Illustration of how water enters and leaves lakes

Natural lakes in Wisconsin are classified into three types based on how water flows in and out of the lake.  A lake may gain water from precipitation, stream inflow, or groundwater inflow.  It may lose water from evaporation, stream outflow, and groundwater outflow.  Based on these characteristics, the lakes featured on our website fall into three types: drainage lakes, seepage lakes, and spring lakes.

Drainage Lakes

These lakes have both inlet and outlet streams, with the inlet stream being the main source of lake water.

While most major rivers in Wisconsin have drainage lakes along their course, drainage lakes support fish populations that are not necessarily identical to the streams connected to them.

Drainage lakes usually have higher nutrient levels than many natural seepage or spring lakes.

Seepage Lakes

Seepage lakes are the most common lake type in Wisconsin.

These lakes do not have an inlet or an outlet, with precipitation or runoff being the principal water source, supplemented by groundwater from the immediate drainage area. Water levels in seepage lakes may fluctuate seasonally with changing groundwater levels and rainfall patterns.

Since seepage lakes are landlocked and not influenced by streams, they frequently have a less diverse fishery and lower nutrient levels than drainage lakes.

Spring Lakes

Spring lakes have an outlet but no inlet. Their primary water source is groundwater flowing into the bottom of the lake from nearby surface areas.

Spring lakes are the headwaters of many streams and are a relatively common type of lake in northern Wisconsin.


A lake’s type significantly influences its water quality and the species of fish present. Therefore, knowing a lake’s type can help you decide if a lakefront property is right for you.

Understanding Lake Data