Applicability. Surface water quality criteria shall apply: In fresh water streams and rivers: For toxic substances, under the conditions stipulated in Regulations .03-2A and .05A, and Under design stream flow for all other substances; In tidal waters: For toxic substances, under the conditions stipulated in Regulations .03-2A and .05A, and Under average tidal conditions during design stream flows for all other substances; Outside of any mixing zones which may be designated by the Department. If the natural water quality of a stream segment is not consistent with the criteria established for the stream then: The natural conditions do not constitute a violation of the water quality standards; and The water quality to be maintained and achieved is not required to be substantially different from that which would occur naturally. When coal remining permits are issued under §301 of the Federal Water Pollution Control Act (33 U.S.C. §1311), a variance to the specific water quality criteria for pH, iron, and manganese in the State's water quality standards may be given at the discretion of the Department for the duration of the remining activity. This variance may not be given if there is no demonstrated potential for improved water quality from the remining operation and if degradation of existing in-stream conditions is likely to occur. General Water Quality Criteria. The waters of this State may not be polluted by: Substances attributable to sewage, industrial waste, or other waste that will settle to form sludge deposits that: Are unsightly, putrescent, or odorous, and create a nuisance, or Interfere directly or indirectly with designated uses; Any material, including floating debris, oil, grease, scum, sludge, and other floating materials attributable to sewage, industrial waste, or other waste in amounts sufficient to: Be unsightly; Produce taste or odor; Change the existing color to produce objectionable color for aesthetic purposes; Create a nuisance; or Interfere directly or indirectly with designated uses; High temperature or corrosive substances attributable to sewage, industrial waste, or other waste in concentrations or combinations which: Interfere directly or indirectly with designated uses, or Are harmful to human, animal, plant, or aquatic life; Acute toxicity from any discharge outside the mixing zone established under Regulation .05 of this chapter for the application of acute criteria for protection of aquatic life; and Toxic substances attributable to sewage, industrial wastes, or other wastes in concentrations outside designated mixing zones, which: Interfere directly or indirectly with designated uses, or Are harmful to human, plant, or aquatic life.