DES MOINES, Iowa (AP) – An official says Des Moines Water Works likely will sue three counties that manage drainage districts with high concentrations of nitrates. Water Works officials say the nitrates flow into the Raccoon River and threaten the city’s water quality. Water with concentrations above a certain threshold can be deadly to children younger than 6 months because nitrates can reduce the amount of oxygen carried in their blood.

Water Works board chairman Graham Gillette told The Des Moines Register that the board will vote Thursday to move forward with the lawsuit.  The trustees’ vote would trigger a notice to the boards of supervisors in Buena Vista, Calhoun and Sac counties, notifying them of Water Works’ intention to sue.

Experts say most of the nitrates come from fertilizer applied to farm fields.