From about Memorial Day through Labor Day, the Iowa Department of Natural Resources (DNR) conducts weekly monitoring of bacterial pollution in Iowa’s 39 state park beaches.
The DNR analyzes water samples from the beaches for certain one-celled microorganisms, known as indicator bacteria, that are visible only under a microscope. High levels of E. coli, a common indicator bacteria, indicate feces is in the water, most commonly in Iowa from livestock sources.
These indicator bacteria are commonly used by state environmental agencies and by the U.S. Environmental Protection Agency to determine the suitability of beaches for swimming-type uses.
Microcystin, a toxin produced by harmful blue-green algae blooms, has also been detected in Iowa’s water bodies.
Due to health risks, when microcystin or E. coli levels exceed certain standards/thresholds, the DNR posts swim advisories telling beach-goers to stay out of the water.
The Iowa DNR and the Iowa Environmental Council track these weekly beach monitoring reports and swim advisories and compare advisory trends from year to year. To review recent trend data, visit the Iowa DNR website.
Eight beach advisories were issued for Iowa beaches for E. coli contamination for the week of July 31-Aug. 6. The Iowa beaches with E. coli-related warnings or advisories were:
- Backbone Beach (Dundee, Delaware County)
- Denison Beach (Black Hawk Lake, Lake View, Sac County)
- Emerson Bay Beach (West Okoboji Lake, Milford, Dickinson County)
- George Wyth Beach (Waterloo, Black Hawk County)
- Lake Darling Beach (Brighton, Washington County)
- Lake Keomah Beach (Oskaloosa, Mahaska County)
- McIntosh Woods Beach (Clear Lake, Ventura, Cerro Gordo County)
- Nine Eagles Beach (Davis City, Decatur County)