What's the Difference Between a Lake and Pond?

When does a pond become a lake? It may surprise you to know there is no technical difference between lakes and ponds. However, there is a general rule of thumb: If a body of water is large and deep it's a lake, and if it's short and shallow it's a pond. But how deep is deep? And how small is small?

Snapper Pond at Goodenow Grove Nature Preserve. (Photo by Chad Merda)

While the distinction between lakes and ponds can be a bit blurry, there are some guidelines. For example, if sunlight can reach the bottom of the entire body of water, it's generally considered a pond. If the body of water is deep enough in some places that sunlight cannot reach the bottom, it's generally considered a lake.


When it comes to size, there are no exact guidelines. Ponds are generally smaller than lakes, but there's no universal standard. That means some bodies of water we call ponds might be considered lakes by some individuals. And some lakes may be more pond-like to some people.

 

Words to know

Distinction: A difference between two similar things or people.

Inexact: Not quite accurate or correct.

Universal: Affecting all things in a particular group.

 

Illinois attempts to differentiate lakes and ponds, but it's not absolute. Bodies of water of more than 20 acres are considered lakes and reservoirs, and those under 20 acres are ponds. However, a body of water of less than 20 acres is still considered a lake if its maximum depth is greater than 6 1/2 feet or if bedrock shorelines make up all or part of the waterway's boundary. See, it’s confusing.


No matter how you define them, there are a lot of lakes and ponds in Illinois. The state is home to some 2,900 lakes and 8,400 ponds. But that's nothing compared to states like Minnesota, which is known as the Land of 10,000 Lakes. Actually, though, Minnesota is home to far more lakes than its nickname implies. Minnesota has about 14,380 lakes, a figure that does not include any bodies of water of less than 10 acres.


All these inexact standards for lakes and ponds can cause confusion for sure. Take the Caspian Sea, which lies between Europe and Asia. It's the largest inland body of water in the world, which would seem to make it the world's largest lake and not a sea at all. The difference between a sea and a lake? While lakes are fully surrounded by land, a sea is only partly surrounded by land.


The Caspian Sea is fully surrounded by land, but it contains saltwater, which is not typical for lakes. However, it's by no means the only saltwater lake in the world. Take Great Salt Lake in Utah. It, too, is a saltwater lake, and there are many others in the world as well.


If you remove the Caspian Sea from the equation, the world's largest lake is Lake Superior, one of the five Great Lakes. Lake Superior is the largest freshwater lake in the world, at about 32,000 square miles. It contains 3 quadrillion gallons of water, which is more water than in the other four Great Lakes —Huron, Michigan, Erie and Ontario — combined. Lake Michigan is the world's fifth largest lake, but it has another claim to fame as well: It's the largest lake in the world located entirely in one country. The other four Great Lakes are bordered by Canada as well as the United States.


Collectively, the Great Lakes are one of the largest freshwater systems in the world, accounting for 21% of the world's supply of fresh surface water. In North America, 84% of all available fresh surface water is in the Great Lakes. More than 30 million people — 10% of the U.S. population and 30% of Canada's population — rely on the Great Lakes for their drinking water.

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