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A Great Lake Diminished
Lake Michigan is stressed. Restoring its health will take more than a few quick fixes.

By John Kaufman

Photo by Taylor Keating

Henry David Thoreau, author of Walden and “Civil Disobedience,” traveled east across Wisconsin by train in June of 1861. He had been to Minnesota and was headed home with his traveling companion, Horace Mann Jr. The two spent the night, according to Thoreau’s journal, at a Milwaukee hotel called the Lake House. On the morning of June 28th, they boarded the Edith, a propeller steamship that would take them up and across Lake Michigan to Mackinac Island.

“Milwaukee, of all the settled places,” wrote Thoreau, “has the best harbor on Lake Michigan. There are shoals and rocks up the lake, but good harbors at Traverse Bay and behind islands on the northeast side. The lake is ninety miles wide and we cannot see across it; but we see the land loom sometimes on each side, from our steamer in the middle.”

Had Thoreau spent more time by our Great Lake, he would have noted the first signs of ecological decline: runoff from clearing of forests, the sewage of a growing urban population, commercial overfishing and industrial pollution.

Margaret Beattie Bogue, in her book Fishing the Great Lakes: An Environmental History, 1783-1933, notes that in the latter half of the 19th century, the industrialized Menomonee River near Milwaukee produced only crayfish, and that as early as 1870, the abundant and commercially prized lake whitefish was becoming hard to find in Lake Michigan near Milwaukee’s harbor.

But Lake Michigan was still fairly healthy and ecologically intact as Thoreau steamed out of Milwaukee on that early summer day.

A CENTURY AFTER THOREAU CROSSED Lake Michigan, lake trout and whitefish were commercially scarce due to invasive species and a much diminished ecosystem. In 2011, the last commercial fishing boat operating out of Milwaukee quit trying.

There is, surprisingly, hope for native lake trout. Over in Lake Huron, salmon numbers have dropped sharply after a steep decline in alewives due to invasive mussels filtering out alewife food. The absence of alewives and salmon in Lake Huron produced a significant increase in lake trout, which now seem able to reproduce naturally in greater, nearly self-sustaining numbers.

Bradley Eggold, the Wisconsin Department of Natural Resource’s Southern Lake Michigan Fisheries supervisor, says something similar is happening in Lake Michigan: Fewer alewives may mean more lake trout. “Alewives are high in thiaminase, which breaks down thiamine, a key component in early [lake trout] development.” Lake trout, unlike the salmon and other stocked trout, have a wider range of food choices. Should alewives be severely reduced or disappear in Lake Michigan, trout can adapt to eat other small fish, while salmon and stocked trout do poorly and dwindle, says Eggold. To be native, it seems, is to have a natural advantage.

But many other threats to lake trout and Lake Michigan, including global warming, now lurk.

THE GREAT LAKES ENVIRONMENTAL Assessment and Mapping Project (GLEAM) provides a new way to map and visualize just how the Great Lakes are bearing up under various kinds of environmental stress.

GLEAM’s Lake Michigan stressor map contains a significant area of highly stressed yellow and red zones, especially in shallower coastal waters and off major metropolitan areas. Green Bay is now mapped as mostly a sea of red, and last summer, it was reported that an oxygen-deprived “dead zone” in Green Bay stretched from off Dyckesville on the Door Peninsula to Sturgeon Bay.

I asked Peter McIntyre of the University of Wisconsin-Madison’s Center for Limnology and one of the team leaders of GLEAM whether it was right to assume that Lake Michigan is in a severe state of decline.

“Much of Lake Michigan is certainly highly stressed,” McIntyre said in an email. “However, decline implies that its condition is continuing to change for the worse. The main message is that highly stressed areas will require restoration and remediation against a wide range of stressors.”

I wondered which of the “stressors” should be fixed first. “It really depends on the specific location in the lake,” McIntyre said. “Our work supports the general conclusion that invasive species, toxic chemicals, and habitat disruption are major problems, but we also found new evidence that the rate of water warming from climate change is much higher in some places than in others. In those red-zone areas, we have moved beyond the point where it is possible to tackle a couple of problems and see major ecological benefits.” In other words, to restore Lake Michigan, a few tweaks here and there won’t do.

CLIMATE CHANGE IS PERHAPS MOST worrisome. According to the Environmental Protection Agency, if the amount of carbon dioxide reaches about 560 ppm, there will be 23 to 50 percent less water in the Great Lakes’ “net basin supply.” Scientists believe that the level of the Great Lakes will fall due to a greater rate of evaporation caused by less ice cover and higher air temperatures. Periods of drought will also likely increase.

Winter ice on the Great Lakes has decreased 71 percent over the last 40 years, according to data collected by the Great Lakes Integrated Sciences and Assessments (GLISA), and this trend is expected to continue, despite this odd year of extreme cold and better-than-average ice cover.

GLISA calculates that global warming will mean less water in the Great Lakes Basin for agriculture and industry. Extreme precipitation events will not balance increased evaporation, but will cause more flooding and pollution from runoff. Warming water will also spawn more algae blooms and toxic dead zones, like the one in Green Bay. Cold water species such as lake trout and whitefish will decline, and coastal wetlands and fecund estuaries are likely to suffer due to lower levels.

Although Lake Michigan is currently more than a foot higher than it was in January 2013, it’s still about 1.5 feet below its long-term average. And the EPA notes that if the atmosphere continues to warm at present rates, the average level of the Great Lakes could soon fall by as much as 6 feet.

STANDING ON LAKE MICHIGAN’S shore on a frigid, brilliant February day, I thought of something Thoreau wrote of Walden Pond: “Ice is an interesting subject for contemplation.” Massive, frozen waves marked the end of Bradford Beach. Shiny cones and cryovolcanoes, or “ice volcanoes,” rose up between miniature mountain ranges of ice and snow.

A distinct crackling sound grew louder as I moved forward until, at the very edge of the shore ice, looking down at the lake’s calm surface, the crackling was as loud as someone crumpling cellophane – and a bit unnerving, as if the lake were speaking. The ice, thin and transparent, extended out farther than sight, broken only by narrow openings here and there filled with floating ducks and geese. Off shore, a few thicker, gleaming rafts of ice brightened the foreground, while in the far distance, a bank of low, dark clouds hovered gloomily over the horizon.

It was a pristine, almost polar scene, and if I ignored the more obvious signs of the city – the Hoan Bridge, the flash of traffic, the polluting plumes of power plants – it could have been 1861.

 

But what will Lake Michigan look like, what sort of life will it support in 2061? Will such icy music and winter beauty be a thing of the past? Will its water level have receded to a permanent low tide? Will the lake itself have abandoned us? 
This article appears in the April 2014 issue of Milwaukee Magazine.
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