8250

• UCREFRP Catalog Number: 8250
• Author: Lamarra, V. A.
• Title: Longitudinal Variation in the Trophic Structure of the Upper Colorado River.
• USFW Year: 1999.
• USFW - Doc Type: Logan, Utah.
• Copyright Material: NO

COLORADO RIVER-RIFFLES COLORADO RIVER-RUNS
Mean Void Volume Mean Void Volume
90
000 90.000
,
80.000 ... ..
. 80.000
....
t o.000 - o.ooo ......... .. ,
0.000 0.000
$0.000 ............... a0.000 ..... ......

e
940.000 _ o

940.000
.... ....................
9°30.000 9°80,000
m ..... .... p
ko.000 i1o,Goo _
10.000 10,ooo -

- 0
0 Spring 1994 Fall 1994 Spring 1995 Fall 1995 Spring 1994 Fall 1994 Spring 1995 Fall 1995
PERIOD PERIOD
GUNNISON RIVER-RIFFLES GUNNISON RIVER-RUNS
Mean Void Volume Mean Void Volume
90,000 90,000
.
8
0.000 8
0.000 ...._
'x
,
0,000 na
,
? 0•000
... 0,000

.._. - _ ....
..
_-
o0,000
E5 ... _. - _.
.. a
0.000
8 ..... ....
X40,000 ... 940,000
V ..

;%0.000
9°30.000 ....
;,, _.._ ...
...
4
0.000 .._ ..........
-._- -?-_ _... ._.....
...... _ .-. -._ ...... w
°0.000 .....
__ __ ?,,
... ..... ....... .........
i,. ...... ..... .......
10.000 ...__ _... :_. ..... _.... ........ 10,000 __._._ __. .__...: _... __- ....._
0
0 Spring 1994 Fall 1994 Spring 1995 Fall 1995 Spring 1994 Fail 1994 Spring 1995 Fall 1995
PERIOD PERIOD
Figure 21. The seasonal distribution of total void volumes for riffles and runs in the Colorado River (above) and the
Gunnison River (below).
HabitatDistribution-During the winter of 1996, at the conclusion of the field sampling, each
reach (A, B and C) within each stratum was mapped based upon the categories described in
Table 2. The linear distance mapped in each area can be seen in Table 4. An example of the
mapping detail can be seen in Figure 22.
Although 37 habitat types were utilized in the field mapping, these habitats were combined
into eight categories noted in Table 5 for analysis on a river-wide basis. A summary of this
analysis can be seen in Figure 23. Osmundson et al. (1995) has noted that habitat surface
areas can change with flow. These habitats were mapped between December 9-15, 1996
within the flow range of 5,450 to 5,590 cfs. Runs were the most dominant habitat type within
the Colorado River at this flow over the entire 11 strata, making up over 87.3 percent of the
total wetted area. The second largest habitat category was represented by riffles (5.08%)
followed by low velocity habitats (3.65%). Backwaters (1.55%), slackwater types (1.35%),
shoal types (0.62%) and overhanging vegetation (0.49%) made up the remaining habitat
types.
21