  Resources,  L.L.C.
If ODC shall fail to make such  payment  when due, it shall also pay to AROC all
costs and expenses  (including  reasonable  attorney's fees) incurred by AROC in
connection  with the  collection  thereof,  plus  interest  at a rate of 10% per
annum.

     10.  Brokerage.  Each party represents and warrants to the other party that
it has not incurred any  obligations  or  liabilities  for brokerage or finders'
fees or agents'  commissions or like payment in connection with the transactions
contemplated by this letter.

     11. Counterparts. This letter may be executed in multiple counterparts, any
one of which need not contain the  signature of more than one party,  but all of
which counterparts, taken together, shall constitute one and the same agreement.
Signatures  may be exchanged by telecopy,  with  original  signatures to follow.
Each party hereto agrees to be bound by its own telecopied signature and that he
or it accepts the telecopied signature of the other parties hereto.




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November 1, 1996
Page 6

     12. No Strict  Construction.  The  language  used in this  letter  shall be
deemed to be the language  chosen by the parties to express their mutual intent,
and no rule of strict construction shall be applied against any person.

     13.  Termination.  Subject to the  provisions  of Section 9 and  Section 14
hereof, either party shall be entitled to terminate this Letter of Intent at any
time, by written notice to the other party,  without cause and without liability
to the other. Further, if definitive agreements with respect to the transactions
contemplated  hereby have not been entered into prior to 5:00 p.m. Mountain time
on November 30, 1996, this Letter of Intent shall terminate and be of no further
force and effect unless extended by mutual agreement.

     14. Binding and Non Binding Aspects.

          (a) Except as hereinafter set forth, (i) the understandings  contained
herein do not  constitute  a binding  agreement  between the parties  hereto but
merely  express  their intent with respect  thereto and (ii) the  understandings
contained  herein  shall only become  binding  when a  definitive  agreement  is
executed.  Anything  contained  herein  to  the  contrary  notwithstanding,  the
obligations of the parties  hereto  pursuant to Sections 5, 6, 7, 9, 10, 11, 12,
13 and this Section 14 are intended to be binding and enforceable obligations of
the  parties.  The  provisions  of Section 9 and the last  sentence of Section 6
shall continue in full force and effect  following the termination or expiration
of this Letter of Intent. In addition,  all obligations of the parties under the
Confidentiality  Agreement  shall survive the  termination or expiration of this
Letter of Intent.

          (b) To the extent set forth in  subparagraph  (a) of this  Section 14,
this  Letter of Intent  shall be  binding  upon and inure to the  benefit of the
parties hereto and their  respective  successors  and assigns;  but shall not be
assignable without the prior written consent of the other party hereto.

     Except for the  provisions  of  Sections  5, 6, 7, 9, 10, 11, 12, 13 and 14
above,  each of which shall be deemed to be an  agreement  and binding upon both
ODC and AROC, it is understood that this letter does not constitute or give rise
to any legally binding  commitment.  ODC and AROC understand that this letter is



American Rivers Oil Company
November 1, 1996
Page 7

intended to set forth the fundamentals of the proposed combination, but that the
foregoing  intentions  may be revised  and new  issues  presented  upon  further
investigation by AROC or ODC.

     Please indicate your acceptance and approval of the foregoing  proposal and
statement of our intentions by signing below.

                                      Very truly yours,

                                      OPON DEVELOPMENT COMPANY


                                      By:  /S/  DOUGLAS K. CHILDS
                                          -------------------------------------
                                           Douglas K. Childs
                                           President


          The  foregoing  is  accepted  and  approved as of the date first above
written.

                                      AMERICAN RIVERS OIL COMPANY


                                      By:  /S/  KARLTON TERRY
                                           ------------------------------------
                                           Karlton Terry
                                           Chief Executive Officer