(4)__The existing impounded waters are able to support all species of fish indigenous to those waters and the structure and function of the resident biological community in the impounded waters is maintained.

B.__For the purposes of water quality certification under the Federal Water Pollution Control Act, Public Law 92-500, Section 401, as amended, and licensing of modifications under section 636, Ragged Lake, located in the Penobscot River, West Branch drainage, is deemed to have met the habitat characteristics and aquatic life criteria in the existing impoundment if that habitat and aquatic life satisfy the aquatic life criteria contained in section 465, subsection 4, paragraph C, except that habitat and aquatic life in the portions of the water body affected by annual drawdowns of up to 20 feet may reflect the effects of such drawdowns, based on a use attainability analysis conducted by the board pursuant to subsection 2-A.

C.__For the purposes of water quality certification under the Federal Water Pollution Control Act, Public Law 92-500, Section 401, as amended, and licensing of modifications under section 636, Seboomook Lake, located in the Penobscot River, West Branch drainage, is deemed to have met the habitat characteristics and aquatic life criteria in the existing impoundment if that habitat and aquatic life satisfy the aquatic life criteria contained in section 465, subsection 4, paragraph C, except that habitat and aquatic life in the portions of the water body affected by annual drawdowns of up to 17 feet may reflect the effects of such drawdowns, based on a use attainability analysis conducted by the board pursuant to subsection 2-A.

D.__Other than those described in paragraphs A, B and C, all hydropower projects with impoundments in existence on June 30, 1992 that remain classified under section 465-A after June 30, 1992 and that do not attain the habitat and aquatic life criteria of that section must, at a minimum, satisfy the aquatic life criteria contained in section 465, subsection 4, paragraph C.

E.__When the actual water quality of the impounded waters attains any more stringent characteristic or criteria of