A. Standards for the quality of WOTUS shall assure water quality, if attainable, which provides for protecting the public health and welfare, and shall enhance the quality of water taking into consideration its use and value for public water supplies, the propagation of fish and wildlife and recreational, agricultural, industrial and other purposes including navigation.

B. The director shall adopt standards for the quality of all WOTUS that establish numeric limitations on the concentrations of each of the toxic pollutants listed by the administrator pursuant to section 307 of the clean water act (33 United States Code § 1317).

C. In setting numeric standards for the quality of WOTUS, the director may consider the effect of local water quality characteristics on the toxicity of specific pollutants and the varying sensitivities of local affected aquatic populations to such pollutants, and the extent to which the natural flow of the stream is intermittent or ephemeral, as a result of which the instream flow consists mostly of treated wastewater effluent, except that such standards shall not, in any event, be inconsistent with the clean water act. In applying such standards the director may establish appropriate mixing zones.