This project will study and numerically model road salt impact on water quality in a typical aquifer in eastern Massachusetts. The study area is a public water well field in the Town of Norwell presently instrumented with 3 multiparameter sensors at different aquifer depths and one sensor located in the nearby stream. The well field is within a glacial outwash area with simple subsurface geology and lies a short distance from major road salt sources including MA Rt. 3, a mall, and lies downstream from a road salt storage shed. The study will include an expanded water quality monitoring, field measurements and chemical analyses of water samples at Boston College, and stable isotope ratios analyzed at other laboratories with the objective to delineate sources of road salt. Since the brine runoffs in the winter months have higher densities, the contaminated water will inevitably force a free convective transport within the aquifer in addition to an advective flow. We plan to use a variable density simulation model (USGS SEAWAT finite difference model) to determine road salt pathways in the subsurface by constructing multiple 2D numerical simulations of chloride concentrations and flow paths around the highway toward the public wells.