WSP02976

• File Number: 8271.300
• Description: Colorado River Basin Salinity Control Program - General Information and Publications-Reports
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 12/1/1979
• Title: An Economic Evaluation of the Salinity Impacts From Energy Development - The Case of the Upper Colorado River Basin
• Water Supply Pro - Doc Type: Report/Study

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Economic Activities
of the Basin

~iculture

Agriculture in the Upper Colorado River
Basin consumes a major portion of the water
depletions. Further, salt loading [rom
return flows is estimated to be 30 percent,
which significantly affects the water quality
of the river. This sector is the most
promising potential supplier of water for
energy development in the basin as well as a
promising candidate for salinity control
measures to upgrade river water quality.

Irrigation has played an important role
in the development of the Upper Basin.
Because of its arid climate, irrigation is
essential for crop production. The principal
sources of water are the streams fed by
melting mountain snows. Irrigated lands are
generally located along streams where water
can be diverted conveniently. Most crop
fields are supplied by dirt ditches and flood
or furrow irrigated. Less than 10 percent of
the crop acreage is sprinkler irrigated.
This results in low efficiency of water use.
Lengths of unlined canals and irrigation
efficiencies by county are presented in Table
9. Only 14 percent of total length of canal
(13,839 miles) is lined, and the overall
average irrigation efficiency is 0.46. This
efficiency, however, represents the fraction
of the water diverted that is consumed in
crop production by the diverting irrigator.
Irrigation efficiency on a basinwide basis is
much higher because the return flows from
upstream irrigators provide the water supply
for those downstream.

An estimated 2.7 MAF of water was
applied to crop land in 1974. Some of this
was returned to the stream, and most of the
rest was used by plants in the evapotrans-
piration process. Evapotranspiration or
consumptive use is defined as the water used
by growing vegetation due to transpiration
through plant foliage and evaporation from
the plant and surrounding environment (Hyatt
et ale 1970). The rate of consumptive use
depends on the type and density of crop, soil
moisture supply, soil salinity, and climate.
In addition, consumptive use losses occur as
water is taken by weeds or other nonproduc-
t ive plants. Climatological parameters
influencing water consumption are precipita-
t ion, temperature, daylight hours, solar
radiation, humidity, wind velocity, cloud
cover, and length of growing season. The
yearly average water consumptive uses (acre-
feet) for various crops have been estimated
(Table 10). The amounts vary with the
climatic differences among the subbasins.

Crops grown are primarily forage and
feed for livestock, the major agricultural
activity in the Upper Colorado River Basin.
Alfalfa hay and and native hay are the main
hay crops grown; in 1974 they used about 58
percent of the irrigated land. Pasture and

small grains ranked second and third amon~
the irrigated crops produced in the basin.
Barley and wheat were the primary ~rains for
feed. Total acreages of irrigated land
used to grow selected field crops in 1974 are
shown in Table 11. Since several field crops
are included due to insignificant amounts of
land use and lack of production cost data,
total acreages of irrigated land in this
study IDay be less than in other documents.

The irrigation water not consumed by the
crops nor wasted as evapotranspiration by
nonproductive plants ends up as either
surface runoff or percolation through the
soil, beyond the root zone. The unconsumed
water usually finds its way back to streams.
Loss of water to evapotranspiration increases
salinity levels downstream via the salt
concentrating effect. Movement of water
through the soil also collects salts and
carries them back to the stream through
return flows. Hence, irrigation generally
increases salinity downstream by both salt
loading and salt concentrating mechanisms.
The salinity increase caused by irrigated
agriculture has been estimated to be between
l7 to 37 percent in the Upper Colorado River
Basin. Energy development decisions need to
consider effects on salinity as well as those
on water supply.

Energ y

The Upper Colorado River Basin contains
a vast supply of energy resources including
coal, oil shale, oil, natural gas, uranium,
tar sands, hydropower, and geothermal re-
sources. At present, the most extensive
and commercially important mineral resources
of the Upper Basin are coal, oil, and natural
gas. The recent nationwide shortage of
energy has resulted in an intens ive search
for expansion of old sources and location of
new sources. As a result, investigations are
underway for the commercial development of
shale oil in Colorado, Utah, and Wyoming.
Several coal-fired electric generating plants
are either being constructed or are in
the planning stages for construction. Coal
gasification is another energy industry
being planned for Wyoming and New Mexico.

Dee is ions on whe ther or not to deve lop
these resources depend largely upon economic
feasibility and environmental impacts. Water
resource and water quality are important to
both determinations. Water is an important
input in energy production. Each process
requires water, and total water requirements
per unit of output have been estimated (Table
12).

Wa ter pollut ion problems, ar is ing from
the production of various energy related
products, are of major concern. Sources of
pollution include surface disturbances pro-
ducing sediments and salt, mine drainage
producing heavy metals and other toxics, and
wastewater discharges containing organic and
carcenogenic agents and causing increases in

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