ERC was the surface water resource specialist tasked with reviewing Denver Water’s Platte and Colorado Simulation Model (PACSM) of the Colorado and South Platte River Basins for Denver Water’s Moffat Collection System Project EIS. ERC identified and implemented changes to improve PACSM. ERC’s review of modification of PACSM required detailed knowledge and understanding of South Platte and Colorado River basin administration, water rights, facilities and operations. ERC reviewed the configuration of each of the EIS alternatives in PACSM and was responsible for assessing Denver Water’s diversions under the EIS alternatives and the effects on other water rights and streamflows in the Colorado River and South Platte River basins. ERC used model output to complete the surface water impacts analysis and associated sections of the EIS document and support evaluations of resources affected by changes in flow and reservoir contents including wildlife, aquatic resources, recreation, stream channel morphology, wetlands and riparian habitat, floodplains, and water quality. ERC also assisted with the review of the Purpose and Need Statement and alternatives development and screening for the EIS process.