With coordination between Conservation, Planning, and Zoning, Parks, Recreation, and Forestry, and the Health Department, Marathon County will be piloting a project sampling the water at the Big Eau Pleine (BEP) County Park Beach. The Marathon County Public Health Laboratory will be testing the water at the Big Eau Pleine for Escherichia coli (E. coli).

The goals of the pilot project are to:

• provide education and information to users of the Big Eau Pleine waters so they can make informed decisions about recreating there;
• increase awareness and collaboration for efforts to improve water quality at the Big Eau Pleine; and
• evaluate the value in establishing long-term beach monitoring in Marathon County.

When will testing occur?

Sampling will be conducted once a week in 2024, August through September. In 2025 and 2026 sampling will be conducted weekly beginning the week before Memorial Day and ending the Friday following Labor Day. Testing periods may be adjusted as budget and staff availability permit. The website will always post the most recent test results.

Generally, the first test of the week will be taken on a Monday or Tuesday. If the first test of the week returns an E. coli level in excess of 1000 colony forming units (cfu)/100mL or above, additional sampling will occur that Wednesday or Thursday, as County staff are available, to attempt to provide updated results before the weekend.

	The Green (Low Risk) sign will be posted when E. coli levels are below 235 cfu/100mL. The sign reminds users that they should enter the water at your own risk.
	The Yellow (Moderate Risk) sign will be posted under the following conditions: Whenever the sample results for E. coli exceed 235 cfu/100mL, indicating: Moderate levels of bacteria are present. Entering the water is at your own risk.
	The Red (High Risk) sign will be posted under the following conditions: Whenever the sample results for E. coli, exceeds 1000 cfu/100mL, indicating: High levels of bacteria are present. Entering the water is not advised, and entering the water remains at your own risk.

What Causes An Elevated E. Coli Level?

The actual source of these E. coli are unknown. All warm-blooded animals have E. coli in their stool, otherwise known as feces, manure, or poop. This includes, but is not limited to, humans, birds, cows, and dogs. High amounts of E. coli found in water is often due to runoff from fields treated with cow manure, failing septic systems, or large numbers of birds near the water. Different strains of E. coli may cause a range of gastrointestinal illness. Although the Health Department is not testing for specific strains of E. coli, high amounts of this bacteria serves as an indicator of the possible presence of other health risks in the water, such as other bacteria, viruses, or other organisms.