Des Moines Water Works, an entity in charge of providing the Iowa city with safe water, this week said it plans to take three of the city's neighboring counties to court for contributing to high nitrate levels in the Raccoon and Des Moines rivers.
The nitrate levels, Des Moines Water Works CEO Bill Stowe told Iowa Public Radio, are caused by nitrogen spread on farm fields that later turns to nitrate and ends up in streams.
Because some of the county governments manage the pipelines that carry nitrates to larger bodies of water, Des Moines Water Works argues that they can be responsible for the nitrate levels. Counties in question include Sac, Buena Vista and Calhoun, the Water Works said.
According to the Des Moines Register, more than 2 million acres, mostly farmland, drain into the Raccoon River, which, in part, supplies the Des Moines area with drinking water. Man-made tiles are installed on about 78% of that land, the Register noted.
Recent water monitoring by Des Moines Water Works at 72 sample sites in the three counties have shown nitrate levels as high as 39.2 mg/L in groundwater discharged by drainages districts, four times the federally required Safe Drinking Water regulatory limit of 10 mg/L, the Water Works said.
In 2013, when nitrate levels in the Raccoon and Des Moines Rivers were at a record high, Des Moines Water Works said it incurred approximately $900,000 in treatment costs and lost revenues.
According to the Wall Street Journal, Water Works estimates the extra steps required to purify the drinking water in Des Moines cost up to $7,000 per day. Plant upgrades will be required if the high nitrate levels continue, Stowe said.
Stowe said the Water Works District and upstream counties will have to determine a way forward to avoid a court battle.
"We need to get down to specific steps that they need to take. If they aren't willing, we'll see them in federal court," Stowe told IPR.
Stowe plans to argue that drainage systems in farm fields have actually concentrated nitrates in runoff, WSJ reported. Water Works has been collecting samples to prepare for the lawsuit, it said.
In nearby Madison County, farmer Dan Hanrahan told IPR his fellow growers are signing up for federal assistance in implementing voluntary pollution-control practices on their farms.
"We've got over a two-year waiting list of people waiting to put practices in place," he told IPR.
The Iowa Department of Natural Resources supports efforts to improve the state's waterways, its spokesman Kevin Baskins told the Des Moines Register last year, but it will take time for voluntary efforts to work.
"This isn't something where you just get instant results," Baskins told the Register. "We didn't get into the kind of situation we have today in terms of excess nutrients overnight and we won't get out of it overnight."