AN ECONOMIC EVALUATION OF THE COLORADO RIVER BASIN SALINITY CONTROL PROGRAM

Gardner and Young

Salinity Control Evaluation

TABLE 2. Municipal Damages from Salinity, or Municipal Benefits of Salinity Control.

Source: adapted from USBR, 1980.

^a Lagged benefits have been discounted to reflect approximate six-year retention time of the reservoir system
between the upstream project locations and the points of use.

agriculture in the entire Lower Colorado
Basin by accepting the USBR (1980) esti-
mate that Imperial Valley damages are
about 90 percent of the total. This as-
sumption translates to (in 1982 dollars)
$51,400 per mg∕liter damages to agricul-
ture in the Lower Basin.

We further adjust for the hydraulic re-
tention time of the river and reservoir sys-
tem. Using the hydrologic assumptions
described above and an eight percent dis-
count rate, the present value of total an-
nual agricultural benefits of salinity con-
trol becomes $39,100 per mg∕liter or $3.95
per ton of salt removed. (We adopted the
view that the social discount rate should
reflect, in this case, the opportunity cost
of displaced private spending, further ad-
justed for the high risks of salinity control
projects. Our chosen rate also closely ap-
proximates the Water Resources Council
mandated rate for fiscal year 1983.)

Municipal Benefits

Due to limitations on research re-
sources, this analysis utilizes previous re-
ports (Anderson and Kleinman, 1978:19;
d’Arge and Eubanks; and U.S. Bureau of
Reclamation, 1980) for estimates of the
municipal benefits of salinity control.
Those estimates were based on cross-sec-
tional surveys of Lower Basin cities whose
water supplies differ in salinity. Plumbers
and appliance dealers in each area were
asked to estimate average lifetimes of var-
ious plumbing fixtures and water using
appliances. Generally, the lower the salin-
ity of the water the less often fixtures must
be replaced, and the less the salinity dam-
ages. In addition to capital replacement
costs, estimated damages avoided include
the costs of bottled water, additional de-
tergents, and central water softening
needed to mitigate the more saline water.
The annual costs per household are con-
verted to 1982 dollars and listed in Ta-
ble 2.

The costs must be multiplied by the
number of households to get annual area
municipal damages. Estimates of house-
hold numbers are taken from USBR (1980:
14). (In practice, Colorado River water is
often blended to lower the concentration
below the recommended level of 500 mg∕
liter. Therefore, an estimate of equivalent
full service households which could be
served solely with Colorado River water
is used.) For the Metropolitan Water Dis-
trict of southern California 1,052,000 acre-
feet of water are assumed to be used an-
nually for municipal purposes, with a
cutback to 400,000 acre-feet after 1987.
Annual use is assumed to be 0.67 acre-feet
per household.

An estimate of 245,000 full service

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