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Water Quality Management
Swimming Beach Bacteria Guidelines
E. Coli bacteria levels are monitored at Three Rivers Park District swimming beaches weekly during the summer to evaluate the safety of the beaches from a public health perspective.
Although E. Coli bacteria themselves are not usually harmful, these bacteria can be associated with other disease causing bacteria or parasites. Obviously, the more E. Coli bacteria there are in the water, the greater the possibility that some harmful organisms are also present. Therefore, in order to maintain healthy swimming beaches, the State of Minnesota established the following recommendations:
- The average of five swimming beach samples in a 30-day period should not exceed a count of more than 126 bacteria cells per 100 mL of water.
- No one sample should have a E. Coli count greater than 1,260 bacteria colonies per 100 mL of water. If a sample exceeds 1,260 bacteria colonies per 100 mL, consideration should be given to closing the swimming beach.
 In order to ensure a safe swimming experience for park guests, Three Rivers Park District has adopted standards more restrictive than the State guidelines. Whenever a single E. Coli bacteria sample exceeds 126 colonies per 100 mL, action is taken to identify and eliminate the bacteria source. If counts above 126/100 persist for two or more weeks, the beach is closed.
There are many sources of E. Coli bacteria, including the following:
- Animal droppings from geese, gulls, dogs, etc.
- Runoff from residential streets and yards.
- Sewage spills near the beach.
- Children having "accidents" in the water.
The most problematic sources of E. Coli bacteria at Three Rivers Park District facilities are droppings from geese, and children having "accidents". In order to minimize these problems, Three Rivers Park District has an active goose control program, does not allow feeding of geese at the beaches, does not allow pets on beaches, and requires small children to wear rubber pants when swimming.
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