Lakes Appreciation Month: The Great Lakes Facts and Features
July is Lakes Appreciation Month. Let’s celebrate it by learning more about the Great Lakes.
When people think of water resources for boating, fishing or swimming, they think of local or state rivers and lakes. The don’t think of these “close to home” water resources as part of a much bigger water system that encompasses all or part of a number of states and Canadian provinces: The Great Lakes watershed.
The Great Lakes and its watershed are massive. So large in fact, its natural features can be seen from the Moon. It has a coastline of 10,200 miles (if you include its many islands coasts, it increases to 10,900 miles) and its water surface area is more than 95,000 square miles. The entire watershed from Minnesota to the St. Lawrence Seaway covers about 295,000 square miles. Michigan’s Great Lakes coastline of 3,288 miles is second only to Alaska. About 80 percent of United States shoreline is privately owned while only 20 percent in Canada is in private ownership.
The Great Lakes contain approximately six quadrillion gallons of water which is more than one-fifth of the world’s fresh water. If all of these quadrillion gallons were poured over the 48 contiguous states, it would be nine and a half feet deep from coast to coast.
Retention time in a lake is the amount of time it takes for a lake to move pollutants through and out of it. These times vary for each of the Great Lakes based on size, depth and current. These are the retention times for each of the Lakes:
- Lake Superior: 191 years
- Lake Michigan: 99 years
- Lake Huron: 22 years
- Lake Erie: 2.6 years
- LakeOntario: 6 years
The Great Lakes contain more than 30,000 islands. Most are too small for inhabitants; however, the ManitoulinIsland in Lake Huron is nearly 1100 square miles in size and the largest island in any water body on earth.
The Great Lakes borders eight U. S. states: Michigan, New York, Pennsylvania, Ohio, Indiana, Illinois, Wisconsin and Minnesota and two Canadian provinces: Ontario and Quebec. Four of the 12 largest cities in the United States are located on Great Lakes shores.
35 million people live in the Great Lakes watershed and these lakes provide drinking water for 40 million people and an additional 56 billion gallons of water are used daily in municipal, agricultural and industrial activities.
The Great Lakes are the largest inland water transportation system in the world. Dozens of national and international ships move cargo through these waters to a number of Great Lakes ports. Freighters transport a variety of materials, including iron ore, coal and grain, and provide approximately 60,000 jobs throughout the region.
There have been numerous shipwrecks on the Great Lakes over time. The most recent was the Edmond Fitzgerald, the largest freighter to sail the Great Lakes at that time. On November 10, 1975 it sank during a storm in Lake Superior taking 29 lives. It sinking was recorded in history through Gordon Lightfoot’s ballad “The Wreck of the Edmond Fitzgerald.”
Using Google Earth, the Great Lakes Environmental Research Laboratory (GLERL) has developed a narrated tour of the Great Lakes that highlights points of interest in each of the Great Lakes and identifies some unique underwater features. The intent of this tour is to inspire people to use the tool to create their own tours. For instructions on using the National Oceanic and Atmospheric Administration (NOAA) Great Lakes Tour Page.
For information on Great Lakes history, go to Michigan State University Extension’s article Lakes Appreciation Month: Great Lakes History & Inhabitants.