To aid urban entities desiring to reduce runoff from precipitation while increasing aquifer recharge, we present an approach for simultaneously quantifying runoff and infiltration. Developing the approach involved using: (1) the Windows version of the Source Loading and Management Model (WINSLAMM) to estimate runoff from precipitation in areas with green infrastructure (GI); and (2) the SCS runoff curve method to estimate infiltration. Computed infiltration and runoff values enable the estimation of the runoff reduction and infiltration increase due to alternative GI construction modes. We relate infiltration ratios to land use for a range of event rainfall depths in southwestern USA. These ratios can aid estimation of aquifer recharge while improving storm water management. We apply the approach to a Salt Lake City residential area for current land use and three assumed runoff control practices. Although currently applicable for a wide range of precipitation and urban land use situations in southwestern USA, the approach is extensible to guide urban development elsewhere.