Wash. Rev. Code § 90.44.510
The department shall issue a superseding water right permit or certificate for a groundwater right where the source of water is an aquifer for which the department adopts rules establishing a groundwater management subarea and water from the federal Columbia Basin project is delivered for use by a person who holds such a groundwater right. The superseding water right permit or certificate shall designate that portion of the groundwater right that is replaced by water from the federal Columbia Basin project as a standby or reserve right that may be used when water delivered by the federal project is curtailed or otherwise not available. The period of curtailment or unavailability shall be deemed a low flow period under RCW 90.14.140(2)(b). The total number of acres irrigated by the person under the groundwater right and through the use of water delivered from the federal project must not exceed the quantity of water authorized by the federal bureau of reclamation and number of acres irrigated under the person's water right permit or certificate for the use of water from the aquifer.
RCW 90.44.510