Crews from the Three Rivers Department of Public Services reported a sanitary sewer overflow from a manhole Wednesday afternoon in the 100 block of West River Drive.
DPS officials said the overflow was the result of blockage caused by a rag. Crews cleared the obstruction and cleaned the area.
As a result of the backup, approximately 400 gallons of sanitary sewage entered the St. Joseph River. Clean Water Plant crews have collected water samples from the river at the 6th Street and South Main Street for analysis.
The incident has been reported to the Michigan Department of Environmental Quality and the county health department.