As used in this chapter:

(1) "Activity" means any site, area, facility, structure, vehicle, installation, or discharge which may produce pollution.

(2) "Artificial groundwater" means groundwater that has been put in place through means, such as irrigation, other than natural recharge.

(3) "Background water quality" means the concentrations of chemical, physical, biological, or radiological constituents, or other characteristics in or of groundwater at a particular point in time and upgradient of an activity that have not been affected by that activity.

(4) "Beneficial uses" means uses of waters of the state which include but are not limited to use for domestic, stock watering, industrial, commercial, agricultural, irrigation, mining, fish and wildlife maintenance and enhancement, recreation, generation of electric power and preservation of environmental and aesthetic values, and all other uses compatible with the enjoyment of the public waters of the state.

(5) "Best management practices" or "BMPs" mean schedules of activities, prohibitions of practices, maintenance of procedures, and other management practices, to prevent or reduce the pollution of groundwaters of the state. BMPs also include treatment requirements, operating procedures and practices to control plant site runoff, spillage or leaks, sludge or water disposal, or drainage from raw material storage.

(6) "Carcinogen" means any substance or agent that produces or tends to produce cancer in humans. For implementation of this chapter, the term carcinogen will apply to all substances on the United States Environmental Protection Agency Integrated Risk Information System, IRIS database, of A (known human) and B1 and B2 (probable human) carcinogens for which IRIS listed an oral slope factor.

(7) "Contaminant" means any chemical, physical, biological, or radiological substance that does not occur naturally in groundwater or that occurs at concentrations greater than those in the natural levels.

(8) "Criteria" means numerical values or narrative standards that represent the maximum allowable contaminant concentrations in the groundwater.

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

(10) "Early warning value" means a concentration set in accordance with WAC 173-200-070 that is a percentage of a groundwater quality enforcement limit.

(11) "Enforcement limit" means the value assigned to any contaminant for the purposes of regulating that contaminant.

(12) "Groundwater" means water in a saturated zone or stratum beneath the surface of land or below a surface water body.

(13) "Human-caused pollution" means pollution resulting from human activity.

(14) "Isolated groundwater" means groundwater fully separated from other groundwaters by an impermeable layer of rock or strata.

(15) "Maximum contaminant level" or "MCL" means the maximum concentration of a contaminant in water established by the Environmental Protection Agency under the Federal Safe Drinking Water Act (42 U.S.C. 300f et seq.) and published in 40 C.F.R. 141 as presently promulgated or as subsequently amended or repromulgated.

(16) "Maximum contaminant level goal" or "MCLG" means the maximum concentration of a contaminant established by the Environmental Protection Agency under the Federal Safe Drinking Water Act (42 U.S.C. 300f et seq.) and published in 40 C.F.R. 141 as presently promulgated or subsequently amended or repromulgated, for which no known or anticipated adverse effects on human health occur including an adequate margin of safety.

(17) "Natural groundwater quality" means groundwater quality that was present before any human-caused pollution.

(18) "Naturally nonpotable groundwater" means groundwater that is unsuitable for drinking water because of natural groundwater quality and for which current treatment methods are considered unreasonable and impractical.

(19) "Permit" means a department authorization, license, or equivalent control document issued to a facility, activity, or entity authorized to treat, store, dispose, or discharge materials or wastes. This includes, but is not limited to, state waste discharge permits issued pursuant to chapter 173-216 WAC, permits for dangerous waste management facilities issued pursuant to chapter 173-303 WAC, and permits for groundwater withdrawal issued pursuant to chapter 90.44 RCW.

(20) "Person" means any political subdivision, government agency, municipality, industry, public or private corporation, partnership, association, firm, individual, or any other entity whatsoever.

(21) "Point of compliance" means the location, set in accordance with WAC 173-200-060, where the groundwater quality enforcement limit shall not be exceeded.

(22) "Pollution" means such contamination, or other alteration of the physical, chemical or biological properties, of any waters of the state, including change in temperature, taste, color, turbidity, or odor of the waters, or such discharge of any liquid, gaseous, solid, radioactive, or other substance into any waters of the state as will or is likely to create a nuisance or render such waters harmful, detrimental or injurious to the public health, safety or welfare, or to domestic, commercial, industrial, agricultural, recreational, or other legitimate beneficial uses, or to livestock, wild animals, birds, fish, or other aquatic life.

(23) "Practical quantification level" or "PQL" means the lowest concentration of a substance that can be reliably achieved within specific limits of precision, accuracy, representativeness, completeness, and comparability during routine laboratory operating conditions.

(24) "Root zone" means the zone that extends from the surface of the soil to the depth of the lowest root and is specific to a species of plant, group of plants, or crop.

(25) "Saturated zone" means the zone below the water table in which all interstices are filled with water.

(26) "Seasonal groundwater" means groundwater that exists for a temporary period of the year and is usually associated with a particular activity or phenomenon.

(27) "State waste discharge permit" means a permit issued in accordance with the state waste discharge permit program, chapter 173-216 WAC.