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and 0.7) to establish stage versus discharge relationships. Kevlar cable was stretched across the entire channel between two steel fence posts. Channel cross sections encompassed the entire river channel and usually extended to the high-water mark. Transects were surveyed from high points from the right shoreline to the left shoreline. Elevation was correlated with known control points and recorded as absolute (feet above sea level). For each transect, a person in a one-man kayak held a staff rod with a reflecting laser prism and worked from one shoreline to the other. All distance and elevation measurements were recorded with an EDM (electronic distance meter), that corrected for up- and downstream distances from the transect. Data were calibrated with 1,100 cfs in the study reach. FWS Transects During low-flow periods in July and August 1994, water depths were measured across six transects identified by the hydrological model (HEC-2) and by direct observation as having critically shallow water depths to adequately provide passage for sub-adult and adult Colorado squawfish. These field surveys were conducted during experimental low flows to determine, 1) if the water depths and corresponding streamflows predicted by the HEC-2 model were comparable to the empirical water depths measured at known flows, and 2) at what flow level and locations insufficient depth might become limiting for passing sub-adult and adult Colorado squawfish in the reach. Kevlar cable was stretched across the entire channel between two steel fence posts. The transect line was usually located at the upstream end of a hydraulic control, which was not necessarily perpendicular to the channel. Water depths, recorded to the nearest 0.1 ft, were taken every 1- to 2 feet across the transect from the waterline of the right shoreline to the left shoreline by a person wading with a depth rod. While the orientation to the channel (e.g., 30°, 45°, or 60° vs. 90°), may have varied between the FWS and BR transects, the locations corresponded closely. Other information recorded included surface water temperature, total width of the river channel (high-water mark), and total width of the wetted area. Data Compilation and Analysis Fishery Data Past Sampling. Data from 1979, 1981-82, 1986-1988, and 1991-1995 were used. Capture data, positive sightings, and locations of radiotagged Colorado squawfish in the 2.3-mile reach from CRFP files are summarized, and correlated with streamflows in the reach on dates of occupancy (Appendix: Tables D.1-D.3). Catch rates (total catch per unit effort [CPUE]: total fish collected/total hours sampled [Fish/h=F/h]), is summarized by sampling date and by the number of fish captured in the plunge pool and from the 2.2-mile reach (Appendix; Tables D.1- D.2). Finally, monthly totals were summed for all years. Because effort was not always recorded for sampling trips during some earlier years, some method was w needed to calculate relative effort from past data. When effort was not 9