The 2026 Oakland County Health Division Beach Monitoring Program begins on June 1 and will run for ten weeks. The County will monitor 251 beaches on 123 different lakes.
The water collection and beach surveying are conducted by Environmental Health students hired by Oakland County. Beaches are sampled at least weekly and tested for E. coli bacteria, which can cause stomach cramps, nausea, fever, and skin and respiratory issues. The presence of E. coli bacteria at a beach may also indicate the presence of other harmful organisms.
Monitored beaches are to meet the one-day standard of 300 E. coli colonies per 100 milliliters of water AND the 30 day geometric average standard of 130 E. coli colonies per 100 milliliters. If a beach does not meet the water quality standard, it will be closed until satisfactory samples are obtained. Sampling results can be found on the Michigan Department of Environment, Great Lakes, and Energy (EGLE) BeachGuard website.
The Health Division will also sample 12 beaches more frequently (five times per week) using a new testing technology. The new technology, qPCR, allows the Health Division to provide same-day results. Currently being used as a pilot project, the Health Division will issue an advisory if it believes the results indicate the following day's results will be greater than 300 E. coli colonies per 100 milliliters. The Health Division continues to work with EGLE and the US EPA to ensure qPCR is a true reflection of water quality. The advisory will recommend avoiding swimming at the beach and be posted here, as well as on EGLE's BeachGuard website.
We conduct bathing beach sampling every summer during June through August. The water is tested for E-coli bacteria and judged against limits established by state law.
Public beaches are tested annually, on a weekly basis during June through August. Public beaches sampled every year include government owned beaches (state, county, and city parks), commercial beaches (pay-to-swim beaches, country clubs, etc.), beaches at educational institutions and foster care homes, and children's camp beaches.
If you live on lakefront property and choose to swim right at your house rather than at an established beach area, you need to know that the bacteria results from the beach area do not necessarily correspond to where you are swimming. Concerned homeowners that swim at private beaches are encouraged to conduct their own bacteria sampling. The procedure is very easy and our laboratory only charges $12 for a sampling kit as long as:
If you are conducting some sampling of your own, you will need to know the E-coli limits and the sampling schedule. It is important to understand that random, individual samples are not a reliable indicator of water quality. We are required by law to take a minimum of three samples each time we test a particular beach area. We will then calculate a daily geometric average (different from a normal arithmetic average) from those three samples, which must be below 300 E-coli to be considered safe for swimming.
Sometimes one or two of the samples may be above 300, but the daily geometric average is below 300, so the beach is not closed. Also, if you want to get an accurate idea of your beach's overall water quality, you must sample on more than one occasion.
The law requires a minimum of five sampling events (consisting of at least three samples per event) within a 30-day period to be considered a valid and reliable study of the water quality. After 30 days you need to calculate a seasonal geometric average for all of your individual samples within that time frame. This seasonal geometric average must be below 130 E-coli to be considered safe for swimming.
It is a popular misconception that if one area of the lake is contaminated, then the whole lake is contaminated. This is not true.
Bacteria contamination originates from conditions or factors present on or near the shore in the immediate vicinity of the beach. Two beaches on opposite ends of a lake that have different on-shore conditions will not have the same bacteria levels. This is why it is important for private homeowners who swim near their house to periodically take samples from where they swim and not rely on results from a beach down the road. Since contamination originates on-shore, it is generally considered to be safer in deeper areas away from the shoreline because wind direction and wave action could trap bacteria against the shore.
Quantitative Polymerase Chain Reaction, or qPCR, is a laboratory technique measuring E. coli DNA. The goal of qPCR is to allow for the Health Division to provide the public with quicker results. Compared to Colilert (the method used at all beaches and the test that triggers a beach closure), qPCR results are ready within four hours while Colilert results are not available until the next morning. More work is being done to ensure qPCR methods are as protective as Colilert in Oakland County's inland lakes.
Due to state water quality standards, only Colilert results may be used to issue a beach closure. With the quicker results from qPCR, the Health Division will issue an advisory recommending beachgoers avoid swimming. The following day, the advisory will either be lifted or the beach will be closed, depending on the Colilert results.