(a) Standards are prescribed to protect the natural quality of underground water: - (i) Receiving pollution or wastes directly from a subsurface discharge or by migrating water or fluid of a discharge;
- (ii) Invaded by underground water of inferior quality as a result of well or exploration hole drilling or completion practices;
- (iii) From pollution that may result from above-ground facilities capable of causing or contributing to pollution;
- (iv) From pollution that may result from surface mining operations.
(b) Groundwaters of the State are classified in order to apply standards to protect water quality. Groundwaters of the State are classified by use, and by ambient water quality.
(c) Waters that are known sources of supply and appropriated for uses identified in W.S. 35-11-102 and 103(c)(i) are classified herein as: Domestic water; Water for fish and aquatic life; Water for agriculture; Water for livestock; and, Water for industry. A discharge or activity that impacts an underground source of water for existing uses identified in W.S. 35-11-102 and 103(c)(i) shall not make the affected water unsuitable for its intended use or uses, at any place or places of withdrawal or natural flow to the surface.
(d) Unappropriated waters are classified by ambient water quality. - (i) Class I Groundwater of the State - This water is suitable for domestic use. The ambient quality of underground water of this suitability does not have a concentration in excess of any of the standards for Class I Groundwater of the State (see Table I, page 9).
- (ii) Class II Groundwater of the State - This water is suitable for agricultural use where soil conditions and other factors are adequate. The ambient quality of underground water of this suitability does not have a concentration in excess of any of the standards for Class II Groundwater of the State (see Table I, page 9).
- (iii) Class III Groundwater of the State - This water is suitable for livestock. The ambient quality of underground water of this suitability does not have a concentration in excess of any of the standards for Class III Groundwater of the State (see Table I, page 9).
- (iv) Class Special (A) Groundwater of the State -This water is suitable for fish and aquatic life. The ambient quality of underground water of this suitability does not have a concentration in excess of any of the standards for Class Special (A) Groundwater of the State (see Table I, page 10).
- (v) Underground water of Class I, II, III or Special (A)
- (A) Shall not contain biological, hazardous, toxic or potentially toxic materials or substances in concentrations or amounts that exceed maximum allowable concentrations based upon information of the EPA in the Federal Register for December 24, 1975 (Part IV), Water Programs, National Interim Primary Drinking Water Regulations; and in the Federal Register for March 13, 1978 (Part II), Water Programs, Hazardous Substances. In addition, underground water of Class I, II, III or Special (A) shall not contain any biological, hazardous, toxic or potentially toxic materials or substances in concentrations or amounts that, based upon the latest available scientific information and as determined by the Administrator, will impair this water for its use suitability or that may contribute to a condition in contravention of groundwater quality standards or to any toxic or hazardous effect on natural biota.
- (vi) A discharge into an aquifer containing Class I, II, III or Special (A)
- (A) Groundwater of the State shall not result in variations in the range of any parameter, or concentrations of constituents in excess of the standards of these regulations at any place or places of withdrawal or natural flow to the surface. A discharge that results in concentrations in excess of standards shall be permitted if post-discharge water quality can be returned to a quality of use equal to, or better than, and consistent with the uses for which the water was suitable prior to the operation.
- (vii) Class IV Groundwater of the State - This water is suitable for industry. The quality requirements for industrial water supplies range widely and almost every industrial application has its own standards.
- (A) Class IV (A) Groundwater of the State has a total dissolved solids concentration not in excess of 10,000 mg/L.
- (B) Class IV (B) Groundwater of the State has a total dissolved solids concentration in excess of 10,000 mg/L.
- (C) A discharge into an aquifer containing Class IV (A) or IV (B) Groundwater of the State shall not result in the water being unfit for its intended use.
- (D) A discharge into an aquifer with Class IV (A) or IV (B) Groundwater of the State shall not result in oil and grease concentrations in excess of 10 mg/L or a lesser amount if a concentration in excess of the lesser amount is determined to be toxic; or oil and grease in excess of background concentrations of the underground water, whichever is greater, at any place or places of withdrawal or natural flow to the surface.
- (E) A discharge into an aquifer with Class IV (A) or IV (B) Groundwater of the State shall not result in radioactivity concentrations or amounts that exceed the standards for Class I through III and Special (A) Groundwaters of the State; or in concentrations or amounts that exceed background concentrations of the underground water, whichever is greater, at any place or places of withdrawal or natural flow to the surface.
- (F) A discharge into an aquifer with Class IV (A) or IV (B) Groundwater of the State shall not result in biological, hazardous, toxic or potentially toxic materials or substances including pesticides, insecticides or herbicides in concentrations or amounts that exceed maximum allowable concentrations, based upon information of the EPA in the Federal Register for December 24, 1975 (Part IV), Water Programs, National Interim Primary Drinking Water Regulations, and in the Federal Register for March 13, 1978 (Part II), Water Programs, Hazardous Substances; or that exceed background concentrations of the underground water, whichever is greater, at any place or places of withdrawal or natural flow to the surface.
In addition, a discharge shall not result in any biological, hazardous, toxic or potentially toxic materials or substances, in concentrations or amounts that, based on the latest available scientific information and as determined by the Administrator, will impair the quality of ambient Groundwaters of the State of this class; or that may contribute to a condition in contravention of groundwater quality standards or cause, allow or permit any deleterious effect on natural biota.
- (viii) Groundwater of the State found closely associated with commercial deposits of hydrocarbons and/or other minerals, or that is considered a geothermal resource, is Class V (Hydrocarbon Commercial), Class V (Mineral Commercial) or Class V (Geothermal) Groundwater of the State.
- (A) A discharge into a Class V (Hydrocarbon Commercial) Groundwater of the State shall be for the purpose of the production of oil and gas and shall not result in the degradation or pollution or waste of other water resources.
- (B) A discharge into a Class V (Mineral Commercial) Groundwater of the State shall be for the purpose of mineral production and shall not result in the degradation or pollution of the associated or other groundwater and, at a minimum, be returned to a condition and quality consistent with the pre-discharge use suitability of the water.
- (C) A discharge into a Class V (Geothermal) Groundwater of the State shall be for the purpose of the production of geothermal resources and shall not result in the degradation or pollution or waste of other water resources.
- (ix) Class VI Groundwater of the State may be unusable or unsuitable for use:
- (A) Due to excessive concentration of total dissolved solids or specific constituents; or
- (B) Is so contaminated that it would be economically or technologically impractical to make the water useable; or
- (C) Is located in such a way, including depth below the surface, so as to make use economically and technologically impractical.