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were made on maps when the video and mapping occurred on different days. The finalized habitat mosaics were sent to the Remote Sensing Geographic Information Group at BR. These mosaics were scanned into a PC and the habitat delineations were digitized and areas calculated using Map and Image Processing System (MIPS) software (Microimages Co.). These area measurements were then sent back to USFWS in tabular form for graphing and interpretation. Water Depth and Stream-bed Monitoring In addition to habitat quantity (area), factors affecting habitat quality also had to be considered. Depth and velocity are important variables that affect site selection by fish (Bovee 1982). Water velocity was taken into account in the definition of each habitat type (Appendix Table II), though depth was not. Thus, if a given habitat type was preferred, we assumed that favorable velocities typical of that type were in part responsible for the fishes selection of sites of that type. Because velocity is taken into account in defusing the habitat types, favorable velocities are automatically provided when flow levels create or enlarge preferred habitat types. Depth, on the other hand, was not taken into account in some of the definitions and thus an otherwise preferred habitat could be rendered unfavorable if depth at the site dropped below some unknown suitability threshold. Thus, the situation could arise where at a given discharge level adequate or even maximum area of preferred habitat (as viewed from the air) is provided but is of little benefit to the fish because of insufficient depths. We therefore needed some measure of how habitat depth varied with change in discharge. To measure the effect of discharge level on depth, permanent transects were set across various river features and stage height (water surface elevation) was monitored there at the time of each mapping exercise. In November of each year bed elevation was measured along the transects so that depth at the various flow levels could be derived from the stage height readings. One or two channel transects were established within each study site and 2-3 transects established across a backwater if one was present within the site. A total of six channel cross-sections and six backwat- er cross-sections (two backwaters) were monitored during 1990-1991. In fall of 1992, an addition- al transect was established at the mouth of each of the two backwaters; these were also monitored again in fall of 1993. Reinforcing rod headpins were used as reference elevations. Transect ends were marked with reinforcing rod and orange flagging. All measurements were taken using a surveyor's level and 25- foot, recessed-faced, level rod. Cross-sections were measured by reading the elevation off the bed at every 10-ft interval or at every significant ground break, whichever was least. Intervals across the channel were determined using a marked kevlar cable stretched between two fence posts. A fiberglass, I/10th-foot-graduated tape was used across backwaters, islands and shores. Transects extended across channels between high points on shore that we estimated to be above the 10-year floodplain; across backwaters, from a high point on shore to the transect high point on the island. Some channel cross-sections encompassed the entire width of the 10-year floodplain (including active and dormant side channels) while others did not. River Discharge Mean-daily stream flow was obtained from U.S. Geological Survey (USGS) gages for the dates when habitat was mapped and when stage elevations and bed cross-sections were measured. For sites in the 15-mile reach, two methods were employed: after September 1990, readings from a new gage set up near the top of the reach (Station No. 09106150) were used; prior to that, 11