For the purposes of this chapter, the following definitions shall be used. In the event that these definitions differ from those contained in related rules, the definitions presented here will supersede any others for this chapter:

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

(2) "Appropriation" means the process of legally acquiring the right to specific amounts of water for beneficial uses, as consistent with the requirements of the ground and surface water codes and other applicable water resource statutes. This term refers to both surface and groundwater right permits and to groundwater withdrawals otherwise exempted from permit requirements under RCW 90.44.050.

(3) "Consumptive use" means a use of water that diminishes the amount or quality of water in the water source.

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

(5) "Domestic water use" means, for the purposes of administering WAC 173-505-090, potable water to satisfy the human domestic needs of a household or business, including water used for drinking, bathing, sanitary purposes, cooking, laundering, and other incidental uses. Outdoor watering shall be limited to an area not to exceed a total of 1/12th of an acre, or three thousand six hundred thirty square feet, for all outdoor uses for each individual domestic water use. Under all circumstances, total outdoor watering for multiple residences under the permit exemption (RCW 90.44.050) shall not exceed one-half acre.

(6) "Instream flow" means a stream flow level set in rule that is required to protect and preserve fish, wildlife, scenic, aesthetic and other environmental values, and navigational values. The term "instream flow" means a base flow under chapter 90.54 RCW, a minimum flow under chapter 90.03 or 90.22 RCW, or a minimum instream flow under chapter 90.82 RCW.

(7) "Mitigation plan" means a scientifically sound plan voluntarily submitted by a project proponent to offset the impacts of a proposed water use and approved by the department. A mitigation plan can be submitted to the department for a stream, basin, reach, or other area. A mitigation plan must show that the withdrawal with mitigation in place will not impair existing water rights, including instream flow rights, or diminish water quality. The plan must provide mitigation for the duration of the water use.

(8) "Municipal water supplier" means an entity that supplies water for municipal water supply purposes. (RCW 90.03.015.)

(9) "Municipal water supply purposes" means a beneficial use of water: (a) For residential purposes through fifteen or more residential service connections or for providing residential use of water for a nonresidential population that is, on average, at least twenty-five people for at least sixty days a year; (b) for governmental or governmental proprietary purposes by a city, town, public utility district, county, sewer district, or water district; or (c) indirectly for the purposes in (a) or (b) of this subsection through the delivery of treated or raw water to a public water system for such use. (Partial definition; for the complete text of this definition refer to RCW 90.03.015.)

(10) "Nonconsumptive use" means a use of water that does not diminish the amount or quality of water in the water source.

(11) "Permit-exempt withdrawals" or "permit exemption" means a groundwater withdrawal exempted from permit requirements under RCW 90.44.050, but which is otherwise subject to the groundwater code.

(12) "Reservation" means an allocation of water for future beneficial uses. The effective date of a reservation, as well as the priority date of a given appropriation from a reservation, is the same as the effective date of this chapter.

(13) "Stream management unit" means a stream segment, reach, or tributary used to describe the part of the relevant stream to which a particular instream flow level applies.

(14) "Withdrawal" means the appropriation or use of groundwater, or the diversion or use of surface water.