DNR says 15 state beaches are ‘not recommended for swimming’ due to E. coli

The Iowa Department of Natural Resources is recommending that Iowans avoid swimming in 15 beaches across the state due to high E. coli levels.

That’s two more than last week, when 13 beaches were flagged for high E. coli levels.

Three additional beaches are considered vulnerable following this week’s water testing.

The DNR tests water at about 40 state beaches weekly, between Memorial Day and Labor Day.

For single samples, if the E. coli levels exceed 235 organisms per 100 milliliters of water, the DNR issues a “swimming not recommended” warning and posts signs.

The 15 beaches flagged by the DNR this week that surpassed either the single sample threshold, the geometric mean sample threshold, or both, for E. coli includes:

Last week, Black Hawk Beach in Sac County and Lower Pine Lake Beach, near Eldora, were on the “not recommended for swimming list,” but were removed this week.

  Buy Photo

This week — week 11 of the testing — McIntosh Woods Beach, Emerson Bay Beach, Brushy Creek Beach and Pine Lake South Beach were added due to high E. coli levels.

E. coli in recreational waterways can be dangerous because it can indicate fecal contamination, which can potentially expose swimmers and other users of the water to pathogens that can cause illness.

Avenues of transmission

Dan Kendall, lake and beach monitoring coordinator for the DNR said that high E. coli levels in beaches can pop up in a multitude of ways.

One of the most typical ways high E coli levels get into Iowa’s waterways is through animals — especially geese, Kendall said.

Kendall said the E. coli levels from the goose manure itself are higher than the levels that are found in the waterways.

“So, when you have direct deposition like that, you could jump those numbers up pretty quickly,” he said.

  Buy Photo

Kendall said that sand is also a “great” host for bacteria because the heat of the sand can help incubate the bacteria and it can be easily pulled into the water by waves.

Kendall said that other animals, like deer, can also contribute to a spike in E. coli levels, along with “human interactions,” like young children entering the beaches wearing diapers.

Other avenues of E. coli transmission could include manure runoff from farm fields and septic tank discharges, as well.

There has not been any manure spill along any waterways that could have led to higher levels of E. coli in along the beaches reported to the DNR, Kendall said.

Backbone beach

Last week, Delaware County’s Backbone State Park Beach had reported E. coli levels of 24,000 organisms per 100 milliliters of water, which is more than 100 times the limit set by the Environmental Protection Agency.

Between last week and this week, Backbone beach’s E. coli level dropped significantly from 24,000 to 6,500 organisms, although the beach still is flagged for “swimming not recommended.”

Kendall said the culprit for Backbone’s exceptionally high E. coli levels is due to a few different factors, including that Backbone is one of the few beaches in the state that is on a river.

He said beaches on a lake versus a river “interact a bit differently.”

  Buy Photo

“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.”

When there are spikes in E. coli — or other bacterium in Iowa beaches — Kendall said that there isn’t anything the DNR can do to help mitigate the levels or help “flush it out.”

“We're not going to apply bleach to the beach,” Kendall said. “Solar radiation is one of the main ways that it gets inactivated. So, a lot of times you'll see high numbers at that beach at that sandy beach area, and as you move out into the lake, those numbers decrease as you go out into the into the lake, because of solar radiation.”

Kendall said that E. coli comes from the gut of warm-blooded animals, so whenever they are out of an animal’s gut, they already start the process of dying.

An ongoing issue

High E. coli levels have been an issue at Iowa’s beaches for years. Last year, Iowa had the highest number of swimming advisories for bacteria at state beaches in more than a decade, possibly because of abundant rainfall that washed fecal material into Iowa’s lakes.

Over the course of 15 weeks of testing in 2024, the DNR issued 145 swimming advisories, including 130 for bacteria, seven for toxins and eight for both.

  Buy Photo

A Gazette and Investigate Midwest investigation in 2022 showed a fifth of water monitoring tests administered on Iowa lakes between 2002 and 2022 exceeded the state’s threshold of 126 units of bacteria per 100 milliliters of water.

If Iowans choose to recreate near the beaches with posted warnings, Kendall said they should take some basic precautions.

“The biggest thing, when you go out and you recreate in the water, always wash up afterward. It's the same recommendation when you go to the local swimming pool,” Kendall said.

“All of these advisories are based on risk, in a sense. So, if there's advisory in place and you really can't take risk, you might want to alter how you interact with that water. But the biggest thing is, wash up afterward, wear life jackets and enjoy the water.”

Olivia Cohen covers energy and environment for The Gazette and is a corps member with Report for America, a national service program that places journalists in local newsrooms to report on under-covered issues. She is also a contributing writer for the Ag and Water Desk, an independent journalism collaborative focusing on the Mississippi River Basin.

Sign up for our curated, weekly environment & outdoors newsletter.

Comments: olivia.cohen@thegazette.com