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Study: Nitrate Contamination In Water More Likely To Affect Lower Income Communities In Iowa

A water tower in Marion, Ohio. The city has been gripped by heroin addition.
Maddie McGarvey for NPR
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A water tower in Marion, Ohio. A recent analysis by the Environmental Working Group found that Iowa communities dealing with nitrate contamination in their drinking water are more likely to be lower income.

Iowa communities whose drinking water is contaminated with nitrate are more likely to be lower income, according to a new analysis conducted by the Environmental Working Group. Communities across Iowa have long struggled with nitrate pollution from farm practices such as the extensive drainage of agricultural lands and the over-application of fertilizer and manure on farm fields. The new analysis by the EWG suggests the communities with less resources to deal with the pollution are more likely to be impacted by it.

Bonnie Koel has been grappling with elevated nitrate levels for years as the manager of the Lyon & Sioux Rural Water System in northwest Iowa. She’s watched as the utility’s levels have crept up towards 10 milligrams per liter, the current maximum contaminant level for drinking water set by the U.S. Environmental Protection Agency.

Koel says installing an expensive nitrate removal system, which can run in the millions of dollars, is not financially feasible for the system that serves some 1,900 homes and businesses.

“It's extremely expensive,” Koel told IPR earlier this month. “You could expect that if we ended up having to treat all the water, the rates are going to more than double because it's a very expensive, slow process. So we're basically doing everything we can to avoid that.”

According to the recent analysis by the EWG, the Lyon & Sioux Rural Water System is one of 236 Iowa water supplies identified as having detected elevated levels of nitrate, defined as 3 mg/L or more, between 2003 and 2017.

While 3 mg/L is below the EPA’s current drinking water standard for nitrate, that is the level that state and federal regulators say generally indicates contamination related to human activities.

The 236 systems identified as having elevated nitrate levels serve some 1.3 million Iowans, more than 40 percent of the state.

The EWG analysis found that those communities dealing with nitrate contamination are more likely to have median household incomes lower than the state median, generally leaving them with fewer resources to address the pollution, both at a household and community level.

“In Iowa, 68 percent of communities with elevated nitrate had incomes below the state’s median. But that jumped to 85 percent for communities with levels at or above the federal Safe Drinking Water Act’s legal limit of 10 mg/L,” the report reads in part.

Report author Anne Schechinger reasoned that the impacts on lower income communities are partially a function of the state’s demographics and the nature of nitrate pollution. Iowa’s nitrate loads overwhelmingly stem from agricultural practices in the state’s most rural areas, which tend to have lower incomes.

“Because of the nature of the problem, where it’s a rural contaminant in a lot of places, that’s kind of partially why we think it affects so many lower income communities, because these rural communities are often lower income,” Schechinger said.

Of course Iowa’s largest cities have also grappled with persistent nitrate pollution, namely the state capital of Des Moines. In 1991, the city's water works installed what was then the largest nitrate removal system of its kind in the world. In 2015, the utility sued upstream drainage districts over the pollution, but a federal judge ultimately dismissed the case.

The EWG report also highlighted the city of Waterloo, where in 2015, nitrate levels in one of the city’s wells “were so high that the city had to stop using it altogether."

Still, Schechinger argues that smaller, more rural system feel the impacts of nitrate contamination more acutely because they have fewer customers to share the costs of addressing the problem.

“That’s really why we care about this situation, because drinking water treatment to remove nitrate from water is really, really expensive. So paying for extra water treatment to remove nitrate is an added cost burden on these lower income communities. And that’s especially a problem for smaller communities,” Schechinger said. “Small, lower income communities are the most likely to struggle to afford nitrate treatment in Iowa.”

Public health research suggests that Iowans are paying for rising nitrate levels in another way too: with their health. Research indicates that elevated risks of colorectal cancer, thyroid issues and neural tube birth defects are associated with nitrate exposure in drinking water, even at levels below the EPA’s current standard of 10 mg/L.

An Iowa study published two decades ago found that nitrate in the state’s drinking water was associated with an increased risk of bladder cancer among women.

“In the U.S. we think we have safe drinking water and that it’s regulated by the federal government so it should be totally OK to drink and not have any health impacts that come from what we’re consuming,” Schechinger said. “But it’s just devastating that people have to experience things like cancer just from drinking water every day.”

For years, scientists and environmental advocates have been calling on state lawmakers to enforce mandatory agricultural conservation practices to protect the state’s water. An analysis by the Iowa Environmental Council calculated that the state’s current voluntary approach could take centuries to achieve the goals set out in the Iowa Nutrient Reduction Strategy.

The Iowa Supreme Court recently tossed out another water quality case, arguing the issue should be left to the state legislature.

In the meantime, communities across the state are watching their nitrate levels steadily increase over time, with few long-term options for stemming the flow of the pollutants that flow off fields upstream.

In some areas, drought conditions are adding further pressure to systems that typically blend different water sources to balance out nitrate levels. Now, some of their safer wells are running low, too.

“At times we can use that to blend with the water that is very low in nitrates. We can use a blending system. But when they're all getting very low, then you get to the point where there are some that are not usable,” Koel said. “It's scary. It really is.”