Wash. Rev. Code § 90.44.055
The department shall, when evaluating an application for a water right or an amendment filed pursuant to RCW 90.44.050 or 90.44.100 that includes provision for any water impoundment or other resource management technique, take into consideration the benefits and costs, including environmental effects, of any water impoundment or other resource management technique that is included as a component of the application. The department's consideration shall extend to any increased water supply that results from the impoundment or other resource management technique, including but not limited to any recharge of groundwater that may occur, as a means of making water available or otherwise offsetting the impact of the withdrawal of groundwater proposed in the application for the water right or amendment in the same water resource inventory area. Provision for an impoundment or other resource management technique in an application shall be made solely at the discretion of the applicant and shall not be made by the department as a condition for approving an application that does not include such provision.
This section does not lessen, enlarge, or modify the rights of any riparian owner, or any existing water right acquired by appropriation or otherwise.
RCW 90.44.055
Findings-Purpose-1997 c 360: See note following RCW 90.03.255.