Lake Michigan is a freshwater lake. Lake Michigan is not saltwater.
Lake Michigan is Freshwater
Lake Michigan is a freshwater lake. How does a body of water qualify as freshwater?
What is Freshwater?
Definitions for freshwater differ. The Groundwater Foundation defines freshwater as water containing less than 500 parts per million (ppm) dissolved salts (source). The American Meteorological Foundation defines freshwater as water containing less than 1000 ppm dissolved solids, a definition that includes other materials besides salt (source).
Lake Michigan is Freshwater
By either definition, Lake Michigan is freshwater and is not saltwater. The water in Lake Michigan has 15 ppm of dissolved salts. This means that Lake Michigan is a freshwater body of water.
Lake Michigan is not Saltwater
Because Lake Michigan is a freshwater body of water, by definition it is not a saltwater body of water. This is the case for all of the Great Lakes, which are all freshwater bodies of water.
The Salinity of Lake Michigan is Increasing
Even though Lake Michigan’s salinity is far below the threshold necessary to be considered freshwater, scientists are concerned that the salinity is increasing. It seems to have increased 7 times over the last 200 years (source).
The majority of that increase in salinity is attributable to road salt washing into tributaries of Lake Michigan and then passing into the lake itself. Lake Michigan is heavily settled, especially along its shores that border Indiana, Illinois, and southern Wisconsin.
These areas have harsh winters with plenty of snowfall and ice, meaning that road crews often use much salt to keep travel safe. While that road safety is certainly a benefit, it has come at a cost to the salinity of Lake Michigan.
While Lake Michigan has a long way to go before becoming a saltwater sea, scientists are concerned that increased salinity will have poor outcomes for public health and for fragile ecosystems.
The Great Lakes of North America
The Great Lakes of North America are one of the world’s largest freshwater reserves, containing 21 percent of the world’s freshwater and 84 percent of North America’s freshwater. They are one of North America’s easiest identifiable features from space. They are important for shipping and recreation. They do supply drinking water. For example, much of Chicago’s drinking water comes from Lake Michigan. However, they supply a relatively small amount of drinking water.
The five Great Lakes of North America are:
- Lake Superior
- Lake Michigan
- Lake Huron
- Lake Erie
- Lake Ontario
Lake Michigan/Huron
Hydrologically, Lake Michigan is one hydrological unit along with Lake Huron. Lake Huron and Lake Michigan are connected to each other through the Straits of Mackinac, which are about five miles wide. Lake Michigan is connected to Lake Superior, which drains into it, through the St. Mary’s River.
States that have shorelines along Lake Michigan include Wisconsin, Michigan, Illinois, and Indiana. Major settlements along the Lake Michigan shore include:
- Sheboygan, Wisconsin
- Milwaukee, Wisconsin
- Chicago, Illinois
- Gary, Indiana
- Benton Harbor, Michigan
The Great Lakes of Africa
North America is not the only continent with a region of huge, freshwater lakes. This might surprise many people, but Africa also has a Great Lakes region. The Great Rift area of East Africa has ten large lakes containing about 25 percent of the world’s unfrozen fresh water.
The Great Lakes of Africa include:
- Lake Victoria
- Lake Kyoga
- Lake Albert
- Lake Edward
- Lake Tanganyika
- Lake Kivu
- Lake Mweru
- Lake Malawi
- Lake Turkana
- Lake Rukwa
Lake Baikal
Another large freshwater lake is Lake Baikal in southern Siberia of Russia. Even though Lake Baikal has a relatively small surface area, its great depth means that it holds 20 percent of the world’s unfrozen freshwater reserves. Lake Baikal has about 1,000 species that can be found nowhere else in the world. (Source)
List of the World’s Largest Freshwater Lakes
These are the world’s largest freshwater lakes, from largest to smallest:
- Lake Baikal
- Lake Tanganyika
- Lake Superior
- Lake Nyasa
- Lake Michigan
- Lake Huron
- Lake Victoria
- Great Bear Lake
- Great Slave Lake
- Lake Ontario
- Ladoga
- Titicaca
- Reindeer
- Helmand Erie
Summary
- Lake Michigan is freshwater.
- Lake Michigan is not saltwater.
- The salinity of Lake Michigan is increasing due in large part to human activity.
- Lake Michigan is one of the Great Lakes in North America.
- There are other large freshwater lakes around the world.
