Ownership Submission
FORM 4
Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).
UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940
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(Print or Type Responses)
1. Name and Address of Reporting Person *
THORSON JOHN A
  2. Issuer Name and Ticker or Trading Symbol
WESTAMERICA BANCORPORATION [WABC]
5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
_____ Director _____ 10% Owner
__X__ Officer (give title below) _____ Other (specify below)
SVP/Treasurer
(Last)
(First)
(Middle)
3. Date of Earliest Transaction (Month/Day/Year)
04/01/2005
(Street)

 
4. If Amendment, Date Original Filed(Month/Day/Year)
04/04/2005
6. Individual or Joint/Group Filing(Check Applicable Line)
_X_ Form filed by One Reporting Person
___ Form filed by More than One Reporting Person
(City)
(State)
(Zip)
Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1.Title of Security
(Instr. 3)
2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 3. Transaction Code
(Instr. 8)
4. Securities Acquired (A) or Disposed of (D)
(Instr. 3, 4 and 5)
5. Amount of Securities Beneficially Owned Following Reported Transaction(s)
(Instr. 3 and 4)
6. Ownership Form: Direct (D) or Indirect (I)
(Instr. 4)
7. Nature of Indirect Beneficial Ownership
(Instr. 4)
Code V Amount (A) or (D) Price
Common Stock 04/01/2005   F   1,066 (1) D $ 50.8289 4,030 I Deferred
Common Stock 04/01/2005   G V 830 D $ 0 3,200 (2) I Deferred
Common Stock 04/01/2005   G V 415 (3) A $ 0 415 (2) I by daughter RPT
Common Stock 04/01/2005   G V 415 (3) A $ 0 415 (2) I by daughter SRT
Common Stock               3,006.2841 (1) D  
Common Stock               125.858 (1) I ESOP

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security
(Instr. 3)
2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (Month/Day/Year) 3A. Deemed Execution Date, if any (Month/Day/Year) 4. Transaction Code
(Instr. 8)
5. Number of Derivative Securities Acquired (A) or Disposed of (D)
(Instr. 3, 4, and 5)
6. Date Exercisable and Expiration Date
(Month/Day/Year)
7. Title and Amount of Underlying Securities
(Instr. 3 and 4)
8. Price of Derivative Security
(Instr. 5)
9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s)
(Instr. 4)
10. Ownership Form of Derivative Security: Direct (D) or Indirect (I)
(Instr. 4)
11. Nature of Indirect Beneficial Ownership
(Instr. 4)
Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares

Reporting Owners

Reporting Owner Name / Address Relationships
 Director  10% Owner  Officer  Other
THORSON JOHN A

 
      SVP/Treasurer  

Signatures

 by John "Robert" A Thorson   04/05/2005
**Signature of Reporting Person Date

Explanation of Responses:

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1) This is not an amended item, but shown to provide clarification.
(2) The reporting person deferred delivery of 2,600 restricted performance shares vesting in January 2003 until March 31, 2005. The shares were held in a rabbi trust ("deferred") until the prescheduled distribution. At the time of the distribution from the rabbi trust, 704 shares were delivered to the reporting person's direct holding, 415 shares were gifted to each of two custodial accounts for minor children, and 1,066 shares were sold by the rabbi trust to pay the tax liability. Also, since the reporting person's last report, 1570 restricted performance shares vesting 1/26/05 and reported as direct holdings until delivery, were delivered to the reporting person's deferred holdings.
(3) This item was erroneously identified previously as a disposition rather than an acquisition.

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