The Lake Wingra watershed totaling about 4525 acres (2056 hectares) in Dane County, Wisconsin is about 75% developed. Urbanization, storm water runoff laden with pollutants and sediment, and reduced flow from natural springs have opened niches for aquatic and terrestrial pest species that have invaded the lake and surrounding wetlands and uplands. These changes affect property values, diminish the recreational experiences we all enjoy, and threaten to lessen the educational and scientific value of the lake and watershed.
The undeveloped portions of the watershed contain a mix of remnant, restored, partially restored and degraded wetlands, grasslands and woodlands. These natural areas are found in a larger landscape context of residential, commercial and industrial activity. Major restoration challenges include impacts from land use and cover type changes, fragmentation of habitat, altered hydrologic regimes and human overuse.
We normally think of the watershed in terms of surface water, or where the storm water flows. The size and shape of this kind of watershed is typically determined by topography and the layout of streets and roads. But there is also an invisible watershed below ground–the groundwater boundary. The figure linked below shows these two watersheds in the Lake Wingra basin.
Groundwater/Storm Water Boundaries
The Lake Wingra watershed has a long history of human occupation dating from native American times. Native Americans and European settlers valued the natural springs that surrounded the lake. Early in the 20th Century large-scale disruption began when developers divided Lake Wingra’s eastern marsh in two and cut off it from the Lake by a residential development and Arboretum Drive. Subsequently, they ditched, dredged, and filled the marshes. For more perspective and detail see “about the lake and the watershed”, provided by the Friends of Lake Wingra
As the Cities of Madison and Fitchburg and the Town of Madison have grown up around the watershed, population growth, residential and commercial development and associated highways, utility lines and storm water conveyances have further fragmented and perforated the watershed.
In the end, human activities have replaced soft, permeable soil with roofs, roads, and parking lots the result is that more storm water runoff enters the wetlands and lake and less water infiltrates into the soil. Annually, an estimated 110 million cubic feet/year (nearly 823 million gallons) of storm water runoff flows into the Arboretum and on to the lake.
These land use changes have dramatically altered watershed hydrology. Originally, the watershed had nearly 30 groundwater springs, mostly near the lake; today only about 13 survive, the rest having been lost to road, houses and utility infrastructure.
The social and cultural history of springs is fascinating. Springs are where groundwater emerges to replenish wetlands, streams, and lakes. Springs are important indicators of social and ecological health. We will explore the death and revival of Lake Wingra’s springs in this blog. To learn more about Lake Wingra’s watershed management issues, checkout my Storm Water page or Pest Species page.