January 7, 2014, Blocking Asian carp from invading the Great Lakes could require an engineering marvel that rivals the reversal of the Chicago River more than a century ago, according to a new federal study that promises to reignite a fierce debate about the region's waterways.
Among the options outlined Monday by the Army Corps of Engineers to thwart the voracious fish and other invasive species from spreading is permanently separating Lake Michigan from the river and its connected waterways. Such a project would restore the once natural divide between the Great Lakes and rivers southwest of Chicago that drain into the Mississippi River.
Chicago blasted through that hydrological barrier when it dug the Sanitary and Ship Canal and Cal-Sag Channel at the turn of the last century to divert the region's sewage away from its source of drinking water. It also created a shipping link between two of the nation's major trade routes.
Separating the lake and the river again could cost more than $18 billion and take up to 25 years, the Corps' study concluded, making that option the most expensive of the eight studied. Another option, carrying a $15 billion price tag, would allow portions of the Chicago River, Sanitary and Ship Canal and Calumet River to flow into Lake Michigan.