Beach Monitoring: Beaches and Recreational Waters in Minnesota - Minnesota Dept. of Health

Beach Monitoring

The goal of beach monitoring is to determine if the beach water is safe for recreational activities and minimize the risk of recreational water illnesses. Beach goers should always remember that water conditions can change rapidly and beach monitoring results are not always representative of current water conditions.

On this page:
Agencies Monitoring Beach Waters
Water Testing
Predictive Water Quality Nowcast models
Recommended Water Quality Criteria
Beach Advisories

Agencies Monitoring Beach Waters

Local monitoring programs

Although not required by Minnesota state law, some local public health departments or cities regularly monitor beach water quality.

Coastal beach monitoring programs

MDH administers the Coastal Swimming Beach Monitoring Program funded by the US Environmental Protection Agency (EPA) under the Beaches Environmental Assessment and Coastal Health (B.E.A.C.H.) Act of 2000. The Minnesota Lake Superior Beach Monitoring Program monitors bacterial counts at swimming beaches along the northern shore of Lake Superior and posts health advisories when counts are above acceptable levels.

Water Testing

The quality of beach water is determined from collecting and analyzing beach water samples. Monitoring authorities test water samples for indicator organisms, like fecal coliform and E. coli, in the laboratory because it is impractical and expensive to test for specific germs. Fecal coliform and E. coli are found in the gut of warm-blooded animals (humans, livestock, birds, pets, etc.) and are excreted in feces. Fecal coliforms and most E. coli strains will not cause illness, but their presence indicates that germs that can cause illness may also be in the water.

Because samples cannot be taken constantly, at best, water quality sampling can only provide a snapshot of water conditions and cannot always determine whether people will become ill from swimming.

Predictive Water Quality Nowcast Models

The Minnesota Lake Superior Beach Monitoring Program has developed nowcast models that predict current water quality conditions at select Lake Superior beaches. The nowcast models are calibrated for each beach and were developed based on historical climate and water quality measures. Models use readily available information such as rainfall, cloud cover, wave height, water clarity, and temperature to estimate the probability that E. coli counts will exceed the acceptable standard. Nowcast models allow MDH staff to make timely beach advisory decisions and issue same-day notifications instead of waiting a day for laboratory results to become available.

Recommended Water Quality Criteria

MDH recommends posting an advisory at the beach indicating swimming and wading are not recommended when laboratory or model results show E. coli counts exceed established standards.

Minnesota Lake Superior beach monitoring program sample standard (based on EPA guidelines):

  • The geometric mean based on not less than 5 samples within a 30-day period shall not exceed 126 organisms per 100 milliliters, and
  • A single water sample shall not exceed an E. coli count of 235 organisms per 100 milliliters.

Beach advisories

A beach advisory is typically posted to reduce the likelihood of people getting sick when increased bacterial levels in the water are found. Advisories may occur for a variety of reasons, for example, pollution events (such as breaks in sewage pipes or rainfall carrying pollutants into the water) or contamination of the water by bathers, pets, or wildlife. Advisories are removed when bacterial levels fall within the acceptable standard.

Updated Wednesday, 30-Jan-2019 15:36:00 CST