On Monday mornings, Rich Gradoville visits the streams near his home in Johnston, not for fishing or recreating, but to test the nitrate concentration of the flowing water.

The retired school teacher is part of a network of citizen scientists contributing to the Nitrate Watch program, through the Izaak Walton League of America, to monitor the levels of nitrate and nitrite in surface and drinking water across the country.

Monitors expect increased nitrate concentrations this month as part of the “spring flush,” when April showers wash fertilizer and other nutrients into the waterways.

In past years, surface water in Iowa during this time tested in concentrations in excess of 10 milligrams per liter, which is the maximum contaminant level for drinking water set by the U.S. Environmental Protection Agency.

Why monitor?

Gradoville got involved with the program two years ago, shortly after finding out he had a pre-cancerous tumor on his bladder. It’s a type of cancer, he said, typically associated with tobacco smokers, but Gradoville had never smoked.

He met someone with the same type of tumor who also wasn’t a smoker, which led him to poke around for other potential causes and he learned about nitrogen pollution in Iowa’s waters.

A 2016 published study, analyzing bladder cancer in postmenopausal women in Iowa, found a link between long-term ingestion of elevated nitrate levels and bladder cancer. But other organizations, like the Bladder Cancer Advocacy Network hold that “more research is needed” to determine the link between nitrate in drinking water and bladder cancer.

Gradoville can’t say for sure what caused his, but it was inspiration enough to get involved with Nitrate Watch, which is open to anyone willing to test and submit their results.

Heather Wilson, the Midwest Save Our Streams coordinator with Izaak Walton League, said the human health concerns of the nutrient concentrations are “more and more” present in volunteers’ minds as they participate in the program.

“Definitely more research is needed, but there’s a lot of research that already points to health impacts occurring even when the amount of nitrate in water is below the current drinking water standard,” Wilson said.

Wilson said the associated impacts include blue baby syndrome, thyroid disease, neural tube birth defects and cancer.

“That is of course a major concern, especially in Iowa, where cancer rates are climbing,” Wilson said.

The recently released Cancer in Iowa report for 2025 found that Iowa is one of only two states with rising rates of new cancer.

Nutrient pollution in water also leads to environmental concerns, like algal blooms and dead zones. Iowa is part of a multistate effort to shrink the size of the hypoxia in the Gulf of Mexico, by reducing the amount of nitrogen and phosphorus in the Mississippi River watershed.

The task force engages state agencies, with a goal of reducing overall nitrogen load, through practices like cover cropping, reduced tillage, extended crop rotations and more intentional fertilizer application.

Recent survey data showed the amount of cover crops planted on Iowa cropland has more than doubled since 2017. The Iowa Department of Agriculture and Land Stewardship and Iowa State University released a free nitrogen application tool to help farmers fine tune their fertilizer applications, and lawmakers are pushing forward a bill to establish a pilot program and a $2 million appropriation to study ag practices that reduce overall nitrogen application.

Wilson said the goal of Nitrate Watch is to support efforts, like these, to stop the pollution from getting into the water and to encourage water treatment efforts that protect consumers from potentially harmful drinking water.

Testing the water

The Iowa Department of Natural Resources monitors water quality across the state and provides assessments on the segments every other year, per the Clean Water Act. Wilson said citizen science monitoring doesn’t provide the same level of testing that a trained environmental specialist could, but it helps to “fill the gaps.”

“There just simply aren’t enough people, professionals, DNR employees,” Wilson said. “They can’t possibly measure all the waterways, even if they wanted to.”

Wilson said Nitrate Watch serves as the “eyes on the ground” for acute pollution problems and can help draw attention to areas of high pollution.

“We’re not replacing the monitoring of the DNR, or your local soil and water conservation district, we’re supplementing it,” Wilson said.

A map from the Nitrate Monitor 2024 report, shows high participation in the program in Iowa, and high nitrate concentration levels across the state.

 Maps from the Izaak Walton League of America’s Nitrate Watch 2024 report shows participation in the citizen science program and areas with the highest concentration of nitrate in surface and drinking water. (Map courtesy of Izaak Walton League of America)

Wilson said Iowa has a lot of groups, like Iowa Citizens for Community Improvement, local Izaak Walton Leagues, the Iowa Environmental Council, local conservation boards and more that are part of why “the map just lights up in Iowa.”

Wilson said the goal with Nitrate Watch is to make it “easy” and “enjoyable” for volunteers to participate. While volunteers are not prescribed a sampling regime, Gradoville has implemented his own schedule for testing.

Each Monday, when the rivers aren’t frozen over, he tests at a site on the Des Moines River just downstream of Saylorville Lake, a site on Beaver Creek and the tap water in his home.

Gradoville stops at a flowing part of the water, dips the test strip in quickly, then sets a timer for 30 seconds before reading the pink hue on the strip and logging it on the mobile app.

Each stop takes him a couple of minutes.

“It’s not a huge time commitment,” Gradoville said.

Now, after years of regular testing, he can see a chart of his three monitoring sites and the fluctuating nitrate and nitrite concentrations in the water.

Especially now, but even before he started monitoring, Gradoville said his relationship to Iowa’s waters changed.

“I used to love to jump into every stream and creek and pond and lake here in Iowa,” Gradoville said. “Well over the last number of years, you start seeing the water and see what’s in it … I don’t have any interest in doing that.”