Trout fishers in the Driftless Area of the upper midwest know that their fishery depends upon cold waters emerging from thousands of springs throughout the region. They also know that groundwater quality in the region is vulnerable to agricultural practices, pollution, industrial spills and inadequate waste management. A seven-year study, recently completed by Prof. Calvin Alexander at the University of Minnesota, has mapped a number of springsheds in the region, providing a high-resolution tool for understanding the effects of surface events on groundwater quality. A watershed description of the catchment basin contributing flow to a stream system has long been useful in understanding water quality and flow. The springshed concept, identifying and mapping the basin contributing to the flow of an individual spring, now makes it possible to examine specific surface inputs, for example, from sinkholes, roadside ditches, cropland tiling, and manure spreading, in order to better understand how to protect groundwater resources from irreparable damage.
For more information on the techniques for mapping subterranean waters, see the excellent article in the most recent issue of the Minnesota Conservation Volunteer.