Storm Lake Times Pilot

Environmental group says Iowa must improve toxin testing

Algae, nitrates force state’s largest water utility to drill wells


Union Grove State Park beach near Gladbrook has had issues with algae toxins and fecal bacteria. (Photo courtesy of Iowa Environmental Council)

An environmental advocacy group has called on the State of Iowa to ramp up its testing for an environmental toxin caused by agricultural pollution because Des Moines Water Works and the Iowa Department of Natural Resources constantly find them in their water sources.

A report released by Environmental Working Group on Wednesday found all of the beaches the DNR has monitored have registered trace levels of microcystins at least once since 2006. Some, like Black Hawk Lake in Sac County, have registered above the Environmental Protection Agency’s recreational guidelines for 11 out of the last 15 years. Microcystins are toxins released by blue-green algae, whose blooms are caused by a combination of sunlight and watershed farm runoff.

Exposure to microcystins considered a serious health hazard, both in the short-term and long-term. Liver failure and various cancers have been linked to exposures.

“Agriculture in Iowa is the number one cause of these algal blooms,” said Anne Schechinger, an analyst with EWG. “Climate change events like heavy rains make them worse, but these blooms are caused by nutrients that run off of farm fields.”

The fact every beach has registered trace levels of microcystins over the last 15 years warrants a broader scope of testing, Schechinger argued. The state only tests 39 beaches every year among the state’s 846 water bodies.

The report says Storm Lake was last tested in 2011, when Awaysis Park Beach registered microcystin levels of 0.7 micrograms per liter. The state didn’t issue a “do not swim” advisory because it was far below the EPA’s recreational guideline for microcystin levels.

Schechinger recommended weekly testing for major rivers and those with high recreation traffic. Iowa is the only state in the Midwest that tests regularly for microcystins, the report notes. She pointed to the Des Moines River, which didn’t exhibit an algae bloom last year, but Des Moines Water Works last year opted against using the Des Moines as a raw water source. The utility detected heightened microcystin levels for much of the summer, according to CEO Ted Corrigan.

“More testing is essential because algae blooms are super tricky,” Schechinger said. “Sometimes they produce toxins and sometimes they don’t, and you can often find microcystins when you don’t see green blooms. These need to be tested every week in the summer.”

Corrigan told The Times the utility started monitoring microcystins and three other cyanotoxins after the city of Toledo, Ohio experienced an algae bloom on Lake Erie that resulted in a half million residents losing water service.

He noted the utility has detected microcystins in one of its raw water sources in five of the last seven years.

DMWW first discovered cyanotoxins in April 2017 in the Des Moines River, roughly two years after then-CEO Bill Stowe sued Buena Vista, Sac and Calhoun counties over excessive nitrate levels in the Raccoon River, its other main raw water source. Cyanotoxins like microcystins aren’t believed to be caused by nitrate, rather, they are caused by high phosphorus levels and a combination of sunlight and relatively low water flow. High nitrate levels occur usually after major rain events, Corrigan explained.

The increasing frequency of blue-green algae in the Des Moines River’s Saylorville Reservoir and persistently high nitrate levels in the Raccoon River have prompted DMWW to explore a $30 million well-drilling project in the Des Moines’ alluvial aquifers. Corrigan told The Times in January the aquifers are believed to be protected from blue-green algae and nitrate runoff.

Still, the utility must rely on surface water on some level, Corrigan cautioned. The new well system won’t draw close to the 50 million to 80 million gallons the utility draws per day, he said. Hence DMWW is continuing to hone its testing for cyanotoxins.

As water temperatures rise, DMWW collects samples from the Des Moines and Raccoon rivers and conduct visual counts of blue green algae under a microscope, Corrigan said. As algae counts increase, weekly toxin testing will ramp up to daily testing for the four most common cyanotoxins: microcystins, cylindrospermopsin, anatoxin-a, and saxitoxin.

“We do toxin testing probably on a weekly basis most of the year on both the Des Moines and Raccoon. So we’ll test for toxins and can do that analysis in our own lab for microcystin,” Corrigan said. “If we see a lot of a certain type of blue-green algae we’ll start the toxin testing, which is pretty involved. There are three cycles of freeze-thaw, and then we do the analysis. It’s not difficult, just time consuming.”

DMWW will stop using either the Des Moines or the Raccoon if the level of cyanotoxin exceeds 0.3 parts per billion. The DNR issues a “do not swim” advisory when the level of microcystins exceeds eight parts per billion, a standard that’s much higher than DMWW’s.

Schechinger, the EWG analyst, noted the DNR’s “do not swim” advisories are issued when microcystin levels exceed the EPA’s recreational standard. Corrigan said the EPA hasn’t issued a regulatory maximum for microcystins in finished drinking water. He noted the phenomenon of mass contamination from blue-green algae started only six years ago after the Toledo incident.

“The Toledo incident was the beginning stages of awareness of these cyanotoxins and the fact they exist in our rivers,” he said. “Since then, we’ve done significantly more monitoring and have had no problems since then.”

Leave a Reply