Restore upstream fish migration in Northwest Branch and Sligo Creek by modifying twelve existing “in-stream” fish barriers. Barriers are in the form of exposed utility lines and dams that were installed in the past to protect utility lines and control water elevations. Because most of these utilities are still in use, removal of the utilities is not practical. Therefore, each of the blockages will be modified by constructing natural rock structures known as riffle-grade control structures (RGC) and boulder-step pools (BSP). The RGC and BSP structures serve to raise upstream water surface elevations through flow constriction and water elevation control. Within the RGC, a low flow channel will be designed to provide the appropriate velocities and depths of flow during spring fish spawning season. In addition to ensuring appropriate velocity and flow characteristics, the structures provide fish resting areas in the form of large boulders where fish can rest and make use of the flow eddies to propel them upstream.