Hundreds of Iowans turn out to hear scientists discuss Polk County water quality report

During a summer that’s featured high-profile nitrate spikes in Iowa waterways and water use restrictions for thousands of central Iowans, hundreds of people gathered in Des Moines this week to listen to discussion about the findings of a comprehensive water study that was commissioned by Polk County.

In what the researchers of the study — called the Central Iowa Source Water Resource Assessment, or CISWRA, report — said were their top concerns, the report focused on livestock manure management, stream channel protection, land use adjacent to rivers, harmful algal blooms, and waterborne pathogens and nutrients — all of which can affect water quality across the state.

Through more than 4,000 hours of research for the report, 16 science advisors determined that about 80 percent of the total contribution of nitrogen to the Des Moines and Raccoon rivers’ watersheds comes from agricultural land.

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Jerald Schnoor, a professor emeritus of civil and environmental engineering at the University of Iowa, said 40 percent of that comes from fertilizers applied directly to the land. Another 20 percent comes from soybeans and legumes, which pull nitrogen from the atmosphere and turn it into nitrate. The other 20 percent is from manure applied to the land.

Schnoor said other sources of nitrate — although less significant than agricultural activities — are from “atmospheric deposition,” like rain and snow, which makes up about 18 percent of nitrate.

He said wastewater from developed land contributes only about 2 percent of nitrate in the watersheds.

According to the CISWRA report, the total amount of annual precipitation and the occurrence of extreme rainfall have been increasing in recent decades, which has resulted in increases in streamflows “interspersed with severe drought periods.”

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“More frequent heavy rainfall increases the risk of flooding, damaging property, infrastructure and crops, while also posing potential harm to human health. Flooding erodes riverbanks, transports pollutants and disrupts aquatic habitats, the report states.

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Larry Weber, director of hydroscience and engineering in the College of Engineering at the University of Iowa, was among the scientists who spoke at the event Monday at the Harkin Institute at Drake University.

He said the most recent report by the National Climate Assessment indicates that Iowa could see a 10 percent increase in the 5 percent rainiest days by 2050. Weber said the report projected a 20 percent increase in the same 5 percent rainiest days of the year in Iowa by 2100.

“With our soils being able to accept about two inches of infiltration in a 24-hour period, we'll see about a 33 percent increase in runoff,” said Weber, who also director of the Iowa Flood Center. “Intensification of rainfall will lead to greater runoff and greater flooding.”

Water contamination

Elliot Anderson is a research scientist at the University of Iowa who works with the College of Engineering and the Iowa Geological Survey.

In addition to increased rainfall events, Anderson said the quality of the water in Polk County — and elsewhere across the state — is affecting Iowa’s ecological health.

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“We're really getting at the well-being of the plants and animals that form the communities that are in our water bodies,” Anderson said. “This is a very important topic, because ultimately, the health of these creatures impacts the health of all of us and society. Our lives are better when the ecological communities in our water are better.”

Anderson said when a body of water is healthy, it naturally boosts its resilience to handle more pollution or human-made disruption.

He said that one of the most significant events Iowa rivers tend to go through are fish kills, since they can occur “very quickly and cause a lot of damage.”

Fish kills happen when there is a sudden death of a large number of fish in a body of water. They can occur from environmental factors, like temperature changes or water acidity. They also can occur as a result of human activity, like polluting waterways.

Anderson said there have been about 140 fish kill events since the Iowa Department of Natural Resources first began keeping count about 40 years ago.

Impacts on recreation

Claire Hruby, assistant professor of environmental science and sustainability at Drake University, researched the risks Iowa’s current water quality pose for recreationists.

“If you think about risks related to recreation, they have implications for public health, obviously, but also for economic development,” Hruby said. “If we put a lot of time and taxpayer dollars into our waterways and recreation, we need to make sure that water is safe, or else we're perhaps wasting our money.”

Hruby said when measuring recreational risks, it’s important to consider the risks of waterborne diseases that might make someone sick from ingesting the water or if the water comes into contact with an open wound.

Using E. coli as an example, Hruby said the bacteria standard for beaches is 235 E.coli organisms per milliliter.

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Hruby said that the E. coli levels she’s seeing in Iowa are higher in streams compared to Iowa’s beaches, with some waterways exceeding health standards as much as 60 to 80 percent of the time.

“There are studies of genetic testing on some of these waters that help us to identify the source of the fecal material and what we're finding in the urban area is that we have some work to do on our human waste infrastructure,” Hruby said. “We're seeing quite a bit of human DNA in our waters in Polk County. We get a different mixture upstream. But if anybody thinks there's only one source of bacteria in our waters, that's not correct.”

Hruby said rainfall also can affect bacterium in water, as she and her team are seeing higher levels of bacteria in Iowa waterways after rainstorms.

“Maybe that means you wait a day or two after a big rainstorm before you get in the stream or beach,” Hruby said. “But that's not necessarily the only time that there's high risk. Some of our streams at very low flows show high risk. That means that, again, there's probably an undiluted, direct discharge of some sort, a waste that's going into our streams.”

Decreased nitrate research funding

Anderson said nitrate has long been recognized as one of Iowa’s major pollutants, and that about 10 years ago the state government funded one of the “most extensive, world renowned nitrate monitoring networks that's ever been in existence.”

The networks include about 80 sensors throughout Iowa.

He said the sensors are installed by the side of rivers throughout the state and can quickly measure the nitrate concentration in a body of water.

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Through this program, he said researchers have been able to learn more about nitrate in Iowa by identifying areas that are particularly at risk, identifying which management practices and strategies are most efficient and learning how nitrate behaves as it circulates throughout Iowa watersheds.

But Anderson said, the network’s funding is set to be cut.

“The funding for this program has been ended by the by the Iowa government starting in the next year,” Anderson said. “We're set to contract this network from about 80 sensors that we've had down to about 20. With this, there is a lot less that we can say about nitrate in the state.”

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.

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Comments: olivia.cohen@thegazette.com