McHenry County Department of Health - Environmental Health
Translate this page:

Public Beaches - Frequently Asked Questions

Press Enter to show all options, press Tab go to next option

BeachQ: How do I know if the beach water is safe?
A: No one can guarantee the quality of natural bodies of water. The minimal sampling that the Department conducts indicates the water quality only on the particular day the sample was collected and at that specific location. Those sample results are not usually known until the following day after the sample was collected. The Department recommends not entering the water if it is very murky or turbid, if it has an odor or there has been a heavy rainfall within the past 24 hours. Beach patrons should not drink the water and should not enter the water if they have any open sores.

Q: What is E. coli?
Escherichia 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. E coli is used as the indicator of the bacterial quality of the water as it is considered to be a measure of fecal contamination.

Q: How does the bacteria get in the water?
A: There are a variety of sources that contribute bacteria to surface water: 

  • Storm runoff following a rain
  • Agricultural runoff
  • Wild and domestic animal waste
  • Bather Defecation
  • Wastewater

Q: What type of illness can you get from swimming in contaminated water?
A: Gastroenteritis type illness is the most common, with symptoms such as diarrhea, nausea, vomiting, abdominal pain, headache and low grade fever. Skin rashes and earaches may also be experienced.  If you believe you are experiencing any of these symptoms, please contact your physician.

Q: Is it necessary to report any illness that might be associated with the use of the beach? 
A: Yes, the beach manager should be notified if you become sick after swimming at the beach. Managers are required to report illnesses to the Illinois Department of Public Health for investigation. Early notification can prevent hundreds of additional people from becoming ill.

Q: What is the difference between a Beach Advisory and a Beach Closing?
A: A Beach Advisory means that the results of the bathing beach water sample exceeded the E coli advisory limit of 126 colony forming units per 100 milliliter of water.  The Beach Advisory is intended to alert bathers to a potentially higher risk for illness associated with swimming particularly for bathers who are very young, very old or immunocompromised.

A beach Closing means that the results of the bathing beach water samples exceed the E coli closing standard of 235 colony forming units per 100 milliliter of water.  These are considered unacceptable levels.  The beach remains closed until re-samples confirm E coli bacteria are at acceptable levels.

Q: Why is the beach closed?
A: The beach is closed because monitoring conducted by the McHenry County Department of Health determined that bacteria levels exceed those established in the Swimming Facility Act (235 colony forming units [CFU] of E coli per 100 milliliters of water is the level at which closing is required). The beach may also be closed because a heavy rainfall or known incident may have contaminated the water.

Q: If a beach is closed, when will it re-open?
A: Factors such as natural die-off, wind, and wave action, and ultraviolet rays from the sun will help reduce the level of bacteria.  The length of time that takes is unpredictable.  The water needs to be re-sampled and the samples from both the shallow and deep areas must be below 235 CFU of E coli/100ml. before the beach will be allowed to re-open.  It typically takes 24 hours after receipt of the samples to confirm the bacteria levels.

Q: Why are the beaches monitored by the McHenry County Department of Health?  

A: To protect the public's health, the Department requires that each of the licensed public beaches in Illinois be sampled every two weeks on a routine basis. Beach water samples are collected in the shallow and deep areas and are sent to a Department laboratory for analysis. If the results exceed the Department's limits, the risk of illness increases and the beach is required to be closed.

Q: When will the beach re-open?  
Factors such as natural die-off, wind and wave action, and ultraviolet light from the sun will help to reduce the level of bacteria. The length of time this takes is unpredictable; however, it is usually less than 24 hours. The water needs to be re-sampled and the samples from both the shallow and deep areas must be below 235 CFU of E. coli/100 ml. before the beach will be allowed to re-open. It takes 24 hours after receipt of the samples to determine the bacteria levels.

Q: What can I do to assure the best water quality at the beach?  
A: While some contamination may occur by nature and cannot be controlled, there are several things that beach patrons can do to assure the best water quality.
  • Be sure infants wear tight fitting rubber or plastic pants if they enter the beach water.
  • Do not encourage waterfowl by feeding ducks or geese.
  • Encourage children to use toilets frequently.
Q: Will a beach be closed for swimmers' itch?

A: In extreme cases the beach will be closed. In other cases where sporadic cases are found, the beach can remain open only if the beach operator posts signs and informs beach bathers of the situation.

Swimmers' itch is an allergic reaction of the skin to a microscopic larva called cercaria (released from snails). When cercariae come in contact with the skin, they will penetrate into the skin. This causes itching at the point of entrance as well as raised red spots, which resemble chigger bites. Click here for more information about swimmers' itch.

One of the simplest preventive measures to remember is to briskly rub your body dry with a towel immediately after getting out of the water. Showering immediately, using a lot of soap, is also an excellent method of prevention.


Related Links

For information on Blue Green Algal Blooms:

Environmental Protection Agency

Center for Disease Control


Back to Top

Free viewers are required for some of the attached documents.
They can be downloaded by clicking on the icons below.

Acrobat Reader Download Acrobat Reader Flash Player Download Flash Player Windows Media Player Download Windows Media Player Microsoft Silverlight Download Microsoft Silverlight Word Viewer Download Word Viewer Excel Viewer Download Excel Viewer PowerPoint Viewer Download PowerPoint Viewer