Building on earlier work on the Oak Ridges Moraine, Earthfx worked with the Toronto and Region Conservation Authority (TRCA) to develop key surface water and groundwater components of the Rough River Watershed Plan. Earthfx tasks included surface water modelling, land development impact assessment, climate change, and groundwater model simulations of the watershed. A surface water model was developed using the WABAS model, which Earthfx converted and applied in a fully distributed form for this study. Model simulations were used to evaluate changes in recharge and runoff patterns in the watershed due to land development and climate change. Sustainable Community scenarios included simulation of recharge enhancement due to pervious pavement, roof water management and other Low Impact Development (LID) practices. Recharge estimates were applied to a USGS MODFLOW groundwater model to evaluate long term changes in groundwater levels under a variety of scenarios, and particle tracking simulations from high discharge reaches were used to understand groundwater flow pathways. Finally, the coupled SW and GW models were used to estimate all major components of the watershed water budget.