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 1.-Range, mean x, and standard deviation s of field measurements for phase 1 (Oct. 1986 to June 1987)

Station" Water
temperature
°C Dissolved
oxygen
mg/L Specific
conductance
µs/cm Oxidation-reduction
potential
Eh, mV
pH
Turbidity
NTU
Davis Dam Range 11.7-17.2 9.36-11.86 820-904 307-347 7.99-8.35 1.0-8.2
X 14.5 10.50 861 323 8.14 3.7
S 2.3 0.85 39 15 0.11 3.8
Park Moabi Range 11.2-23.1 9.17-11.66 822-910 292-336 7.99-8.40 1.2-2.9
X 14.2 10.51 864 316 8.16 1.8
S 2.5 0.94 40 18 0.13 0.6
Parker Dam Range 11.4-23.1 9.03-11.36 822-909 299-337 7.91-8.38 2.4-4.8
X 16.7 10.12 868 318 8.09 3.4
S 4.2 1.04 41 14 0.14 0.9
Headgate Rock Dam Range 11.6-24.0 10.63-12.75 821-909 305-328 7.86-8.35 3.3-11.2
X 17.2 12.09 856 318 8.08 4.6
S 4.4 0.85 41 8 0.14 2.7
Palo Verde Range 11.8-25.4 10.01-12.23 826-931 297-336 7.92-8.37 3.4-5.3
Diversion Dam x 17.8 11.06 880 314 8.10 4.0
S 4.7 0.95 41 14 0.14 0.7
Cibola Range 11.2-24.6 8.97-11.93 859-1013 286-325 7.89-8.38 4.1-7.9
X 16.8 10.51 928 313 8.16 5.7
S 4.6 1.00 46 13 0.16 1.1
Imperial Dam Range 11.8-26.3 9.17-11.41 890-1056 299-412 8.01-8.33 6.8-8.6
X 17.9 10.28 960 326 8.13 7.8
S 5.0 0.85 56 39 0.10 0.6
Yuma Range 12.0-26.9 8.94-12.92 980-1362 298-331 7.90-8.33 7.2-39.0
X 18.4 10.45 1 151 318 8.05 14.0
S 5.2 1.44 127 14 0.14 10.5
Number of samples at all stations is 8
water temperatures decrease below 10 °C.2 Water
temperatures recorded are reported in table 4A.
Dissolved oxygen (D.O.) concentrations (table 1)
generally ranged from 8.97 to 12.92 mg/L and
resulted in saturation from 80 to 100 percent (at all
stations) and were not limiting to POM production. At
all stations, D.O. followed the typical annual cycle of
higher values during the cooler months and lower
values during the warmer months. The D.O. was not
limiting to the aquatic biota in the river during this
study. D.O. concentrations are reported in table. 5A.
In the main channel, specific conductance ranged
from 820 to 904 )uS/cm at the upstream tailwater
of Davis Dam and from 980 to 1362 µS/cm at Yuma
(table 1). The Yuma station was only 8 kilometers
downstream from the Gila River, which may have
contributed tothe higher specific conductance levels.
Specific conductance levels at downstream stations
were significantly higher (p<0.05) than levels
reported upstream. Specific conductance levels are
reported in table 6A.
2 Personal communication with Mike Giusti, Calif. Dept. of Fish
and Game, Blythe, Calif., and on-site observation by authors.
At all stations, pH was slightly alkaline (table 1), and
only a slight fluctuation existed in the pH values from
October 1986 through June 1987 at all stations. The
pH values are reported in table 7A.
In the lower Colorado River, oxidation-reduction
potential was 307 to 347 mV below Davis Dam and
298 to 331 mV at Yuma (table 1). The redox values
are reported in table 8A.
Below Davis Dam, turbidity ranged from 1.0 to 8.2
NTU and from 7.2 to 39.0 NTU at Yuma (table 1).
Generally, turbidity levels did not fluctuate a great
deal between sampling periods-although turbidity
was high at Davis Dam, in February 1987. This higher
turbidity could have been the result of increased
phytoplankton concentration released from the
reservoir during this same time period. The increase
was not reflected downstream at the other stations
on the same sampling date. At downstream stations,
from Palo Verde Diversion Dam to Yuma, turbidity
was fairly constant between sampling periods.
However, turbidity at Yuma increased four fold in
December 1986, which corresponded to the increase
in river flow during this same period. Turbidity is
reported in table 9A.
6