Great Lakes Water Abundant But Could Run Low, Report Says

Feb 7th, 2011 | By | Category: Green Living

The Great Lakes region still has more fresh water than anywhere else, but some locations could experience shortages due to climate shifts or demand surges, according to a five-year study scheduled to be released by the U.S. Geological Survey Monday, obtained early by the Associated Press.

The Great Lakes themselves contain 6 quadrillion (6,000 trillion) gallons of water, which is enough to spread a layer of water a foot deep across North and South America as well as Africa. Additionally, groundwater volume surpasses that of Lake Huron.

Huge amounts of this water are drained regularly for drinking, agriculture, industry, and other uses, and only 1 percent is replenished annually by runoff and precipitation. But the overall supply is so large that this has had little impact on the Great Lakes system, the report said.

G131 Great Lakes from space Great Lakes Water Abundant But Could Run Low, Report Says

Great Lakes from Space. Provided by the SeaWiFS Project, NASA/Goddard Space Flight Center, and ORBIMAGE

With a few major exceptions, urban and suburban development also has not had a major effect on supplies, although surface water diversions and groundwater pumping have impacted some flow patterns over large areas. The 2.1 billion gallons that Chicago drains from Lake Michigan daily has lowered it and Lake Huron by about 2.5 inches.

Weather and climate have had more significant impact on groundwater and lake levels and stream flow rates. Declining lake levels over most of the past decade resulted mainly from drought and warming temperatures that limited ice cover and increased evaporation.

As a result, despite overall abundance, some areas in the Great Lakes basin could face shortages, even though others have plenty available, according to the report’s lead author Howard W. Reeves.

For instance, groundwater levels have dropped about 1,000 feet in the Chicago-Milwaukee metropolitan area because of pumping for municipal supplies. Groundwater levels could drop an additional 100 feet over the next three decades if withdrawal rates rise as expected, according to the report. The Milwaukee suburb of Waukesha, suffering from deep wells contaminated with radium, is seeking approval to tap Lake Michigan under a compact signed by the region’s eight states in 2005.

Reeves recommended trying to understand potential problems in other areas, rather than assuming water will always be available everywhere.

The report implements a 2002 Congressional order for the U.S. Geological Survey to make a nationwide assessment of fresh water supplies and address concerns about shortages in the coming century. The Great Lakes report is the first step in the assessment. Future reports will analyze the Colorado, Delaware, and Apalachicola-Chattahoochee-Flint River basins.

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