Northwest Pipe Company

                                      2005

                     LONG TERM INCENTIVE PLAN - SUMMARY PLAN
                                   DESCRIPTION

1.    Establishment of the Plan. The name of the Plan is the Northwest Pipe
      Company "Performance Unit Plan (PUP)" (hereinafter called the "plan"). The
      effective date of the Plan is January 1, 2005 (retroactive to 1/1/02).

2.    Purpose. The purpose of the Plan is to provide an incentive to key
      employees of Northwest Pipe Company (the "Company") to improve the
      earnings and performance of the Company.

3.    Administration. The Compensation Committee (the "Committee") of the Board
      of Directors of the Company shall administer the Plan. No member of the
      Committee shall be eligible to participate in the Plan. The Committee
      shall have power to construe and interpret the Plan and to establish and
      amend rules, regulations and forms for its administration and to certify
      all payments made under the Plan. The determination of the Committee on
      all matters relating to the Plan shall be conclusive. No member of the
      Committee shall be liable for any action or determination made in good
      faith with respect to the Plan or any award thereunder.

4.    Eligibility. Employees eligible to participate in the Plan shall be key
      employees of the Company (who have been employed for one year) in salary
      grade 13 or higher whose efforts may have an effect upon the growth and
      performance of the Company and who shall be selected to participate in the
      Plan by the Committee or any successor thereto. The eligibility date for
      selection by the Committee shall be January 15 in the first year of each
      three-year cycle of the Plan ("Eligibility Date").

5.    Award of Performance Units. Awards under the Plan consist of Performance
      Units. A Performance Unit is a contingent right to receive cash at the end
      of a respective vesting period, at the discretion of the Compensation
      Committee. Average Return on Assets ("ROA", defined as Operating Income
      divided by Average Assets) shall be used as the performance measure for
      determining the award of Performance Units. An ROA target range shall be
      established by the Committee annually which will be used, in part, to help
      determine the number of Performance Units awarded.

6.    Value of Performance Units. The value of Performance Units shall be
      determined by the Committee using the Company's stock price as an initial
      guide, but the Committee has discretion in setting the final value. The
      Committee will plan on awarding and valuing units each year in association
      with the Company's Annual Meeting, although other dates may be set at
      their discretion.

7.    Vesting of Performance Units.

      A.)   The plan is set up to apply "overlapping" three-year performance
            periods or cycles. The initial cycle would be for 2002 - 2004.
            Thereafter, performance cycles would overlap. Each performance cycle
            may generate a performance award that will vest and payout over a
            three-year period starting no earlier than April 1 following the
            completion of the performance cycle. The dates for each cycle will
            be set by the Committee. April 1, 2007 represents the first date
            when the overlapping cycles have the opportunity to produce three
            cash payouts.


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                           Overlapping      Initial Vesting     Subsequent
             Period #      Periods          Date                Vesting Dates
             --------      -------          ----                -------------
             1             02-03-04         4/1/05              4/1/06 & 4/1/07
             2             03-04-05         4/1/06              4/1/07 & 4/1/08
             3             04-05-06         4/1/07              4/1/08 & 4/1/09
             4             05-06-07         4/1/08              4/1/09 & 4/1/10

      B.)   Performance Units Vest Upon Change in Control. For purposes of this
            Plan, a "Change in Control" shall mean the occurrence of any of the
            following events:

            (i)   The approval by the shareholders of the Company of:

                  (a) any consolidation, merger or plan of share exchange
                  involving the Company (a "Merger) in which the Company is not
                  the continuing or surviving corporation or pursuant to which
                  shares of Common Stock of the Company ("Company Shares") would
                  be converted into cash, securities or other property, other
                  than a Merger involving Company Shares in which the holders of
                  Company Shares immediately prior to the Merger have the same
                  proportionate ownership of common stock of the surviving
                  corporation immediately after the Merger,

                  (b) any sale, lease, exchange or other transfer (in one
                  transaction or a series of related transactions) of all, or
                  substantially all, the assets of the Company; or

                  (c) the adoption of any plan or proposal for the liquidation
                  or dissolution of the Company.

            (ii)  At any time during a period of two consecutive years,
                  individuals who at the beginning of such period constituted
                  the Board ("Incumbent Directors") shall cease for any reason
                  to constitute at least a majority thereof unless each new
                  director elected during such two-year period was nominated or
                  elected by two-thirds of the Incumbent Directors then in
                  office and voting (with new directors nominated or elected by
                  two thirds of the Incumbent Directors also being deemed to be
                  Incumbent Directors); or

            (iii) Any Person (as hereinafter defined) shall, as a result of a
                  tender or exchange offer, open market purchases, or privately
                  negotiated purchases from anyone other than the Company, have
                  become the beneficial owner (within the meaning of Rule 13d-3
                  under the Securities Exchange Act of 1934), directly or
                  indirectly, of securities of the Company ordinarily having the
                  right to vote for he election of directors ("Voting
                  Securities") representing thirty (30%) or more of the combined
                  voting power of the then outstanding Voting Securities.

                  Notwithstanding anything in the foregoing to the contrary,
                  unless otherwise determined by the Board, no Change in Control
                  shall be deemed to have occurred with respect to an employee
                  for purposes of this Plan if (1) such employee shall acquire
                  (other than on the same basis as all other holders of the
                  Company Shares) an equity interest in an entity that acquires
                  the Company in a Change in Control otherwise described under
                  subparagraph (B) (i) above, or (2) such employee is a part of
                  a group that constitutes a Person which becomes a beneficial
                  owner of Voting Securities in a transaction that otherwise
                  would have resulted in a Change in Control under subparagraph
                  (B) (iii) above.


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      C.)   For purposes of the Plan, the term "Person" shall mean and include
            any individual, corporation, partnership, group, association or
            other "person," as such term is used in Section 13 (d) (3) or
            Section 14 (d) (2) of the Securities Exchange Act of 1934 (the
            "Exchange Act"), other than the Company or any employee benefit
            plan(s) sponsored by the Company.

8.    Limitation on Value of Performance Units. Prior to the beginning of each
      three-year cycle, the Committee will establish a hurdle rate ("Hurdle
      Rate") based on the average return on assets. No payments on account of
      Performance Units will be paid unless the Company has met or exceeded the
      Hurdle Rate.

9.    Payments on Account of Performance Units. Payments on account of
      Performance Units which have fully vested shall be made to the employees
      in whom such Units have vested, in cash within 90 days of the date, or as
      soon as practicable thereafter, upon which such units become vested.

10.   Adjustments. The Committee may make adjustments from time to time in the
      number of Performance Units credited to any employee's account in such
      reasonable manner as the Committee may determine to reflect (i) any
      increase or decrease in the number of issued shares of common stock of the
      Company resulting from a subdivision or consolidation of shares or any
      other capital adjustment, the payment of stock dividends or other
      increases or decreases in such shares effected without receipt of
      consideration by the Company; or (ii) material changes in the Company's
      accounting practice or principles; or (iii) material acquisitions or
      dispositions, the effect of which would be to distort ROA described above.

11.   Death, Disability, Retirement or Termination. If, before the vesting of
      Performance Units, an employee holding such Performance Units ceases to be
      employed by the Company or any of its subsidiaries for any reason other
      than death, disability or retirement, unvested Performance Units will be
      forfeited.

      In the event of an employee's death, disability or retirement before the
      vesting of any Performance Units which he/she may hold, the Committee may,
      but is not obligated to, vest his/her unvested Performance Units. Payment
      of any such vested Performance Units shall be done on an equitable basis
      determined at the sole discretion of the Committee, taking into
      consideration, for example, the performance of the Company during the
      period beginning on the date when such employee was awarded Performance
      Units and ending upon the date of death, disability or retirement.

12.   Amendment or Termination of Plan. The Board of Directors, other than
      Directors who are participants under the Plan, may amend, suspend or
      terminate this Plan at any time.

13.   Continuance of Employment. The Plan shall not impose any obligation on the
      Company or its subsidiary corporations to continue the employment of any
      person.

IN WITNESS WHEROF, the Corporation has caused this instrument as amended and
restated to be executed effective as of except as otherwise stated herein.

7/11/05


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