Iowa’s state park beaches had 79 swim advisories this past summer sparked by bacteria and toxins that raise health risks for swimming, skiing and other contact with the water.
The total was down from 2018, when the state had 111 advisories.
This year, there were 19 warnings for microcystins, toxins generated by harmful algae. Microcystins can cause gastroenteritis, skin irritation and allergic responses, as well as potentially life-threatening liver damage. Iowa only had six microcystin warnings in 2018.
E. coli bacteria, which indicate feces in the water, caused 58 advisories and, on two additional occasions, beaches had advisories for both pollutants the same week, according to data from the Iowa Department of Natural Resources.
The Iowa DNR tests the water at the state’s 39 state park beaches once a week from Memorial Day weekend through Labor Day. If the microcystin or E. coli levels are higher than state standards for safe swimming, the department posts signs each week at the beach and online.
The state park beach with the most advisories this summer was Backbone, near Strawberry Point, with E. coli postings 13 of 15 weeks of summer. Green Valley State Park, near Creston, was next highest with eight microcystin advisories.
Lake Darling State Park, near Brighton, had four microcystin advisories and one for E. coli in 2019. The Washington County lake had four E. coli warnings in 2018 — just a few years after the state completed a $16 million restoration project there in 2014, The Gazette reported.
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The project started in the early 2000s with installation of erosion control features in the watershed to prevent agricultural runoff to the lake. Officials said at that time more than 80 percent of watershed landowners installed ponds, terraces and other conservation practices.
Chris Jones, a University of Iowa research scientist, wrote an April 9 blog post about Lake Darling’s water quality. He asserts the lake’s proximity to hundreds of confined animal feeding operations makes it vulnerable to manure runoff.
“Does the above scenario put the lake at more risk than others without such a stressor?” Jones wrote. “The scientific literature says yes.”
Jones and his colleagues published a study in December showing some western Iowa landowners were applying fertilizer, in the form of manure or commercial fertilizer, at more than double the recommended rate, causing higher nitrate levels in streams.
Two state park beaches were closed for renovations this summer. The state has been dredging sediment from Geode State Park, near Danville, to reduce the potential for harmful algae. A $3.5 million renovation of Marble Beach Campground, near Milford, has caused the beach to be closed this summer.
Viking Lake, near Stanton, has been drawn down since mid-July to restore fish populations.
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