Living near the Great Lakes these days has become a bit like having a giant glass of water that everyone wants to share, but with not assurance of a refill.
For years cities, manufacturers, and utilities bordering the Great Lakes have been freely tapping them for water. Compared with the amount of moisture flowing into the lakes, the water taken out over the years has been considered relatively small. Even so, most users have taken some conservation steps.
But any suggestion that this rich national resource was being, or could ever be, depleted was dismissed as ridiculous. After all, these five huge bodies of water amounted to a full 95 percent of the entire freshwater supply available in the 48 contiguous states.
Lately, however, the basis for such confidence has been seriously questioned. The reason is twofold:
* Western and Great Plains states have been eyeing the Great Lakes as a possible source of water for irrigation, drinking, and such energy projects as coal slurry pipelines and oil shale processing.
* A new report suggests that, such transfer possibilities aside, "consumptive" use of the Great Lakes by municipalities, power plants, and industries in the immediate region may well increase fivefold over the next 55 years. If that assumption holds, water levels in the three middle lakes -- Michigan, Huron, and Erie -- would be six inches lower by the year 2035, according to the US-Canadian report which will be presented later this month to the International Joint Commission (IJC).
The water flow through the system would be reduced by about 8 percent. Frank Kudrna, head of the Water Resources Division of the Illinois Department of Transportation, who worked on the report, says that the scale of the growth in use the researchers discovered was unexpected and "dramatic."
Lee Botts, chairman of the Great Lakes Basin Commission, calls the study a "warning flag. It's generally been assumed," she says, "that there was just so much water in the system that any significant consumptive use was impossible. This study has raised that possibility, and it's going to receive a lot more attention."
Of particular concern to most who watch over the Great Lakes professionally will be the effect the reduced lake levels could have on ports and harbors, navigation, power generation, wetlands, and fisheries.
Many Great Lakes researchers, however, question the IJC study's assumption that there will be a marked increase in the use of lake water for generating electricity. The pull will come, according to the study, from new power plants and from the expected increase in closed-cycle cooling systems for nuclear power plants that lose much water through evaporation. Clean water legislation now bars the return of heated water to the lakes, but alarm over increased consumption of Great Lakes water may increase the pressure for revising the law.
Some Great Lakes researchers say they fully expect that the West will fight hard to get Great Lakes water in years to come, and may well try to justify it on grounds of population shifts and the national interest. But major physical, financial, and political problems accompanying the transfer could delay or prevent such a move.
Charles Johnson, a hydraulic engineer with the US Army Corps of Engineers, says that to get water to either Wyoming or Montana for use in coal pipelines or to the Plains states for drinking water would require pumping it to heights of some 4,000-to-6,000 feet.
"The energy requirements of doing that are a huge roadblock," he says. "There are definite trade-offs involved."
Recalling the days when some predicted that Lake Erie was too big ever to become contaminated, Donald Mount of the Environmental Protection Agency's Environmental Research Laboratory in Duluth, Minn., predicts a "battle of exploitation vs. preservation" ahead for the Great Lakes.
In his view, it is critical to make long-term policy decisions -- such as making one or more lakes an international or national park or reaching an international agreement not to divert water out of the Great Lakes -- early on.