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.
Thirteen beach advisories were issued for Iowa beaches with E. coli-related contamination for the week of July 30-Aug. 5.
- Backbone Beach (Dundee, Delaware 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)*
- Lake Manawa Beach (Council Bluffs, Pottawattamie County)*
- Lake of Three Fires Beach (Bedford, Taylor County)*
- Lower Pine Lake Beach (Eldora, Hardin County)*
- McIntosh Woods Beach (Clear Lake, Ventura, Cerro Gordo County)*
- Nine Eagles Beach (Davis City, Decatur County)*
- North Overlook Beach (Lake Red Rock, Pella, Marion County)**
- Prairie Rose Beach (Harlan, Shelby County)*
- Union Grove Beach (Gladbrook, Tama County)*
Two beach advisories were issued for Iowa beaches with microsystin-related contamination for the week of July 30-Aug. 5.
- Lake of Three Fires Beach (Bedford, Taylor County)*
- Springbrook Beach (Guthrie Center, Guthrie County)*
*Data from the Iowa DNR State Park Beach Monitoring Program
**Data from the U.S. Army Corps of Engineers, Rock Island District
Note: Storm Lake experienced a significant algae bloom last week. DNR testing indicated the bloom was not producing microcystin at the time, but the Iowa Lakeside Lab is doing additional testing this week. Blooms can begin producing toxins at any time, so it is important to be cautious and avoid scummy areas. Storm Lake will be added to the list if Lakeside Lab’s results are above the advisory threshold.
