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. In Iowa livestock are the most common source of feces in surface waters.
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.
Three beach advisories were issued for Iowa beaches for the week of May 26, all for E. coli-related contamination and none for Microcystin-related contamination.
3 beaches with an E. coli-related advisory:
- Lake Keomah Beach (Oskaloosa, Mahaska County, IA)*
- Lower Pine Lake Beach (Eldora, Hardin County, IA)*
- Union Grove Beach (Gladbrook, Tama County, IA)*
In addition to the state beaches, two city and county beaches exceed the state’s advisory threshold for E. coli.*
Notable statistics from summer 2022, provided by the Iowa Environmental Council:
- North Twin Lake West Beach experienced its first advisory for microcystin in seven years.
- With 14 advisories for E. coli and 2 for microcystin, Lake Darling was under a swim advisory for all but the week of June 17, the fourth week of the recreation season.
- Since 2014 Backbone has experienced the most E. coli advisories of all monitored beaches at 118.
- Four beaches recorded advisories for both E. coli and microcystin.
- Twenty-five state park beaches recorded swim advisories this summer, and 14 state park beaches did not record an advisory.
- Crandall’s Beach (Spirit Lake), Rock Creek Lake and Springbrook Beach in Guthrie County experienced their first advisories for microcystin since 2015.
Para ver este aviso en español, haga clic aquí.
*Data from the Iowa DNR State Park Beach Monitoring Program
**Data from the U.S. Army Corps of Engineers, Rock Island District