Sioux City officials say our wastewater treatment plant recently experienced an upset condition related to an excessive loading of wastewater solids.
Staff are investigating the cause.
The plant is designed to separate solids from liquids, however the elevated level of solids placed abnormal stress on some critical equipment and processes which has caused the performance of the wastewater treatment plant to temporarily decline.
City officials believe the discharge permit limits were exceeded for a two to three-day period.
Notification was made to Iowa Department of Natural Resources by phone and as is routine, a written report will be provided to the IDNR.
New sample results appear to indicate that the plant is back into compliance with permitted limits.