Northwest Pipe Company (the “Company”) hereby amends its Current Report on Form 8-K filed on February 28, 2023 (the “Original Form 8-K”) which reported the election of Ms. Irma Lockridge to the Board of Directors (the “Board”) on February 22, 2023. At the time of the filing of the Original Form 8-K the Board had not determined on which committees of the Board Ms. Lockridge would serve. This Amendment No.

1 to Current Report on Form 8-K/A is being filed to report that on April 8, 2023, the Board appointed Ms. Lockridge to the Compensation Committee and Nominating and Governance Committee of the Board.