A groundwater-flow model will be developed using the USGS MODFLOW computer program (Harbaugh, 2005). Additional computer programs will be used to track groundwater flowpaths from recharge to discharge and model the saltwater-freshwater interface (Pollock, 1994; Bakker and others, 2013). The model will utilize updated geology and information about the observed location of the freshwater-saltwater interface in the Magothy and Lloyd aquifers. The groundwater-flow model will be calibrated to match observed field data including chloride and water-level information. The model will be used to simulate various scenarios, including changes in groundwater withdrawals, aquifer recharge management, and climate change. These scenarios will be developed in collaboration with the New York State Department of Environmental Conservation and the Steering Committee.