PANORA, Iowa (AP) – Officials say they’re investigating the cause of a wastewater discharge that entered Lake Panorama in central Iowa.

The Iowa Department of Natural Resources says it’s unclear what caused a pump to fail Saturday night at a lift station managed by the South Panorama Sanitary District. Officials reported the problem Sunday morning, around the time officials believe the discharge ended.

DNR officials say it wasn’t clear to the agency that there was a wastewater discharge until Monday night. The sanitary district believes it was likely a small discharge.

It’s unclear what caused a pump to fail, since all pumps at the lift station appear to be functional.

Officials for the sanitary district are considering the construction of a new lift station, where discharges would be less likely to reach the lake.