Page 1

                             UNITED STATES
                  SECURITIES AND EXCHANGE COMMISSION
                        Washington, D.C. 20549

                              Form 11-K

(Mark One)

[X]	ANNUAL REPORT PURSUANT TO SECTION 15(d) OF THE SECURITIES
	EXCHANGE ACT OF 1934

	For the fiscal year ended December 31, 2008

OR

[ ]	TRANSITION REPORT PURSUANT TO SECTION 15(d) OF THE
	SECURITIES EXCHANGE ACT OF 1934

	For the transition period from _______________ to _______________

	Commission file number 001-9383

       A. Full title of the plan and the address of the plan, if
          different from that of the issuer named below:

    	         WESTAMERICA BANCORPORATION TAX DEFERRED
                     SAVINGS/RETIREMENT PLAN (ESOP)

       B. Name of issuer of the securities held pursuant to the plan and
          the address of its principal executive office:

	              Westamerica Bancorporation
	 	             1108 Fifth Avenue
		       San Rafael, California 94901



Page 2

                    WESTAMERICA BANCORPORATION

              TAX DEFERRED SAVINGS/RETIREMENT PLAN (ESOP)


                        FINANCIAL STATEMENTS

                AS OF DECEMBER 31, 2008 AND 2007 AND

        FOR THE YEARS ENDED DECEMBER 31, 2008, 2007 AND 2006

                                AND

                       SUPPLEMENTAL SCHEDULES

             AS OF AND FOR THE YEAR ENDED DECEMBER 31, 2008

                                AND

                  REPORT OF INDEPENDENT REGISTERED

                     PUBLIC ACCOUNTING FIRM




Page 3


                      WESTAMERICA BANCORPORATION
            TAX DEFERRED SAVINGS/RETIREMENT PLAN (ESOP)

                        FINANCIAL STATEMENTS
                   AND SUPPLEMENTAL SCHEDULES



                         TABLE OF CONTENTS

                                                                         Page

Report of Independent Registered Public Accounting Firm                    4

Financial Statements:

      Statement of Net Assets Available for Benefits as of
            December 31, 2008 and 2007                                     5
      Statement of Changes in Net Assets Available for Benefits
            for the Years Ended December 31, 2008, 2007 and 2006           6

      Notes to Financial Statements                                      7-17

Supplemental Schedules:

      Schedule H, Line 4i - Schedule of Assets (Held at End of Year)
            as of December 31, 2008                                     18-19

      Schedule H, Line 4j - Schedule of Reportable Transactions
            for the Year Ended December 31, 2008                          20


Signatures                                                                21

Exhibit Index                                                             22


All other schedules required by Section 2520.103-10 of the Department of Labor's
Rules and Regulations for Reporting and Disclosure under the Employee Retirement
Income Security Act of 1974 have been omitted because they are not applicable.




Page 4

            REPORT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM


To the Employee Benefits and
   Compensation Committee of the
   Board of Directors of
   Westamerica Bancorporation

     We have audited the accompanying statement of net assets available for
benefits of the Westamerica Bancorporation Tax Deferred Savings/Retirement Plan
(ESOP) (the "Plan") as of December 31, 2008 and 2007, and the related statement
of changes in net assets available for benefits for the years ended December 31,
2008, 2007 and 2006.  These financial statements are the responsibility of the
Plan's management.  Our responsibility is to express an opinion on these
financial statements based on our audits.

     We conducted our audits in accordance with the auditing standards of the
Public Company Accounting Oversight Board (United States).  Those standards
require that we plan and perform the audit to obtain reasonable assurance about
whether the financial statements are free of material misstatement.  An audit
includes examining, on a test basis, evidence supporting the amounts and
disclosures in the financial statements.  An audit also includes assessing the
accounting principles used and significant estimates made by management, as well
as evaluating the overall financial statement presentation.  We believe that our
audits provide a reasonable basis for our opinion.

     In our opinion, the financial statements referred to above present fairly,
in all material respects, the net assets available for benefits of the
Westamerica Bancorporation Tax Deferred Savings/Retirement Plan (ESOP) as of
December 31, 2008 and 2007, and the changes in net assets available for benefits
for the years ended December 31, 2008, 2007 and 2006, in conformity with
accounting principles generally accepted in the United States of America.

     Our audits were made for the purpose of forming an opinion on the basic
financial statements taken as a whole.  The supplemental schedules of assets
(held at end of year) and reportable transactions, as of and for the year ended
December 31, 2008, are presented for the purpose of additional analysis and are
not a required part of the basic financial statements, but are supplementary
information required by the United States Department of Labor Rules and
Regulations for Reporting and Disclosure under the Employee Retirement Income
Security Act of 1974.  These supplemental schedules are the responsibility of
the Plan's management.  The supplemental schedules have been subjected to the
auditing procedures applied in the audit of the basic 2008 financial statements
and, in our opinion, are fairly stated in all material respects in relation to
the basic 2008 financial statements taken as a whole.


                                                   /s/ Perry-Smith LLP
                                                   -------------------

Sacramento, California
June 25, 2009



Page 5


                       WESTAMERICA BANCORPORATION
              TAX DEFERRED SAVINGS/RETIREMENT PLAN (ESOP)

            STATEMENT OF NET ASSETS AVAILABLE FOR BENEFITS

                      December 31, 2008 and 2007





                                                        2008        2007
                                                     ----------------------
   ASSETS
                                                          
Investments (Notes 3, 4 and 5)                      $44,591,743 $50,964,340
                                                     ----------------------

Net assets available for benefits                   $44,591,743 $50,964,340
                                                     =========== ===========



                   The accompanying notes are an integral
                     part of these financial statements.





Page 6

                         WESTAMERICA BANCORPORATION
                TAX DEFERRED SAVINGS/RETIREMENT PLAN (ESOP)

        STATEMENT OF CHANGES IN NET ASSETS AVAILABLE FOR BENEFITS

          For the Years Ended December 31, 2008, 2007 and 2006




                                            2008        2007        2006
                                        -----------------------------------
   ADDITIONS
                                                       
Investment income:
   Dividends and capital gains
        distributions                   $1,253,444   $1,860,130  $1,548,212
   Interest on participant loans            86,017       84,168      71,353
                                        -----------------------------------
      Total investment income            1,339,461    1,944,298   1,619,565
                                        -----------------------------------

Contributions:
   Participants                          1,958,673    2,005,817   2,064,360
   Employer                              1,276,990    1,196,990   1,284,649
   Participant rollovers                    67,182       58,629     437,189
                                        -----------------------------------
      Total contributions                3,302,845    3,261,436   3,786,198
                                        -----------------------------------
      Total additions                    4,642,306    5,205,734   5,405,763
                                        -----------------------------------

   DEDUCTIONS

Net depreciation (appreciation) in fair
  Value of investments (Note 3)          4,092,949    2,615,407    (262,793)
Benefits paid to participants            6,901,614    6,498,412   7,044,524
Administrative expenses (Note 7)            16,482       17,262      29,660
Other deductions                             3,858       51,576        - -
                                        -----------------------------------
      Total deductions                  11,014,903    9,182,657   6,811,391
                                        -----------------------------------
      Net decrease                      (6,372,597)  (3,976,923) (1,405,628)


Net assets available for benefits:
   Beginning of year                    50,964,340   54,941,263  56,346,891
                                        -----------------------------------
   End of year                         $44,591,743  $50,964,340 $54,941,263
                                        ===========  =========== ===========



                   The accompanying notes are an integral
                     part of these financial statements.



Page 7


                      WESTAMERICA BANCORPORATION
              TAX DEFERRED SAVINGS/RETIREMENT PLAN (ESOP)

                    NOTES TO FINANCIAL STATEMENTS


1.    DESCRIPTION OF PLAN

The following description of the Westamerica Bancorporation (the "Company") Tax
Deferred Savings/Retirement Plan (ESOP) (the "Plan") provides only general
information.  Participants should refer to the Summary Plan Description and Plan
Document for a more complete description of the Plan's provisions.

General
-------

The Plan is a defined contribution plan covering substantially all employees of
the Company.  The Plan, which became effective October 1, 1985, is intended to
be a qualified stock bonus plan under section 401(a) of the Internal Revenue
Code (IRC) and is designated as an employee stock ownership plan or ESOP.
Portions of the Plan are also intended to qualify as a qualified cash or
deferred arrangement within the meaning of section 401(k) of the IRC.  The Plan
also provides for Roth elective contributions.

The Employee Benefits and Compensation Committee of the Company's Board of
Directors (the "Committee") delegates the administration of the Plan to the
Company's Pension Management Committee.  The Committee has the responsibility
for the general operation of the Plan, including the resolution of any questions
arising under the Plan agreement.  The Plan is subject to the provisions of the
Employee Retirement Income Security Act of 1974 (ERISA).  Investments in the
Plan are participant directed with the exception of employer contributions which
are invested in shares of the Company's common stock at the time of
contribution.  Subsequent to investment in the Company's common stock,
participants may direct employer matching contributions among all investment
options.  Vanguard Fiduciary Trust Company serves as Trustee of the Plan.

Eligibility
-----------

Under the Plan, employees of the Company who are compensated on a salaried basis
become eligible to participate in the plan on the first day of the calendar
month coinciding with or following the date the employee completes 90
consecutive days of service with the Company or completes 1,000 service hours in
a 12-month consecutive period.

Vesting
-------

Participants are immediately vested in their salary-deferral contributions, the
Company's discretionary and matching contributions, plus actual earnings
thereon.

Contributions
-------------

Each year, participants may make salary deferral contributions in any whole
percentage of pretax annual compensation subject to certain IRC limitations.
Participants may also elect to make salary deferral contributions on an after-
tax basis in whole percentage increments ("Roth" elective contributions),
subject to certain limitations defined by the Plan.


Page 8

1.    DESCRIPTION OF PLAN (Continued)

Contributions (Continued)
-------------

The Company makes a matching contribution equal to 100 percent of the
participant's elective contribution and Roth elective contribution, up to a
maximum of 6 percent of the participant's compensation.  Additional amounts may
be contributed at the discretion of the Company's Board of Directors.
Participants may also contribute amounts representing distributions from other
qualified Roth accounts, defined benefit or defined contribution plans.  For the
years ended December 31, 2008, 2007 and 2006, the Company made no discretionary
contributions.  Company contributions are subject to certain IRC limitations.

Participant Accounts
--------------------

Individual accounts are maintained for each Plan participant.  Each
participant's account is credited with the participant's contribution,
allocation of the Company's matching and discretionary contributions, allocation
of Plan earnings, and charged with withdrawals, allocations of Plan losses and
administrative expenses.

Employer matching contributions are allocated to participants based on the
participant's elective contribution.  Employer discretionary contributions are
allocated to the account of each participant in ratio of the participant's
eligible compensation to the total eligible compensation for all Plan
participants.

Participants' Investment Options
--------------------------------

Company matching contributions are invested in the Westamerica Common Stock Fund
in accordance with the Plan Document.  Participants may redirect Company
matching contributions from the Westamerica Common Stock Fund to other
investment options at their discretion.

Participants direct participant contributions in whole or in part in any of the
following investment fund options as of December 31, 2008:

* The Westamerica Common Stock Fund, which is invested in the Company's
common stock and temporary interest-bearing money market funds.

* Vanguard 500 Index Fund, which invests in the 500 stocks that make up the
unmanaged Standard & Poor's 500 Composite Stock Price Index, a widely
recognized benchmark of U.S. stock market performance.

* Vanguard Explorer Fund, which invests in a diversified group of small-company
stocks with prospects for above-average growth.  The fund may invest up to 20%
in foreign securities and up to 15% in restricted or illiquid securities.


Page 9

1.    DESCRIPTION OF PLAN (Continued)

Participants' Investment Options (Continued)
--------------------------------

* Vanguard Morgan Growth Fund, which invests primarily in stocks of large and
mid-sized companies that have strong records of growth in sales and earnings or
that have performed well during certain market cycles.

* Vanguard Prime Money Market Fund, which invests in short-term, high-quality
money market instruments issued by financial institutions, nonfinancial
corporations, the U.S. government, and federal agencies.

* Vanguard Total Bond Market Index Fund, which invests in bonds that attempt to
match the performance of the unmanaged Lehman Brothers Aggregate Bond
Index, which is a widely recognized measure of the taxable U.S. bond market.

* Vanguard Total International Stock Index Fund, which invests in three Vanguard
international index funds: a European fund, a Pacific fund, and an emerging
markets fund.  These funds invest in the stock of companies in more than 30
countries.

* Vanguard Windsor II Fund, which invests in a diversified group of out-of-favor
stocks of large capitalization companies.  The stocks selected generally sell at
prices below the market average compared to their dividend income and future
return potential.

* Vanguard Extended Market Index Fund, which invests in a broadly diversified
portfolio of stocks of small and medium sized companies that are regularly
traded on the New York Stock Exchange and NASDAQ over-the-counter market.  The
portfolio is designed to be representative of the Wilshire 4500 Index.

* Vanguard Short-Term Federal Fund, which invests primarily in short-term
securities issued by U.S. government agencies, but may also invest in U.S.
Treasury securities and in repurchase agreements backed by U.S. Treasury or
federal agency securities.  To reduce fluctuations in its share price, the fund
maintains an average maturity of 1 to 3 years.


Page 10

1.    DESCRIPTION OF PLAN (Continued)

Participants' Investment Options (Continued)
--------------------------------

Vanguard Target Retirement Funds consists of eleven targeted maturity funds as
follows:

* Vanguard Target Retirement Income Fund
* Vanguard Target Retirement 2005 Fund
* Vanguard Target Retirement 2010 Fund
* Vanguard Target Retirement 2015 Fund
* Vanguard Target Retirement 2020 Fund
* Vanguard Target Retirement 2025 Fund
* Vanguard Target Retirement 2030 Fund
* Vanguard Target Retirement 2035 Fund
* Vanguard Target Retirement 2040 Fund
* Vanguard Target Retirement 2045 Fund
* Vanguard Target Retirement 2050 Fund

Each fund invests in other Vanguard mutual funds using an asset allocation
strategy designed for investors planning to retire in or within a few years of
the year in the fund's name, except the Income Fund, which is designed for
investors in retirement.

Vanguard Target Retirement Funds are designed as a balanced fund-of-funds for
long-term investors.  Each Vanguard Target Retirement Fund invests in broadly
diversified funds, which includes stock funds, bond funds and a money market
fund.

With the exception of the Vanguard Target Retirement Income Fund, the relative
allocations among Vanguard Target Retirement Funds' component funds gradually
grow more conservative over a predetermined schedule.

Participants may change their investment options at any time directly through
The Vanguard Group.

Participant Loans
-----------------
Participants may borrow a minimum of $1,000 up to a maximum equal to the lesser
of 50 percent of their account balance, 100 percent of participant
contributions, or $50,000. For the purposes of this limit, all qualified plans
of the Company shall be considered one plan. Loans are secured by the balance in
the participant's account.  Participant loans are funded by selling investments
in the borrowing participant's accounts and bear interest at rates that range
from 5 percent to 9.75 percent, which are commensurate with prevailing market
rates at the time the funds are borrowed.  Loans are made for a term not to
exceed 5 years.  Principal and interest is paid ratably through payroll
deductions and invested in the borrowing participant's accounts in accordance
with their investment directions.


Page 11

1.    DESCRIPTION OF PLAN (Continued)

Payment of Benefits
-------------------

Upon termination of service for any reason, a participant may elect to receive a
lump-sum distribution equal to the value in his or her account.  Distributions
for the value of a participant's account invested in the Westamerica Common
Stock Fund stock are made in the form of the Company's common stock plus cash
for any fractional shares or, if a participant elects, in cash or an in-kind
transfer, as provided by the Plan document. Participants may also receive in-
service distributions on account of hardship or after attaining age 59 1/2.
Cash dividends paid on Westamerica Bancorporation common stock allocated to
participant accounts may be paid to participants in cash or be credited
to the participant's account as earnings.  If the value of a separated
participant's benefit is not more than $1,000, the benefit shall be
automatically paid in a single lump sum in cash or, if elected, directly to an
eligible retirement plan.  Benefits payable to participants for amounts greater
than $1,000 may be made in cash or other form of distribution, as defined by the
Plan.  As of December 31, 2008 and 2007, there were no benefits payable to
participants that had elected to withdraw from the Plan but had not yet been
paid.

Voting Rights
-------------

Each participant is entitled to exercise voting rights attributable to the
Westamerica Bancorporation common stock shares allocated to his or her account
and is notified by the Trustee prior to the time that such rights are to be
exercised.  The Trustee is not permitted to vote any allocated share for which
instructions have not been given by a participant.

Plan Termination
----------------

Although it has not expressed any interest to do so, the Company has the right
under the Plan to discontinue its contributions at any time and to terminate the
Plan, subject to the provisions of ERISA.

Administrative Expenses
-----------------------

The Company provides bookkeeping and other administrative services for the Plan
at no charge.  The Company pays the Plan's annual account maintenance fees for
participants actively employed by the Company and other administrative expenses.

2.    SUMMARY OF ACCOUNTING POLICIES

Basis of Accounting
-------------------

The financial statements of the Plan have been prepared on the accrual basis of
accounting in accordance with accounting principles generally accepted in the
United States of America.


Page 12


2.    SUMMARY OF ACCOUNTING POLICIES (Continued)

Use of Estimates
----------------

The preparation of financial statements in conformity with accounting principles
generally accepted in the United States of America requires the Plan's
management to make estimates and assumptions that affect the reported amounts of
net assets available for benefits and changes therein and disclosure of
contingent assets and liabilities.  Actual results could differ from those
estimates.

Investment Valuation and Income Recognition
-------------------------------------------

The Plan's investments are stated at fair value.  Fair value is the price that
would be received to sell an asset or paid to transfer a liability in an orderly
transaction between market participants at the measurement date.  See Note 5 for
additional discussion of fair value measurements.

Purchases and sales of securities are recorded on a trade-date basis.  Interest
income is recorded on the accrual basis.  Dividends are recorded on the ex-
dividend date. Net appreciation (depreciation) in fair value of investments
includes net unrealized market appreciation (depreciation) of investments and
net realized gains and losses on the sale of investments during the period.

Management fees and operating expenses charged to the Plan for investments in
shares of registered investment companies (mutual funds) are deducted from
income earned on a daily basis and are not separately reflected.  Consequently,
management fees and operating expenses are reflected as a reduction of
investment return for such investments.  Trustee fees for Westamerica
Bancorporation Common Stock are charged to the Westamerica Common Stock Fund.

Risks and Uncertainties
-----------------------

The Plan utilizes various investment instruments, including the common stock of
the Company and mutual funds.  Investment securities, in general, are exposed to
various risks, such as interest rate, credit, currency and overall market
volatility. Due to the level of risk associated with certain investment
securities, it is reasonably possible that changes in the values of investment
securities will occur in the near term and that such changes could materially
affect the amounts reported in the financial statements.

Concentrations of Investments
-----------------------------

Included in investments at December 31, 2008 and 2007 are shares of the
Westamerica Common Stock Fund amounting to $24,331,790 and $22,441,634,
respectively.  The Westamerica Common Stock Fund represents 55% and 44% of total
investments of the Plan at December 31, 2008 and 2007, respectively.  A
significant decline in the market value of the Company's stock would have a
materially adverse effect on the Plan's net assets available for benefits.


Page 13

2.    SUMMARY OF ACCOUNTING POLICIES (Continued)

Redemption Fees
---------------

The Vanguard Total International Stock Index Fund charges a 2% fee ($20 per
$1,000 invested) on shares redeemed within two months of purchase.  The fee is
paid directly to the Vanguard Total International Stock Index Fund and,
therefore, is not considered a load.  These redemption fees are charged at the
participant account level, and are not included in administrative expenses of
the Plan.

Payment of Benefits
-------------------

Benefits are recorded when paid.

Reclassifications
-----------------

Certain amounts shown in the prior year have been reclassified to conform to the
current year presentation.

New Accounting Pronouncements
-----------------------------

Determining Fair Value When the Volume and Level of Activity for the Asset or
Liability Have Significantly Decreased and Identifying Transactions That Are Not
Orderly

In April 2009, the FASB issued FSP FAS 157-4, Determining Fair Value When the
Volume and Level of Activity for the Asset or Liability Have Significantly
Decreased and Identifying Transactions That Are Not Orderly, provides additional
guidance for estimating fair value in accordance with SFAS No. 157 when the
volume and level of activity for the asset or liability have decreased
significantly.  FSP FAS 157-4 also provides guidance on identifying
circumstances that indicate a transaction is not orderly. The provisions of FSP
FAS 157-4 are required to be adopted by the Plan for the year ending December
31, 2009.  The Plan will adopt FSP FAS 157-4 on June 30, 2009, and does not
expect the adoption to have any significant effect on the Plan's financial
statements.

Subsequent Events

In May 2009, the FASB issued FASB Statement No. 165 (SFAS No. 165), Subsequent
Events.  SFAS No. 165 establishes general standards of accounting for and
disclosure of events that occur after the balance sheet date but before
financial statements are issued or are available to be issued.  Specifically,
SFAS No. 165 defines, (1) the period after the balance sheet date during which
management of a reporting entity should evaluate events or transactions that may
occur for potential recognition or disclosure in the financial statements, (2)
the circumstances under which an entity should recognize events or transactions
occurring after the balance sheet date in its financial statements,
and (3) the disclosures that an entity should make about events or transactions
that occurred after the balance sheet date.  The provisions of SFAS No. 165 are
required to be adopted by the Plan for the year ending December 31, 2009.
Management does not expect the adoption of SFAS No. 165 to have a significant
impact on the Plan's financial position or results of operations.


Page 14

3.    INVESTMENTS

The following table presents investments at fair value that represent 5% or more
of the Plan's net assets as of December 31, 2008 or 2007:

    
    

                                                     2008        2007
                                                  -----------------------
                                                       
    Westamerica Common Stock Fund                $24,331,790 $22,441,634
    Westamerica Prime Money Market Fund            4,756,924   4,611,582
    Vanguard 500 Index Fund                        3,089,637   5,361,129
    Vanguard Target Retirement 2015 Fund           2,685,330   3,692,573
    Vanguard Morgan Growth Fund*                   1,649,278   3,185,682
    Vanguard Total International Stock Index Fund* 1,525,282   3,154,834
    Other Investments                              6,553,502   8,516,906
                                                  -----------------------
                                                 $44,591,743 $50,964,340
                                                  =========== ===========

    

* In 2008, these investments fell below 5% of the Plan's net assets but are
included for comparative purposes.

The Plan's investments, including investments bought, sold, and held during the
year, depreciated in value by $4,092,949 and $2,615,407 during 2008 and 2007,
respectively, and appreciated in value by $262,793 during 2006, as follows:

    
    

                                       2008         2007         2006
                                    ------------------------------------
                                                   
    Westamerica Common Stock Fund  $ 3,266,908  $(3,345,183) $(1,609,963)
    Mutual funds                    (7,359,857)     729,776    1,872,756
                                    ------------------------------------
                                   $(4,092,949) $(2,615,407)  $  262,793
                                    ===========  ===========  ===========
    


4.    INVESTMENT IN WESTAMERICA BANCORPORATION COMMON STOCK

The Plan's investments at December 31, 2008 and 2007 in Westamerica
Bancorporation common stock are as follows:

    
    

                                                   2008         2007
                                                -----------------------
                                                     

         Number of shares                           475,695      503,740
                                                ===========  ===========
         Cost                                  $ 14,426,158 $ 14,468,521
                                                ===========  ===========
         Fair value                            $ 24,331,790 $ 22,441,634
                                                ===========  ===========
    


Page 15

5.    FAIR VALUE MEASUREMENTS UNDER SFAS 157

On January 1, 2008, the Plan adopted FASB Statement No. 157 (SFAS No. 157), Fair
Value Measurements.  SFAS No. 157 defines fair value, establishes a framework
for measuring fair value under generally accepted accounting principles, and
expands disclosures about fair value measurement.  Upon adoption of SFAS No.
157, there was no cumulative effect adjustment to beginning net assets available
for benefits and no impact on the financial statements.

In October 2008, the FASB issued FASB Staff Position (FSP) Financial Accounting
Standard No. 157-3, Determining the Fair Value of a Financial Asset When the
Market for That Asset Is Not Active.  The FSP was effective immediately and
clarifies the application of FASB Statement No. 157, Fair Value Measurements in
a market that is not active and provides an example to illustrate key
considerations in determining the fair value of a financial asset when the
market for that financial asset is not active.

Fair Value Hierarchy
--------------------

In accordance with SFAS No. 157, the Plan groups its assets and liabilities
measured at fair value within three levels, based on the markets in which the
assets and liabilities are traded and the reliability of the assumptions used to
determine fair value.  Valuations within these levels are based upon:

Level 1 - Quoted market prices for identical instruments traded in active
exchange markets.

Level 2 - Quoted prices for similar instruments in active markets, quoted prices
for identical or similar instruments in markets that are not active, and model-
based valuation techniques for which all significant assumptions are observable
or can be corroborated by observable market data.

Level 3 - Model-based techniques that use at least one significant assumption
not observable in the market.  These unobservable assumptions reflect the Plan's
estimates of assumptions that market participants would use on pricing the asset
or liability.  Valuation techniques include management judgment and estimation
which may be significant.

In certain cases, the inputs used to measure fair value may fall into different
levels of the fair value hierarchy.  In such cases, the level in the fair value
hierarchy within which the fair value measurement in its entirety falls has been
determined based on the lowest level input that is significant to the fair value
measurement in its entirety.  The Plan's assessment of the significance of a
particular input to the fair value measurement in its entirety requires
judgment, and considers factors specific to the asset or liability.


Page 16

5.    FAIR VALUE MEASUREMENTS UNDER SFAS 157 (Continued)

Assets Recorded at Fair Value
-----------------------------

There were no changes in the valuation techniques used during 2008.  The
following table presents information about the Plan's assets and liabilities
measured at fair value on a recurring basis as of December 31, 2008:

Recurring Basis

The Plan is required or permitted to record the following assets at fair value
on a recurring basis under other accounting pronouncements:





     Description      Fair Value     Level 1     Level 2      Level 3
 -----------------------------------------------------------------------
                                                
Common stock
   Of Plan Sponsor    $24,331,790  $24,331,790
Mutual funds           19,104,495               $19,104,495
Participant loans       1,155,458                            $ 1,155,458
                      --------------------------------------------------
                      $44,591,743  $24,331,790  $19,104,495  $ 1,155,458
                      ===========  ===========  ===========  ===========



Fair value of the common stock of the Plan Sponsor is based on the closing
quoted market price reported on the active market on which the individual
securities are traded.  Such securities are actively traded throughout each day
on the NASDAQ Global Select Market.

Mutual funds are valued using the Net Asset Value (NAV) provided by the trustee
of the fund.  The NAV is computed by dividing the value of the underlying
assets, minus liabilities, allocated to each share class by the number of fund
shares outstanding for that class.  Mutual fund NAVs are calculated once each
business day as of the close of regular market trading.  The NAV is a quoted
price in a market that is not active.

Participant loans are valued at their outstanding balances, which approximate
fair value.

The following table sets forth a summary of changes in the fair value of the
Plan's recurring assets valued under Level 3 for the year ended December 31,
2008.


    
    
                                                             Participant
                                                                Loans
                                                             -----------
                                                          
    Balance, January 1, 2008                                 $  967,041

    Advances and repayments, net                                188,417
                                                             -----------
    Balance, December 31, 2008                               $1,155,458
                                                             ===========

    



The Plan did not have any assets or liabilities measured at fair value on a non-
recurring basis at December 31, 2008.


Page 17

6.    FEDERAL INCOME TAX STATUS

The Internal Revenue Service has determined and informed the Company by a letter
dated December 12, 2001, that the Plan is qualified and the trust established
under the Plan is tax-exempt, under the appropriate sections of the Internal
Revenue Code.  The Plan has been amended since receiving the determination
letter; however, the Plan's management and the Plan's ERISA counsel believe that
the Plan currently is designed and being operated in compliance with the
applicable requirements of the Internal Revenue Code and the Plan continues to
be tax exempt.  Therefore, no provision for income taxes has been included in
the Plan's financial statements.

7.    RELATED PARTY TRANSACTIONS

Plan investments include shares of mutual funds, including the Westamerica
Common Stock Fund which invests in the common stock of the Company, managed by
an affiliate of Vanguard Fiduciary Trust Company (VFTC).  VFTC is the Trustee as
defined by the Plan and, therefore, these transactions qualify as party-in-
interest transactions.  Fees paid by the Plan for investment management services
were included as a reduction of the return earned on each fund.  Fees paid by
the Plan for trustee services in connection with the Westamerica Common Stock
Fund for the years ended December 31, 2008, 2007 and 2006 amounted to $40,615,
$40,648 and $45,837, respectively.

8.    RECONCILIATION OF FINANCIAL STATEMENTS TO FORM 5500




The following is a reconciliation of net assets available for benefits per the
financial statements at December 31, 2008 to Form 5500:

                                                              
Net assets available for benefits per the financial statements   $  44,591,743

Less:  Deemed distributions of participant loans                        (6,848)
                                                                 -------------
Net assets available for benefits per Form 5500                  $  44,584,895
                                                                 =============







The following is a reconciliation of net assets available for benefits per the
financial statements at December 31, 2007 to Form 5500:

                                                              
Net assets available for benefits per the financial statements   $  50,964,340

Less: Deemed distributions of participant loans                         (6,848)
                                                                 -------------
Net assets available for benefits per Form 5500                  $  50,957,492
                                                                 =============




Page 18

                            SUPPLEMENTAL SCHEDULES
                            ----------------------



                              WESTAMERICA BANCORPORATION
                      EMPLOYER IDENTIFICATION NUMBER:  94-2156203
                                 PLAN NUMBER:  002

              SCHEDULE H, LINE 4i - SCHEDULE OF ASSETS (HELD AT END OF YEAR)

                                December 31, 2008




                                              (c)
                  (b)               Description of Investment
          Identity of Issuer,       Including Maturity Date,                  (e)
            Borrower, Lessor        Rate of Interest, Collate    (d)        Current
(a)         or Similar Party         Par or Maturity Value      Cost         Value
---------------------------------------------------------------------------------------
                                                              
 *   Westamerica Common                   Common Stock
         Stock Fund                      475,695 shares     $ 14,426,158  $  24,331,790

 *   Vanguard Prime Money                 Mutual Fund
         Market Fund                   4,756,924 shares        4,756,924      4,756,924

 *   Vanguard 500 Index Fund              Mutual Fund
                                          37,184 shares        4,218,225      3,089,637

 *   Vanguard Target Retirement           Mutual Fund
         2015 Fund                       381,186 shares        3,321,566      2,685,330

 *   Vanguard Morgan Growth               Mutual Fund
         Fund                            145,954 shares        2,532,919      1,649,278

 *   Vanguard Total International         Mutual Fund
         Stock Index Fund                141,361 shares        2,014,285      1,525,282

 *   Vanguard Total Bond Market           Mutual Fund
         Index Fund                      143,410 shares        1,440,491      1,459,917

 *   Vanguard Windsor II Fund             Mutual Fund
                                          55,467 shares        1,663,803      1,059,969

 *   Vanguard Target Retirement           Mutual Fund
         2025 Fund                       100,280 shares        1,222,625        929,600

 *   Vanguard Extended Market             Mutual Fund
         Index Fund                       18,586 shares          635,332        446,259

 *   Vanguard Target Retirement           Mutual Fund
         2035 Fund                        41,093 shares          521,051        380,110

 *   Vanguard Target Retirement           Mutual Fund
         2005 Fund                        24,118 shares          268,622        233,699

 *   Vanguard Target Retirement           Mutual Fund
         2045 Fund                        21,384 shares          276,801        204,649


                                           (Continued)



Page 19

                                WESTAMERICA BANCORPORATION
                         TAX DEFERRED SAVINGS/RETIREMENT PLAN (ESOP)

                         EMPLOYER IDENTIFICATION NUMBER: 94-2156203
                                    PLAN NUMBER: 002

                SCHEDULE H, LINE 4i - SCHEDULE OF ASSETS (HELD AT END OF YEAR)
                                       (Continued)
                                    December 31, 2008

                                              (c)
                  (b)               Description of Investment
          Identity of Issuer,       Including Maturity Date,                  (e)
            Borrower, Lessor        Rate of Interest, Collate    (d)        Current
(a)         or Similar Party         Par or Maturity Value      Cost         Value
---------------------------------------------------------------------------------------

 *   Vanguard Explorer Fund               Mutual Fund
                                           4,773 shares           342,462       201,090

 *   Vanguard Target Retirement           Mutual Fund
         2020 Fund                         8,804 shares           181,655       145,878

 *   Vanguard Short Term                  Mutual Fund
         Federal Fund                     12,985 shares           135,585       141,152

 *   Vanguard Target Retirement           Mutual Fund
         Income Fund                      14,438 shares           153,709       137,449

 *   Vanguard Target Retirement           Mutual Fund
         2050 Fund                         1,346 shares            26,190        20,435

 *   Vanguard Target Retirement           Mutual Fund
         2030 Fund                         1,254 shares            22,652        19,494

 *   Vanguard Target Retirement           Mutual Fund
         2010 Fund                           814 shares            17,367        14,327

 *   Vanguard Target Retirement           Mutual Fund
         2040 Fund                           265 shares             5,086         4,016


     Participant loans              Interest rates ranging      1,155,458     1,155,458
                                    from 5.00% to 9.75%      --------------------------

                                                             $ 39,338,966  $ 44,591,743
                                                             ============  ============
* Party-in-interest to the Plan.




Page 20

                                      WESTAMERICA BANCORPORATION
                             TAX DEFERRED SAVINGS/RETIREMENT PLAN (ESOP)

                             EMPLOYER IDENTIFICATION NUMBER: 94-2156203
                                          PLAN NUMBER: 002

                      SCHEDULE H, LINE 4j - SCHEDULE OF REPORTABLE TRANSACTIONS

                                For the Year Ended December 31, 2008




                                                                                                (f)
                                                                               (e)         Current Value
     (a)                 (b)                        (c)            (d)      Historical      of Asset on     (g)
  Identity of        Description                  Purchase       Selling      Cost of      Transaction    Net Gain
Party Involved         of Asset                    Price          Price        Asset          Date        or (Loss)
-------------------------------------------------------------------------------------------------------------------


Category (l)
------------

      Purchases -
Series of Transactions
----------------------
                                                                                        
Vanguard            Prime Money Mkt Fund           $1,902,954                               $1,902,954
Westamerica Bancorporation Common Stock             2,455,009                                2,455,009

        Sales -
Series of Transactions
----------------------
Vanguard            Prime Money Mkt Fund                         $1,762,784   $1,762,784     1,762,784
Westamerica Bancorporation Common Stock                           3,381,761    2,497,372     3,831,761      1,334,389





Page 21

                            Duly Authorized Signature

Pursuant to the requirements of the Securities Exchange Act of 1934, the
trustees (or the persons who administer the employee benefit plan) have duly
caused this annual report to be signed on its behalf by the undersigned hereunto
duly authorized.

WESTAMERICA BANCORPORATION
TAX DEFERRED SAVINGS/RETIREMENT PLAN (ESOP)


Date:    June 25, 2009
        ---------------------------

By:      /s/ John "Robert" Thorson
        ---------------------------
        John "Robert" Thorson
        Senior Vice President
        And Member, Pension Management Committee





Page 22

                         Exhibit Index


Exhibit
Number            Description
-------        --------------------------------------------------------
   23          Consent of Independent Registered Public Accounting Firm
   99          Certification pursuant to 18 U.S.C. Section 1350