When the Des Moines Water Works went to court two years ago to force Iowa farmers to pay to clean the city's drinking water, it sent shock waves through Midwest agriculture.
The utility sued rural drainage districts that channel farm runoff into the heavily polluted Raccoon River, one of Des Moines' main drinking water sources.
The water works board argued the drainage pipes that dump farm runoff into ditches are point-sources of pollution, making that polluted runoff subject to regulation under the federal Clean Water Act. Farmers warned the costs of complying with the Clean Water Act could ruin them.
A federal judge recently dismissed the case, handing farmers across the country a huge victory. Agricultural interests in Minnesota say the decision strengthens their argument that a voluntary approach to runoff cleanup is best.
But farm pollutants are still a significant problem for the state's lakes, rivers and drinking water. And the court left a vital question unanswered: Is farm run-off point-source pollution?
"Had the Des Moines Water Works succeeded, this case would've provided a handle to regulate those agricultural pollution sources," said Mark Ten Eyck with the Minnesota Center for Environmental Advocacy. "It's a tool that we won't have going forward."
The Des Moines Water Works case was an attempt to impose federal regulations on farm pollution for the first time and it was closely watched. The utility argued that farm runoff should fall under federal codes regulating water quality and human health because that potentially toxic farm drainage flows toward their city and its citizens.
Des Moines filters it, but city leaders say it's become increasingly costly to keep farm field nitrate out of the urban water system and that their customers shouldn't have to pay to hold back that pollution.
"The surface water quality in the Midwest is horrible," said Des Moines Water Works general manager Bill Stowe. "We have very over-nutrified surface waters, too much nitrogen, too much phosphorus,"
While the ruling disappointed environmental organizations, farm groups were relieved.
With the specter of mandatory regulation gone at least for now, farm groups can push crop producers to take voluntary steps to reduce runoff, said Warren Formo, executive director of the Minnesota Agricultural Water Resource Center, which represents many of the state's farm and livestock producers.
"We believe that's really the most productive and effective way to do it," said Formo. "We have to remember the water in the soil, including the nitrates in it; is the food that feeds our crops."
Many farmers have already taken steps to reduce use of fertilizers whose chemicals wind up in surface and ground water, he added.
He says there are signs farmers' efforts are having an impact. A 2013 state report said nitrate concentrations in the heavily polluted Minnesota River appeared to be leveling off.
The Minnesota River, however, remains heavily polluted, and the state list of polluted waters grows with each inventory.
In the absence of regulatory mandates, farmers are moving too slow, said Ten Eyck.
"Other pollution dischargers who are regulated under the Clean Water Act have made an enormous amount of progress," he said. "Agriculture has not made nearly as much progress."
In the wake of the Des Moines defeat in court, there appears to be little appetite to take up the cause among the 50 or so Minnesota communities dealing with high nitrate levels.
Officials in Hastings, which has had to buy equipment to remove nitrate from water, are working with farmers, said city public works director Nick Egger.
"I would maybe characterize it more as a collaborative sort of approach," he said.
With the Des Moines case dismissed, that's about the only option available.