Atwater Park is sampled weekly from May 29th from September 3th.

Heath Units in Wisconsin test beaches from May through September. When sample results are posted on the Wisconsin Beach Health website, Milwaukee Riverkeeper updates Swim Guide.

Recreational public beaches in Wisconsin are tested May through September. High priority beaches are sampled at least five times per week. They are posted when a single sample exceeds 235 E. coli / 100 ml or when the geometric mean of samples collected over a 30-day period exceeds 126 E. coli / 100 ml. Medium priority beaches are sampled at least twice per week. Low priority beaches are sampled at least once per week. They are posted when a single sample exceeds 235 E. coli / 100 ml. All beaches will be closed if E. coli in a single sample exceeds 1,000 / 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.