Session A5- A positive barrier guidance system designed to improve safe downstream passage of anadromous fish

Many anadromous fish species, such as Pacific and Atlantic salmon (Onchorhynchus spp.; Sahno sp.) and the shads and river herring (Alosa spp.), are in danger of extinction throughout some or all of their range. Many state and federal laws now mandate protection of these and other fish populations. Impacts to these populations include entrainment at hydroelectric dams and other water conveyance facilities. Facility operators must often implement physical or operational modifications to reduce fish entrainment. This paper documents a positive barrier Fish Guidance System (FGS) that has successfully guided actively migrating juvenile anadromous fish to safer bypass systems, thereby reducing entrainment. Most juvenile anadromous species migrate in the thalweg, taking advantage of higher velocity water to speed their migration. The FGS design takes advantage of this migratory behavior and guides fish to a safer point of egress. The FGS is composed of a series of floating panels anchored across the channel above an intake structure. The design and configuration of the FGS varies at each site according to hydraulic conditions and species present. Recent fish passage research demonstrates that the FGS provides variable, but significant, guidance for many juvenile fish species in a variety of hydraulic conditions. A prototype FGS installed in a high velocity environment improved guidance of juvenile Pacific salmon to an existing fish bypass system by up to 15%. In a low velocity environment, over 90% of radio tagged juvenile Pacific salmon were guided to the location of a small surface fish collector. The FGS may also provide some benefit to adult fish migrating downstream, but this has not yet been tested to date. Guidance and passage survival are being tested at several more FGS installations in 2011