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 * MAHONEY ROBERT L   2. Issuer Name and Ticker or Trading Symbol NORTHWEST PIPE CO [NWPX] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner __X__ Officer (give title below) _____ Other (specify below) President, Tubular Products (Last) (First) (Middle) 5721 SE COLUMBIA WAY SUITE 200 3. Date of Earliest Transaction (Month/Day/Year) 08/18/2011 (Street) VANCOUVER, WA 98661 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 08/18/2011   M   92 A (1) 16,500 D   Common Stock 08/18/2011   F   42 (2) D $ 25.33 16,458 D   Common Stock 03/15/2012   M   347 A (3) 16,805 D   Common Stock 03/15/2012   F   158 (2) D $ 21.52 16,647 D

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

Restricted Stock Units

(4)

08/18/2011

M

92

(5)

(5)

Common Stock

92

(4)

3,733

D

Restricted Stock Units

(4)

03/15/2012

M

347

(6)

(6)

Common Stock

347

(4)

3,386

D

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
MAHONEY ROBERT L 5721 SE COLUMBIA WAY SUITE 200 VANCOUVER, WA 98661			President, Tubular Products

Signatures

Robert Mahoney		03/19/2012
**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)	Represents shares acquired pursuant to vesting of Restricted Stock Units granted in 2008.
(2)	Represents shares withheld by the issuer for payment of taxes incurred upon vesting event consistent with company policy.
(3)	Represents shares acquired pursuant to vesting of Restricted Stock Units granted in 2009.
(4)	Each Restricted Stock Unit represents a contingent right to receive one share of Northwest Pipe Company common stock.
(5)	The Restricted Stock Units vest in installments as follows: 40% on August 18, 2009, 40% on August 18, 2010 and 20% on August 18, 2011.
(6)	The Restricted Stock Units vest in 3 equal installments on March 15, 2010, March 15, 2011 and March 15, 2012.

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