7823

• UCREFRP Catalog Number: 7823
• Author: Miller, W. H., et al.
• Title: Colorado River Fishery Project, Part II, Final Report, Field Investigations.
• USFW Year: 1982.
• USFW - Doc Type: \
• Copyright Material: NO

during postrunoff (1980). This high conductivity can be partially
attributed to a substantial input of highly mineralized and saline water •
at one location (RM 115.3, 186 kilometers), Crystal Geyser. This stratum
was dominated by riffles, side channels, and eddy habitats. There were
few backwater habitats in stratum B (Figure 10).
Stratum C included Gray Canyon and extended from Gunnison Butte
(RM 132, 211 kilometers) to Desolation Canyon at Three Ford's Rapid
(RM 157, 253 kilometers). Of the six strata it was the shortest, 38 RM
(62 kilometers). During runoff stage, the average depth was 13.3 feet
(4 meters), during postrunoff 7.3 feet (2.2 meters). Mean depth was
9.6 feet (2.9 meters), which was significantly (P = 0.0002) deeper
than all other strata. Conductivity ranged from 260 (runoff 1980) to
851 (postrunoff 1979). The substrate here was predominately a mix of
boulder/rubble with gravel. A diversity of habitat types were available
to fishes in stratum C, including rapids, riffles, and eddies which were
the most common. Other habitats included deep pools at the base of
rapids, side channels, pools, and eddy-created backwaters (Figure 10).
Gray Canyon was composed of low cliffs of gray to yellow tint with sparse
plant life. Inaccessible for most of its extent except by river raft or
kayak, the river was dominated by 16 named rapids.
Desolation Canyon makes up the largest portion of stratum D, which
extended from Gray Canyon (RM 157, 253 kilometers) to Duche's Hole
(RM 211, 340 kilometers). Depths during postrunoff averaged 6.4 feet
(1.9 meters); during runoff depths averaged 8.6 feet (2:6 meters).
Conductivity ranged from 270 micromhos during runnoff (1980) to 1,000
micromhos (Table 6) during postrunoff (1979). The three most prevalent
habitats in this stratum were eddies, rapids, and riffles. Large pools
at the tailrace of rapids were common in this section (Figure 10). The
primary substrate was boulder. This canyon is more constricted than Gray
and composed of high red walls with pinyon-juniper and Douglas fur
growing on the talus slopes.
Stratum E extended from Duche's Hole (RM 212, 341 kilometers) to a
point upstream of the mouth of the Duchesne River (RM 249, 401 kilo-
meters). Depths during postrunoff averaged 4.4 feet 0.3 meters) but
during runoff depths averaged 7 feet (2.1 meters). Conductivity ranged
from 260 micromhos during runoff (1980) to 1,300 micromhos during
postrunoff (•1979). Unlike its downstream stratum (D), this stratum had
no rapids or riffles. Habitats dominating this stratum in descending
order were eddies, backwaters (created by side channels), side channels,
and isolated pools (Figure 10). Substrate type was predominately sand/
silt. Dominated by drainage from open, rolling country (which is largely
undeveloped) and allochthonous input from the Duchesne and White Rivers,
this broad, sandy reach is still deeper than its upstream stratum M.
Stratum F was the most shallow river reach in the study area. This
stratum extended to Split Mountain (RM 320, 515 kilometers). It is
highly braided with islands and was characterized by broad sandy areas
which can be traversed in a floating boat only with difficulty during low
water. Depths averaged 3.2 feet (1.0 meters) during postrunoff periods
and only 4.7 feet (1.4 meters) during runoff. Substrate in this stratum •
was predominately sand/silt; however, some rubble/gravel substrate
was found near the upper end of the reach (near the lower end of Dinosaur
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