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declining runoff flows); here, not only were total DTE's high (140 and 165 nun) but rock size was small (median widths of 38-39 mm). In some situations, a change in rock size led to big changes in relative DTE. For example, at Run No. 1 in reach 9-C, total DTE during base flow was essentially unchanged from 1996 to 1997, but relative DTE almost doubled; the reason: median rock widths had decreased from 71 to 40 mm. It should be noted that relative DTE provides a standard measure of the approximate number of rocks in the armour layer that are free of fine sediment. The actual number of rocks making up this layer likely differs from this standard measure in most cases. Relative DTE is really the ratio of the total DTE to the median rock size measured across the intermediate axis. If all rocks were oriented to the stream bed such that they laid on their sides, relative DTE would be a measure of the actual number of free rocks. However, in most cases, rocks are deposited in a haphazard fashion in terms of their orientation to the bed, i.e., some stand on their ends, or on their sides, lean, or lay flat. We assume that this haphazard arrangement of rocks is the norm for most sites and therefore recognize that the use of one axis in measuring rock size to estimate the number of `free rocks' does not result in an accurate reflection of the real number of free rocks. Instead, it serves to lend a degree of standardization to the procedure and to greatly reduce sampling time. DISCUSSION Summary In general, there were many similarities in rock sizes and embeddedness between years, between reaches, between rifles and runs, and between higher (runoff) and lower (base flow) bank positions. Those differences that were noted are summarized below. Rock sizes were generally larger low in the channel than they were high on the channel margins. A plausible explanation for this is the pattern of sorting that occurs during periods of significant movement of bed materials: smaller rocks are moved more easily than larger ones and are more likely to be deposited on the tops of bars; larger rocks, more resistant to movement, roll along the channel bottom and are deposited higher up on the banks with less frequency. In addition, average rock sizes were somewhat larger in the 18-mile reach than in the 15-mile reach, but only at lower-bank sites; rock sizes on the channel margins were similar between reaches. At several sites, particle size changed between 1996 and 1997, indicating that a substantial amount of bed material movement and particle size resorting occurred during the 1997 runoff period. No major differences in depth-to-embeddedness were found between 15- and 18-mile reaches, between 1996 and 1997, nor between runoff and base-flow samples. The largest 24