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

0.500
0.400
-0.700
5
E
0.200
0.100
0.000
COLORADO RIVER WATER QUALITY
Total Phosphorous
0.050
0.040
-0.030
5
E
00.020
0.010
0.000
COLORADO RIVER WATER QUALITY
Orthophosphorous
Figure 30. The spatial distribution of water quality parameters within the Colorado River. Data are from semi-annual
samples for 1994 and 1995.
Habitat Distribution-As noted in Table 4, almost 80 river kilometers were mapped within
the 11 strata in the Colorado River. The spatial distribution of the six general habitat
categories can be seen in Figure 31. The most evident characteristic of the spatial distribution
of habitat is the dominance of run habitats throughout the river. Percentage of run habitats
also tends to increase with distance downriver. The spatial distribution of the remaining six
general habitat categories which make up only 12.7 percent of the total wetted area can be
seen in the lower plate of Figure 31. Riffle habitats tend to be reduced with distance
downstream while low velocity habitats appear to increase in magnitude. Backwater habitats
were at their highest densities in strata 4, 8 and 10, reaching a maximum in stratum 8.
Biological Parameters- The three biological parameters which quantify the primary and
secondary producers within the Colorado and Gunnison rivers demonstrated consistent
spatial distributional patterns. The biomass estimates of primary producers were highest in
the uppermost stratum 11 and decreased in a linear fashion with distance downstream.
Stratum 11 had mean periphyton values of 18.9 mg/m2 which represented the highest
concentration while stratum 1 had a level of 0.53 mg/m2 (Figure 32). The Gunnison River
had significantly greater densities than those seen (stratum 11) in the Colorado River. In a
similar manner, the concentrations of coarse particulate organic material generally decreased
with distance downstream. Stratum 8 however, was an exception to this decreasing pattern;
it had an increase in detrital biomass from 25.5 gm/m2 to 30.7 gm/m2 (Figure 33). Stratum
28