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<br />~
<br />
<br />number of backwaters was greatest at 1,687 cfs (58). Backwaters
<br />were generally more prevelant at the lower flows and were least
<br />abun2ant aZ 5,260 and 2,423 cfs (32 and 40, respectively). The
<br />>20m <200m size class contained the most backwaters f2r both bank
<br />and channel classes. The largest backwaters (>1,000 m ) generally
<br />increasid in number at lower flows, whereas the smallest backwaters
<br />(>20 m) were greatest at 1,687 cfs and lowest at 1,101 cfs.
<br />Numbers of bank-backwaters were consistently greater than
<br />channel-backwaters for all size classes and the average size of
<br />bank-backwaters was much greater than that of channel-backwaters.
<br />Total backwaters per mile ranged from 4.6 at 5,260 cfs to 8.4 at
<br />1,687 cfs, slightly less2than at Island Park. 2 Backwater area per
<br />mile ranged from 1,118 m at 5,260 to 2,981 m 2t 1,381 cfs. The
<br />avera~e size of all backwaters ranged from 183 m at 2,423 cfs to
<br />447 m at 1,381 cfs.
<br />
<br />Ouray
<br />
<br />Table 5 (Appendix A) presents the area of each class for each flow
<br />at the Ouray site. The relationship between flow and backwater
<br />area is not as well defined at the Ouray site as it is at the
<br />Island Park and Jensen sites. There is a signifi~ant increase
<br />(122%) in backwate2 area from 5,260 cfs [18,789 m (4.6 ac)] to
<br />2,423 cfs [41,722 m (10.3 ac)]. Backwater area increased somewhat
<br />at 1,773 cfs and ag2in at 1,687 cfs where backwater area was
<br />maximized at 52,608 m (13 ac). Large decreases occurred between
<br />1,687 cfs and 1,430 cfs (24%) and between 1,430 cfs and2l,381 cfs
<br />(23%). Finally, backwater2 area increased from 30,849 m (7.6 ac)
<br />at 1,381 cfs to 41,177 m (10.2 ac) at 1,101 cfs. Isolated pool
<br />area increased substantial~y at the lower flows and was maximized
<br />at 1,381 cfs with 31,182 m (7.7 ac).
<br />
<br />Table 6 (Appendix A) presents backwater number, size distribution,
<br />area, and average backwater size for each flow at the Ouray site.
<br />Total backwaters were maximized at 1,381 cfs (74) and were also
<br />high at 1,687 cfs and 1,430 cfs with 71 and 66 backwaters,
<br />respectively. The lowest numbers of backwaters occurred at 5,260
<br />cfs (44), 1,101 cfs (57), and 2,423 and 1,773 cfs (60). With the
<br />exception of 5,260 cfs, there were more bank-backwaters than
<br />channel-backwaters at each ~low. 2As occurred at the Island Park
<br />and Jensen sites, the >20m <200m size class contained the most
<br />backwaters, both bank and channel. However, the Ouray site had a
<br />d~sproportionately higher number of very large backwaters (>1,000
<br />m ), at all flows except 5,260 cfs. The large nature of backwaters
<br />at the Ouray site may account for the different relationship
<br />between flow and backwater area than at Island Park and Jensen.
<br />
<br />Closer analysis
<br />extremely large
<br />
<br />of individual backwaters i~dicates
<br />backwaters (5,000 - 10,000 m ) which
<br />
<br />that a few
<br />occurred at
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