The number of state beach advisories for E. coli hit a record this year as the DNR continues a project to learn more about it. Dan Kendall manages the department’s summer beach monitoring program.
Those samples include testing for E. coli, a large family of bacteria. Most strains are harmless. They live in the guts of warm-blooded animals, including people, geese and cattle. But some escape into the environment through feces and make people sick with stomach cramps and diarrhea. Kendall says high concentrations of E. coli in water also indicate other harmful microbes may be present.
The DNR issued 151 “Swimming Not Recommended” advisories this for state beaches because of E. coli. DNR natural resource biologist Jason Palmer was out recently trying to find out why long-term data shows some state beaches test high for E. coli time and time again.
Data at lakes around Iowa show beaches tend to be E. coli hot spots – specifically within five to six feet from the water’s edge. Farther out, E. coli levels drop off. New research also shows some E. coli strains can do pretty well outside an animal gut.
Palmer says E. coli can thrive in wet sand right below the surface. It gives the bacteria a moist structure to grow on and a stable temperature with protection from direct sunlight. Another piece of this project uses pumps that put lake water through a series of medical-grade filters trying to figure out if there are viruses and other pathogens at the beach. Palmer’s team will ship these filters and some sand samples to a federal lab in Wisconsin. There, scientists will look for the genetic material of harmful microbes and clues to where they came from.
Palmer and field technicians have collected data from Big Creek, Backbone, Clear Lake and MacBride State Parks since 2023. And he’s hoping that results will be available to share next year. By understanding the dynamics of E. coli at state beaches, Palmer says the D-N-R can better communicate risks to the public and find solutions.
