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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.
Water levels on the Great Lakes

4 | How levels and flows are measured

Water levels are measured and recorded at many locations around the Great Lakes and on their connecting channels.

Click to see larger image.The National Ocean Service of the National Oceanic and Atmospheric Administration (NOAA) presently operates 31 water level gages on the Great Lakes and 18 gages on the connecting channels. In Canada, the Canadian Hydrographic Service maintains 29 water level gages on the Great Lakes and 27 on the St. Lawrence River. Other agencies, including the U.S. Army Corps of Engineers, New York Power Authority and Ontario Power Generation, also operate recording gages at various locations on the lakes.

See also: Map of Great Lakes Water Level Gauging Stations

Great Lakes water levels are officially measured from the International Great Lakes Datum 1985 (IGLD 1985). This datum is referenced to sea level, as measured at Rimouski, Quebec, near the mouth of the St. Lawrence River. Because the crust of the earth in the Great Lakes region is continuously rising with respect to sea level, and the rate of movement is not uniform throughout the region, the IGLD must be updated every 25 to 30 years.

See also: FAQ about the International Great Lakes Datum

Click to see larger image.The rate of flow, or discharge, in a river or Great Lakes connecting channel is determined by measuring the channel depth and width, and the velocity of the flow. Measurements can be made by boat, from a bridge, or from a cableway strung across the river. With sufficient measurements of flow over a range of water levels, mathematical relationships can be developed between levels and discharges for various points along the connecting channels and the St. Lawrence River. These equations are essential to the coordination of outflow data, particularly related to hydroelectric power usage of Great Lakes waters.

Graphics: Water level gaging station; measuring outflows at the Niagara Cableway.

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