(a) A use attainability analysis must be conducted to justify the following conditions:

1. (1) Removing a fishable/swimmable designated use, which is not an existing use, from a waterbody; or
2. (2) To identify a subcategory of a fishable/swimmable use that requires less stringent criteria.

(b) (b) In order to remove a designated fishable/swimmable use, which is not an existing use, or identify subcategories of a fishable/swimmable use that require less stringent criteria, it must be demonstrated that the designated use is not attainable because:

1. (1) Naturally occurring pollutant concentrations prevent the attainment of the use; or
2. (2) Natural, ephemeral, intermittent or low flow conditions or water levels prevent the attainment of the use, unless these conditions may be compensated for by the discharge of sufficient volume of effluent discharges without violating state water conservation requirements to enable uses to be met; or
3. (3) Human caused conditions or sources of pollution prevent attainment of the use and cannot be remedied or would cause more environmental damage to correct than leave in place; or
4. (4) Dams, diversions or other types of hydrologic modifications preclude the attainment of the use, and it is not feasible to restore the waterbody to its original condition or to operate such modification in a way that would result in the attainment of the use; or
5. (5) Physical conditions related to the natural features of a waterbody, such as lack of a proper substrate, cover, flow, depth, pools, riffles, and the like, unrelated to water quality, preclude attainment of aquatic life protection uses; or
6. (6) Controls more stringent than those required by Sections 301(b) and 306 of the Clean Water Act would result in substantial and widespread economic and social impact.

(c)

1. (1) The scope of a use attainability analysis shall be in direct proportion to the project involved and the resource value of the receiving stream.

2. (2)

   1. (A) Methods for conducting a use attainability analysis may be found in the November 1983 United States Environmental Protection Agency publication entitled Technical Support Manual: Waterbody Surveys and Assessments for Conducting Use Attainability Analyses.
   2. (B) Other scientific methods, including the use of existing technical data, may be used for justifying the removal of a designated use, provided the methods are agreed upon prior to the study.
   3. (C) Such other methods may include the use of information previously gathered through technical studies, use attainability analysis, or both.