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<br />J <br /> <br />. <br />t <br />! <br /> <br />1 <br />i <br /> <br />. <br /> <br />. <br /> <br />The middle study site is formed by a small alternate bar and side channel located in the 18- <br />mile reach at RM 162.5. This feature is relatively recent Figure 6 shows the layout of cross <br />sections at this site, and Figure 7 shows changes observed at selected cross sections from 1993 to <br />1995. The most recent measurements at the upstream entrance to this backwater (XS-1, Fig. 7) <br />indicate continued deposition of silt and sand along the left bank, but relatively little change across <br />the gravel bar that separates the backwater from the main channel. The more significant changes at <br />this site occurred at the mouth of the backwater (XS-5 and XS-6, Fig. 7). Prior to 1995, this <br />backwater was very shallow and inaccessible to fish, except at high flow. Recent scour of almost <br />1 m of sediment from the mouth of the backwater has enlarged it to the point where it can now be <br /> <br />accessed at low to moderate flows. Whether the site is was utilized by fish is unknown. This <br /> <br />series of measurements also shows that from 1993-1995 the main channel has been steadily <br /> <br /> <br />I degrading at this location. It doesn't appear that the scour in the main channel and the backwater <br /> <br /> <br />are related, however, because sediment was scoured from the backwater only this year, probably <br /> <br />~ <br />, <br />! because vegetation covering the area was finally uprooted, whereas degradation is the main channel <br /> <br />has been on-going. <br /> <br />Middle Site (- RM 162.5) <br /> <br />'"If <br /> <br /> <br />. <br /> <br />~ <br />I <br />, <br />I <br />, <br /> <br />. <br />, <br />. <br />5 <br /> <br />~ ~./ <br />3 2 1 <br /> <br />Figure 6. Layout of cross sections at the middle backwater site at RM 162.5. <br /> <br />9 <br />