Iowa’s beach monitoring program, which issues no-swim advisories for high levels of toxins at state park beaches, posted 86 percent fewer advisories for a toxin caused by blue-green algae in 2017 than the previous year.
The Iowa Department of Natural Resources issued five advisories for microcystin toxins in 2017, down from 37 advisories in 2016 and 34 warnings in 2015.
The sharp decline sparked skepticism from Susan Heathcote, water program director for the Iowa Environmental Council.
“It seems odd we’d have such a big difference one year to another,” Heathcote said, adding the administrator of the DNR program changed from 2016 to 2017. “It seems up a little bit of a red flag to me.”
DNR officials said they didn’t know why fewer problems toxins were detected at Iowa’s beaches, but said they were confident in the monitoring program.
“We definitely have not changed any protocols or procedures,” said Roger Bruner, supervisor of the DNR’s water quality assessment section. “We will be looking at the data to see if there are any conclusions that can be drawn, but we must keep in mind that this is an active area of research.”
The DNR does weekly tests of Iowa’s 39 state park beaches, from Memorial Day to Labor Day, testing for microcystins and E. coli bacteria. The warnings are posted online throughout the summer.
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Exposure to the microcystin toxins produced by some blue-green algae can cause gastroenteritis, skin irritation and allergic responses, as well as potentially life-threatening liver damage, according to the U.S. Centers for Disease Control and Prevention.
E. coli is an indicator for fecal material, which can carry parasites or other pathogens that can sicken swimmers.
The DNR posted 91 no-swim advisories for E. coli over the 15 weeks of testing at the 39 state park beaches. This is down from 108 advisories in 2016.
Weather can influence the level of toxins in lakes and rivers, Heathcote said. During heavy rain, fertilizer and manure washes into streams and can cause spikes in E. coli or microcystins, Heathcote said. Phosphorus from fertilizer feeds blue-green algae blooms, which then grow in sunny weather, she said.
The most no-swim advisories issued in one week this summer was 13 — which was one-third of the state park beaches — in early August, according to DNR data.
The DNR issued bacteria advisories 13 of 15 weeks at Backbone State Park beach, in Delaware County, which was the most of any state park beach. The beach at Nine Eagles State Park, in southern Iowa, had 10 bacteria advisories over the summer.
Green Valley State Park beach, in southwest Iowa, had three microcystin advisories — the most of any state park beach. This beach has had perennial problems with blue-green algae.
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