AP Environmental Writer

TRAVERSE CITY, Mich. (AP) - A federal report says the Great Lakes region could experience water shortages in some locations because of climate shifts or surging demand, despite being the world's largest freshwater system.

The Associated Press obtained the report by the U.S. Geological Survey, which is scheduled for release Monday. It says the Great Lakes have so much surface and ground water that heavy use and development have not greatly affected the overall supply.

Yet it says shortfalls have popped up in some areas and others could happen. Groundwater levels have plummeted about 1,000 feet in the Chicago-Milwaukee area because of pumping for municipal supplies, and the report says they could drop an additional 100 feet over the next three decades.

The report is designed to help local agencies develop long-term water use plans.

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