Construction or modification of storage dam — Plans and specifications — Additional dam safety inspection requirements for metals mining and milling operations.
RCW 90.03.350
in effectExcept as provided in RCW 43.21A.068 , any person, corporation or association intending to construct or modify any dam or controlling works for the storage of ten acre feet or more of water, shall before beginning said construction or modification, submit plans and specifications of the same to the department for examination and approval as to its safety. Such plans and specifications shall be submitted in duplicate, one copy of which shall be retained as a public record, by the department, and the other returned with its approval or rejection endorsed thereon. No such dam or controlling works shall be constructed or modified until the same or any modification thereof shall have been approved as to its safety by the department. Any such dam or controlling works constructed or modified in any manner other than in accordance with plans and specifications approved by the department or which shall not be maintained in accordance with the order of the department shall be presumed to be a public nuisance and may be abated in the manner provided by law, and it shall be the duty of the attorney general or prosecuting attorney of the county wherein such dam or controlling works, or the major portion thereof, is situated to institute abatement proceedings against the owner or owners of such dam or controlling works, whenever he or she is requested to do so by the department. A metals mining and milling operation regulated under chapter 232, Laws of 1994 is subject to additional dam safety inspection requirements due to the special hazards associated with failure of a tailings pond impoundment. The department shall inspect these impoundments at least quarterly during the project's operation and at least annually thereafter for the postclosure monitoring period in order to ensure the safety of the dam or controlling works. The department shall conduct additional inspections as needed during the construction phase of the mining operation in order to ensure the safe construction of the tailings impoundment.
Except as provided in RCW 43.21A.068 , any person, corporation or association intending to construct or modify any dam or controlling works for the storage of ten acre feet or more of water, shall before beginning said construction or modification, submit plans and specifications of the same to the department for examination and approval as to its safety. Such plans and specifications shall be submitted in duplicate, one copy of which shall be retained as a public record, by the department, and the other returned with its approval or rejection endorsed thereon. No such dam or controlling works shall be constructed or modified until the same or any modification thereof shall have been approved as to its safety by the department. Any such dam or controlling works constructed or modified in any manner other than in accordance with plans and specifications approved by the department or which shall not be maintained in accordance with the order of the department shall be presumed to be a public nuisance and may be abated in the manner provided by law, and it shall be the duty of the attorney general or prosecuting attorney of the county wherein such dam or controlling works, or the major portion thereof, is situated to institute abatement proceedings against the owner or owners of such dam or controlling works, whenever he or she is requested to do so by the department.
A metals mining and milling operation regulated under chapter 232, Laws of 1994 is subject to additional dam safety inspection requirements due to the special hazards associated with failure of a tailings pond impoundment. The department shall inspect these impoundments at least quarterly during the project's operation and at least annually thereafter for the postclosure monitoring period in order to ensure the safety of the dam or controlling works. The department shall conduct additional inspections as needed during the construction phase of the mining operation in order to ensure the safe construction of the tailings impoundment.
Source: WA Statutes (Official Site)URL: https://app.leg.wa.gov/RCW/default.aspx?cite=90.03&full=trueFetched: 6/29/2026