Standards of water quality; variance

1. Except as otherwise provided in subsection 4, the Commission shall establish water quality standards at a level designed to protect and ensure a continuation of the designated beneficial use or uses which the Commission has determined to be applicable to each stream segment or other body of surface water in the State. 2. Except as otherwise provided in subsection 4, the Commission shall base its water quality standards on water quality criteria which numerically or descriptively define the conditions necessary to maintain the designated beneficial use or uses of the water. The water quality standards must reflect water quality criteria which define the conditions necessary to support, protect and allow the propagation of fish, shellfish and other wildlife and to provide for recreation in and on the water if these objectives are reasonably attainable. 3. The Commission may establish water quality standards for individual segments of streams or for other bodies of surface water which vary from standards based on recognized criteria if such variations are justified by the circumstances pertaining to particular places, as determined by biological monitoring or other appropriate studies. 4. The Commission may establish a water quality standard variance subject to the review and approval or disapproval of the United States Environmental Protection Agency in accordance with 40 C.F.R. § 131.14. A water quality standard variance established pursuant to this subsection must: (a) Reflect the highest attainable condition of the stream segment or other body of surface water that is achievable during the term of the water quality standard variance; and (b) Establish a time-limited designated use and criteria for specific pollutants or water quality parameters during the term of the water quality standard variance. 5. As used in this section, “water quality standards variance” has the meaning ascribed to it in 40 C.F.R. § 131.3(o).