The Death and Life of the Great Lakes

by Dan Egan

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.

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.

A college kid on a field trip in the late 1980s was the first to discover them in the Great Lakes. In less than 20 years the mussels went from novel find to the lakes’ dominant species.

The mussels, which have no worthy natural predators in North America, have transformed the lakes into some of the clearest freshwater on the planet. But this is not the sign of a healthy lake; it’s the sign of a lake having the life sucked out of it.

Yet another is the grotesque mug of an Asian carp, a monster-sized carp imported to the United States in the 1960s and used in government experiments to gobble up excrement in Arkansas sewage lagoons. The fish, which can grow to 70 pounds and eat up to 20 percent of their weight in plankton per day, escaped into the Mississippi River basin decades ago and have been migrating north ever since. They are now mustering at the Great Lakes’ “back door”—the Chicago canal system that created a manmade connection between the previously isolated Great Lakes and the Mississippi basin, which covers about 40 percent of the continental United States. The only thing blocking the fish’s swim through downtown Chicago and into Lake Michigan is an electrical barrier in the canal—one that has a history of unexpected shutdowns.

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.

A single Seaway ship can hold up to six million gallons of vessel-steadying ballast water that gets discharged at a port in exchange for cargo. And that water, scientists would learn after it was too late, can be teeming with millions, if not billions, of living organisms.

“About 50 percent of the surface freshwater in the 50 states are within the boundaries of Michigan, and the other 49 states shared the rest of it,”

Invasive mussels have increased water clarity. That has led to a bloom in the sunlight-loving Cladophora that eventually dies and burns up massive amounts of oxygen as it decomposes on the lake bottom. That has opened the door to botulism-causing bacteria that thrive in oxygen-starved environments. The invasive mussels, many biologists believe, suck up those bacteria and are, in turn, eaten by gobies. The poisoned gobies become paralyzed and are easy prey for birds like loons, grebes and gulls. The birds die.

But sometimes it takes two foreign organisms working together to cause utterly unpredictable trouble, as in the apparent case with invasive mussels and gobies working together to trigger botulism outbreaks in native birds. These kinds of chain reactions can take years or even decades to unfold, and they make it impossible for biologists at any point to know which introductions will be harmless and which will become troublesome, if not disastrous.

in 2008 the U.S. Seaway operators began requiring all Great Lakes-bound overseas vessels to flush even their “empty” ballast tanks with mid-ocean saltwater. No new exotic organisms have been found in the Great Lakes since, a point shipping industry advocates tout. Although it is generally agreed that mid-ocean flushing is an excellent first step toward closing the door to new ballast water invasions, it is also generally agreed upon that ballast water disinfection systems similar to sewage treatment plants must be used by ships to provide ample protection for the Great Lakes and other U.S. waters.

Although the Great Lakes have more than 10,000 miles of shoreline—more than the United States’ Pacific and Atlantic Coasts combined—the region is uniquely positioned to stop biological invasions because of one incredible geographical fact: every overseas freighter that sails up from the East Coast into the lakes must pass through a single pinch point: the first lock on the St. Lawrence Seaway. It is 80 feet wide. That’s a little broader than some busy city streets and a little narrower than the distance between home plate and first base. There is a boat ramp at Lake Mead that is wider.

consider Indiana Dunes National Lakeshore, a 15-mile ribbon of glorious Lake Michigan swimming beach that draws two million visitors annually—and is only about 15 miles east of Gary, Indiana’s industrially ravaged lakefront.

The warmest, shallowest and furthest south of the Great Lakes, it was naturally loaded with the building blocks of life—among them carbon, oxygen, hydrogen, nitrogen, zinc, copper, calcium and silicon. This is why Lake Erie, which holds only 2 percent of the overall volume of Great Lakes water, is home to about 50 percent of Great Lakes fish. But

this biological richness left Lake Erie particularly vulnerable to an ailment called “cultural eutrophication,” which is the condition of a pond or lake so overdosed with nutrients that have been put into the water by human activity (farming, sewage, lawn fertilizer, etc.) that the resulting explosion in algae suffocates other aquatic life. It is a condition that can, eventually, destroy a lake. As seasons, years and decades pile up, a body of water can be subsumed by all its accreting dead plant and animal life and eventually it turns into a bog, killed by all the things it gave life to. This pond-to-bog process happens naturally and is known as eutrophication; cultural eutrophication speeds the progression immeasurably, like throwing gas on a fire. On a lake the size of Erie, the immediate worry with cultural eutrophication is that the nutrient overdosing creates so much life that its inevitable decay burns up so much oxygen that almost nothing can survive.

But the important and troublesome fact for Atlanta isn’t how much rain falls from the sky. It is how little of that precipitation then flows down rivulets, streams and rivers and into what is now Atlanta, which still sits atop a ridgeline, a very bad place for a major city to be. The driest spot on a roof in a rainstorm, after all, is the peak, where raindrops hit and immediately head, one direction or the other, for an eavestrough on one side or the other. Watersheds work similarly, and if you live in one of the fastest growing metro areas in the nation, one that is adding more than a million residents per decade, you’d want your city to be situated not on a ridge but near a trough, a place where waters gather and run deep and wide.

one of history’s great hydrologic ironies, today the Milwaukee suburb that is only a 20-minute interstate trip from the Lake Michigan shoreline has so depleted the groundwater that fed the famous springs that all but a handful have vanished. Waukesha is now forced to tap a pool of ancient water in wells stretching 2,000 feet below ground. Levels in this deep reserve have plunged some 500 feet and the water that is left comes out of the ground as a low-grade poison; it’s laced with radium, a naturally occurring radioactive element that is a known carcinogen, at levels about three times above the federal limit. The city now uses a patchwork treatment system that removes the radium from water pulled from the deep wells and mixes it with the non-contaminated water that’s left in the shallow aquifer. Despite the jerry-rigging, Waukesha still exceeds federal radium limits and is under a government order to find a new water source. The obvious answer is Lake Michigan, which you can almost see from town. But the problem is that Waukesha, like Georgia, lies on the wrong side of a border—a border that, like Georgia, it is now trying to nudge.

“Do you know how hard it is to be ideologically so out of touch with reality that you’ve concluded Michigan could run out of water?” former Speaker of the House Newt Gingrich told a Michigan state chamber of commerce gathering in 2005 after he learned there was a controversy in the state about allowing bottled Great Lakes water to leave the basin. His audience chuckled. Nobody in the room that day, apparently, made mention of the Aral Sea, the Ogallala Aquifer or Waukesha’s once “bottomless” mineral springs.

The diversion ban carries two primary exceptions. One is water that leaves the Great Lakes basin in containers that are 5.7 gallons or less. The other is water that leaves in a pipeline but goes only to a city that lies inside a county that straddles the Great Lakes watershed border, and can demonstrate that it has no other viable public water supply, and will agree to send its treated wastewater back to the lakes. The exemption was tailor made for Waukesha, which was not surprisingly the first city to apply for such a diversion under the new compact.

And if science does someday allow us to recast the characters in the Great Lakes in a manner never before possible, how do we decide what those characters should be? Do we continue to manage the lakes for maximum sport fishing fun and maybe even modify certain species so they fight harder and have tastier flesh? Do we farm the lakes for energy-producing, genetically modified algae? Or do we try to resuscitate any and all native species in any way possible?

When Lake Michigan alewife numbers dipped in the 1990s, for example, the state of Wisconsin banned commercial harvest of the fish, which were being sold for cat food and fertilizer. Alewife numbers rebounded; the lake’s native perch population crashed.

With evidence piling up that what is good for native lake trout (no alewives) is bad for salmon (which are alewife-dependent), and vice versa, the states and federal government are trying to strike a dicey balance to keep sportsmen happy and lake trout on the road to recovery. “The idea is that you keep enough alewives so you have a chinook fishery but not so many that you don’t have natural lake trout reproduction. Well, that’s a razor-thin line,” said Dale Hanson, a biologist with the U.S. Fish and Wildlife Service working to restore Lake Michigan’s lake trout.