Inland lakes of Wisconsin are categorized by size, alkalinity, water source, and depth. Topography, glaciation, soil composition, surrounding land use, rock composition, and post-glacial water flow all factor in to the lake’s characteristics and classification.

Depth:

Water depth influences stratification, along with surface area, water clarity, and the water source. Deeper lakes are typically stratified, marked by levels of variation in temperature at different depths.

Size:

The Wisconsin DNR classifies lakes greater than 10 acres as either mixed or stratified. Stratification is important when determining if the lake has a suitable habitat for fish, aquatic life, as well as determining the overall lake condition. Bodies of water less than 10 acres are considered part of the small lake community and not frequently monitored for water quality, fish, or aquatic plant data.

Alkalinity:

Alkalinity refers to hard water or soft water. Generally, soft water lakes have a ppm below 50 and less ability to buffer acids. Hard water lakes have a total alkalinity equal to or above 50 ppm, and this makes them less prone to acidification. The carbonate and bicarbonate ions help to buffer acid from forming.

Water Source:

1- Spring

Spring lakes are headwaters of many streams, and a fairly common lake type in Northern Wisconsin.

2- Seepage

Seepage lakes primarily source water from precipitation and runoff. These landlocked bodies of water are also the most common type of lake in Wisconsin.

3- Drainage

These lakes are often found along major rivers. They have both an inlet and and outlet, and the water mainly comes from streams.

4- Impoundment

Impoundment Lakes form when a dam adds one-half or more to the depth of a drainage lake.