Ecological connectivity between the Great Lakes and their tributaries is widely impaired, and many agencies and organizations are currently investing in restoring these connections to enhance target fish and wildlife populations. To assist in targeting these investments, we have been developing spatial data on the location and attributes of barriers (dams and road-stream crossings) and fish breeding habitat throughout the Great Lakes basin to analyze the optimum strategy for enhancing connectivity and restoring fish migrations. The proposed work will result in guidance for barrier restoration at scales from individual watersheds to the entire basin, refine methodologies for spatial analysis of barriers, and provide an initial framework for comparing costs (direct economic costs, species invasions) and benefits (connectivity, focal fish species) of barrier removal. Our work is also filling a need for greater coordination and data exchange among agencies, NGOs, and academics working on connectivity in the Great Lakes.