Source Information
Minnesota Department of Health samples beaches weekly from May to September. When sample results are reported on the Beach Monitoring Program website, Lake Ontario Waterkeeper updates Swim Guide.
All recreational public beaches in Minnesota are tested weekly, typically from Memorial Day to Labor Day. High priority beaches may be monitored twice a week during the swimming season. Popular kayaking and canoe areas are also monitored during May and September-October. Minnesota beaches are posted when a single sample exceeds 235 E. coli / 100 ml or when the geometric mean of 5 samples collected over 30 days exceeds 130 E. coli / 100 ml. The Minnesota Lake Superior Beach Monitoring Program has also developed Nowcast predictive models that predict current E. coli levels at select Lake Superior beaches. These models are based on historical data and calibrated for each beach.
In the USA, the Environmental Protection Agency has two sets of recommendations for freshwater and marine beaches. A single sample at a freshwater beach should not exceed 235 E. coli / 100 ml of water. A single sample at a marine beach should not exceed 104 Enterococci / 100 ml of water. The geometric mean of 5 samples from a freshwater beach should not exceed 126 E. coli / 100 ml of water. The geometric mean of 5 samples from a marine beach should not exceed 35 Enterococci / 100 ml of water. States may choose to use this standard or they may substitute a standard that is "as protective as" the EPA's recommendation. The Beach Act is the nation's primary beach protection law.
