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conducted in the Gunnison River up- and downstream of the Redlands Diversion Dam (RM 35-0.7) and in the Upper Colorado River from the Grand Valley Irrigation Dam to the Utah/Colorado state line (RM 185-131). Description of the Fish Passageway The 107-m long Redlands fish passageway is primarily constructed of concrete and skirts the diversion dam on the east side of the river (Figure 2). It is a non-alternating, vertical slot/orifice design with 49 removable aluminum baffles (weirs). The baffles were designed to be removable so that the hydraulic slope of the ladder and length of the pools could be changed, if desired. In developing the design, it was believed that Colorado pikeminnow would use a 10% sloped fishway, but was not known if a 5% sloped fishway would work better. So gentler slopes could be tested, baffles were made removable. The final bottom slope of the fishway is 3.75%. The width of the vertical slot is 0.5 m and the orifice is 0.3-m wide by 0.5-m high. The maximum combined flow to run the passageway and the 1.1-m diameter bypass pipe which provides attraction flow at the entrance gates is about 100 cfs (25 cfs for the fish passageway and 75 cfs for the bypass). The stage of the river primarily determines the depth of water in the fish passageway; however large amounts of debris, algae, and accumulation of trash on the trash grates can decrease the flow and lower the water depth in the passageway and bypass pipe. The fish passageway is self-regulating, that is, hydraulics within and velocity between the 1.8-m individual pools remain relatively constant regardless of the stage of the river. There are four riverside entrance gates at the bottom of the fish passageway and a fish trapping facility located at the upper end or forebay. At the lower end of the fish trap is a "V"-shaped structure constructed of 2.1-cm diameter aluminum conduit placed vertically (0.9-cm spacing) that serves to guide and direct fish into the trap and deter them from escaping downstream. A free- floating log boom is attached to the concrete walls on both sides by chain and spans the mouth of the forebay. The log boom traps and deflects large floating riverborne debris past the forebay downstream. Two sets of metal trash grates, located within the forebay, trap smaller debris. The first set of four vertical grates has a spacing of 10.2 cm; the second set has a spacing of 1.9 cm. The passageway was primarily designed to allow larger-sized fish to move exclusively upstream; larger fish upstream of the dam that desire to move downstream must do so by "falling back" over the dam. Therefore, it is not considered a "run-of-the-river" passageway. Once fish have negotiated the entire 7