The "sweetwater seas," as some call the Great Lakes, hold 20 percent of the world's fresh water. Yet even that vast resource is at risk of being depleted, environmentalists warn.
Fast-rising water use and global warming together could cause the water level in the Great Lakes to drop up to three feet and outflow to the St. Lawrence River to fall by a quarter over the next 40 years, a new report says.
"We know there are going to be water shortages in the United States after the turn of the century," says Sarah Miller, co-author of the report by Great Lakes United, a Toronto-based environmental umbrella group. "If we don't do something now, we're putting the lakes at risk."
Titled "The Fate of the Great Lakes," the report pulls together numerous scientific studies on lake water levels and climate change. While there have been many studies on Great Lakes pollution, the new report is unusual in focusing on the quantity of water being diverted for municipal development, agriculture, and other uses. Its key recommendation is to chop per capita water use in the region by 50 percent by 2005.
The Great Lakes Basin is home to 33 million people, about 10 percent of the US population and about one-quarter of Canada's. With such abundance so near by, American and Canadian households use twice as much water as European households but pay only half as much for it.
In 1991, for instance, Americans used 3,961 gallons per person and Canadians 3,306 gallons each. By comparison, Japanese used 1,759 gallons per person in 1991 and Swedes used 1,097 gallons.
Still, the area "consumed" only about 3 billion gallons per day in 1992 - just a fraction of the lakes' daily outflow to the St. Lawrence River, the report says.
But it warns this fraction is growing fast as development in the eight US states and two Canadian provinces that surround the lakes increasingly diverts Great Lakes water for various uses.
Late last year, for instance, the Mud Creek Irrigation Board in Michigan approved piping 8.6 million gallons per day for 60 to 70 days a year from Saginaw Bay in Lake Huron to irrigate local farms. Though small by itself, 10 similar projects are being weighed in the same part of Michigan.
Cities want more water so they can grow, too. Akron, Ohio, is proposing to divert up to 5 million gallons per day of Great Lakes water. And there are plans to divert 50 to 60 million gallons per day from Georgian Bay on Lake Huron to provide water to York, Peel, and other fast-growing regions of Ontario.
Such requests for Great Lakes water really begin to pile up, though, when drought strikes. In brief previous dry spells, New York City; Lowell, Ind.; and Kenosha, Wis., have all sought Great Lakes water - unsuccessfully.
But what of long-term dry spells, if global warming prognosticators are correct? Government and private climate-change studies cited by the report show demand for Great Lakes water rising as hotter weather causes higher evaporation. Meanwhile, rain and runoff decrease.
"There is a considerable amount of uncertainty over the degree of [the climactic] impact on the lakes - depending on the model," warns Murray Clamen, an engineering adviser at the International Joint Commission (IJC) in Ottawa, an organization monitoring the lakes for the US and Canada.
Still, he says the IJC is concerned about Great Lakes water use. In a 1995 report, it recommended that a permanent panel be set up to monitor diversions and consumption of lake water.
Most climate-change models currently predict warming that would dry out the agricultural midsections of continents. Others agree that severe depletion of ground water already happening in the plains states, California, the US Southwest, and Mexico could lead to demand for fresh water derived from the Great Lakes, if it is economical.
"If the Corn Belt's soil moisture should dry out, I would presume we would need to irrigate," says Sandra Postel, director of the Global Water Policy Project of the Washington-based Worldwatch Institute. "But where would that water come from - the Great Lakes?"
During the drought of 1988, the Illinois and Mississippi Rivers fell to record lows, causing navigational challenges and irrigation problems for farmers. At that time, the US Army Corps of Engineers recommended tripling the flow of water out of Lake Michigan through the "Chicago diversion" to the Mississippi. That plan was never followed.
Among many steps needed to avoid drastic large-scale diversions from the Great Lakes, the report says state and provincial governments need to set a goal of cutting per capita water use in the region by 50 percent by 2005.
But since 1985, when the Great Lakes Charter was signed by the eight lake states and two provinces, pollution, not "quantity issues," has been the focus.
Now, however, even modest climate-change models predict significant declines in Great Lakes levels, says Michael Donohue, executive director of the Great Lakes Commission, an agency representing Great Lakes states.
"We're glad environmental groups are looking more at quantity issues," he says. "The sky isn't going to fall tomorrow. But even if it's not going to happen for 50 years, the region does need to get its house in order with respect to water use."