WSP00818

• File Number: 8273.100.50
• Description: Colorado River Basin Salinity Control - Federal Agency Reports - BOR
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 12/1/1980
• Title: Colorado River Salinity - Economic Impacts on Agricultural, Municipal, and Industrial Users
• Water Supply Pro - Doc Type: Report/Study

differing water qualities. Annual values were
derived and compared among subgroups and
a resulting damage function was defined.

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In the case of M & I (municipal and industrial)
damages. because one pattern of expenditure
is substituted for another somewhat different
pattern. it is concluded that no secondary
effects are generated.

3. Industrial. The approach here was to
determine the demineralization costs incurred
by major industrial water users. It is apparent
that water treatment costs vary among firms
and industries because of the specific nature
of water quality requirements. The procedure
was to rely mainly on secondary sources to
produce physical and monetary parameters
and. if necessary. collect limited primary data
as supplemental material. This information
was to be used to establish treatment costs at
several levels of TDS and become the basis
from which to estimate a salinity damage
function relative to industrial water use.
Problems in securing the tremendous
quantities of data required precluded analysis
of increased costs incurred by industrial users.

IV. ESTIMATION OF DAMAGES

A. Direct Acricultural Damages

The first step of this portion of the analysis was
to identify the agricultural areas that should be
considered. This was based on the current
agricultural acreages receiving or expected to
receive water in the near future from the
Colorado River. The relevant areas for analysis
of salinity impacts on agriculture are: the CAP
service area. the Yuma County service area. and
the Colorado River Indian Reservation-all in
Arizona; the Imperial Irrigation District. the
Coachella Valley County Water District. the Palo
Verde Irrigation District. the Reservation
Diversion of the Yuma Project. and the San
Diego Coastal region-all in California. Data
requirements for.the CAP made it necessary to
divide this area into six subareas which included
the following irrigation districts: Salt River Valley
Water Users' Association. Lands Supplemental
to Salt River Project. Roosevelt Water
Conservation District. Roosevelt Irrigation
District. and the San Carlos Project (Indian and
non-Indian). This was also the case in the Yuma

County service area where three major subareas
were required: Gila (North Gila. South Gila. Yuma
Mesa. Yuma Auxiliary), Yuma Valley (Reservation
Diversion in California and Yuma Valley in
Arizona). and Wellton-Mohawk Division.
Acreage estimates for these areas placed total
cultivated land at about 505900 hectares (1.25
million acres) including slightly over 80 000
hectares (200000 acres) as available for double
cropping.

Irrigators faced with the problem of increasing
salinity in their irrigation water have. in essence.
two options. (1) They can accept the damages in
the form of declining yields and ultimately
reduced acreages. as water supply conditions
dictate. to the point of zero economic returns
and ultimately go out of production; or (2) They
can exercise several management options which
mitigate or dampen some of the major
detriments of increasing salinity and withstand
the associated costs of implementation for each
alternative mitigation scheme.

A number of salinity adaptation practices are
currently known which can help 'to alleviate
decreases in crop yield resulting from increasing
water and soil salinity. Farmers in Arizona and
California receiving Colorado River water have
already been applying various management
practices in order to minimize impacts from
water containing high levels of TDS. Some of
these practices are applied by individual farms
while others are implemented by entire water
districts. For example, some districts have
supported the efforts of farmers in installing tile
drains under their lands which discharge into
master drains. usually constructed by the district.
Irrigation districts have also installed and
operated pumps to lower the ground-water level
and thereby more efficiently drain lands. Most of
the irrigated lands receiving Colorado River
water in California and Arizona have some type
of man made drainage facilities to carry away the
volume of water required to keep the soil-water
salinity content at acceptable concentrations.

Other management measures are adopted by
farmers. as necessary, to meet individual
circumstances of coping with high-salinity water.
For example, land surface is carefully leveled and
releveled so as to achieve more uniform
application. Flood irrigation is an effective aid in
percolating dissolved salts in the soil-water
solution below the root zone and into the

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