EXHIBIT 10.15

NOTWITHSTANDING  ANY  OTHER  PROVISION  OF  THIS  AGREEMENT,  NO  SHARES  OF THE
COMPANY'S  STOCK MAY BE ISSUED  PURSUANT  HERETO UNLESS IN  COMPLIANCE  WITH THE
COMPANY'S  1988 STOCK OPTION PLAN, AS AMENDED,  AND WITH  APPLICABLE  SECURITIES
LAWS AND REGULATIONS.


                                                  SIERRA TAHOE BANCORP
                                                  AMENDED AND RESTATED
                                          NON-QUALIFIED STOCK OPTION AGREEMENT


     THIS  AMENDED  AND  RESTATED  NON-QUALIFIED  STOCK  OPTION  AGREEMENT  (the
"Agreement") is dated August 17, 1995, and is entered into by and between SIERRA
TAHOE BANCORP,  a California  corporation  (the "Company") and RICHARD S. GASTON
("Optionee");

                                                       WITNESSETH:
     WHEREAS,  pursuant  to the  1988  Stock  Option  Plan of the  Company  (the
"Plan"),  as amended on August 16, 1995 by the  shareholders  of the Company and
approved  on August  17,  1995 by the Board of  Directors  of the  Company  (the
"Action"),  there is hereby granted to Optionee a stock option (the "Option") to
purchase  all or any  part  of One  Thousand  Five  Hundred  Eight-Five  (1,585)
authorized  but unissued  shares of the  Company's  common stock for cash at the
price of Nine Dollars and Seventy-Five  Cents ($9.75) per share,  such Option to
be for the term and upon the terms and conditions hereinafter stated;
     NOW, THEREFORE, it is hereby agreed:
     1.       Grant of Option
              Pursuant  to the  above-referenced  Action and,  where  necessary,
pursuant  to   authorizations   granted  by  all   appropriate   regulatory  and
governmental  agencies,  the Company  hereby  grants to  Optionee  the Option to
purchase,  upon and subject to the terms and  conditions  of the Plan,  which is
incorporated in full herein by this  reference,  all or any part of One Thousand
Five  Hundred  Eight-Five  (1,585)  Shares of the  Company's  Common  Stock (the
"Stock") at the price of Nine Dollars and Seventy-Five  Cents ($9.75) per share,
which price is not less than one hundred percent (100%) of the fair market value
of the stock as of the date of the above-referenced Action granting this Option.

Non-Qualified Stock Option Agreement


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     2.       Exercisability
              The  Option  granted  hereby  will be fully  vested  and  shall be
exercisable for a period of ten (10) years from August 17, 1995. Any unexercised
shares must be exercised or forfeited before the conclusion of that period.
     3.       Exercise of Option
              This Option may be  exercised by written  notice  delivered to the
Company  stating the number of shares with respect to which this Option is being
exercised,  together  with  cash in the  amount  of the  purchase  price of such
shares.  Not less than ten (10) shares may be  purchased  at any one time unless
the number  purchased  is the total  number  which may be  purchased  under this
Option and in no event may the Option be exercised  with  respect to  fractional
shares. Upon exercise, Optionee shall make appropriate arrangements and shall be
responsible for the withholding of any federal and state taxes then due.
     4.       Cessation of Directorship Without Cause
              Except as  provided  in  Paragraphs  5 and 6 hereof,  if  Optionee
ceases to serve as a director of the Company or a subsidiary corporation for any
reason other than cause, this Option shall not expire and shall be retained as a
continuing right by the former director.
     5.       Termination of Directorship for Cause
              If  Optionee's   directorship  of  the  Company  or  a  subsidiary
corporation  is  terminated  for cause,  this Option shall  expire  immediately,
unless  reinstated  by the Board of  Directors  within  thirty (30) days of such
termination by giving written  notice of such  reinstatement  to Optionee at his
last known address.  In the event of such  reinstatement,  Optionee may exercise
this  Option  only to such  extent,  for such  time,  and upon  such  terms  and
conditions  as set forth in  Paragraph  4,  above.  Termination  for cause shall
include  termination for malfeasance or gross  misfeasance in the performance of
directorship duties or conviction of illegal activity in connection therewith or
any  conduct  detrimental  to the  interests  of  the  Company  or a  subsidiary
corporation and, in any event, the  determination of the Board of Directors with
respect thereto shall be final and conclusive.
     6.       Nontransferability; Death of Optionee
              This  Option  shall not be  transferable  except  by  testamentary
disposition or by the laws of descent and  distribution and shall be exercisable
during Optionee's lifetime


Non-Qualified Stock Option Agreement


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only by Optionee.  If Optionee dies while acting as a director of the Company or
a subsidiary  corporation,  this Option shall continue to be exercisable for the
remaining  period set forth in  Paragraph  2, above,  unless  sooner  terminated
pursuant to this Agreement. After Optionee's death (but before expiration of the
Option),  the persons to whom  Optionee's  rights  under this Option  shall have
passed by  testamentary  disposition  or by the  applicable  laws of descent and
distribution or the executor or  administrator  of Optionee's  estate shall have
the right to exercise this Option as to those shares  granted under  Paragraph 2
hereof as of the date on which  Optionee  ceased to be a director of the Company
or a subsidiary corporation.
     7.       Privileges of Stock Ownership
              Optionee shall have no rights as a stockholder with respect to the
Company's stock subject to this Option until the date of payment and issuance of
stock  certificates  to Optionee.  Except as provided in the Plan, no adjustment
will be made for dividends or other rights for which the record date is prior to
the date such stock certificates is paid for and issued.
     8.       Modification and Termination by Board of Directors
              The rights of Optionee are subject to modification and termination
upon the occurrence of certain events as provided in the Plan.
     9.       Representations of Optionee
              No shares  issuable  upon the  exercise  of this  Option  shall be
issued and delivered unless and until all applicable  requirements of applicable
state and federal law and of the Securities and Exchange  Commission  pertaining
to the issuance and sale of such shares, and all applicable listing requirements
of the securities exchanges,  if any, on which shares of the Company of the same
class are then  listed  shall have been  complied  with.  Upon  exercise  of any
portion of this Option,  the person entitled to execute the same may be required
to execute a  representation  letter with respect to compliance with federal and
applicable state securities laws. In addition, if the Optionee is an "affiliate"
for purposes of the Securities Act of 1933, there may be additional restrictions
on the resale of stock,  and Optionee  therefore  agrees to ascertain what those
restrictions are and to abide by those restrictions and other applicable federal
and state securities laws. The




Non-Qualified Stock Option Agreement


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Company may, if it deems appropriate,  issue stock transfer instructions against
any shares of stock  purchased upon the exercise of this Option and affix to any
certificate  representing  such  shares  the  legends  which the  Company  deems
appropriate.  Optionee understands that the shares of stock purchased under this
Option may be subject to holding periods and/or other restrictions on resale.
     10.      Notices
              Any notice to the Company provided for within this Agreement shall
be addressed to it in care of its  CEO/President or its Chief Financial  Officer
at its main office and any notice to Optionee  shall be addressed to  Optionee's
address on file with the Company or a subsidiary  corporation,  or to such other
address as either may  designate  to the other in writing.  Any notice  shall be
deemed to be duly given if and when enclosed in a properly  sealed  envelope and
addressed as stated above and deposited, postage prepaid, with the United States
Postal  Service.  In lieu of giving  notice by mail as  aforesaid,  any  written
notice  under this  Agreement  may be given to  Optionee  in person,  and to the
Company  by  personal  delivery  to its  CEO/President  or its  Chief  Financial
Officer.
     IN WITNESS WHEREOF, the parties hereto have executed this Agreement.

OPTIONEE

By:           /s/ Richard S. Gaston
     RICHARD S. GASTON

SIERRA TAHOE BANCORP,
a California Corporation ("Company")


By:           /s/ Jerrold Henley
     JERROLD HENLEY
Its:          Chairman, Board of Directors


By:           /s/ William T. Fike
     WILLIAM T. FIKE
Its:          CEO/President


By:           /s/ A. Morgan Jones
     MORGAN JONES
Its:          Secretary




Non-Qualified Stock Option Agreement

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