1109

• UCREFRP Catalog Number: 1109
• Author: Pucherelli, M. J., R. C. Clark and J. N. Halls.
• Title: Green River Backwater Habitat Mapping Study, 1987
• USFW Year: 1987.
• USFW - Doc Type: Draft.
• Copyright Material: NO

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occurred at 2,423 cfs (32). The >20m2(200m2 size class consistently
represented the highest number of both bank- and channel-backwaters.
Very large backwaters (>1,000 m2) were more abundant at the lower flows.
Channel-backwaters were slightly more abundant than bank-backwaters
which was expected because of the braided nature of the Island Park
site; however, the average bank-backwater size was significantly larger
than the average channel-backwater size. The average size of all
backwaters usually increased at lower flows, and was maximized at 1,101
cfs (426 m2).

Figure 2 (Appendix A) presents backwater area (m2) versus flow (cfs).
Bank-backwater size was maximized at 1101 cfs, channel-backwater size
was maximized at 1381 cfs and total backwater size was maximized at 1101
cfs. Figure 3 (Appendix A) presents numbers of backwaters versus flow
(cfs). Bank-backwater numbers were maximized at 1101 cfs,
channel-backwater numbers were maximized at 1381 cfs and total backwater
numbers were maximized at 1381 cfs. Figure 4 (Appendix A) presents
backwater size distribution versus flow (cfs). The (20m2 size class was
maximized at 1101 cfs, the >20m2(200m2 size class was maximized at 1381
cfs, the >200m2(5002 size class was maximized at 1381 cfs, the
>500m2(1000m2 was maximized at 5260 cfs, and the >1000m2 class was
maximized at 1381 cfs.

Jensen

Table 3 presents the area (m2) of each class for each flow at the Jensen
site. Generally, an inverse relationship between flow and backwater
area occurred similar to that at the Island Park site. Again, the
largest increases in backwater area occurred between 2,423 cfs and 1,773
cfs where area increased 49% from 7,328 m2 (1. 8 ac) to 10,944 m2 (2.7
ac) and between 1,430 cfs and 1,381 cfs where area increased 38% from
15,041 m2 (3.7 ac) to 20,775 M2 (5.1 ac). Total backwater area was
maximized at 1,381 cfs (20,775 m2). Isolated pool area increased at the
lower flows, again with the exception of the 1,430 flow. Isolated pool
area was maximized at 1,101 cfs (9,007 m2) and was lowest at 5,260 cfs
( 372 m2).

Table 4 (Appendix A) presents backwater number, size distribution, area,
and average size for each flow at the Jensen site. Total number of
backwaters was greatest at 1,687 cfs (59). Backwaters were generally
more prevelant at the lower flows and were least abundant at 5,260 and
2,423 cfs (31 and 40, respectively). The >20m2(200m2 size class
contained the most backwaters for both bank and channel classes. The
largest backwaters (>1,000 m2) generally increased in number at lower
flows, whereas the smallest backwaters (>20 m2) were greatest at 1,687
cfs and lowest at 1,101 cfs. Numbers of bank-backwaters were
consistently greater than channel-backwaters for all size classes and
the average size of bank-backwaters much greater than that of
channel-backwaters. The average s~ze of all backwaters ranged from 183
m2 at 2,423 cfs to 442 m2 at 1,381 cfs.

Figure 5 (Appendix A) presents backwater area (m2) versus flow (cfs).
Bank-backwater size was maximized at 1381 cfs, channel-backwater size
was maximized at 1687 cfs and total backwater size was maximized at 1381
cfs. Figure 6 (Appendix A) presents numbers of backwaters versus flow