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<br />t'- Table 4.
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<br />Summary of cumulative areas and percent of total wetted area (TWA) over the
<br />geomorphically similar reaches for the June and August habitat mappings 1994.
<br />Mapping was done between RM 2 and RM 224. Flows at Four Corners ranged from
<br />5,660-7,930 cfs in June and 504-1,040 cfs in August. (From Bliesner and Lamarra 1995.)
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<br /> TOTAL AREA A VERAGE MILE PERCENT OF TOTAL
<br />HABITAT TYPE
<br /> June August June August June August '
<br />Runs 24,936,621 15,210,918 111 ,823 68,210 81.90 73.98
<br />Riffles 156,253 2,245.454 701 10,069 0.51 10.98
<br />Shoals 582,570 1,290,818 2,612 5,788 1.91 6.28
<br />Low Velocity Habitats 503,118 942,355 2,256 4,226 1.65 4.58
<br />Vegetative Associated 2,082,091 141,691 9,337 635 6.84 0.69
<br />Habitats
<br />Slackwaters 556,740 569,798 2,497 2,555 1.83 2.77
<br />Others 1,631,896 160,373 7,236 645 5.36 0.78
<br />TOTAL 30,445,824 20,560,681 136,528 92,220 100.00 100.00
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<br />Analysis of aerial videograph:y and habitat mapping conducted in November 1994 and April and
<br />September of 1995 from RM 2 to RM 180 showed generally similar trends to previous years (Table
<br />5) (Bliesner and Lamarra 1996). One exception appeared to be in the vegetative associated habitats,
<br />.which increased during higher flows in 1994 but appeared to show the opposite trend in 1995.
<br />Another difference is the substantial drop in the percentage of TW A represented by low velocity
<br />habitat in September 1995 (1.9 percent) compared to August 1994 (4.6 percent). This difference
<br />may be related to slightly lower flows during August 1994 or may be related to an overall decline
<br />, of backwater habitat availabilty during recent years as noted by Bliesner and Lamarra (1996).
<br />" .
<br />
<br />Utah indirectly evaluated availability oflew velocity habitat types as part qfthe Early Life History
<br />Fisheries Survey of the San Juan River during 1993 (Buntjer et al. 1994). Since backwaters were
<br />the target habitat in their investigation, analyses were based on the differences in amount of
<br />backwater habitat sampled during different periods and flows. Backwater habitats accounted for 53
<br />percent of the total area seined during spring 1993 at flows of 5,860 to 6,700 cfs (Figure 2). During
<br />July, at flows of 740 to 1,200 cfs, 84 percent of the total area seined was backwater habitat, and in
<br />early August at flows of 412 to 533 cfs, 97 percent of the area seined was backwater habitat. By
<br />September, at flows of 1,180 to 2,390 cfs, 68 percent of the area seined was backwater habitat.
<br />
<br />These data, although somewhat qualitative, suggest that available backwater habitat increased with
<br />decreasing discharge in the San Juan River.
<br />
<br />San Juan River Recovery Implementation Program
<br />Summary Report
<br />
<br />18
<br />
<br />17 January 1997
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