Drained lakes - These lakes have no inlet, but like spring lakes, have a continuously flowing outlet. Drained lakes are not groundwater-fed. Their primary source of water is from precipitation and direct drainage from the surrounding land. Frequently, the water levels in drained lakes will fluctuate depending on the supply of water. Under severe conditions, the outlets from drained lakes may become intermittent.
Drained lakes are the least common lake type found in Wisconsin.
Artificial Lakes Artificial lakes are human-made bodies of water referred to as impoundments . In this publication, a lake is considered an impoundment if one-half or more of its maximum depth results from a dam or other type of control structure. An impoundment is considered a drainage lake since it has an inlet and outlet with its principal water source coming from stream drainage. Approximately 13 percent of Wisconsin's lakes fit this definition. The water quality of a lake and species of fish present are significantly influenced by the lake type.