DES MOINES, Iowa (AP) – The Des Moines Water Works board has scheduled a vote on whether to sue three northern Iowa counties, alleging that they are responsible for the high nitrate levels in rivers the utility uses for water. The board’s meeting agenda for Tuesday afternoon indicates a closed session to discussion potential litigation. The board is expected to publicly vote to sue Calhoun, Buena Vista and Sac counties.

In January it sent a notice of intent to sue, which is part of a procedure outlined in the federal Clean Water Act. The counties oversee 10 drainage districts north of Des Moines that help move water from fields. The lawsuit will claim the drainage districts are the same as city wastewater treatment plants and should be regulated.