What Makes a Lake

Nature Watch
June 25, 2008

By Sue Benson,
Director of Education, CNHM


What Makes a Lake?

The natural history of Wisconsin is a story of water, with the main characters being the glaciers, lakes and rivers that shaped and are still shaping the land. In fact, the word “Wisconsin” means “gathering of the waters.” In addition to wetlands, rivers, streams, and 1,000 miles of Great Lakes shoreline, Wisconsin is home to more than 15,000 inland lakes.

What makes a lake?

A lake is a body of standing water that can be formed naturally (by melted glacial ice, naturally dammed rivers, or other natural processes) or by human actions (reservoirs or farm ponds). Lakes are a critical part of the environment, serving as the collection point for all of the water that falls in its watershed — the surrounding rivers, streams and land that drains water into the lake. Lakes also provide important habitat for countless plants and animals, and provide us with aesthetic beauty and recreational opportunities.

Though we may come up to our favorite lake summer after summer, lakes don’t last forever. They get old naturally over time, filling with sediments, nutrients, plants and algae. The process usually takes thousands of years, though different human activities can either delay or speed the process.

Near the shores of the lake grow reeds and cattails and floating mats of sedges. Slowly, generations of sedge-mats die and sink to the bottom of the lake and decompose. Given enough time, the lake becomes a cattail marsh or sphagnum peat bog, where eventually there is no open water left. The lake has transformed from an aquatic community to a wetland community and will eventually become a wet meadow or perhaps a black spruce forest growing on peat.

As you travel the back country of the northland, keep your eyes open for “old” lakes — grassy lowland areas or depressions that may still be wet and spongy and are less thickly wooded than the surrounding land.

Brought to you by the Cable Natural History Museum. For 40 years, the Museum has served as a guide and mentor to generations of visitors and residents interested in learning to better appreciate and care for the extraordinary natural resources of the region. They invite you to visit their facility in Cable on 43570 Kavanaugh Street or at the website at www.cablemuseum.org to learn more about their exhibits and programs.