For the purposes of this chapter the following definitions shall apply:

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

(2) "Groundwater right" means an authorization to use groundwater established pursuant to chapter 90.44 RCW, state common or statutory law existing prior to the enactment of chapter 90.44 RCW, or federal law.

(3) "Withdrawal facilities" means and includes any well, infiltration trench or other excavation that is drilled, cored, bored, washed, driven, dug, jetted or otherwise constructed, together with the casing, screen, pump, pump column, motor and related equipment, which is used for the withdrawal of groundwater.

(4) "Aquifer" means any geologic formation that will yield water to a well or other withdrawal works in sufficient quantity for beneficial use.

(5) "Groundwater" means all waters that exist beneath the land surface or beneath the bed of any stream, lake or reservoir, or other body of surface water, whatever may be the geological formation or structure in which such water stands or flows, percolates or otherwise moves.

(6) "Contamination" means an impairment of the beneficial use of groundwater arising from the modification of the quality thereof by the introduction of organisms, chemical, organic or radioactive material or of heated or cooled water.

(7) "Significant modification" means the deepening or reaming of a well, lowering the pump bowls by adding lengths of pump column, adding water quality treatment devices, or other similar modifications, where the total cost or value of such modifications exceeds (1) $500.00 for domestic, stock or other water withdrawal facilities withdrawing less than 5,000 gallons per day, or (2) $2500.00 for all other facilities.

(8) "Qualifying withdrawal facilities" means those withdrawal facilities which in the opinion of the department constitute a reasonable development of the aquifer. A reasonable development must satisfy the following requirements:

(a) The withdrawal facilities must be constructed in accordance with chapter 18.104 RCW (Water Well Construction Act) and chapter 173-160 WAC (Minimum standards for construction and maintenance of water wells) and the water right permit provisions, if any, or the applicable state laws and the regulations of the department which were in effect at the time of construction of the facilities.

(b) The withdrawal facilities must have a depth of aquifer penetration which will allow the withdrawal of water from a reasonable or feasible pumping lift;

(c) The withdrawal facilities must be able to accommodate a reasonable variation in seasonal pumping water levels;

(d) The withdrawal facilities, including the pumping facilities, must be properly sized to the ability of the aquifer to produce water.