THE GREAT-LAKES DIVERSION AT CHICAGO AND ITS IMPLICATIONS FOR CLIMATE-CHANGE

In 1900 the city of Chicago began diverting sizable amounts of water f rom Lake Michigan to move its sewage down the Illinois River. This div ersion launched a series of continuing legal controversies involving I llinois as a defendant against claims by the federal government, vario us lake states, and Canada who wanted the diversion stopped or drastic ally reduced. During the past 96 years extended dry periods have lower ed the lake levels. Using these dry periods as surrogates for future c onditions, their effects on the past controversies were examined as an alogs for what might occur as a result of climate change from an enhan ced Greenhouse effect. The results reveal that changing socioeconomic factors including population growth will likely cause increased water use, and Chicago will seek additional water from the Great Lakes. New priorities for water use will emerge as in the past. Drier future cond itions will likely lead to enhanced diversions from the Great Lakes to serve interests in and outside the basin. Future lower lake levels (r eflecting a drier climate) will lead to conflicts related to existing and proposed diversions, and these conflicts would be exacerbated by t he consequences of global warming. In any event, a warmer, drier clima tic regime will challenge existing laws and institutions for dealing w ith Great Lakes water issues.