11 December 2024

While writing about Lake Erie last month I found this amazing fact.

The Great Lakes hold nearly 20% of the world’s fresh surface water. And, more astonishingly, the lakes hold more than 90% of North America’s fresh surface water.

But this water supply is not unlimited. The Great Lakes are a one-time gift from the glaciers that melted in our region thousands of years ago. Less than 1 percent of the lakes’ water is renewed annually through rainfall and snowmelt. That means the Great Lakes can be depleted if we don’t keep Great Lakes water in the Great Lakes Basin.

— Alliance For The Great Lakes: The Great Lakes Compact

The Great Lakes watershed map shows how little of the surrounding land drains into lakes. This is especially true of northern Pennsylvania and Chautauqua County, NY.

As climate change puts enormous strains on fresh water resources, multinational companies look longingly at bottling our rivers and lakes. Fortunately the Great Lakes basin had an early wake up call.

In 1998, an obscure Canadian consulting company, the Nova Group, announced its intention to ship 158 million gallons of Lake Superior water to Asia. Though that specific plan seemed unlikely to materialize, it raised alarms about the vulnerability of the Great Lakes in an increasingly hot and thirsty world.

— Alliance For The Great Lakes: The Great Lakes Compact

And so the Great Lakes Compact was born. Signed into law in 2008, it prohibits diversion of water outside the Great Lakes basin with very limited exceptions.

This one-time gift of the Ice Age glaciers won’t be frittered away.

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p.s. Prior to 1945 humans diverted Great Lakes water in four locations but these have barely made a dent in the total watershed.

• Ogoki pulls water from Hudson Bay watershed into Lake Superior. 1943.
• Long Lac pulls water from Hudson Bay watershed into Lake Superior. 1939.
• The Chicago River is diverted away from Lake Michigan and into the Mississippi watershed. Beginning in the 1800s.
• Welland Canal is a navigation channel from Lake Erie to Lake Ontario that bypasses Niagara Falls. Beginning in 1824.

The combined effects of the Long Lac, Ogoki and Chicago diversions and the Welland Canal have been to permanently raise Lake Superior by an average of 2.1 centimeters (0.8 inches), lower Lakes Michigan-Huron by 0.6 cm (0.2 in), lower Lake Erie by 10 cm (4 in) and raise Lake Ontario by 2.4 cm (1 in), according to the IJC’s 1985 Great Lakes Diversions and Consumptive Uses report. 

— international Joint Commission: An Overview of Great Lakes Diversions