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Field trip grants make fourth grade so much better
Great Lakes Echo (2/11)
Pictured Rocks National Lakeshore, in Mich., is one of 186 federal parks to receive a portion of the $1.1 million National Park Foundation grant to set up field trip programs.

State awards $3.6 million in grants to combat invasive species
WLUC-TV, Marquette, MI (2/11)
The Michigan departments of Natural Resources, Environmental Quality and Agriculture and Rural Development announced the award of 19 grant projects totaling $3.6 million, under the Michigan Invasive Species Grant Program.

UT dedicates lab to analyze wide range of research jobs
The Toledo Blade (1/29)
A laboratory that opened in mid-2015 at Ohio's University of Toledo allows monitoring of water quality and detection of dangerous algal toxins in Lake Erie more accurately and faster.

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

table of contents
Introduction
Three types of water level fluctuations
History repeating itself: Hydrographs illustrate historical levels
How levels and flows are measured
Effects of lake level fluctuations
References and more information

Water levels on the Great Lakes

Click to see larger image. Water levels are part of the ebb and flow of nature.

The difference between the amount of water coming into a lake and the amount going out is the determining factor in whether the water level will rise, fall or remain stable. When several months of above-average precipitation occur with cooler, cloudy conditions that cause less evaporation, the levels gradually rise. Likewise, prolonged periods of lower-than-average precipitation and warmer temperatures typically result in lowering of water levels.

The recent decline of Great Lakes' water levels, now at lows not seen since the mid-1960s, is due mostly to evaporation during the warmer-than-usual temperatures of the past three years, a series of mild winters, and below-average snowpack in the Lake Superior basin.

Because the major factors affecting the water supply to the lakes--precipitation, evaporation and runoff--cannot be controlled or accurately predicted for more than a few weeks into the future, the influence of man-made regulation of lake levels is very limited. Nature has most of the control, adding water through snow and rain, and taking it away through evaporation.

Graphic: Lake Superior's south shore, April 2000.

Detailed Map: The Great Lakes-St. Lawrence River system


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