TRAVERSE CITY, Mich. — A "drain hole" in the St. Clair River caused by dredging and other commercial projects is costing Lakes Huron and Michigan a combined 2.5 billion gallons of water each day, according to a Canadian study released Tuesday.
That exceeds the amount diverted from Lake Michigan to provide Chicago's daily water supply, the Georgian Bay Association said.
The group based its findings on water level data compiled by U.S. government agencies.
The association first reported on water losses from Lake St. Clair dredging in 2005. But the latest report says the volume flowing south from Lakes Michigan and Huron — which are hydrologically connected — is three times greater than originally believed.
"This new report reveals that the problem is far more serious than first thought and underscores the need to fix the problem immediately," Mary Muter, chairwoman of the association's Environment Committee, said in a statement.
The drainage hole has caused an overall water level decline of nearly 2 feet since 1970, the study said. The outflow goes into Lake Erie, then east to Lake Ontario and eventually through the St. Lawrence River to the Atlantic Ocean.