40 CFR 125.61 - Existence of and compliance with applicable water quality standards.
(a) There must exist a water quality standard or standards applicable to the pollutant(s) for which a section 301(h) modified permit is requested, including:
(1) Water quality standards for biochemical oxygen demand or dissolved oxygen;
(2) Water quality standards for suspended solids, turbidity, light transmission, light scattering, or maintenance of the euphotic zone; and
(3) Water quality standards for pH.
(2) Provide a determination signed by the State or interstate agency(s) authorized to provide certification under §§ 124.53 and 124.54 that the proposed modified discharge will comply with applicable provisions of State law including water quality standards. This determination shall include a discussion of the basis for the conclusion reached.