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Water classifications

Fishing Wisconsin

A water body must be classified as either a lake or a river by the Wisconsin Department of Natural Resources (DNR) to enforce Wisconsin boating restrictions and apply provisions of the shoreland access and zoning laws.


Impoundments are generally considered to be the pool created by the dam. The DNR is considering whether the waters upstream of the pool, which is raised but still generally in the original river channel, should be considered part of the impoundment. The terms "flowage" and "impoundment" are synonymous.

Streams and rivers versus lakes

In Wisconsin, there is no legal distinction between a river or a stream. However, Wisconsin law does distinguish between lakes and rivers. Over 100 years ago, in a case involving a dispute over a marshy area in Green Lake County, the court ruled that:

the controlling distinction between a stream and a lake or pond is that in the one case, the water has a natural motion, a current, while in the other, the water is, in its natural state, substantially at rest... Ne-pee-nauk Club v. Wilson, 96 Wis. 290 (1897)

In some instances, the classification of a water body as either a lake or stream is under dispute. The DNR primarily uses the concept of motion known as the perceptible flow test to make its determination. In addition, DNR may use the DNR publication Wisconsin Lakes (PUB-FH-800 2001) and common understanding as secondary factors in making this determination.

Frequently asked questions

For additional information on Wisconsin fishing (e.g., maps, fish consumption advisories), please see our list of frequently asked questions.