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

the sampling stations. (Return flow from All-
American Canal-by way of Pilot Knob Power Plant-
increased the flow at the Northerly International
Boundary below Yuma to 175 m3/s.)
Power generation schedules made it impossible to
correlate instantaneous flow at a particular sampling
point with mean daily flow. For example, at Parker
Dam, a midday rise in flow from 450 to 650 m3/s
would be reflected at Headgate Rock Dam one hour
later and at Palo Verde Diversion Dam five hours
later. At Headgate Rock Dam the rise in flow was
sudden and pronounced, whereas at Palo Verde
Diversion Dam the rise in flow was less dramatic.
The process continued, as the slug (release) of water
moved downstream, with a gradual attenuation of
the peak flow and velocity as observed initially at
the source of release. During sample collection (at
a particular station), knowing whether the flow had
risen or lowered could not be ascertained since
instantaneous flow was not measured. To what
extent these variations of instantaneous flow
affected the samples cannot be determined. Flows
recorded for each station are recorded in table 3A.
700
600
N
M
E
500
0
J
cr 400
w
Lr
0
300
w
0
0
U
cr 200
w
3
O
J
100
Generally, water temperatures in the lower Colorado
River (table 1) were warmer from upstream to
downstream as flows decreased (water depths
decreased) and air temperatures became warmer.
During the study (both phases 1 and 2), main channel
temperatures observed ranged from winter lows of
8.2 °C at Havasu Delta, to summer highs of 28.6 °C
at Imperial Dam. In the tailwater below Davis Dam,
water temperatures were influenced by hypolimnetic
releases from Lake Mohave; temperatures here
fluctuated less than at other stations and remained
below 17.5 °C from October 1986 through June
1987. During phase 1, water temperatures were
found to be significantly lower [p<0.05, Analysis of
Variance (ANOVA)] at Davis Dam and Park Moabi
than at downstream stations. Below Parker Dam,
water temperatures had a greater seasonal range,
which reflected epilimnetic releases from Lake
Havasu. None of the observed temperatures were
considered to be detrimental to aquatic life with the
possible exception of some winter lows in the Palo
Verde Division where tropical fishes of the genus
Ti/ipia exist. Periodic winter kill occurs of these fish
in small agricultural drains (in this division) when
PHASE 1 and 2 Oct., 1986- Aug., 1988
? DAVIS DAM
+ PARKER DAM
O PALO VERDE DIVERSION DAM
n IMPERIAL DAM
x YUMA
i
?I
AAA
I
TT1TT 1TFRTT?7TTTT??
0 N D J F M A M J J A S 0 N D J F M A M J J A
Figure 2.-Mean weekly river flows at Davis Dam, Parker Dam, Palo Verde Diversion Dam, Imperial Dam, and
Yuma for phases 1 and 2 (Oct. 1986 to Aug. 1988).
5