ABOUT A YEAR AGO, we moved to a small community nestled in the Indiana Dunes, a heavily forested landscape of dramatic sand dunes that extends along the southern edge of Lake Michigan. A few miles east is Cowles Bog — the wetland that inspired Henry Chandler Cowles to launch the science of ecology. His work also sparked a movement to save the dunes from wholesale industrial development, though anyone who visits now will quickly notice the constant hum of steel mills, the acres of power lines marring stretches of highway, and the great cooling tower of the power plant in Michigan City, Indiana.

Sandwiched between these icons of industry is a magnificent state park that provides crucial habitat to 352 bird species, including owls, loons, kestrels, and sandhill cranes. It is also home to creatures like deer, foxes, wild turkeys, and frogs. The beach glints with glacier-age rocks and Paleozoic fossils, all washed clean by cool sparkling waters. Now and then beachgoers may kick aside clumps of tiny mussel shells, unaware what tragedy they signify: the Great Lakes are in danger.

The health of the Great Lakes is the subject of a fascinating and brilliant new book by award-winning journalist Dan Egan, reporter at the Milwaukee Journal Sentinel. He catalogs the history and ecology of the lakes — from creation to present day — revealing how human hands have altered, and ultimately threatened, these expansive waters. Egan describes how the creation of the Saint Lawrence Seaway resulted in “an environmental scourge whose scope and costs are spreading by the day.” This is particularly alarming given recent reports that the White House has called “for the Great Lakes Restoration Initiative to be cut from $300 million a year to about $10 million.”

Egan’s story begins in prehistory, with the geological formation of the Great Lakes and the birth of rich new ecosystems after the end of the last Ice Age. When the links between the lakes and the ocean dried up about 2,500 years ago, this vast aquatic region became as isolated “as a one-acre pond in the middle of a forest.” Fish could pass downstream through the Niagara Falls, but species could no longer enter from the ocean. The native food chain included phytoplankton, zooplankton, sticklebacks, emerald shiner, perch, walleye, and the magnificent lake trout, which “evolved over millions of years to survive the frigid, relatively sterile glacier-fed rivers.”

Today’s route from the Atlantic to the interior lakes was blasted, dredged, and dammed in various waves of work beginning as far back as 1781, continuing through the 19th century with the Welland canals and the Erie Canal, and culminating in the opening of the Saint Lawrence Seaway in 1959. Slowly but surely, exotic species began to invade the lakes. By 1949, sea lampreys had decimated the lakes’ native trout population. Alewives and spiny water fleas abounded. Some invaders hitched a ride in the ballast water of overseas cargo ships. Perhaps the most pervasive and dangerous of these invaders are the tiny exotic zebra and quagga mussels. If Lake Michigan was drained, it would “be possible to walk almost the entire 100 miles between Wisconsin and Michigan on a bed of trillions upon trillions of […] quagga mussels.” By consuming prodigious amounts of plankton, the invasive mussels leave the water “vodka clear”; Cladophora thrives in the increased sunlight and then dies, consuming all the oxygen; botulism strikes in such conditions; mussels absorb the toxins; small fish eat the mussels, winding up on shore where they are easy fodder for birds, who are then poisoned.

The great irony is that the Seaway never fulfilled its commercial promise. In the 1950s, the United States spent $133.8 million and Canada spent $336.5 million working on the Seaway; the countries spent another $600 million to build a related dam. But by the time it was opened, the new, larger ships could not make it through the locks. Now, only around 450 overseas ships come through each year. Worse, the cost of controlling invasive species is escalating. Keeping underwater industrial pipes clear and free of quagga mussels has cost $1.5 billion over the past 25 years. Managing ecological damage caused by ballast invasions has cost $200 million per year, while fines for illegal ballast dumping are just $3,000. Egan argues persuasively for closing the Seaway — even though it could cost as much as $55 million. It would by no means vanquish other threats to the lakes from contaminated bait buckets and pleasure boats, industrial pollution, and drier regions clamoring for access to Great Lakes water, but it would certainly help. Egan refers to the Seaway as the Great Lakes’ “front door”; closing it would keep out infested overseas cargo ships once and for all.

Egan’s narrative often moves like a thriller, with scientists trying to understand strange new phenomena and then racing against time to bring them under control. Take, for example, the story of how researchers in the 1960s ordered carp from Asia to control weeds in farm ponds and irrigation ditches without the use of chemicals. At the time, one biologist notes ruefully, “this was right.” The catastrophe struck later when a few people discarded a batch of fish that had been ordered accidentally — bighead and silver carp — into streams and ditches, where their numbers grew rapidly. Soon there was a large-scale invasion threatening Lake Michigan. Egan also gives a gripping account of an Army Corps General’s last stand against the carp using a high-tech underwater electric barrier in the Chicago canal, while a scientist likened the genetic evidence of carp already in Lake Michigan to fingerprints at a “murder scene.” Later we learn about the “biological bombshell” developed by an Australian laboratory: by adding genetically engineered carp that cannot produce female offspring, they hoped the fish would eventually “breed themselves to oblivion.” Unfortunately, for ethical and ecological reasons, this method is probably unusable.

The eutrophication of Lake Erie is yet another story of unintended consequences and botched attempts at ecological management. Shallow, warm Lake Erie is especially vulnerable to this phenomenon — the process by which fertilizer runoff delivers an overdose of nutrients, stimulating algae growth that in turn consumes oxygen to such a degree that it suffocates other aquatic life. Around 1800, Lake Erie received about 3,000 tons of phosphorus per year from natural sources. In the 1960s, this amount had multiplied to an astounding 24,000 tons annually. Between World War I and the 1960s, algae in the lake increased six-fold. After a public outcry, stringent regulation effectively curbed phosphorus use in the 1970s. But then new algae slicks surfaced in the mid-1990s. This second coming included large amounts of deadly microcystis, a form of bacteria that can cause lethal liver damage if swallowed; not even boiling the water kills it. Ironically, the infestation seems to be linked to sustainable agriculture. Fertilizer pebbles are now deposited on untilled land to avoid soil erosion. But when rain dislodges the pebbles before they are absorbed into the soil, they deliver a potent punch of phosphorus into the lake. Egan warns that microcystis could easily taint the water supply of major cities around the Great Lakes.

As bad as phosphorus runoff is for the health of the region, at least it is a threat that can be remedied locally. Climate change is a very different beast: only collective action across the planet can curb greenhouse gas emissions effectively. Egan’s account of climate change focuses on the rise and fall of water levels in the Great Lakes. For the past 4,000 years, the level has been relatively stable. In records dating back to the 19th century, we can track long-term, gradual fluctuations of about three feet from high to low water. But then in 1998–’99, water levels in Lake Michigan and Huron suddenly fell three feet. This drop was not followed by the usual rhythmic rebound, but stayed low for the next 15 years. Indeed, in 2013 the lake levels fell further to six and a half feet below the average of the previous high water mark. Water temperature seemed to be the culprit. Warmer water reduces winter ice cover, which in turn allows more heat to be absorbed by the lake; the warmer the water, the higher the rate of evaporation, not just in the summer but also in the fall and winter. Yet after 2013, water levels in Lake Michigan and Lake Huron surged back four feet. Record-breaking rain and snow from the polar vortex lay behind the shift. Climate change is destabilizing the hydrologic regime of the Great Lakes. In the future, lake levels may swing dramatically by as much as eight to 10 feet, with severe social consequences. For more than a century, economic developers in the Great Lakes have taken stable lake levels for granted. Cities, industries, suburbs, and major transportation networks all follow the modern coastline.

How will we handle an increasingly unpredictable natural world? Should we engage in massive engineering projects to control the lakes’ water levels as some suggest? Egan interviews one biologist who notes that humans can change nature, but not always control it — as happened with the Saint Lawrence Seaway. Perhaps we should simply close the Seaway as Egan suggests, and restore the lakes to some previous level of health. Deciding which stage of the past offers a fitting baseline, however, would be tricky; clearly we cannot return the lakes to their pristine preindustrial state. We could also choose to do less rather than more. There are promising signs of ecological recovery, with native fish stocks evolving on their own to eat invasive goby fish. Egan himself has already begun sharing his passion for fishing with his young son. The key to the future of the Great Lakes may lie in the concept of “adaptive management” — that is, learning to live with uncertain fluctuations and being “strategic in your decisions on how to cope.” This is a humble path, but one not lacking in hope and pleasure.

¤

Vicky Albritton and Fredrik Albritton Jonsson recently co-authored Green Victorians: the Simple Life in John Ruskin’s Lake District (Chicago, 2016). Vicky’s work has appeared in a variety of media, including The Eighth Lamp: Ruskin Studies Today and Kritik, and the Chicago Book Review. Fredrik teaches environmental history at the University of Chicago. He is also the author of Enlightenment’s Frontier: the Scottish Highlands and the Origins of Environmentalism (New Haven, 2013). They currently live in Ogden Dunes, Indiana.