ANN ARBOR Early Tuesday morning at approximately 5:30 a.m., staff at the City of Ann Arbor Wastewater Treatment Plant discovered an overflow of partially treated wastewater. According to city officials, the water was treated with settling and chlorine disinfection before it flowed directly into the Huron River. Over five-hours, an estimated 600 to 1,500 gallons of partially treated wastewater discharged into the Huron River. During this time, the flow into the Huron River was an estimated 437,580,000 gallons. According to protocol, city of Ann Arbor staff notified the Michigan Department of Environment, Great Lakes and Energy and the Washtenaw County Health Department of the incident.