WSP10002

• File Number: 8270.100
• Description: Colorado River Basin Water Quality/Salinity -- Misc Water Quality
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 3/1/1989
• Author: USDOI
• Title: Quality of Water - Colorado River Basin - Progress Report No. 14 - January 1987
• Water Supply Pro - Doc Type: Report/Study

Table II-I. Comparison of river basin drainage and runoff.

~
CO
CJl
-...]

River basin
Col<ilrado
Mississippi
Columbia
Delaware

Area
(1,000 square
miles)
244
1,234
258
12

Runoff
(mt llion ac.re-
feet per year)
15
440
180
14

Runoff pet.
un i tarea
(inches/years)
1.2
6.7
13.1
2,0.'9

The flow at various points in the Colorado River Basin for the 1941.-:87
period is given in Tables 1 through 20 at the end of this report. The records
of flow depict wide fluctuations from month to month and considerable
variations from year to year. The storage reservoirs presently reduce some of
the fluctuation in the reaches below the major dams.

c. Reservoir Storage

Wet and dry cycles have played a significant role in bringing ahout the
development of the Colorado River Reservoir complex. In the past, the annual
flow of the river has varied from less than 6 million to over 20 million
acre-feet per year. The reservoir system allows sufficient storage water to
maintain the flows of the river to meet downstream needs during dry periods.

The construction and filling of the main stem reservoirs of the Colorado
River Basin have brought about significant changes in the flow patterns of the
river. In addition to the major reservoirs, numerous smaller reservoirs have
been built on many of the tributaries. Since major storage began with Lake
Mead in 1935 and concluded wi th the filling of Lake Powell in 1980, the
Colorado River Basin reservoirs now have a combined storage capacity equal to
approximately four times the total average annual virgin (undepleted) flow of
the entire Colorado River.

The flow of the San Juan River is controlled by the Navajo Dam, the Green
Rive~ by Fontenelle and Flaming Gorge Dams, and th~ Gunnison River by the
Wayne N. Aspinall Unit Dams. Glen Canyon Dam is the only major dam on the
main stem of the Colorado above Lee Ferry, but it will permit control of
almost all flows leaving the Upper Basin.

Lake Mead, formed by Hoover Dam, supplies most of the storage and
regulation in the Lower Colorado River Basin, providing for irrigation,
municipal and industrial uses, power generation, flood control, recreation,
and many other beneficial uses.

Lake Mohave, the reservoir formed by Davis Dam, backs water at high
stages about 67 miles upstream to the tailrace of Hoover Powerplant. Storage
in Lake Mohave is used for some reregulation of releases from Hoover Dam, for
meeting treaty requirements with Mexico, and for developing power head for the
production of electrical energy at Davis Powerplant. The river flows through
a natural channel for about ]0 miles below Davis Dam at which point the river
enters the broad Mohave Valley 33 miles above the upper end of Lake Havasu.

II-2