DEVELOPING A GROUNDWATER FLOW MODEL FOR SLOUGH MANAGEMENT IN SAUK COUNTY, WI

In recent years, there has been a marked decrease in the water quality of the Lower Wisconsin River floodplain lakes. In particular, high nitrogen concentrations, low dissolved oxygen levels, and dense metaphyton cover have been observed in Jones Slough, Norton Slough, and Bakkens Pond - all located within Sauk County, WI. Although the exact causes for the deterioration in water quality are unclear, nutrients applied via fertilizer and manure to sandy soils in the agricultural areas of the adjacent Pleistocene terrace are likely contributors to the problem. The goal of this project is to develop a groundwater flow model that delineates the recharge areas for groundwater that discharges to these lakes in order to identify possible pollutant sources. The study area includes parts of the Driftless Area groundwater flow system that traverses the Pleistocene terrace and eventually flows into the floodplain. Within the floodplain, wetlands and oxbow lakes intercept some of the groundwater before it reaches the river. Groundwater and lake water sampling and water level monitoring have been ongoing since May 2014 at sites within the floodplain and along the river itself. These data will provide calibration targets for the flow model. The final model will be used to evaluate the design and effectiveness of “groundwater buffers” as well as other conservation measures to mitigate nutrient loading and restore sensitive fish habitat while balancing the economic and recreational needs of the surrounding community.