macomb county public health

Beach Monitoring Questions and Answers


Beach Monitoring Questions and Answers


Why are beaches monitored by the Macomb County Health Department? To protect public health, the Macomb County Health Department (MCHD) monitors the levels of Escherichia coli (e. coli) bacteria at six public bathing beaches throughout the county. The Michigan Public Health Code sets limits for levels of bacteria at bathing beaches open to the public. If the levels detected during monitoring exceed these limits, the risk of illness increases.
What is E. coli? E. coli bacteria live in the digestive systems of humans and other warm blooded animals. Therefore, they are found in sewage and other wastewater. Most strains are not dangerous, but they can indicate the presence of other disease-causing bacteria.
What are the risks associated with bacteria in the water? Swimming in unsafe water may result in minor illnesses such as sore throats or diarrhea. It may also result in more serious illnesses that can last a longer period of time. Children, the elderly and persons with weakened immune systems are at greater risk for illness when they come into contact with contaminated water.
How is the water at the beach tested? MCHD staff routinely collect water samples twice weekly. Samples are taken one foot below the surface in water that is between three and six feet in depth. Analysis is performed by a State certified laboratory using standard analytic methods. Laboratory testing takes about 24 hours to perform, so water quality results are reported the following morning.
Why do the beaches close? A beach is closed because monitoring conducted by the MCHD determined that, at the time of testing, levels of bacteria exceeded the limits set by the Michigan Public Health Code. If either the single-day or 30-day average bacteria count exceeds the established limit, the beach is closed for swimming.
How long will the beach remain closed? Water is a hostile environment to the bacteria, so they generally do not live long in water. Factors such as wind and wave action, as well as UV light from the sun will help to reduce the level of bacteria. The length of time this takes in unpredictable, however it is usually less than 48 hours. It is important to note that bacteria levels may remain high if a continuous source of pollution is impacting the area.
When will the beach re-open? The MCHD will continue monitoring the beach water quality and will permit a beach to re-open for swimming when bacteria levels fall back to acceptable levels. Check with the park or beach authority as recreational activities other than swimming are usually still available.
How do the bacteria get in the water?

There are a variety of sources that contribute bacteria to our surface waters. These include:

  • Illicit waste connections to storm sewers or roadside ditches.
  • Malfunctioning septic systems
  • Combined and sanitary sewer overflows
  • Storm (rain) runoff
  • Wild and domestic animal waste
  • Agricultural runoff
How do I know if it is safe to swim?

You are the best person to decide when and if it is safe to swim at a particular location. Our changing weather means that swimming conditions can vary throughout the day and from day to day. Here are a few recommendations for deciding when and where to swim:

  • Check the weather
  • Don't swim for 2 days after heavy rains
  • Watch for "signs" of water pollution such as discolored water, fast flowing and strong smelling drains and/or street litter floating in water.
  • Avoid swimming next to drain openings or outlets
  • Check for pollution warning notices and/or beach closing signs.
  • Swim only in areas designated as "swim areas". Do not swim in the river or streams.


If you have any questions, call us at 586-469-5236, Monday-Friday, 8:30 a.m. - 5:00 p.m. or E-mail us now.

Other Resources

Center for Disease Control - Healthy Swimming information

Great Lakes Information Network - Regional watershed information

Environmental Protection Agency - Beach standards and national monitoring

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