A manhole in the University of Michigan Arboretum was clogged Sunday, causing 300,000 gallons of sewage to discharge into the Dow Prairie.
On June 10, the City of Ann Arbor was notified that water was leaking from a manhole. Following further investigation, public works crews found 3,000 feet of rope and an uninflated sewer plug blocking the sewer line, causing the overflow.
It was determined the rope belonged to a contractor who recently conducted sewer inspections and lost the rope. The source of the plug is still unknown.
As a result, approximately 300,000 gallons of sewage flowed into the Dow Prairie and "an unknown portion ultimately then flowing to the Huron River."
Impacted areas of the water have been marked off and closed until clean up is complete.
River trips were immediately suspended for Sunday and Monday, officials say.
