Lake Erie is a prominent physical feature of North America and forms part of the political boundary between the United States and Canada.
Lake Erie is the shallowest, warmest and most biologically productive of the Great Lakes. Lake Erie contains three basins, each with distinctive features, circulation and ecology, along with many harbors, bays and embayments.
While smallest by volume, Lake Erie is an integral part of the Great Lakes, the world's largest supply of fresh surface water. Lake Erie's shore and watershed include the most southerly reaches of the Great Lakes ecosystem.
- Lake Erie contains approximately 127.7 trillion gallons of fresh water which is 3 percent of the Great Lakes volume.
- The Great Lakes ecosystem contains approximately 6 quadrillion gallons of fresh surface water which is 95 percent of North America's and nearly 20 percent of the world's fresh surface water supply.
- Including the shore length of natural islands, Lake Erie's coast is 871 miles long. The most southern part of the shore is just east of Huron, Ohio. This is the most southerly shore location of the Great Lakes coast which is more than 10,000 miles long, longer than the east coast of the United States.
- The most southerly location of Lake Erie's watershed is in Auglaize County near Minster, Ohio just under 10 miles south of the south east corner of Grand Lake St. Marys. See map at (http://ohiodnr.com/Portals/7/watersheds/ohio_erie_basin.pdf )
Lake Erie is connected to the other Great Lakes which together form a watershed that drains to the Atlantic Ocean. The upper Great Lakes (Superior, Huron and Michigan) drain down the Detroit River into Lake Erie. Lake Erie flows over the Niagara Falls into Lake Ontario which flows through the St. Lawrence River into the Atlantic Ocean. Nutrients, dissolved gases, salts and minerals, sediments and pollutants from the upper Great Lakes and their watersheds are transported down rivers and through wetlands into Lake Erie.
- Land areas that drain directly into Lake Erie (aka are in Erie’s watershed) include portions of the U.S. states of Indiana, Ohio, Pennsylvania, New York and Michigan, and the Canada Province of Ontario.
Lake Erie is an integral part of the Midwestern United States’ and Canada’s (or North American) water cycle and is connected to the region’s watersheds and hydrologic cycle. Changes in the hydrologic cycle affect the quality, quantity and movement of water.
Water currents circulate within Lake Erie and are powered by energy from the sun, wind, waves and differences in water density. The shape of the lakebed and its geographic orientation, the direction of the prevailing winds, the shore and the human-made structures along the shore influence the paths of circulation.
Lake level is the height of Lake Erie relative to sea level as measured using the International Great Lakes Datum. Lake level changes are caused by basin-wide variations in precipitation, evaporation, runoff, snow melt, changes in the levels of the upper Great Lakes, wind and waves, as well as water withdrawals. Tides are not discernable in Lake Erie, a wind driven lake whose southwest to northeast orientation parallels the prevailing winds. This orientation combined with the shallowness of the lake makes Lake Erie especially prone to seiches or wind set-up.
- Great Lakes water levels are officially measured by using the International Great Lakes Datum 1985 (IGLD 1985). The implementation and publication of IGLD 1985 occurred in January, 1992.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.
Lake Erie stratifies in the summer and in winter under ice cover, forming distinct layers based on water density differences due to temperature variations. Turnover occurs in the spring and fall when weather minimizes temperature differences and the layers mix. Turnover is the main way that oxygen-deficient and nutrient-poor water in the deeper areas of the lake can be mixed with oxygen-abundant and nutrient-rich surface water.
- In summer, the warmer surface water known as the epilimnion is lighter and “floats” on top of the cold bottom layer or hypolimnion. The line of rapid temperature change between these two layers is called the thermocline. In winter, the surface is the colder layer and the water becomes ice.
- The shallowness of Lake Erie makes it the only Great Lake whose thermocline disappears each winter with turnover and reforms each summer.
Although Lake Erie is large, it is finite and its resources are limited.