Chicago Diversion

The Chicago Diversion is the historical descendant of the Illinois & Michigan Canal, which was constructed in the mid-1800s to allow river transportation between the Great Lakes and the Mississippi River. As Chicago grew, the primary purpose of diverting water shifted from navigation to managing sewage and providing a source of potable water for a population suffering from repeated outbreaks of water-borne disease. In 1885, 90,000 people, roughly 12 percent of the population, died when a heavy rainstorm overwhelmed the sewage system and polluted drinking water sources.

The possible impacts of the diversion on the Great Lakes riparian community and downstream interests in both the United States and Canada have been matters of discussion and litigation since the turn of the century16. Canada has objected, through diplomatic notes and other communications, to each of the proposals to increase the Chicago diversion. The Commission notes that the U.S. government has been at pains to ensure that decision-makers in the United States are aware of the Canadian government’s views and that indeed they have been taken into account. In 1967, the U.S. Supreme Court limited the diversion to 3,200 cfs (91 cms) and subsequently permitted Illinois to average the diversion over a 40-year period. Until recently, the amount of water for the Chicago Diversion has been measured at the end of the Diversion works at Lockport, Illinois, where water is deposited into the Des Plaines River, which empties into the Illinois River. In 1996, the state of Illinois, the other Great Lakes states, and the Department of Justice on behalf of the U.S. federal government entered into a Memorandum of Understanding that, among other things, allows for a change in the Diversion-accounting system. Under the new procedures, water managers will measure the water entering the Diversion at the lakefront Diversion structures. This new arrangement required the parties to agree on an estimate for the amount of stormwater runoff (i.e., rainfall that falls in the Lake Michigan Basin, is captured by the drainage sewers in the Chicago urban area, and never enters Lake Michigan). The parties have agreed that this figure will be 800 cfs (23 cms). The new arrangement also required the parties to agree on an estimate of water consumed in the Chicago urban area and never transferred to the Illinois River. The parties have established this amount as 168 cfs (4.9 cms). Taking these two figures into account, both of which are figures established by negotiation and not from actual measurements, the amount of measured water that the state of Illinois can take directly from Lake Michigan is 2,568 cfs (73 cms)—3,200 cfs (91 cms) minus 800 cfs (23 cms) plus 168 cfs (4.9 cms).

Long Lac and Ogoki Diversions

The United States agreed to the Long Lac and Ogoki diversions to enable Canada to increase its production of electricity during World War II. Canada has sole use of the water to generate electricity immediately downstream from the diversions, at Niagara, and in the St. Lawrence River in Quebec. It shares the water with the United States at Sault Ste. Marie and in the international section of the St. Lawrence. The two diversions operate under an exchange of diplomatic notes between the United States and Canada dating back to 1940 and under Article III of the Niagara Treaty of 1950 (Appendix 7). The additional water in times of high supply has contributed to problems for riparians living on Lake Superior and other Lakes. In 1952, 1973, and 1985, Canada agreed to U.S. requests to reduce the flow from these diversions to help alleviate problems caused by high lake levels. In future, Canada might also wish to reduce or terminate these diversions for its own reasons. Thus, there can be no assurance that the contribution of Long Lac and Ogoki diversions to the water supplies of the Great Lakes will be continued indefinitely. Reducing or terminating these diversions would adversely affect hydroelectric power and also affect other interests. When high water levels are also occurring in the Albany River watershed, the natural outlet for Long Lac and Ogoki, reducing the diversions may cause flooding in the Albany basin.