Equipment shut down after a power outage at the Burlington wastewater treatment plant Tuesday morning.
The outage occurred just after 9:30 Tuesday morning, and an estimated 105,000 gallons of untreated wastewater flooded the building and discharged into the Mississippi River.
It took staff 15 minutes to restart the equipment.
Plant workers are working to clean the building and the area where the untreated wastewater flowed into the river. The DRN will monitor the cleanup.