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Grams and Schmidt 8 July 1995. Characteristics such as bed and bank material, high-water marks, bankfull stage indicators, and distinct geomorphic surfaces were noted and surveyed at each site. The precise location of each cross section was recorded on aerial photographs (1:5000 scale) and topographic maps. Channel geometry characteristics at low and post-dam bankfull discharge were calculated from the survey data. The bed material was determined at each cross section either while wading or by interpreting fathometer traces. Sand beds have a smooth fathometer trace, sometimes showing ripples or dunes. A gravel bed produces an uneven fathometer trace indicative of coarse bed material. The fathometer trace of a boulder bed is even more irregular, often showing sudden changes in depth corresponding to individual boulders. The bed material coarsens from bank to thalweg at most cross sections. The bed material recorded for each cross section is the dominant material in the channel thalweg. Gravel and sand bars exposed at low water represent the only portion of the stream bed that is easily accessible. Bed material size was measured at 18 gravel bars; each bar was sampled at the upstream end below the high-water line. Particles were sampled at regularly-spaced intervals along a tape measure for the above-water portion of the bar and by random walk for the submerged areas that were wadable (Wolman, 1954). Median diameter, lithology, and roundness were recorded for each particle. Roundness was ,:Visually estimated on a scale from angular to rounded. The primary criteria for cross section establishment were the desired 1-km spacing, the existence of uniform downstream flow, and feasibility of measurement. Cross sections were generally not surveyed in rapids or in large recirculating eddies. Because these areas were avoided, few cross sections traversed eddy-deposited sand bars, gravel bars in flow expansions, and coarse material in rapids. Therefore, analysis of bed material distribution determined from cross-section data describe characteristics of uniform flow reaches. Our observations of bed material in rapids and eddies indicate that the thalweg is coarser in the unsurveyed areas.