INVENTORYING SPRINGS IN SUPPORT OF GROUNDWATER SUSTAINABILITY

Over the last decade, the number of new high-capacity wells approved in Wisconsin has steadily grown. Some of the new high-capacity wells, defined as pumping 70 gallons per minute or more, serve municipalities, but many are for agricultural and industrial uses. In an effort to maintain a sustainable balance between beneficial human uses and ecological water needs, Wisconsin law requires consideration of a well’s impact on springs, trout streams, or other outstanding resource waters prior to approval. This permit review process has prompted funding of a statewide inventory of springs by the Wisconsin Geological and Natural History Survey. Over a three-year period, county-level field surveys of springs and semiannual surveys of reference springs selected from representative geological, hydrological, and ecological regions of the state are being conducted. During the first seven months of field work, project personnel recorded locational, environmental, geological, geomorphic, and hydrologic conditions of over 100 springs in 18 counties. This information is useful not only in evaluating the effects of pumping on spring discharge, but also in revealing spatial patterns of springs that inform geological controls on groundwater flow in different regions of the state. For example, many large springs in southern Wisconsin are associated with shallow groundwater flow near the margins of terminal and recessional moraines, whereas others line the subcrops of major geologic units suggesting more complex groundwater flow paths. Comparing modern inventory results to older maps of springs from the 1950s helps assess the effects of land use or climate change on groundwater resources. When completed in 2017, the springs database will represent a comprehensive source of information to better manage the aquifers that support the agricultural, industrial, and ecological water needs of the state.