DES MOINES, Iowa (AP) — The Des Moines Water Works board has voted to sue three northern Iowa counties in an effort to hold them responsible for the high nitrate levels in rivers the utility uses for source water. The board voted Tuesday afternoon to sue Calhoun, Buena Vista and Sac counties in U.S. District Court in Des Moines.

The counties oversee 10 agriculture drainage districts north of Des Moines. The lawsuit will allege the drainage systems are no different than city wastewater treatment plants in that they discharge pollutants and should be subject to heightened regulatory oversight.

Nineteen citizens spoke in support at the meeting. Several farm groups say in a statement the lawsuit undermines the relationship between the water utility and farmers upstream but they’ll continue to work on water quality.