2023 Summer Guide

Truth and myths about the Great Lakes

Dave Dempsey, author of “The Great Lakes: Fact or Fake,” on the shores of Grand Traverse Bay.
Dave Dempsey, author of “The Great Lakes: Fact or Fake,” on the shores of Grand Traverse Bay.
Courtesy photo

As summer approaches, so do trips to the Great Lakes. Some of us are lucky enough to own or rent cottages on or near them. Others go back to favorite B&Bs, motels and cabins year after year or take trailers and tents to campgrounds. And many of us make a day trip or two before the warm weather escapes us. 

But how much do you know about the Great Lakes?

Dave Dempsey knows more than most. Dempsey has spent the last 40 years working on environmental policy for the governor of Michigan, various nonprofit organizations and the International Joint Commission, through which the United States and Canada manage bodies of water along their border. Dempsey, a Michigan State University graduate, is a prolific writer (and a former environmental columnist for City Pulse). His 12th book, which was just published by Mission Point Press, is “The Great Lakes: Fact or Fake?” In it, he poses questions you can ask your car mates as you head west, east or Up North for your summer trip destinations — then use his answers to grade your knowledge of one of the world’s greatest wonders.

Here is an excerpt from “The Great Lakes: Fact or Fake,” by Dave Dempsey.



The Great Lakes are impossible to overlook. Whether you’re an astronaut circling the globe, a student examining a map of North America  or a tourist standing on the shore of one of the five lakes, they dominate our attention.

And yet, even most of those living within the roughly 200,000-square-mile Great Lakes watershed — an area larger than Thailand, Spain or Zimbabwe — don’t know many of the most interesting things about them. Others who have never visited or studied them may lack knowledge or have misconceptions about the Great Lakes. Filling gaps and correcting misconceptions is a major purpose of this book. But learning should stimulate minds and, might we suggest, even be fun. Gaining Great Lakes’ insights should be as inviting as deep-blue Lake Michigan on a sweltering summer day.

So, rather than lecturing, this book aims to challenge and entertain with 40 statements and asks you to guess what’s fact or fake. No homework and no grading.

You are encouraged, however, to improve your Great Lakes knowledge to become more intimate with the 20% of the world’s available surface freshwater they contain. “Available” means water that is not captured in ice caps, glaciers and permanent snow. “Surface water” excludes groundwater.

You can then become a better steward of these majestic lakes and an informed advocate for their protection.

A close-up of the Great Lakes on a map: Superior, Michigan, Huron, Erie and Ontario.
A close-up of the Great Lakes on a map: Superior, Michigan, Huron, Erie and Ontario.



The Great Lakes have tides.

Oceans have tides. Thanks to the gravitational pull of the sun and moon, oceans rise and fall twice each day.

Tides are long-period waves. They originate offshore and move toward coastlines. They are usually measured in feet or meters. At their extreme highs, tides in the Bay of Fundy, with shorelines touching Maine and the Canadian provinces of Nova Scotia and New Brunswick, average 47.6 feet (14.5 meters) but have varied by as much as 53.5 feet (16.3 meters) — the approximate height of a five-story building

So do the Great Lakes, with mammoth open waters, have tides?

It depends on your definition.  The Great Lakes rise and fall in response to the gravitational pull of the sun and moon, but never more than 2 inches (about 5 centimeters). Consequently, the National Ocean Service considers the Great Lakes non-tidal.

Still, much bigger water level changes occur over a short period of time in the Great Lakes. Known as seiches, the changes typically occur when high winds drive water from one side of a Great Lake to another. Seiches can even occur on Great Lakes’ connecting waters, like Lake St. Clair between Michigan and Ontario. The effect is reminiscent of a sloshing bathtub, as water can surge back and forth several times. Waves related to seiches have reached 22 feet and washed people off piers and even resulted in fatalities on shores and piers. On June 26, 1954, a storm drove an 8-to-10-foot swell from Chicago to the east shore of Lake Michigan. The water then rebounded, suddenly inundating a Chicago pier where anglers were fishing, sweeping many into the churning water. Eight people died.

The Great Lakes also experience meteotsunamis, large waves whipped up by changes in atmospheric pressure associated with storms. The phenomena has led to waves up to 20 feet high and multiple incidents along Lake Michigan’s southern coast (10 killed in Grand Haven, Michigan, in 1929 and seven in 2003 in Michigan’s Berrien County). 

ANSWER: Fact – barely.



There are whales in the Great Lakes.

Each spring, visitors to Traverse City enter a building inquiring about whales. Traverse City Tourism, an agency that promotes recreational visits to the bays and open waters of the Great Lakes, reports that visitors walk in the doors “asking about the best places to view migrating whales or wanting to know what companies offer the best whale-watching tours.” 

And the lore of the Great Lakes whale emerges again like a humpback breaching the lake surface.

There is considerable evidence of whales in the Great Lakes. One is the Great Lakes Whale Migration Station on Beaver Island in northern Lake Michigan. The station “collects migration data and records sighting of whales as they migrate throughout the Great Lakes,” the station says on its Facebook page. A website, Lake Michigan Whale Watching, informs visitors:

As winter turns to spring and the cool waters of the lake are warmed by the sun, the freshwater sperm whales and dolphins begin their annual southbound 1300-mile journey from Hudson Bay. Although there are a number of locks at Sault Ste. Marie, these beautiful and intelligent creatures forge a faster route through nearby streams, and by mid-June, they have reached the breeding
grounds of southern Lake Michigan that they know as their “summer home.”

The first whale-watch cruise originating from Chicago took place in June 1985. The organizer pointed out that Great Lakes whales are rarely seen because, “Through evolution, the Great Lakes whales are carefully camouflaged.”

Early in the 2000s, some Michigan instructors received a teaching aid, also distributed nationally to 1.2 million third through sixth grade students in the U.S, which described Great Lakes whales. The guide also mentioned the annual migration of the whales.

But whales thrive only in salt water, the nearest of which is 800 miles from Lake Michigan. Krill, the dietary staple of many whale species, do not live in freshwater. These small, shrimp-like crustaceans, averaging only about 2 inches, are critical to marine ecosystems. Saltwater helps heal small wounds on whales. And the 1985 Chicago whale watching cruise was tongue-in-cheek.

Whale bones have been found in Michigan but may reflect their transport from ocean waters by Indigenous peoples through trade.

The point where Great Lakes water reaches saltwater in the Saint Lawrence River is home for about 900 beluga whales. White with a rounded forehead, female beluga whales average 11.5 feet (3.5 meters) while males can exceed 13 feet (4 meters). The species faces threats from toxic chemicals that exit the Great Lakes system.  Flame retardants, mercury and pesticides all contribute to the toxic burden borne by the beluga.

So — whales may be close to the Great Lakes and influenced by the Great Lakes, but they do not live in the Great Lakes.






Some residents of the Great Lakes region, proud of their freshwater heritage, celebrate that identity with signs, personalized license plates and  decals.

One decal commanding attention declares that the Great Lakes are unsalted and shark-free, and we’ve already seen that whales don’t inhabit their waters. No sober sightings of sharks have been confirmed, but are the Great Lakes unsalted?

Not if you consider road salt and salt from water softeners, they’re not. In 2021, researchers estimated chlorides in Lake Michigan had risen from about 1 to 2 milligrams per liter before European settlement to more than 15 milligrams per liter. Canadian researchers found levels ranging from 1.4 milligrams in Lake Superior to 133 milligrams per liter in Lake Ontario. Although these levels are well below the chloride concentrations in ocean water, about 35 grams per liter, and below the aesthetic standard for chlorides in drinking water, about 250 milligrams per liter, rising concentrations may have biological impacts. These include killing or otherwise harming aquatic plants and invertebrates.

The Lake Michigan salinity level studies found that watersheds with a greater surface area of roads, parking lots and other impervious surfaces tended to have higher chloride levels due to direct runoff into streams and lakes.

Although road salt is likely the largest source of chloride pollution of the Great Lakes, livestock, fertilizer and water softeners also contribute. Still, the simplest solution to rising chloride levels in the Great Lakes is to use less road salt, and transportation officials have sought ways to apply less salt on roads during winter while keeping roads clear and safe for motorists. The most direct way is to put salt on fewer roads. In some cases, sand or ash is used as an alternative in lower-traffic areas. 

As for sharks, well, there was a report of a bite taken out of a Chicago-area man by a bull shark on Jan. 1, 1955. The best guess of the Chicago Tribune is that it was a hoax published in 1975, the year the movie “Jaws” was released. So, “shark-free” is accurate.


ANSWER: Fake – Only half right, the half involving sharks.




Some residents of the Great Lakes watershed may eat the equivalent of a credit card every week.

Where do plastic bottles and plastic grocery bags go to die when they’re discarded?

The better question might be, do they ever die?

Worldwide studies have shown that many plastics break into small pieces, or microplastics, that persist indefinitely. They clutter the ocean — and the Great Lakes. The U.S. Geological Survey estimates there are 112,000 particles of plastic per square mile of Great Lakes water. A sampling of Lake Ontario and Lake Superior fish found the “highest concentration of microplastics and other anthropogenic (synthetic) microparticles ever reported in bony fish, including 12,442 anthropogenic microparticles in 212 fish from nearshore Lake Ontario, and 3,094 in 119 fish from Lake Superior. Between 35% and 59% of the particles were microplastics.

Plastic particles 5 millimeters (0.2 inch) or smaller are considered microplastics. Studies have found microplastics in the atmosphere, on land and oceans and freshwaters. They also have made their way into drinking water and foods for human consumption. The impact on human health is unknown, but they may act as stressors, entering the human digestive, respiratory and circulatory systems.

Another study estimated the global mean rate of human consumption of microplastics at between 0.1 and 5 grams per week. Variability is high and depends on the individual’s home location, age, size and cultural factors. In the worst-case scenario, consumption is roughly equivalent to a credit card.

While no one knows yet the impact of microplastics on human health (or fish and wildlife) there are worrisome signals that suggest preventing human exposure to microplastics should be a priority. Finding substitutes for microplastics intentionally added to agricultural chemicals, paints, cosmetics, and detergent, for example, is critical. Scientists are piloting a system based on biodegradable silk instead.

There is hope — and urgency.

ANSWER: Fact – Some residents of the Great Lakes watershed may eat the equivalent of a credit card every week.



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