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What criteria are used to determine water contamination?

Minnesota and U.S. Environmental Protection Agency (EPA) recommendations for posting advisory signs at swimming beach areas are based upon the E. coli or fecal coliform bacteria content of water samples collected.

Evaluation of water sample results is based on the EPA recommendations for acceptable E. coli levels, and Minnesota fecal coliform standards as specified in Minnesota Rule 7050.0222.

The federal acceptable water sample standard for E. coli is:

The state acceptable water sample standard for fecal coliform is: