Great Lakes are estimated at 900 trillion. The influx of parasitic lamprey populations after the development of the Erie Canal and the much later Welland Canal led to the two federal governments of the US and Canada working on joint proposals to control it. By the mid-1950s, the lake trout populations of Lakes Michigan and Huron were reduced, with the lamprey deemed largely to blame. This led to the launch of the bi-national Great Lakes Fishery Commission. "The Great Lakes: An Environmental Atlas and Resource Book" (1972) noted: "Only pockets remain of the once large commercial fishery." But, water quality improvements realized
Great Lakes Dredge and Dock Company system had begun. The work performed on the Kinzie Street Bridge conformed to specifications and did pass City inspection upon completion in 1991. In the lawsuits that followed Great Lakes was initially found liable but was later cleared after it was revealed that the city was aware the tunnel was leaking before the flood and the city had also not properly maintained the tunnel. In addition the case went the United States Supreme Court in which ruled that since the work was being done by a vessel in navigable waters of the Chicago River, Admiralty law applied and Great Lakes