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The lower site is associated with a small but relatively permanent islandjocated in the 18- <br />mile reach near RM 160. Figure 8 shows the layout of cross sections at this site, and Figure 9 <br />shows a series of observations from 1993 to 1995 at selected cross sections. The most recent <br />measurements at the upper end of this site show essentially no change in the elevation of the gravel <br />bar that forms the entrance to this side channel (XS-4, Fig. 9). It was evident in the field, <br />however, that much of the gravel forming the surface of the bar did indeed move. Cross section <br />measurements at the mouth of this side channel (XS-7 and XS-10, Fig. 9) likewise reveal relative <br />minor changes. The mouth of this backwater has a tendency to fill with fine sediment in years of <br />low flow, but the recent high flows have prevented this from occurring. Otherwise, silt and fine <br />sand continued to accumulate along the right bank of the side channel, building up a small berm <br />that was deposited in 1993. <br />Lower Site <br />• <br />8 <br />W 1W <br />6 5 RM 160 <br />Figure 8. Layout of cross sections at the lower backwater site at RM 160. <br />11