Source Information
Recreational public beaches in Michigan are tested several times a week, typically from May to September. However, some beaches are tested bi-weekly or monthly.
Officially, the water should be clean for swimming from May 1 to October 31.
Michigan beaches are posted 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.
