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

7-2090 (4-81)
Bureau of Reclamation TECHNICAL REPORT STANDARD TITLE PAGE
1. REPORT NO. 2. GOV N ENT ACC * NO. 3. RECIPIENT'S CATALOG NO.
REC-ERC-91-1.
4. TITLE AND SUBTITLE S. REPORT DATE
Limnology and Drift of Particulate Organic Matter April 1991
Through the Lower Colorado River 6. PERFORMING ORGANIZATION CODE
D-3742
7. AUTHOR(S) 8. PERFORMING ORGANIZATION
Davine Lieberman REPORT NO.
Thomas Burke REC-ERC-91-1
9. PERFORMING ORGANIZATION NAME AND ADDRESS 10. WORK UNIT NO.
Bureau of Reclamation

Denver Office 11. CONTRACT OR GRANT NO.
Denver CO 80225
13. TYPE OF REPORT AND PERIOD
COVERED
12. SPONSORING AGENCY NAME AND ADDRESS
Bureau of Reclamation
Lower Colorado Region
Boulder Cit
NV 89005
y
14. SPONSORING AGENCY CODE
DIBR
15. SUPPLEMENTARY NOTES
Microfiche and hard copy available from Denver Office, Denver, Colorado.
Ed:RNW
16. ABSTRACT
The lower Colorado River from Laughlin, Nevada, to the U.S. and Mexico borders has six
mainstem dams; it is one of the most regulated rivers in North America. The main stem dams
have been shown to block transport of sediment, but their effect on particulate organic matter
(POM) transport has not been investigated. The lower reaches of the Colorado River have
a diverse assemblage of temperate and subtropical fishes that are heavily dependent on
organic detritus for food. An analysis of POM transport through the system was made by
the Bureau of Reclamation to determine how dams and civil structures affect this transport.
POM showed a general increase in volume from upstream to downstream. POM was dominated
by organic detritus in the less than 25-µm size fraction. Reservoirs released more POM than
they received during spring and summer, but less during fall and winter. Reservoirs tended
to process and recycle POM internally and release mostly limnoplankton. Backwater complexes
functioned as filters during high flow-trapping coarse material and releasing fine material.
Agricultural drains made constant low-level contributions of both POM and nutrients for
in-channel production of POM. Reservoir water diversions tended to shunt POM off-channel,
and more POM was generated in warm, slow water conditions downstream. The variety
of potential POM sources-each able to be a dominant contributor as physical and
meteorological conditions change-allowed for a rather constant supply of POM for
consumption by downstream detritivores.
17. KEY WORDS AND DOCUMENT ANALYSIS
a. DESCRIPTORS-- /*particulate organic matter /*organic drift /detrital material /phytoplankton
/zooplankton /nutrients /chlorophyll a /dams /backwater complexes /agricultural drains
b. IDENTIFIERS-- lower Colorado River
c. COSATI Field/Group 06 COWRR: 0603 SRIM:
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