Source Information
City of Evanston Parks and Recreation Department updates the status of its beaches daily from Memorial Day to Labour Day. When water quality alerts are issued via email or Twitter, Lake Ontario Waterkeeper updates Swim Guide.
The City of Evanston samples beaches daily - 7 days a week - pending weather conditions. Recreational public beaches in Illinois are tested at least once every week, typically from May to September. In popular beach areas such as Chicago, beaches are tested five times per week or even daily. Illinois beaches are posted when a single sample exceeds 235 E. coli / 100 ml.
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.
