INSIGHTS GAINED FROM A STATEWIDE INVENTORY OF SPRINGS

With the aim of improved management of groundwater and groundwater-dependent ecosystems, the Wisconsin Geological and Natural History Survey undertook a statewide inventory of springs with flow rates of 0.25 cubic feet per second (cfs) and higher. The inventory, completed in July 2017, consists of one-time surveys of individual springs and semi-annual surveys of six reference springs selected from representative geological, hydrological, and ecological regions of Wisconsin. Quantitative and qualitative descriptions of 415 springs indicate the extent to which the features have been impacted by human activities. Over half of the springs display moderate to high levels of disturbance, such as dredging, the presence of a spring house, recreation, or access to livestock. The springs also reveal spatial patterns of geologic origin, topographic position, and spring water chemistry, which will help in developing or refining questions that are most relevant to certain classes of springs in the state. Most springs in Wisconsin form as a result of preferential groundwater flow through fractures in exposed or shallowly buried Paleozoic sedimentary strata. Others form at the break in slope along end and interlobate moraines in glaciated regions of the state. Patterns in spring water chemistry align with those in geologic origin and topographic position, providing further insight into groundwater flow paths and residence times. Finally, the inventory allows for summary statistics of properties for all surveyed springs at the time of the inventory, such as mean (0.96 cfs) and median (0.61 cfs) spring flow. Used in association with spring morphology and area, spring fluxes (spring flow/spring area) provide a meaningful way to categorize springs and distinguish between those dominated by more discrete versus more diffuse groundwater flow.