Wash. Rev. Code § 90.46.240
All required feasibility studies, planning documents, engineering reports, and plans and specifications for the construction of new reclaimed water, agricultural industrial process water, and industrial reuse water facilities, including generation, distribution, and use facilities, or for improvements or extensions to existing facilities, and the proposed method of future operation and maintenance of said facility or facilities, shall be submitted to and be approved by the lead agency, before construction thereof may begin. No approval shall be given until the lead agency is satisfied that the plans, reports, and specifications and the methods of operation and maintenance submitted are adequate to protect the quality of the water for the intended use as provided for in this chapter and are adequate to protect public health and safety as necessary.
RCW 90.46.240