Courtesy & Copyright Utah Division of Wildlife Resources, Phil Tuttle, Photographer
Let’s backtrack.
The opening of the St. Lawrence Seaway in 1959 allowed cargo ships to bypass the rapids on the St. Lawrence River and enter Lake Ontario. From there ships could access Canada’s Welland Canal, which also uses a series of locks to allow ships and barges to bypass Niagara Falls and access the rest of the Great Lakes. Proponents of the St. Lawrence Seaway sold the project on the grounds that it would turn the Great Lakes into a North American “Mediterranean” by transforming cities from Rochester, New York to Duluth, Minnesota into global ports.
They got what they wished for, but with a twist. “Salties,” or oceangoing cargo ships, traveling from the Mediterranean, Black, and Caspian Seas, emptied their ballast tanks in Great Lakes ports as cargo was loaded. In June of 1988 the first documented zebra mussel was found in Lake St. Clair—a small lake (in comparison to the Great Lakes) where the St. Clair River pools about halfway along its journey from Lake Huron to Lake Eire. This single, fingernail-sized mussel signaled a catastrophe. By the end of 1989, invasive zebra and quagga mussels were found in all five Great Lakes.
Courtesy USGS, Wetland and Aquatic Research Center,
Amy J Benson, Photographer
Zebra mussels thrive in water less than about fifty feet deep and on hard surfaces. Quagga mussels thrive in soft lake bottoms in water as deep as 500 feet. Together these invasive mollusks wreak havoc on aquatic ecosystems where they are most vulnerable—the bottom of the food chain.
Razor sharp zebra and quagga mussels filter microscopic nutrients from the water, This makes lakes clearer, while stripping them of nutrients aquatic species depend upon. By 2009 phytoplankton levels in the Great Lakes were diminished by 90% compared to pre-mussel levels. Clearer water makes for easier fishing for predatory birds and clearer water allows sunlight to penetrate deeper into lakes, warming them up faster and creating prime conditions for toxic algae blooms. Algae blooms deplete the water of oxygen and create ideal conditions for botulism, which then causes massive waterfowl die-offs. All of this has happened in the Great Lakes in a viscous cycle set in motion by zebra and quagga mussels.
Invasive mussels were found in Lake Mead in 2007 and in Lake Powell in 2013—transported from the Midwest recreational boats. What has happened in the Great Lakes can—and is—happening in the west.
Courtesy & Copyright Eric Newell, Photographer
I am Eric Newell and I am wild about Utah’s lakes and rivers.
Credits:
Images: Quagga Mussels exposed at Lake Powell, Phil Tuttle, Photographer, Utah DWR
Boating, Eric Newell, Photographer
Featured Audio: Courtesy & Copyright J. Chase and K.W. Baldwin.
Text: Eric Newell, Edith Bowen Laboratory School, Utah State University & Lyle Bingham, Bridgerland Audubon Society
Additional Reading:
WildAboutUtah pieces by Eric Newell, https://www.upr.org/people/eric-newell
Egan, Dan, Zebra Mussels’ Takeover of the Great Lakes, January 2, 2019, https://www.discovermagazine.com/zebra-mussels-takeover-of-the-great-lakes-2626
What are Invasive Mussels?, Invasive Mussel Collaborative, Great Lakes Commission, https://invasivemusselcollaborative.net/about/mussel-facts/#:~:text=They%20were%20first%20discovered%20in,at%20the%20bottom%20of%20lakes
Howard, James, When Zebra Mussels Made the Great Lakes “Clean”, October 8, 2025, https://jameshoward.us/2025/10/08/when-zebra-mussels-made-the-great-lakes-clean
Zebra Mussels, BB-17, Environmental Fact Sheet, New Hampshire Department of Environmental Services, 2026, https://www.des.nh.go v/sites/g/files/ehbemt341/files/documents/2020-01/bb-17.pdf
Map of Lake St Clair, The Great Lakes, Google Maps, https://www.google.com/maps/place/Lake+St+Clair/@44.6782974,-87.146707,1192993m/data=!3m1!1e3!4m6!3m5!1s0x88253a42a07febbd:0x679a153523440e7c!8m2!3d42.4356504!4d-82.6915429!16zL20vMDJnMzdn?entry=ttu&g_ep=EgoyMDI2MDkwOS4wIKXMDSoASAFQAw%3D%3D
Great Lakes St. Lawrence Seaway Development Corporation, https://greatlakes-seaway.com/en/
Leahy, Colleen, Quadrillions of invasive mussels are damaging the Great Lakes, documentary shows, Wisconsin Public Radio, February 28, 2025, https://www.wpr.org/environment/drebert-melnick-documentary-quagga-mussels-great-lakes#:~:text=The%20quagga%20mussel%20has%20infiltrated,are%20felt%20throughout%20lake%20ecosystems.
Book recommendation:
Egan, Dan, The Death and Life of the Great Lakes, W. W. Norton & Company, 2017, https://www.betterworldbooks.com/product/detail/the-death-and-life-of-the-great-lakes-9780393355550
