Beach water is tested for E. coli, which is a type of bacteria found in the intestines of animals and humans. At certain levels, E. coli can increase the likelihood of swimming-associated illnesses. The State of Michigan has developed the Water Quality Standard for E. coli to protect human health during work and play in the surface waters of the state. 

Currently, daily sample results must be below 300 E. coli per 100 milliliters for water to be considered safe for swimming. The 30-day geometric mean, calculated using the daily composite sample results within that time frame, must be below 130 E. coli per 100 mL for the water to be considered safe for swimming. If a sample result, or the calculated 30-day geometric mean, are higher than the Water Quality Standard, ACHD will issue a swim advisory until results come back below those values.

ACHD samples monitored beaches weekly, from Memorial Day to Labor Day. When there is an exceedance, resamples will be taken as soon as possible after results come back.

Beach monitoring is done to ensure that Allegan County residents and visitors can recreate safely and make informed decisions when using our public beaches. Each week, ACHD staff go to monitored beaches to take water samples and complete a sanitary survey. The sanitary survey helps create a full picture of beach conditions during monitoring, including noting the weather, visible water quality, and beach use. Staff then collect three samples from the left, right, and center of the swim area, that are then combined to make one, composite sample. That sample is sent to the lab for water quality testing. 

A water sample result from the beach may not necessarily reflect E. coli levels across the entire lake. E. coli bacteria levels can vary greatly from one location to another due to factors such as rainfall, water currents, wind, wildlife activity, inputs from nearby streams, and local runoff. Therefore, a high E. coli result at one beach may not mean the entire lake has elevated bacteria levels. Samples taken at specific locations assess conditions at those particular sites, and they may not reflect water quality conditions across the entire lake.

MiEnviro Beach Guard is a website that shows current and historical water quality data for select beaches in Allegan County, as well as throughout the state. Allegan County Health Department posts water sample results and any advisories for monitored beaches throughout the summer season. Residents and visitors can use this resource to stay informed before visiting beaches in the county.

There is a delay in results reporting as current testing methods take up to 18-24 hours to complete. Results are typically received the next day and are required to be reported within 36 hours. Results are posted on MiEnviro Beach Guard. Any advisories for E. coli levels exceeding the safe limits can be found on MiEnviro Beach Guard, as well as the ACHD website and ACHD Facebook page. Beaches with advisories will have signage posted onsite informing visitors of the advisory.

Testing shouldn't be relied upon as an instant alert system, and beachgoers should use good judgment when swimming. It is best to follow safe swimming practices and avoid swimming in water that smells foul, looks murky, or directly after a heavy rain.

There are many sources that can contribute to E. coli in surface waters including rain runoff, pet waste being washed into the water, or faulty septic systems, as well as waterfowl and other wild animals living near or in the water.