The Death and Life of the Great Lakes Read online

  The project, Cronkite told his viewers, was big, big as “reshaping a continent, completing the job nature had begun thousands of years ago—of creating an eighth sea . . . a sea of opportunity!”

  More than a half century later, the hoped-for flood of global cargo has yet to roar into the lakes from overseas, but something else has—an environmental scourge whose scope and costs are spreading by the day. The St. Lawrence Seaway, you see, didn’t conquer nature at all.

  It unleashed it in the form of an ecological catastrophe unlike any this continent has seen.

  IT IS HARD TO FAULT CRONKITE TODAY FOR HIS OPTIMISM, BECAUSE the nautical magic he and so many others were convinced the Seaway would uncork had happened before. Some six million years ago, the Mediterranean Sea itself was isolated from the Atlantic Ocean. It was little more than a salty puddle at the bottom of a vast basin laced with dusty canyons, some of which plunged more than a mile below sea level. This arid wasteland had previously been a massive Atlantic Ocean inlet, as it is today. But then a tectonic fusion of Africa and Europe created a narrow strip of land that plugged the Mediterranean’s connection to the Atlantic Ocean near what is now the Strait of Gibraltar. This pretty much killed the ancient Mediterranean Sea, which owed its existence to a constant inflow of ocean water, just as it does today. With that Atlantic input plugged, the rivers feeding the suddenly landlocked basin proved too feeble to keep pace with evaporation, and the sea all but vanished in about 1,000 years—which is to say, geologically speaking, nothing. But on a human scale the sea would have shrunk at an imperceptibly slow pace; each day on its shores would have seemed exactly like the last.

  The Mediterranean Sea basin, one popular theory goes, remained in this desiccated state for the next 700,000 years or so. But about 5.3 million years ago a seismic hiccup at the Gibraltar isthmus opened a small channel for the Atlantic Ocean to begin dribbling back in. The trickle soon turned to a torrent, many of today’s geologists reckon, as an ever-widening and deepening tongue of saltwater roared back into the basin with incomprehensible speed, volume and violence. It carried the equivalent of some 40,000 Niagara Falls flowing at about 90 miles per hour. This all happened around the time our ancestors’ thigh bones formed a bridge with their hips strong enough to allow them to walk upright and, perhaps—if any of them happened to be in the area at the time the Atlantic came roaring back—to run.

  At the peak of the Atlantic cascade the new Mediterranean Sea was rising at a rate of about 30 feet per day, and geologists hypothesize that the entire basin—roughly 2,500 miles long and 500 miles wide—could have filled to sea level in less than three years.

  The Mediterranean’s revival indubitably wrought devastation for the terrestrial creatures scratching out a life in the scorched basin, including dwarf elephants and hippos. But it proved a boon for the dolphins and fish and even microscopic life sucked in from the North Atlantic. The devastation also, eventually, opened the door for civilization to blossom, because the Mediterranean Sea connected cultures and economies in a manner that would not have been possible had the basin remained a desert. Today the Mediterranean gives 21 countries from three continents nautical access to each other and—thanks to the eight-mile-wide Strait of Gibraltar carved by the Atlantic Ocean—to the rest of the globe.

  About 7,600 years ago, the Black Sea was isolated from the Atlantic Ocean. It was an inland freshwater lake cut off from the Mediterranean Sea to the west by a spit of land called the Bosporus Valley. At the peak of the last ice age some 20,000 years ago, so much of the earth’s water was tied up in glaciers that, according to some estimates, sea level was nearly 400 feet lower than it is today. As the glaciers melted and the oceans rose, so did the Mediterranean. And eventually the Mediterranean did to the Black Sea what the Atlantic Ocean had done to it more than 5 million years earlier: it came crashing in.

  The speed with which this happened, as well as its scale, is a matter of some controversy, but a popular hypothesis is that the salty water tumbled in at a force equivalent to 200 Niagara Falls. The inundation that submerged some 60,000 square miles under hundreds of feet of water happened so swiftly—some geologists estimate the sea was rising at a rate of about six inches per day—that it would have sent scrambling any humans who had found the lakeshore an oasis in an otherwise parched landscape. The salty water also ravaged the lake’s freshwater biological community, rendering extinct the species that could not adapt and sending others—like the Black Sea sturgeon—darting for safety in the freshwater rivers that still feed the sea today.

  To call this a natural disaster of biblical proportions is what two Columbia University geophysicists did when they published a book in 1998 titled Noah’s Flood. They argue that this geologic event, which is commonly known as the Black Sea Deluge, could be the inspiration for the great flood stories of the past, including the one in the Book of Genesis. That two geologists contend a real flood could be tied to a story in the Bible was not without some controversy in the academic community—and, of course, among believers. But leaving aside any biblical implications, their geological evidence for the disaster itself is solid. And, like the torrent that roared through the Strait of Gibraltar millions of years earlier, there was an upside to it; the merging of the Black and Mediterranean Seas opened up a critical nautical link stretching from Asia to the Atlantic Ocean. Today the Bosporus Strait is one of the world’s busiest shipping channels, with freighters sailing from the once-landlocked Black Sea to ports around the globe.

  About 200 years ago, North America’s Great Lakes, the largest expanse of freshwater in the world, remained essentially isolated from the Atlantic Ocean. For thousands of years, the five inland seas wrapped by more than 10,000 miles of shoreline (islands included) sat cloistered in the middle of the continent. The four “upper” lakes—Erie, Huron, Michigan and Superior—lie some 600 feet above the level of the ocean, which made them unreachable from the Atlantic by boat. Much of that elevation is gained at the dolomite cliffs that are Niagara Falls, over which the collective outflows of all those lakes tumble on their way into Lake Ontario and from there down the thundering St. Lawrence River on their rush to the ocean.

  Like the plugs of land that once isolated the basins that are now the Mediterranean and Black Seas, erosion has been having its way with Niagara Falls. It is expected the falls will disappear in about 50,000 years—which is to say, geologically speaking, pretty soon. When that happens, the cliffs that have for millennia separated the upper Great Lakes from the Eastern Seaboard will be gone. All that will remain is a fast-flowing, ever-eroding riverbed that will draw the lakes, every day, one step closer to sea level. How this all precisely plays out in terms of perhaps opening a nature-carved sailing route between the middle of the continent and the ocean is a matter of geological conjecture that won’t be answered for eons—an unbearably long period for the 19th- and 20th-century Great Lakes politicians and businessmen who were not content to leave the lakes as they had found them, as isolated inland seas upon which giant cargo boats could float from one Midwestern city to another, but never out to the ocean.

  Their idea was to finish the job nature started when the last glaciers carved out the Great Lakes basins 10,000 years ago. Their dream was to create, by the hand of man, a North American “Fourth Seacoast,” thus flexing the Midwest’s burgeoning manufacturing might across the globe, prying open new markets in far-away cities and squeezing from them all manner of exotic bounty. They lusted for their own Mediterranean, for their own Strait of Gibraltar or Bosporus to emerge, but they were not willing to wait for such a natural disaster to unfold.

  So they hatched an unnatural one.

  THE MAP PRACTICALLY TAUNTED THE UNITED STATES AND CANADA to build the St. Lawrence Seaway. The tendril of blue reaching out to the Atlantic Ocean from Lake Ontario—the Gulf of St. Lawrence and the St. Lawrence River that feeds it—stretches some 1200 miles inland. And, on a map, that flat ribbon of blue continues on from Lake Ontario, through Lake Erie, into Lakes Michigan and Huron and all the way across Lake Superior to Duluth, Minnesota, on its western shore. If you were to plot a voyage based on this map, you might assume you could paddle or sail your way from the Atlantic Coast almost to the dead-­center of North America—a distance of about 2,300 miles. And, in a boat, you would indeed find waters as flat as those on a map for almost half the trip. But everything changes about 1,000 miles inland.

  Jacques Cartier, the first European known to reach the area by boat, learned this firsthand when the yawning river up which he sailed so effortlessly in 1535 turned narrow and vicious in an instant. The 44-year-old lifelong explorer, descended from a long line of mariners, had been handpicked by France’s King Francis I to find a nautical shortcut across North America to tap the riches of Asia and, of course, to pick up any gold and silver nuggets he found along the way.

  The summer before, Cartier led a two-boat expedition across the Atlantic Ocean that probed as far west as the Gulf of St. Lawrence but stopped short of sailing up the St. Lawrence River that feeds it. He returned to France that fall, his cargo hold empty of precious metals but his head filled with Native American tales that a vast sea did indeed lie at the head of the St. Lawrence River. The next year the king gave Cartier 110 men and three boats, including one specially modified to sail up rivers.

  The boat wasn’t special enough for the St. Lawrence job. No boat would be for hundreds of years.

  Just upstream from the island that is now downtown Montreal, Cartier encountered a set of oversized rapids, a word that doesn’t adequately capture how angry and impenetrable to upstream navigation this river was. There were waves approaching six feet in height, like those you’d expect to see on an ocean beach when the red no-swim flags are snapping. But these waves didn’t crash. They forever arced, never tumbling into a froth that might be breached by some well-timed paddling. It was a standing, ever-rolling wall of water created by the plunging St. Lawrence riverbed. Cartier remained convinced there were loads of gold beyond the waves and, perhaps, the fabled shortcut to Asia, but the water was so violent it stopped him mid-voyage. He turned around and sailed back down the river. The French explorers who came after remained convinced that somewhere beyond this violent water lay the riches of China, and the rapids today remain named Lachine, which is French for that promised land.

  The voyageurs who eventually pressed further inland by portaging their birch bark canoes around the rapids quickly learned that far upstream lay something almost as miraculous: a set of connected fish-filled freshwater seas larger than any explorer had ever encountered, surrounded by forests of pine and hardwoods that teemed with game—and pelts—on a scale incomprehensible in Europe. But the Lachine Rapids were just the first line of defense for what would one day be called the Great Lakes. In the thousand miles or so it took to sail from the Atlantic to Montreal, the St. Lawrence River rose all of 18 feet. In the 189 miles upstream from Montreal to Lake Ontario the river climbed some 245 feet in a series of impassable torrents.

  Then the real whitewater started. On the far side of Lake Ontario lay another frothing river that gained about 160 feet in just 35 miles. Anyone who tried to paddle or portage up that gorge hit a wall. Literally.

  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.

  Other giant freshwater bodies that have evolved over tens of thousands or even millions of years have been subjected to epic changes in temperature, salinity, water levels as well as wave upon wave of invading and evolving organisms, all in a manner that leaves those water bodies inhabited by a cast of species steeled by the crucible of evolution. This gives them something of an “immune system” when it comes to maintaining ecological stability in the face of disruptions from the outside world. The Great Lakes of Cartier’s time, on the other hand, were what biologists today call “ecologically naïve.” This means the lakes were inhabited by fish and other aquatic species whose isolation left them uniquely exposed to foreign perturbances. None of this, of course, was pondered by the early explorers desperate to exploit their ecological bounty.

  The ditch-digging to open a commercial passage into the Great Lakes by first building a canal around Lachine Rapids started in 1689 but was scuttled soon after when French crews equipped with only the crudest of tools ran into more stubborn rock than expected—and attacks from Native Americans. Work on that tiny section of river alone would sputter all the way into the 1800s, even as progress was made in taming other St. Lawrence rapids farther upstream toward Lake Ontario, particularly after the English captured Canada from the French in 1763.

  In the next two decades the English military, eager to maintain control of the region in the face of rebellion from the 13 U.S. colonies, began chewing its way upriver to supply troop outposts. The first big bite through the St. Lawrence barrier came in 1781, during the height of the Revolutionary War, with the opening of a canal running parallel to the northern bank of the St. Lawrence River, about 25 miles upstream from Montreal. It stretched scarcely the length of a football field and was less than six feet wide and three feet deep. But it was not the size of this little detour around the rapids that made the canal so significant. It was the technology built into it. It had three navigation locks that may well have been the first constructed on this continent.

  In a navigation lock, an upriver-bound boat enters a watertight chamber that has a downstream front door and an upstream back door. At the time an upriver boat noses through the open downstream door and into the chamber, the upstream door is already closed. Once the boat is fully within the chamber the downstream door is closed as well. Then a gate is opened to a sluice fed by river water on the upstream side and the chamber is filled until it matches the water level on the upper side. The upstream doors swing open so the boat can smoothly progress upriver. Downstream boats go through the process in reverse. The only engine a system like this needed was gravity to send the water into and out of the chambers, and human muscle to crank the lock doors open and shut.

  This first short canal allowed a boat to ascend, or descend, a mere six feet before it returned to the main river channel. It was a modest breach in the defense of the Great Lakes, but the canal building inexorably progressed upriver and soon stretches that had been accessible only by birch bark canoes that could be portaged around rapids were being plied by flat-bottomed rowboats 40 feet long. These “bateaux” had a draft of less than three feet but each could carry more than three tons of cargo—furs and timber downstream and food, tools and people upstream. By 1800, the river beyond Montreal had become accessible to larger Durham boats (the kind George Washington used in 1776 to cross the Delaware River in his Christmas night raid) that could be equipped with a sail and haul more than double the cargo of a bateau. Yet at the beginning of the 19th century the Lachine Rapids at Montreal had yet to be breached with an adequate canal, and in other particularly rough stretches along the St. Lawrence River cargoes had to be unloaded as the boats were tugged through the whitewater. It took about 12 days to make the 180-mile trip that started just above Lachine to Lake Ontario.

  Moving cargo and people along the river got much easier in 1825, when the Lachine Rapids were finally bypassed with their own lock and canal system. The manmade waterway was more than 8 miles long and included seven lock chambers that collectively raised boats about 45 feet. Completion of the canal finally provided boats a reliable float from the Atlantic Ocean into Lake Ontario, and the impact this had on goods flowing into North America’s interior was almost immediate. By the early 1830s about 2,000 trips on the river between Montreal and Lake Ontario occurred annually and 24,000 tons of cargo was hauled—four times the volume of traffic in the year before the Lachine canal opened. It took a century and a half of chipping rock and plowing earth to put this crack in the geographic barrier protecting the Great Lakes from the outside world below, but it was about to turn into a chasm.

  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.

  The surface elevation (in relation to sea level) of the Great Lakes, and the

  natural barrier at Niagara Falls.

  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.