Door County Beach Water Monitors
Most of the time, we don’t think much about water quality when we choose a beach to enjoy. However, knowing that beach water is clean and safe for swimming is a huge benefit to both residents and tourists who enjoy our Door County beaches. The beach water warning light system now in place at five Door County beaches is a collaboration of the Door County Health Department, the Wisconsin Department of Natural Resources, the Environmental Protection Agency, the University of Wisconsin-Oshkosh, and the respective municipalities that provide the space and access for the warning lights.
The county first installed the signs last year at five Door County beaches: Frank E. Murphy County Park in the town of Egg Harbor; Baileys Harbor Ridges County Park; Egg Harbor Beach; and, in Sturgeon Bay, Otumba Park Beach, and Sunset Park Beach. However, the villages of Sister Bay and Ephraim elected not to install beach water monitors in their respective villages primarily due to sign restrictions.
Visitor at the Baileys Harbor Ridges Park Beach — Photo by Mike Bahrke
Each summer, between Memorial Day and Labor Day, Professor Greg Kleinheinz and his team from the UW-Oshkosh collect and analyze water samples from over 30 Door County beaches. One of the water contaminants they test for is E. coli which can make swimmers ill and is also an indicator of the possible presence of other health risks in the water such as bacteria, viruses, and other organisms. All warm-blooded animals have E. coli in their feces, which means that if high levels of E. coli are found in beach water, there is a high chance of fecal matter being in the water.
The EPA E. coli standards are risk assessments for human health based on data from adults engaging in swimming. It’s recommended that people and pets stay out of the water when "Caution" or "Closed" advisory signs are posted. The standards developed for the Great Lakes in Wisconsin which may also be used for inland beaches, are as follows:
If the E. coli count is greater than 1,000 MPN/100 mL (MPN stands for "Most Probable Number” and is the amount of E. coli in the water), the beach is closed and sampled every day until concentrations fall below that threshold. At that point, the beach is then reopened. This "Closure" level, adopted by the Wisconsin DNR, represents a risk of approximately 14 cases of gastrointestinal illness per 1,000 recreational water users.
If the E. coli count is greater than 235 MPN/100 mL but less than 1,000 MPN/100 mL, an “Advisory” is issued. This level represents a risk of approximately eight cases of gastrointestinal illness per 1,000 recreational water users.
If the E. coli count is below 235 MPN/100 mL, no advisories or warnings are issued.
The results from E. coli testing can take up to 10 to 12 hours. So, it’s important to note that an advisory for a given day is often based on the results of samples taken the previous day. E. coli levels can also vary from hour to hour and from area to area at a beach. Consequently, a posted advisory sign may not reflect the actual conditions present in the water. The advantage, and why we should have a beach water monitoring system like the SwimSmart monitoring system now being used in Door County, is because the monitors are connected to the Internet and can be updated immediately via cell phone when results become available. The immediacy of the monitoring system is important because beach water is not always clean, the monitors will increase the awareness of beach goers to water quality, and they will also engage people in protecting our water.
During the summer of 2023, there were 47 advisories and 20 closures of Door County beaches. So, what can you do to improve beach water quality in Door County? Here are some steps you can take to help keep our beaches clean and reduce health risks for everyone at the beach.
Don't swim if you’re ill.
Don't feed the birds.
Properly dispose of all trash, diapers, and pet waste in appropriate trash cans if they are available. Put swim diapers on babies and toddlers who are not toilet trained before allowing them in the water. Human feces contain viruses and bacteria that can make others sick if ingested.
Don't swallow lake water and wash your hands before eating.
Keep your eyes open and report any water quality problems you experience at the beach to local health authorities and the DNR (DNRBeachHealth@Wisconsin.gov).
A good day at the beach is a shared experience bringing people together!
By Mike Bahrke, Executive Director, DCEC
Adapted in part from: Frequently Asked Questions | Beach Program, Beach Health and Beach Monitoring | Wisconsin DNR, https://dnr.wisconsin.gov/topic/Beaches/FAQ.html
