Surface Water Quality Criteria For Recreation Use Designations

01. Toxics Criteria. Waters designated for recreation must meet the Fish Only water quality criteria set forth in Subsection 210.01.b. (3-31-22) 02. Fecal Indicators. Waters designated for recreation must meet criteria for indicator bacteria of fecal contamination. Either of the following indicators is sufficient for determining compliance with the fecal indicator criteria: (3-31-22) a. E. Coli Bacteria. (3-31-22) i. Waters designated for recreation are not to contain E. coli bacteria, used as indicators of human pathogens, in concentrations exceeding: (3-31-22) (1) A geometric mean of one hundred twenty-six (126) E. coli counts per one hundred (100) mL based on a minimum of five (5) samples taken every three (3) to eleven (11) days over a forty-five (45) day period; or (3-31-22) (2) A statistical threshold value (STV) of four hundred and ten (410) E. coli counts per one hundred (100) mL in more than ten percent (10%) of samples collected over a forty-five (45) day period. The Department will ensure samples collected represent the forty-five (45) day duration. (3-31-22) ii. For public swimming beaches, a single sample value of two hundred thirty-five (235) E. coli counts per one hundred (100) mL should be used in considering beach closures. (3-31-22) b. Enterococci. Waters designated for recreation are not to contain enterococci bacteria, used as 204 . 7 204 . 7 10 1 4 . 58 10 1 411 . 0       pH pH CMC IDAHO ADMINISTRATIVE CODE IDAPA 58.01.02 Department of Environmental Quality Water Quality Standards Section 252 Page 165 indicators of human pathogens, in concentrations exceeding: (3-31-22) i. A geometric mean of thirty-five (35) enterococci counts per one hundred (100) mL based on a minimum of five (5) samples taken every three (3) to eleven (11) days over a forty-five (45) day period; or (3-31-22) ii. A statistical threshold value (STV) of one hundred and thirty (130) enterococci counts per one hundred (100) mL in more than ten percent (10%) of samples collected over forty-five (45) day period. The Department will ensure samples collected represent the forty-five (45) day duration. (3-31-22) c. For comparing permit effluent bacteria samples to the criteria, the averaging period shall be thirty (30) days or less based on a minimum of five (5) samples. (3-31-22)