Not all the water in a watershed is running water. Some of it is standing water. Lakes, ponds, and wetlands form when running water gets caught in low places. People use them for fishing, swimming, boating, and water-skiing. We usually take them for granted. Have you ever stopped to think of how important they are?
 
Lakes and ponds are dimples in the earth's crust. Underground springs and runoff from precipitation and melting snow fill them and keep them filled. They are formed in many different ways.
 
Lakes can be formed by sediment blocking a stream or river. They can also be formed by glaciers which carve out deep depressions in the surface of the earth.

Lakes can also be man-made. They are called reservoirs. They are formed by damming a stream or river. Water backs up behind the dam, forming a lake.
 
Reservoirs are made for several reasons. First, they help prevent flooding during periods of heavy rainfall or melting snow. They also can be used to store drinking water for nearby cities. The running water behind the dam can be used to make electricity.