"Hog buildings aren't bad," Manning said. "We're meeting a need. Everyone loves bacon, and there's only one way to get it."
Des Moines Water Works CEO Bill Stowe blames livestock producers and farmers for problems with ammonia and nitrates in the Raccoon and Des Moines rivers, which are the source of drinking water for 500,000 people.
Treating water for nitrates cost consumers almost $1 million last year, the newspaper reported.
"We are a mecca of intensive livestock and row-crop farming, and there are consequences," Stowe said. "Throughout the state, there are a number of impaired surface waters — rivers and streams — that aren't suitable for human contact. They're not fishable. They're not swimmable."
But experts say it's hard to determine the exact source of nitrates and ammonia in water.
"We see failures of urban waste treatment plants, too, or rain events that overwhelm storm sewers," said Paul Lasley, chairman of Iowa State University's sociology department, who studies rural issues.
Nitrates can come from golf courses, city lawns and salt used on slippery roads and parking lots.
"Whether we're spraying for weeds in our fields or our gardens, we all share in and contribute to the problems," he said.
Iowa farm leaders say they are working to reduce the amount of nitrates and phosphorus that ends up in the state's waterways.
Information from: The Des Moines Register, http://www.desmoinesregister.com