The United States Department of Energy's Hydropower Program has recently completed a study of fish passage and protection mitigation practices at conventional hydroelectric projects. The study used 16 projects as case studies to provide detailed illustrations of mitigation practices, allowing a better understanding of the resource and economic requirements, and the ramifications of mitigation choices. The study also surveyed fish passage and protection mitigation practices at 1,825 hydroelectric plants regulated by FERC to determine the frequencies of occurrence, temporal trends and regional practices based on FERC regions. Facilities with upstream mitigation employed fish ladders (62% of facilities), trapping and hauling (11%), fish lifts (5%), and other methods (35%). Some facilities used multiple forms of mitigation, this accounts for the percentage total greater than 100%. Downstream mitigation is used in some form at 13% of the 1,825 sites studied. Mitigation costs varied greatly, depending on the size of the facility and extent of mitigation. Fish ladder capital costs rang from $1000- $34.6million with an average cost of $7.4million per fish ladder. The costs of fish passage and protection measures can have significant effects on the economics of a project. However, forecasting the need for fish passage mitigation is complicated due to many site-specific concerns. Specific mitigation needs are often met with specific technologies including fish lifts, trapping and hauling systems, or fish ladders. In any case, mitigation determinations should be made with an eye toward biological needs as well as economic feasibility.