An estimated 378,000 gallons of untreated sewage spilled into the Des Moines River in Des Moines on Monday. Tom Atkinson, with the Iowa Department of Natural Resources, says a computer malfunction is to blame.

That computer failure shut down a pumping station and also took the station’s alarm system offline. The wastewater discharged from around 12:30 a.m. until the problem was discovered and fixed at 11:30 a.m. The city is collecting water samples upstream and downstream of the discharge, but Atkinson says it should not impact drinking water.

“There’s no downstream intake until Ottumwa and that’s a pretty decent distance. They weren’t intending to change any of their operations as far as drinking water in Ottumwa,” Atkinson said. “It’s also downstream of any drinking water intakes for the city of Des Moines.” It does not appear the discharge killed any fish or aquatic life in the river.

Atkinson said Des Moines Water Works personnel are trying to determine what caused the computer glitch.