Iowa beach advisories hit decade high after rain-fueled bacteria spikes

Two-thirds of Iowa’s state park beaches faced “swimming not recommended” advisories at least once this summer, with heavy rains fueling higher bacteria levels that pushed advisories to their highest rate in a decade, according to state monitoring officials and data.

The Iowa Department of Natural Resources issued 156 advisories across 39 state beaches, up from 145 advisories last year. That meant about 26 percent of weekly water samples collected from Memorial Day through Labor Day tested high enough for bacteria or toxins to trigger warnings — the highest advisory rate since at least 2016.

Wet years tend to drive bacteria spikes, while calm, dry summers allow algal blooms to build. Iowa was wetter this year than the past few summers, washing bacteria downstream into Iowa’s lakes and beaches, said Daniel Kendall, who oversees the DNR’s beach monitoring program.

“We've had a lot of rain this year flushing through those beach watersheds,” Kendall said. “We've had a lot of days where we were out in the rain collecting the samples. That's a big difference compared to how we had it last year with a lot of dry days, and the previous years, a lot of dry days where you're able to get out there with less disturbance.

“A lot of the bacteria gets attached to the sediment, and so that's just constantly churned up in the water ... all that water flushing through the beach area, flushing that fecal matter and whatever else is up there down into the water,” he said.

Rain-driven increases

The DNR tests state park beaches weekly for two main health concerns: E. coli bacteria, an indicator of fecal contamination, and microcystin, a toxin produced by cyanobacteria, or blue-green algae. Either can trigger advisories, though most warnings are issued for bacteria spikes.

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This year’s wet summer meant more bacteria-laden runoff flowing into lakes. Sediment churned up by storms also made it harder for contaminants to settle out of the water, Kendall said.

“Bacteria attach to sediment, and when you’ve got storm after storm, it keeps that sediment churned up,” he said, compared to drought years, when they tend to see more problems with algal toxins.

In 2025, the DNR reported about a dozen advisories for algal toxins, a number Kendall described as well within the program’s typical 2 to 6 percent range.

Consistent but higher

Iowa has about 40 state-managed beaches. Bobwhite State Park in far southern Iowa is owned by the state, but operated by Wayne County, so it was not included in the analysis of this year’s advisories.

Of those roughly 40 beaches, 26 experienced at least one advisory this summer and 13 beaches remained clear all season. One beach — at Lake Keomah near Oskaloosa — was not tested this year because of ongoing renovations at the park.

That share — about two-thirds of beaches posting warnings — is consistent with recent years. But the total number of advisories was up.

Fifteen beaches logged more advisories than in 2023, 10 saw fewer and 14 showed no change. Swimming was not recommended for all but three weeks this summer at three perennial hot spots: Backbone State Park, Beeds Lake and Pine Lake South, each received advisories during 12 out of the 15 weeks of testing.

“Some of the beaches were only off by one or two advisories compared to last year, but overall, we had more sites with issues,” Kendall said, adding it lined up with where the storms tracked — more across the central and eastern part of the state.

“It was just like every storm system seemed to go across the same region,” he said. “And just in general, it looks like that was more of possibly what our driver might have been this summer versus last year, where we were in more of a drought.”

Local highlights

Two popular Eastern Iowa beach destinations — Lake Macbride State Park near Solon and Pleasant Creek Recreation Area near Palo — both saw more beach advisories this year.

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Lake Macbride, which recorded no advisories last summer, had three this year, including one over Labor Day weekend. Pleasant Creek had eight advisories, up from five in 2024.

That was disappointing, especially at the end of the season when families were trying to get one last beach day, Kendall said.

“But again, that increase was pretty much in line with what we saw across the board,” he said.

Duration and trends

Despite the uptick, Kendall said the duration of advisories was similar to last year. Most warnings lasted a week until the next test showed improvement. Only a few beaches saw repeated advisories stretching across much of the summer.

“In terms of length, it was pretty typical,” Kendall said. “The difference was really the total number.”

The state has now monitored beach conditions for more than two decades. Over that time, the advisory rate has consistently hovered between 20 percent and 25 percent of weekly samples. This summer’s 26 percent rate sits at the high end but still within the long-term pattern, Kendall said.

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Testing and standards

The DNR monitors state public beaches weekly from the week before Memorial Day through Labor Day, a 15- to 16-week season.

Iowa follows U.S. Environmental Protection Agency guidance and tests for “indicator bacteria” — organisms that are not usually harmful themselves but signal the presence of fecal material. When these levels are high, it suggests that sewage, manure or other waste has contaminated the water and that pathogens could be present. The state also tests for microcystins, toxins sometimes produced by blooms of cyanobacteria, or blue-green algae

Advisories are triggered if:

Signs posted at affected beaches warn visitors that “swimming is not recommended.” Advisories are lifted once water quality returns to safe levels.

Contamination can come from septic failures, manure spills, stormwater runoff, or even droppings from pets, livestock and waterfowl. Heavy rains often drive bacteria into lakes and stir up murky water, helping the organisms survive. Health officials warn that children, the elderly and people with weakened immune systems are especially vulnerable to illness and other infections linked to swimming in polluted water.

In late July this year, tests at Backbone State Park Beach reported E. coli levels of 24,000 organisms per 100 milliliters of water, which is more than 100 times the limit set by the EPA. One week later, the beach’s E. coli level had dropped to 6,500 organisms.

Kendall, talking with The Gazette at the time, said the high levels may have been caused by several factors, including that Backbone is one of the few beaches in the state that is on a river.

“There's a giant goose population that loves to live on (Backbone) Beach,” Kendall said. “And with the amount of rainfall we've had recently, all of that goose manure can be pulled right into the water pretty easily, especially if the water levels come up or they go down, you know, because the beach sits pretty flat.”

Flooding, storm damage closed two beaches

Beyond bacteria and algae, some beaches were closed for other reasons.

George Wyth Beach in Waterloo was closed for five weeks due to flooding, while McIntosh Woods Beach on Clear Lake was shut down for two weeks due to storm damage.

Balancing risk and recreation

The monitoring program is designed to protect swimmers, particularly children and other vulnerable groups, from health risks that can include diarrhea, skin rashes and respiratory issues.

But Kendall stressed that advisories do not mean Iowa’s lakes are broadly unsafe or deteriorating. The testing reflects conditions at the time of sampling and at specific beaches, not long-term water quality trends across entire lakes.

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“The beach advisory program is designed to be a public health advisory program to protect the sensitive population,” he said. “... It's there to protect public health. It's not really designed to get in and say, ‘What is water quality overall doing’,” but rather protecting people from immediate risks.

Even in a year with more advisories, Kendall emphasized that the majority of beach days remained open for recreation.

“When we look at a 26 percent advisory rate for a season, there's 74 percent of the time that all these beaches are available across the state,” he said. “And that's a pretty good rate for being able to get out and recreate. We always strive to do better, but it is a pretty good rate as far as the amount of stuff that we do have open. And there's always, every week, there's always multiple beaches that do not have advisories.”

Iowa Environmental Council calls for stronger monitoring

The DNR has emphasized that it does not investigate specific contamination sources each week but points to agricultural runoff, stormwater and failing septic systems as common contributors.

Sarah Howe, water and climate resiliency specialist with the Iowa Environmental Council, said safe and clean lakes are essential not only for recreation and tourism but also for wildlife habitat and drinking water sources.

“Keeping them safe and free of pollutants is paramount to our health,” Howe said, noting that fertilizers, manure and agricultural contamination remain the biggest threats.

The DNR monitors state park beaches for bacteria and algal toxins, but Howe warned that city and county beaches are not held to the same reporting standards.

“The DNR isn’t in charge of monitoring every public beach, and other entities don’t regularly post advisories,” she said. “These differences make monitoring confusing for the public and can lead to serious illnesses if accurate beach data is not reported in a timely manner.”

Since the council began tracking advisories in 2014, Howe said this year has seen the highest number on record — including significantly more E. coli-related warnings than last summer.

The council is urging state leaders to strengthen water monitoring and focus on addressing pollution at its source to protect Iowa families and visitors who rely on lakes for safe recreation.

State officials last month announced more than $450,000 in financial assistance to help landowners adopt conservation practices aimed at improving water quality in eight Iowa lakes.

The funding comes through the Publicly Owned Lakes program, a joint effort of the Iowa Department of Agriculture and Land Stewardship and the Iowa Department of Natural Resources. The program provides cost-share funding to private landowners for practices such as terraces, cover crops, grassed waterways and sediment control basins to reduce nutrient runoff and soil erosion into lakes and reservoirs.

“We are fortunate to have some beautiful public lakes in our state that significantly enhance the quality of life for many Iowans and provide valuable recreational opportunities and wildlife habitat,” Iowa Agriculture Secretary Mike Naig said in a statement. “Through collaborative efforts with farmers, landowners and partners, we’re improving water quality and ensuring these lakes remain vibrant and healthy destinations.”

Comments: (319) 398-8499; tom.barton@thegazette.com