The Death and Life of the Great Lakes

by Dan Egan

There are few views that can draw noses to airplane windows like those of the Great Lakes. From on high, the five lakes that straddle the U.S. and Canadian border can appear impossibly blue, tantalizing as the Caribbean. Standing on their shores and staring out at their ocean-like horizons, it hits you that the Great Lakes are, in one significant way, superior to even the Seven Seas. The Great Lakes, after all, are so named not just for their size but for the fact that their shorelines cradle a global trove of the most coveted liquid of all—freshwater.

The biggest lake in France, after all, is 11 miles long and about 2 miles wide; the sailing distance between Duluth, Minnesota, on the Great Lakes’ western end and Kingston, Ontario, on their eastern end is more than 1,100 miles.

Roughly 97 percent of the globe’s water is saltwater. Of the 3 percent or so that is freshwater, most is locked up in the polar ice caps or trapped so far underground it is inaccessible. And of the sliver left over that exists as surface freshwater readily available for human use, about 20 percent of that—one out of every five gallons available on the planet—can be found in the Great Lakes.

It would be hard to design a better invasive species delivery system than the Great Lakes overseas freighter. The vessels pick up ballast water at a foreign port to balance less-than-full cargo loads. When the ships arrive in the Great Lakes, cargo is taken onboard and the ballast water—up to 10 Olympic swimming pools’ worth per ship—and all the life lurking in it gets set loose in the lakes. As one exasperated Great Lakes biologist once told me: “These ships are like syringes.”

The Great Lakes are now home to 186 nonnative species. None has been more devastating than the Junior Mint–sized zebra and quagga mussels, two closely related mollusks native to the Black and Caspian Seas.

Niagara Falls are what made the Great Lakes unique in the natural world. The falls are the most famous 1,100 yards of a 650-mile-long ridge of sedimentary rock arcing from western New York, into the province of Ontario, and down into Wisconsin. This escarpment is the rim of a 400-million-year-old seabed that cradled a shallow, tropical ocean that once sloshed across what is today the middle of North America. At about 170 feet high, the falls that tumble over the Niagara escarpment near present-day Buffalo, New York, are nowhere near the world’s tallest or even largest by volume. But they were among the most ecologically important because they created an impassable barrier for fish and other aquatic life trying to migrate upstream from Lake Ontario into the other four Great Lakes.

THEY MIGHT BE CALLED THE GREAT LAKES, BUT THE FIVE INLAND seas are essentially one giant, slow-motion river flowing west-to-east, with each lake dumping like a bucket into the next until all the water is gathered in the St. Lawrence River and tumbles seaward.

Lake Superior sits at the system’s headwaters. It is about 350 miles long and 160 miles wide, and it holds enough water to submerge a landmass about the size of North and South America under a foot of water. The lake basin might have been carved by the glaciers, but the 1,300-foot-deep sea is not simply an oversized puddle of ancient ice melt. Lake Superior is a dynamic system, ever filling up with precipitation and stream inflows, and ever flowing out toward the Atlantic. Lake Superior inflows are balanced by its outflows down the St. Marys River. Along its 60-mile course the river drops about 22 feet in elevation until it spills into Lake Huron, which is, really, the same body of water as Lake Michigan. They are two lobes of the same big lake connected at the five-mile-wide Straits of Mackinac. Both Michigan and Huron flow into the St. Clair River, which flows toward Lake Erie, whose elevation is only about 9 feet lower than that of Michigan and Huron. All of Erie’s waters move eastward toward its outlet—the Niagara River that plunges 325 feet into Lake Ontario. Most of that drop happens midway down the river at Niagara Falls.

“Your ballast water from the Black Sea is destroying our Great Lakes!” the late James Oberstar, a Minnesota member of the U.S. House of Representatives, recalled for me one steamy June day in his Capitol office in 2005. “It’s that simple.”

This is not a story about climate change. It’s a story about climate changed.

That 12-year-old, you see, is perhaps the best hope the lakes have to recover from two centuries of over-fishing, over-polluting and over-prioritizing navigation: almost every person I’ve ever talked to who cares anything about the lakes and the rivers that feed them does so because they have a childhood story about catching the fish that swim in them.