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

and is bordered by Nevada and Arizona. It releases
cool hypolimnetic waters from Lake Mohave.
2. Parker Dam is located on the Arizona-
California border, (142 km below Davis Dam) and
impounds Lake Havasu. It began storage in 1938
and provides water to southern California by way
of the Colorado River Aqueduct.
Both Davis Dam and Parker Dams generate hydro-
electric power; the remaining four dams were
constructed to provide civil structures for diverting
irrigation water:
1. Headgate Rock Diversion Dam near Parker
Dam, Arizona.
2. Palo Verde Diversion Dam near Blythe,
California.
3. Imperial Dam near Yuma, Arizona.
4. Laguna Dam near Yuma, Arizona.
Imperial Dam provides water for the AM-American
Canal and is unique in that a large desilting works
was built as part of the structure; sediment is
collected at the canal turnout and diverted back into
the river below the dam.
Sampling Stations
The Bureau of Reclamation divided the lower
Colorado River into ten operational divisions for
administrative purposes (fig. 1). During phase 1 (the
study from March 1986 through June 1987), eight
sampling stations were sampled within eight
operational divisions. The sampling stations were:
1. Tailrace of Davis Dam at the upper end of
Mohave Valley Division.
2. Main river channel of Park Moabi, at the lower
end of Mohave Valley Division and the upper end
of Topock Gorge Division.
3. Tailrace of Parker Dam in the Havasu Division.
4. Tailrace of Headgate Rock Diversion Dam at
the upper end of Parker Division.
5. Tailrace of Palo Verde Diversion Dam at the
upper end of the Palo Verde Division.
6. River channel at Cibola operating bridge in
the Cibola Division.
7. Forebay below Squaw Lake at Imperial Dam
in the Imperial Division.
8. Main river channel below the Gila River inflow
at Yuma in the Yuma Division.
For phase 1, these stations were selected primarily
to provide data relative to the first objective; to
determine quantity, composition, and distribution of
POM in the river system.
During phase 2 (the study from Oct. 1987 through
Aug. 1988), four new sampling stations were added
and Headgate Rock Dam was deleted. These changes
allowed examining the data relative to the second
study objective; i.e., to determine the origin of POM
in the river system. Havasu Delta (a wildlife refuge
marked by buoys) was added at the river delta inflow
area (for Lake Havasu) to further differentiate the
Topock Gorge backwaters from Lake Havasu-a
mainstem impoundment. The station at Headgate
Rock Dam was eliminated because the first year of
data were similar to observations at Parker Dam
tailrace (about 22 km upstream).
Two stations were added to further elucidate
conditions above and below the Palo Verde Irrigation
Drain. First, Cibola station was moved downstream
to a point just above (0.5 km) the inflow of the drain.
(Tributaries or diversions were not included in this
relocation.) Second, Palo Verde Irrigation Drain was
added about a kilometer up the drain (near Walter's
Camp). Finally, a new station, DR3 was added at
Adobe Ruins-about a kilometer below the drain
inflow to the main river channel.
At Imperial Dam, a station was added in the All-
American Canal (AAC) immediately downstream
from the desilting works. Additionally, the Laguna
Dam station was relocated near Bureau of Recla-
mation's Dredge Yard-in the middle of Laguna
Division. When combined with both the Imperial Dam
and the AAC stations, Imperial Dam desilting works
could be isolated. In the appendix, table 1A lists the
field survey dates and frequency of sampling at each
of the 12 sampling stations during this study.
Sampling Techniques
All physical, chemical, and biological parametersthat
were measured and collected are listed in table 2A.
Physical-Chemical Parameters
Water temperature (°C), dissolved oxygen (D.O.,
mg/L), specific conductance (µS/cm), pH, and
oxidation-reduction potential were measured at 0.1
meter depth using a portable multiparameter probe
Hydrolab Surveyor II.
Turbidity (NTU) was measured in triplicate at 0.1
meter with a Portalab Hach (No. 16800-00)
turbidimeter.
River flow daily data (m3/s) at each station, were
obtained from Bureau and U.S. Geological Survey
records.
Nutrient analyses (mg/L) of water samples were
collected from 0.1 meter depth. Nutrient samples
were frozen immediately on dry ice and kept frozen
until analyzed according to the National Handbook
of Recommended Methods for Water-Data Acqui-
sition (USGS, 1977 [44]) for:
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