Twin Lakes State Park

Source Information

Recreational public beaches in Michigan are tested one to four times per month, typically from May to September. Officially, the water is tested for recreational standards from May 1 to October 31. The Michigan Department of Community Health and the Michigan Department of Environmental Quality uses guidance provided by the EPA to develop ambient standards for E. coli. E. coli standards for water used for total body contact recreation are provided in the Michigan Public Health Code and Rule 323.1062(1) of the Part 4. A beach is marked Green the geometric mean of 3 samples collected at the same time is under 300 E. coli / 100 ml or when the geometric mean of 5 samples collected over 30 days is under 130 E. coli / 100 ml. A beach is marked Red when the geometric mean of 3 samples collected at the same time exceeds 300 E. coli / 100 ml or when the geometric mean of 5 samples collected over 30 days exceeds 130 E. coli / 100 ml. A beach is marked Grey when there is no current or reliable monitoring information available.