Wash. Rev. Code § 90.03.070
It shall be the duty of the water master, acting under the direction of the department, to divide in whole or in part, the water supply of his or her district among the several water conduits and reservoirs using said supply, according to the right and priority of each, respectively. He or she shall divide, regulate, and control the use of water within his or her district by such regulation of headgates, conduits, and reservoirs as shall be necessary to prevent the use of water in excess of the amount to which the owner of the right is lawfully entitled. Whenever, in the pursuance of his or her duties, the water master regulates a headgate of a water conduit or the controlling works of a reservoir, he or she shall attach to such headgate or controlling works a written notice, properly dated and signed, stating that such headgate or controlling works has been properly regulated and is wholly under his or her control and such notice shall be a legal notice to all parties. In addition to dividing the available waters and supervising the stream patroller in his or her district, he or she shall enforce such rules and regulations as the department shall from time to time prescribe.
The county or counties in which water master districts are created shall deputize the water masters appointed hereunder, and may without charge provide to each water master suitable office space, supplies, equipment, and clerical assistance as are necessary to the water master in the performance of his or her duties.
RCW 90.03.070
Purpose-Short title-Construction-Rules-Severability-Captions-1987 c 109: See notes following RCW 43.21B.001.
Water master's power of arrest: RCW 90.03.090.