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Coastal Centre concerned about plastic pollution in Lake Huron
Owen Sound Sun Times (7/17)
Everyone has a role to play in turning the tide on the growing problem of plastic pollution in the Great Lakes. That's the message from Ontario's Lake Huron Centre for Coastal Conservation outreach specialist, who is working to educate people on simple ways to help combat the issue.

Elementary Adventure Day outing provides hands-on fun
The Ashland Daily Press (7/12)
Just over half-a-dozen youngsters gathered at the Northern Great Lakes Visitor Center, in Wisconsin, to participate in the first of this year’s three 4-H Elementary Adventure Day’s.

Summer interns help to research Lake Erie issues
The Toledo Blade (7/5)
Eleven college and university students from across the United States are studying freshwater lake issues this summer at the University of Toledo’s Lake Erie Center.

Anglers enlisted in water fight
Great Lakes Echo (6/29)
A recent study by researchers at Cornell University, in N.Y., revealed that anglers in the Great Lakes region are aware of and concerned about the threat of aquatic invasive species (AIS).

Lake State opens Sea Grant office
Sault Ste. Marie Evening News (6/29)
Lake Superior State University officially welcomed its new Michigan Sea Grant office to campus with a ribbon cutting ceremony Monday morning.

Stone Lab hosts series of experts to discuss lake
Port Clinton News Herald (6/28)
In Ohio, people looking to learn more about the issues facing Lake Erie will have several opportunities this summer to hear firsthand from the experts in the field who deal with those issues every day.

TEACH Calendar of Events
What's going on in your neighborhood this month? Meet other people and learn together at recreational and educational events! Our new dynamic calendar is updated daily with current educational events.
TEACH Questions & Answers

Do the Great Lakes freeze in the winter?
from Debbie in Olyphant, Penn., Michael in Kenosha, Wisc., and Jim in St. Clair Shores, Mich.

The Great Lakes do freeze, but not completely. According to Ray Assel of the Great Lakes Environmental Research Laboratory, ice cover on the Great Lakes varies from lake to lake and year to year. For example, in a year with normal temperatures, 25 percent of Lake Ontario will be frozen over, while up to 90 percent of Lake Erie will be frozen. However, wind and water movement over bodies of water as large and deep as the Great Lakes make it unlikely the lakes have ever frozen over completely for any significant length of time.

The Great Lakes have come close to freezing over completely during the extremely cold winters of 1976-77, 1977-78 and 1978-79, with up to 90 percent ice coverage. However, Assel says that severe winter air temperatures are not necessary for large ice cover on the lakes. A cool summer and fall can result in below normal water temperatures by late fall. Extensive ice cover can then form with only average winter temperatures.

Old Ice bridge As for the Niagara Falls, the volume and speed of the water flowing over the falls prevents them from freezing, as does the ice-boom at the mouth of Lake Erie. The ice-boom is a series of floating steel pontoons extending across the river from Buffalo, New York to Fort Erie, Ontario. It prevents ice from clogging the river and hydroelectric intakes by helping an "ice bridge" (a stable ice cover) to form at the mouth of Lake Erie. Before the installation of the ice-boom in 1964, the American side of the falls froze over in 1909, 1938 and 1949 because ice jams upstream reduced the water flow. Ice bridges can also form below the falls when ice goes over the falls and freezes to the edges of the gorge, resulting in a buildup of ice (as thick as fifty feet in some places) stretching across the entire river. For photographs of historical ice bridges on the falls, go to Edsen Breyer's Postcard Museum.

For a look at current and historical Great Lakes surface and ice cover, go to GLERL's Great Lakes Surface Environmental Analysis pages.

Thank you for your questions!

References
Nilsson, Matt. Not Easy to Freeze. Earthwatch Radio, 1/25/00.
Niagara Falls, Thunder Alley.


Answered on January 8, 2001

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