Narrow bar spacing’s (less than or equal to 2 inches) have been installed at many hydro project intakes to reduce entrainment of fish through turbines and, when combined with angled structures, to guide them to downstream bypasses. The ability of narrow bar spacing’s to prevent entrainment is dependent on fish size and behavior and approach velocities. Even when fish are small enough to pass through a given bar spacing, many fish will actively avoid entrainment through intake racks as long as approach velocities are low enough for them to escape. Additionally, the relatively small size (less than 8 inches in length) of most fish that are entrained at hydro projects (with and without narrow bar spacing) usually results in high turbine survival rates. Therefore, determining appropriate bar spacing’s for any species or life stage should include estimation of physical and behavioral exclusion associated with proposed intake modifications, as well as estimates of turbine passage survival for fish that are entrained. These parameters can be estimated using existing data describing bar rack exclusion efficiencies and theoretical models developed for predicting turbine passage survival. When combined with the proportion of fish expected to pass over spillways for the expected river flows during a migration season, the bar rack exclusion and turbine survival estimates can be used to calculate total downstream passage survival for several bar spacing’s and a range of fish lengths in order to assess relative effectiveness. A dataset developed for shortnose sturgeon at a hydro project in the Northeast will be presented to demonstrate how such an analysis can be used for determining appropriate bar spacing’s for effectively protecting sturgeon species at any project.