8132

• UCREFRP Catalog Number: 8132
• Author: Lieberman, D. and T. Burke.
• Title: Limnology and Drift of Particulate Organic Matter Through the Lower Colorado River.
• USFW Year: 1991.
• USFW - Doc Type: Denver, CO.
• Copyright Material: NO

Table 12.-Range, mean x, and standard deviation s for total dry weight
(DW), total ash weight (AW), and total POM for phase 1 (Oct. 1986 through
June 1987).
Station` Total DW Total AW
g/m3 Total POM
Davis Dam Range 0.84-2.01 0.27-1.21 0.57-1.06
x 1.31 0.51 0.80
S 0.36 0.30 0.18
Park Moabi Range 1.88-3.87 1.23-3.26 0.45-0.98
x 2.68 1.91 0.78
S 0.73 0.70 0.18
Parker Dam Range 0.78-3.19 0.26-1.98 0.52-1.39
x 2.25 1.37 0.89
S 0.78 0.57 0.30
Headgate Rock Dam Range 1.73-6.34 1.16-5.25 0.40-1.09
x 3.21 2.47 0.75
S 1.41 1.31 0.21
Palo Verde Diversion Range 1.10-15.07 0.82-14.00 0.28-1.35
Dam x 6.05 4.54 0.99
S 4.00 4.14 0.31
Cibola Range 8.48-45.99 7.00-43.64 1.14-3.66
x 18.55 16.67 1.88
S 11.74 11.51 0.80
Imperial Dam Range 12.59-97.88 10.60-94.63 1.50-3.24
x 28.76 26.61 2.15
S 28.19 27.73 0.57
Yuma Range 11.61-124.26 9.57-119.71 2.04-4.78
x 43.82 40.74 3.14
S 43.03 41.73 1.28
. Number of samples at all stations is 8
As noted, total POM showed higher values in the
two tailwaters (Davis and Parker) than for the next
downstream station:
stream order. These data indicate that the concen-
tration of total mean annual POM in the lower
Colorado River is highly comparable to other streams
in Western United States.
• Davis Dam had a mean of 0.80 g/m3 while Park
Moabi was only 0.78 g/m3.
• Parker Dam had a mean of 0.89 g/m3 while
Headgate Rock Dam was only 0.75 g/m3.
• From Headgate Rock Dam to Yuma, POM showed
the same trend of generally increasing values pro-
ceeding downstream as noted in the total and
inorganic classes. The mean values for total POM
ranged from 0.75 g/m3 at Headgate to 3.14 g/m3
at Yuma.
• Total POM at Cibola, Imperial Dam, and Yuma
stations were not significantly different from one
another but were significantly different (p<0.05)
from all other stations as shown in table 13.
Table 14 presents a comparison of mean annual POM
between phase 1 results for the lower Colorado River
and various western streams of similar size and
Composition of POM varied between size-fractions,
but generally can be categorized as:
- diatoms
- green algae
- other algae (including and dominated by
blue-greens)
- plant material (macrophyte fragments)
- animal material (mostly zooplankton)
- detrital material (defined by any and all of the above
categories)
The <25-µm POM was comprised generally of 95
percent detrital material and 5 percent phytoplank-
ton-mainly diatoms at all stations. This size-fraction
represented the greatest concentration of POM-and
may be the most diverse-but the material was so
small, its origin or parental source could not be
determined.
14