According to Des Moines Water Works officials, the trouble with the Raccoon and Des Moines River is land and what's being spread across and pumped into it, in order to grow crops.
"We've seen nitrate levels come from a number of sources but the primary contributor is chemical fertilizers from agricultural uses,” said Bill Stowe, CEO of Des Moines Water Works.
Stowe says result is river water that's not even close to being safe enough to drink.
He says nitrate levels are nearly double what safety standards allow.
For the last two months, the city has been pulling water from Maffitt Reservoir. Its nitrate levels are lower, but the water still has to be treated which is getting expensive.
“We've spent a half million dollars operating the plant over the last couple of months and certainly we're not done yet,” Stowe told Channel 13 News.
Stowe says that cost will get passed along to customers in the form of higher water bills in 2014.
Others are demanding change.
On the steps of the capitol, a local group called Environment Iowa met with State Senator Dick Dearden.
They want him to work with legislators to better regulate agricultural run-off.
"We're hoping for simple solutions like banning winter time manure spreading and building tall grass in front of the rivers,” said Josh Kublie, with Environment Iowa.
New regulations are at least a year away, but Stowe says there are some things everyone can do to help right now.
"Be wise water consumers and don't irrigate in the heat of the day because want to keep our demands down,” said Stowe.
As for how much water bills may go up in 2014, Stowe said he would have a better estimate by the end of the summer.