How do Great Lakes get water? What feeds the Great Lakes?

The Great Lakes, a series of interconnected freshwater lakes along the Canada–US border, are a marvel of nature. They are the largest group of freshwater lakes on Earth by total area and second-largest by total volume. But have you ever wondered where all that water comes from?

The primary source of water in the Great Lakes is precipitation. The average annual rainfall in the Lake Superior basin is 30 inches, 31 inches in Lakes Huron and Michigan, and 34 and 36 inches in Lakes Erie and Ontario, respectively. This precipitation increases from west to east and from north to south.

In addition to precipitation, the Great Lakes receive water from thousands of streams and rivers covering a watershed area of approximately 520,587 square kilometers (or 201,000 square miles). The flow of water in the Great Lakes system moves from one lake to another eastward, ultimately flowing into the Atlantic Ocean.

Groundwater discharges into local surface water also contribute to the water entering the system. This groundwater comes from the water that soaks into the ground after rainfalls and slowly moves through the ground to eventually reach the lakes.

In conclusion, the Great Lakes get their water from a combination of sources including precipitation, rivers, streams, and groundwater. This diverse water supply helps maintain the lakes’ vastness and supports the rich biodiversity found within and around them.