For purposes of this chapter, the following definitions shall be used.

(1) "Allocation" means the designating of specific amounts of the water resource for specific beneficial uses.

(2) "Appropriation" means the process of legally acquiring the right to specific amounts of the public water resource for application to beneficial uses.

(3) "Consumptive use" means use of water whereby there is diminishment of the amount or quality of the water source.

(4) "Department" means the Washington state department of ecology.

(5) "Director" means the director of the department of ecology.

(6) "Domestic use" means use of water associated with human health and welfare requirements, including water used for drinking, bathing, sanitary purposes, cooking, laundering, and other incidental household uses. Irrigation of lawn and noncommercial garden under the permit exemption in RCW 90.44.050 shall not exceed one-half acre.

(7) "Environmental enhancement project" means a water storage project, above or below ground, that would provide net environmental benefits, with particular emphasis on enhancing salmonids production. Projects that enhance instream flows directly or indirectly qualify under the definition. Projects proposed as mitigation for new consumptive water rights do not qualify under this definition.

(8) "Gravel aquifer" means any geologic formation generally under unconfined, or water table, conditions which consist of sand and gravel and may contain interbedded layers of silt and clay.

(9) "Instream flow" means a level of stream flow, established under chapters 90.54, 90.03, 90.22, and 90.82 RCW, required in perennial streams to preserve wildlife, fish, scenic, aesthetic, and other environmental and navigational values. The term means "base flow" under chapter 90.54 RCW, a "minimum flow" under chapters 90.03 and 90.22 RCW, and "minimum instream flow" under chapter 90.82 RCW. In the Walla Walla Watershed Plan, adopted in June 2005 by Walla Walla and Columbia counties, the term "new appropriation flows" has the same meaning as instream flows under this chapter.

(10) "Municipal water supplier" and "municipal water supply purposes" are defined in RCW 90.03.015.

(11) "Nonconsumptive use" means a type of water use where either there is no diversion or withdrawal from a source, or where there is no diminishment of the amount or quality of the water source.

(12) "Perennial stream" means a stream that normally flows year-round.

(13) "Planning unit" means the Walla Walla watershed planning unit, established under chapter 90.82 RCW, and all successors, formally designated by the Walla Walla watershed planning initiating governments. The initiating governments are Columbia and Walla Walla counties, city of Walla Walla, and Gardena Farms Irrigation District No. 13.

(14) "Water right" means a right to make beneficial use of public waters of the state, including any water right established for instream flow purposes.

(15) "Withdrawal" means the extraction of groundwater, or the diversion of surface water for a beneficial use.