The sandy uplands of the Bayfield Peninsula are primary contributors to regional groundwater recharge and provide baseflow to streams in the area. Few data exist, however, to characterize upland hydrogeology or its susceptibility to groundwater contamination. Here, data from two new cores and wells, one existing well, and a lake in the sandy uplands provide information about the local hydrogeology and contribute to the understanding of the regional groundwater system. Final report to the U.S. Forest Service.