35 Ill. Adm. Code 302.505
Fecal Coliform
Section 302
Section 302.505Â Fecal
Coliform
Based on a minimum of five
samples taken over not more than a 30-day period, fecal coliform must not
exceed a geometric mean of 20 per 100 ml in the Open Waters of Lake Michigan as
defined in Section 302.501. The remaining waters of the Lake Michigan Basin
must not exceed a geometric mean of 200 per 100 ml, nor may more than 10% of
the samples during any 30-day period exceed 400 per 100 ml.