4001

• UCREFRP Catalog Number: 4001
• Author: U.S. Bureau of Reclamation.
• Title: Colorado River System Consumptive Uses and Losses Report 1976-1980.
• USFW Year: 1981.
• USFW - Doc Type: Washington, D.C.
• Copyright Material: NO

table UC-1. Predetermined average
evaporation rates were applied to
historical surface areas to yield
values of evaporation on a monthly
basis.
Adequate data exist to allow a
reasonably accurate estimate of the
basin evaporation. Both an increase
in the number of evaporation stations
and a better estimate of the surface
area of the unmeasured reservoirs would
improve the evaporation calculations.
Stockpond Evaporation and Livestock:
Stockpond surface areas were estimated
from the May 1975 SCS publication,
"Livestock Water Use." The subbasin
stockpond areas were subdivided by
State and basin using the livestock
population distribution. The same
procedure used to calculate the unmea-
sured reservoir evaporation was used to
estimate the stockpond evaporation.
Livestock population data were
taken from annual State Agriculture
Statistics and the 1978 Census of
Agriculture. Livestock population
data included cattle, sheep, horses,
hogs, and pigs. Consumption rates for
the various livestock were derived from
various reports, including the SCS
publication, "Livestock Water Use,"
May 1975.
Stockpond and livestock data are
adequate to prepare an estimate of this
use. Considering the small amount of
water use, any refining effort would be
best spent on the irrigation or evap-
oration categories.
Mineral Resources: Arizona, leads the
nation in the production of copper and
the net water use for its production
represents about 90 percent of the
total water use for mineral resources
in the Lower Basin. The Upper Basin
uses water in the production of numer-
ous minerals in addition to energy-
related materials such as oil and
natural gas.
Estimates of the water consumptively
used were based largely on current
and previous reports of the Bureau of
Mines. These reports include the gross
tonnage produced and the water consumed
per ton of production.
The Bureau of Mines data should
be quite adequate; however, in some
cases, important production data was
withheld for privacy reasons. In these
instances, earlier reports and the
comprehensive framework study were used
to estimate the water use.
Information regarding the annual
use of water by the mineral resource
industry was generally inadequate.
Information over 10 years old was the
best available for certain mineral
production and unit water quantity
requirements and the accuracy of such
information may be in doubt. Much of
the data was not listed by county,
which caused difficulty in disaggre-
gating the data into tributary areas.
Thermal Electric Power: The net use of
water for the production of thermal
electric energy from the tributaries of
the Colorado River Basin was estimated
from records obtained from the various
power companies in the Basin. These
records were complete and were judged
to be accurate.
Municipal and Industrial: The basis
for estimating municipal and industrial
uses was the urban and rural population
within the reporting areas. Prepara-
tion of annual population estimates was
guided by the 1970 and 1980 censuses,
various State and county statistical
reviews, and reports which included
population estimates for local areas.
The yearly population estimates for
the Upper and Lower Basins are shown
in tables UC-8 and LC-10, respectively.
Water withdrawal rates for urban and
rural uses in the various reporting
areas were derived from available
studies in the metropolitan areas,
State Water Plan reports, and Bureau of
Reclamation technical guidelines.
These withdrawals were then converted
to depletions using average basin
consumptive use factors.
The 1980 population of the Colorado
River system, estimated at about 3.8
million, is increasing at an annual
14