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/Chief Financial Officer (Last) (First) (Middle) 3. Date of Earliest Transaction (Month/Day/Year) 03/31/2007 (Street)   4. If Amendment, Date Original Filed(Month/Day/Year) 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 03/31/2007   F   870 D $ 48.13 28.6624 (1) (3) D   Common Stock 04/02/2007   F   880 D $ 47.4923 1,670 (2) I deferred Common Stock               313.571 (4) I ESOP Common Stock               4,164 (1) (2) I by Trust Common Stock               415 I by Daughter RPT Common Stock               415 I by daughter SRT

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/Chief Financial Officer

Signatures

/s/ John "Robert" A. Thorson		04/03/2007
**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)	Of the 1,540 Restricted Performance Shares vesting in January 2007, 870 shares were withheld to pay for the tax liability and 670 shares were delivered to the reporting person's trust.
(2)	The reporting person deferred delivery of 1,570 Restricted Performance Shares vesting in January 2005 until March 31, 2007. The shares were held in a Rabbi Trust ("deferred") until the prescheduled distribution. At the time of distribution from the deferred account, 690 shares were delivered to the reporting person's trust and 880 shares were sold by the administrator to pay the tax liability.
(3)	Includes dividends reinvested through 2/16/07.
(4)	Includes allocations through 3/31/07, to Westamerica Bancorporation's Tax Deferred Savings/Retirement (ESOP) Plan.

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