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<br />,
<br />
<br />Field Work
<br />
<br />An attempt was made to select reference backwaters at the Island
<br />Park, Jensen, Ouray, and Sand Wash sites that would exist at most
<br />or every flow chosen for study. The logistical nature of work on
<br />the river did not allow each site to be visited on the same day
<br />photography was acquired for that site. Consequently, the river
<br />flows during field visits did not correspond well with the flows
<br />present during photographing. However, most sites were visited
<br />during the same week that the photography was acquired, the flow
<br />for that day was noted, and field measurements were taken.
<br />
<br />Table 12 (Appendix A) presents the flow, identifier, river mile,
<br />depth (inches) at three locations at the mouth, mid, and end points
<br />of each backwater, and the length (feet), for each date a site was
<br />visited. No reference backwaters selected at the highest flow
<br />(approximately 5,260 cfs) were still present at any lower flow.
<br />
<br />Island Park - Three reference backwaters were selected for study at
<br />Island Park. Reference backwaters A (river mile 329.8) and C
<br />(river mile 330.5) were present for six flows, from July 11, 1987
<br />(2,365 cfs) until August 12, 1987 (1,031 cfs). Reference backwater
<br />B (river mile 329.9) was present for five flows, from July 16, 1987
<br />to August 12, 1987. At 2,365 cfs, reference backwater A was 111
<br />feet long, and the average depth was 7 inches. It reached it's
<br />maximum length and depth at 1,895 cfs (186 feet and 11.3 inches,
<br />respectively). At the lowest flow measured, backwater A was only
<br />51 feet in length with an average depth of 6 inches. Reference
<br />backwater C was initially 270 feet (maximum length) in length with
<br />an average depth of 9 inches at 2,365 cfs. Backwater C gradually
<br />declined in length and average depth, and at 1,031 cfs was 40 feet
<br />in length with an average depth of 7 inches. Reference backwater B
<br />decreased from 169 feet in length at 1,895 cfs to 105 feet at 1,230
<br />cfs, and then increased to 162 feet at 1,031 cfs. The average depth
<br />of backwater B ranged from 11 inches at 1,031 cfs to 7 inches at
<br />1,895 cfs.
<br />
<br />Jensen - Three reference backwaters were studied at the Jensen
<br />site. Reference backwater A (river mile 307.5) was present for six
<br />flows, from 2,392 cfs to 1,028 cfs. Reference backwaters B (river
<br />mile 307) and C (river mile 309) were present for five flows from
<br />1,978 cfs to 1,028 cfs. Backwater A was initially 178 feet in
<br />length with an average depth of 22 inches and reached a maximum
<br />length of 540 feet (average depth 22 inches) at 1,142 cfs and a
<br />maximum average depth of 23 inches (length 531 feet) at 1,028 cfs.
<br />Backwater B was initially 161 feet in length with an average depth
<br />of 9 inches and increased to it's maximum length (509 feet) and
<br />average depth (17 inches) at 1,028 cfs. Backwater C ranged in
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