Idaho Administrative Code
Title IDAPA 58 - Environmental Quality, Department of
Rule 58.01.02 - WATER QUALITY STANDARDS
Section 58.01.02.070 - APPLICATION OF STANDARDS
Current through August 31, 2023
01. Multiple Criteria. In the application of the use designation, the most stringent criterion of a multiple criteria applies. (3-31-22)
02. Application of Standards to Nonpoint Source Activities. The application of water quality standards to nonpoint source activities shall be in accordance with Section 350. (3-31-22)
03. Application of Standards to Point Source Discharges. The application of water quality standards to point source discharges shall be in accordance with Sections 400 and 401. (3-31-22)
04. Applicability of Gas Supersaturation Standard. The application of gas supersaturation standard shall be in accordance with Section 300. (3-31-22)
05. Mixing Zones. The application of water quality standards to mixing zones shall be in accordance with Section 060. (3-31-22)
06. Application of Standards to Intermittent Waters. Numeric water quality standards only apply to intermittent waters during optimum flow periods sufficient to support the uses for which the water body is designated. For recreation, optimum flow is equal to or greater than five (5) cubic feet per second (cfs). For aquatic life uses, optimum flow is equal to or greater than one (1) cfs. (3-31-22)
07. Temperature Criteria. In the application of temperature criteria, the Director may, at his discretion, waive or raise the temperature criteria as they pertain to a specific water body. Any such determination shall be made consistent with 40 CFR 131.11 and shall be based on a finding that the designated aquatic life use is not an existing use in such water body or would be fully supported at a higher temperature criteria. For any determination, the Director shall, prior to making a determination, provide for public notice and comment on the proposed determination. For any such proposed determination, the Director shall prepare and make available to the public a technical support document addressing the proposed modification. (3-31-22)
08. Protection of Downstream Water Quality. All waters shall maintain a level of water quality at their pour point into downstream waters that provides for the attainment and maintenance of the water quality standards of those downstream waters, including waters of another state or tribe. (3-31-22)
