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

that inorganic matter is not being released. Figure
8 indicates that POM in the tailwaters of both Lake
Mohave and Lake Havasu was small in comparison
to mean concentrations downstream of Palo Verde
Diversion Dam. The two tailwater stations, Davis
Dam and Parker Dam, were located about 80 kilo-
meters above Park Moabi and Palo Verde Diversion
Dam, respectively, which allowed for paired com-
parisons. Figure 9 shows that for each of the five
sampling periods during phase 2, less inorganic
material existed in the drift immediately below both
reservoirs than was present at the next respective
downstream sampling point. The station Havasu
Delta was added during phase 2 at the inflow area
of Lake Havasu. Three of the five collections obtained
here during phase 2 had greater concentrations of
inorganic material than that being released at Parker
Dam. Mean value for total dryweight at Havasu Delta
was 6.35 g/m3, whilst for Parker Dam mean value
was 3.71 g/m3. These data provide both direct and
0
0
a
3G
34
32
30
26
26
24
22
20-
Is-
16-
14-
2
0
161
DDAM
Figure 7.-Percent POM in total particulate matter during
phase 2 at all sampling stations.
20
19
18
K1 17
E 16
15
14
13
a 12
? II
10
Z 9
.4
O 7
= 6
J 5
4
0 3
2
1
0
JAN MAR MAY JUN AUG MEAN
Figure 9.-Concentration of total inorganic matter below
reservoirs during phase 2 (Jan. to Aug. 1988).
indirect evidence that inorganic matter is being
trapped by the reservoirs.
Total POM (all size-fractions) collected from the
tailwaters below reservoirs is depicted on figure 10.
Mean values show only a slight difference and tend
to suggest that the reservoirs neither contributed
nor were a sink for organic matter. Expectedly,
significant differences in these means (p>0.05, t-
test) were unapparent. The importance of reservoirs
is diminished in such an analysis. It is not only how
much, but also in what form-and at what time of
the year-the material is being provided which is
important. Figure 10 shows that more material was
coming out of the reservoirs in May and June than
during the previous sampling months, and more was
present immediately below the reservoirs during
May and June than at their respective downstream
stations. During these periods, the data suggest that
reservoirs function as producers in the river system
4.2 --
4.0 P? HQSE 2
3.81
3.6 JII
3.4
E 3.2 -1
0 3.0 J
p 2.6
a 2.4
a 2.2
0 2.0
1.8
1.6-
1 4.2
1.0-
0.8
0.6
DAMS PARK HAVASU PARKER PALD DIRDLA DRP ..S ruorRiei .r. ..r..... ......
Figure 8.-Concentration of POM during phase ,2 at all
sampling stations.

3 PHASE 2 1988

1.2
I.
1
0
.
1.9 DAM
rn
E
m
0
a
J
0
F
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
__,
I
® DAMS DAM
® PARK MOABI
® PARKER DAM
® PALO VERDE DIVERSION
ti
v
Figure 10.-Concentration of total POM below reservoirs
during phase 2 (Jan. to Aug. 1988).
17
JAN MAR MAY JUN AUG MEAN