The Lake Superior Beach Monitoring Program monitors E. coli levels at 38 Lake Superior public beaches each summer. Higher use beaches are monitored twice a week and beaches that have lower use are monitored once a week. A health advisory is posted at the beach when bacteria counts are high.
An advisory is posted when monitoring results indicate an increased risk of getting sick from swimming or wading. Advisories are posted based on water quality models or when a single water sample exceeds 235 E. coli colonies per 100 milliliters or when the geometric mean of five water samples within a 30-day period exceeds 126 E. coli colonies per 100 milliliters.
Signs are posted at the beach when an advisory is issued. To learn about current advisories before you get to the beach:
Sources of contamination include sewage overflows, stormwater runoff, boating waste, and animal or human waste.