Environmental Health staff collect water samples from the five public beaches throughout Washtenaw County from Memorial Day through September. To protect public health and to prevent the spread of disease, the samples are analyzed for E. Coli bacteria levels. 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. Beaches are closed if deemed unsafe to public health.
Public Beaches in Washtenaw County:
- Pinckney Recreation Area:
Bruin Lake Beach, Lyndon Township
Half Moon Lake Beach, Dexter Township
Silver Lake Beach, Dexter Township
- Waterloo Recreation Area:
- Sugarloaf Lake Beach, Lyndon Township
- Washtenaw County Parks & Recreation:
- Independence Lake, Webster Township
Water Quality Information:
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 are the beaches sampled?
Beaches are sampled a minimum of five times (or "events") per month. Each sampling "event" consists of three samples taken at representative locations within the bathing beach area. The water samples are collected one foot below the surface in three to six feet of water. The samples are then taken to a contracted certified laboratory to be analyzed for E. Coli bacteria.
Why do the beaches close?
A beach is closed because monitoring conducted by Washtenaw County Environmental Health determined that, at the time of testing, levels of bacteria exceeded the limits set by the Michigan Public Health Code. The geometric mean of the results from one sampling "event" cannot exceed 300 E. Coli per 100 mililiters water. In addition, the 30-day geometric mean cannot exceed 130 E. Coli per 100 mililiters water.
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 Washtenaw County Environmental Health Division 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 (especially goose droppings)
- 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. It is a good idea to avoid swimming in lakes and rivers for 48 hours following a heavy rain. Surface runoff from storm sewer systems can carry high levels of pollution such as residue from vehicle exhaust, fertilizer, pesticides, oil, and waste from urban pets and rural barnyards into the water. Overflowing storm systems can also carry untreated sewage into rivers and lakes. 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".
Swimmer's Itch Information:
What is Swimmer's Itch?
Swimmer's itch is a natural phenomenon that occurs in many water bodies in Michigan. It is a temporary skin irritation caused by an invisible parasite found in lakes and ponds. The skin irritation appears as small itchy welts resembling a rash or mosquito bites. The welts are caused by a tiny parasitic organism which normally lives in the blood of waterfowl. The parasite's eggs are passed out of the bird and develop into larvae that seek out snails. Once they mature, they enter the water again to seek out birds, but sometimes select a human by mistake. Humans are not suitable hosts for the parasite, so it dies and is dissolved. Our body reacts to the intrusion by treating the organism as a mild allergy and produces histamines that can cause a red itchy welt. These itchy bumps are no more serious than an insect bite and can be treated with anti-itch creams.
Incidences of swimmer's itch are most common in late June and mid-July, especially after heavy winds. Only 30% to 40% of the population is sensitive to swimmer's itch, and very few of those will ever develop welts. Since swimmer's itch can be reintroduced to the water through goose droppings, please do not feed or attract geese while near lakes or ponds!
Swimmer's itch is:
- Not caused by poor water quality
- Not contagious
- Not dangerous to humans
To reduce the chance of getting swimmer's itch:
- Apply waterproof sunscreen or baby oil to help prevent swimmer's itch organisms from entering the skin.
- Thoroughly and briskly towel-off or shower as soon as you leave the water to help prevent swimmer's itch organisms from entering the skin.
- Change out of your wet bathing suit as soon as possible after exiting the water.
- Keep anti-itch creams handy if your family is prone to allergies or if welts occur.
Washtenaw County Environmental Health does not routinely sample water bodies located on private property. If you are wondering if the pond or lake on your private property or in your subdivison is safe for swimming, or if you want to know how best to sample the water, please see our fact sheet: Is my pond or lake safe for swimming?
For more information on bathing beach or surface water quality, please contact the
Washtenaw County Environmental Health Division at (734) 222-3800.