WSP07871

• File Number: 8271.300
• Description: Colorado River Basin Salinity Control Program - General Information and Publications-Reports
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 4/1/1985
• Author: RL Gardners
• Title: Assessing Salinity-Control Programs on the Colorado River
• Water Supply Pro - Doc Type: Publication

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ports from the basin, and 1 percent t'?,.,;
municipal and industrial use.J The re-
moval of 9,900 tons of salt from the river
in the Upper Basin was believed to result
in a 1.mg-per-liter decrease in salinity at
Imperial Dam, (Since our research began,
the Bureau of Reclamation has changed
this assumption to 10,990 tons per milli-
gram per liter, thereby further lowering
the potential henefits of removing a given
amount of salt.) However, substantial
quantities of salt may precipitate naturally
out of the water in Lake Powell, and other
measures of the sources of salts may be
problematical.

Research on salinity control

The changing view of the severity of the'
problem and the previously unconsidered
lags between controlling salinity and the
realization of benefits raise th~ ques.tion
of whether federal investments in salinity-
control programs are economically effi-
cient. Furthermore. how might program
costs be shared among participants? And
does the method of assessing its costs af-
fect a project's efficiency?
We first approached these questions
empirically by estimating the agricultural
benefits of salinity control through com.
parisons of net fann income at different
salinity levels. Linear programs simulated
fanners' effons to maximize profits in the
Imperial Valley of California with salinity
levels of 800 mg per liter and 1,100 mg
per liter in irrigation water_As salinity
increases. it becomes necessary to under-
take additional irrigations to leach salts
or to switch to more salt-tolerant, but less-
profitable crops, even though these meas-
ures reduce farm net income. Benefits to
municipal water users were adapted from
previous federal studies, and the estimate
of total benefits per ton of salt removed
was compared to cost estimates from the
Bureau of Reclamation and the Soil Con.
servation Service.
Another model simulated irrigated ag-
riculture in a major area of salt loading
in the Upper Basin-the Grand Valley of
Colorado-where irrigation return flows
pass through highly saline soils before
reentering the river. We tested a variety
of economic incentives for their ability to
induce salinity control-management tech..
niques and irrigation technologies.
The salient points of the analysis are
summarized below. The questions of ef.

JU.S. Environmental Protection Agency. Th~
Mineral Wafer Qualiry Problem in ,hI! Colorado
Rivtr Basin (San Fra.ncisco. California. 197t).

~

ficiency and equity are addressed In turn.
together with polley implications,

Benefits versus costs

Average annual damages from salinity to
irrigated agriculture in [he Lower Basin
amount to S51,4oo per milligram per liter
in 1982 dollars, As noted. however, sa-
linity reduction does not occur instanta.
neously, so the damage figure must he
discounted by tbe hydraulic retention time
of the river to obtain the present value of
henefits of Upper Basin salinity control.
We estimate benefits to agriculture from
salinity control (using an 8 percent dis-
count rate) at S39,100 per milligram per
liter,
We adapted a previous study to esti-
mate discounted municipal salinity-con-
trol benefits of S218,700 per milligram per'
Iiter.4 We did not include environmental..
health, and aesthetic benefits in this anal-.
ysis, but most observers do not see them.
as significant in the current salinity range:
We also omitted secondary, or indirect.
economic benefits as they normally are
not included in project analysis from a .
national accounting perspective. Under
nonnal economic conditionS"; these re-
gional impacts are offset by losses or gains
elsewhere in the economy.
We thus estimate the total benefits of
salinity control to be $257,800 per milli-
gram per liter of salinity at Imperial Dam,
or S26 per ton of salt removed from the
upper stretch of the Colorado River, The
Bureau of Reclamation's total estimate of
S513,300 is almost double because it in-
cludes secondary benefits and fails to aI,
low for the river's time lag.
This benefit estimate. can be compared
with projected salinity-control costs of ex. .
isting and' future projects. Cost estimates
were available for nine Soil Conservation
Service (SCS) on-farm projects that de-
crease salt loading mostly by reducing deep
percolation of irrigation water on Upper
Basin fields, although they also include
some lining of irrigation canals. Benefits
exceed costs for only three of the nine
SCS projects-the Virgin Valley, Price-
San Rafael, and Upper Virgin Valley units,
Similarly, of ten Bureau of Reclama-
tion projects. only the Paradox Valley and
Las Vegas Wash units are economically
feasible. Benefit-cost ratios for the other
eight projects generally are lower than the
SCS on-farm projects. This is because the
bureau's projects emphasize capital-in-
tensive solutions. while substantial salt-

~Klc:inman. Alan P.. and F. Bruce Brown,
Colorado River Salinity: Economic Impacts on
Agricultural. Municipal. and lndwrrial Users
(Denver. Colorado River Water Quality Of-
fice. Bureau of Redamation. December 1980).

..:_..... 1'--

~2.:';Jad reductions can be obtained throu~h
relatively inexpensive changes in irriga.
tion-management techniques.

Cost-sharing mechanisms

The Soil Conservation Service subsidizes
the capital cost of improvements to the
irrigation system to achieve salt reduc.
tions; How farmers are required to pay
their share of costs affects the cost per tOn
of salt removed through on-fann pro-
grams, We analyze" the effect of a wide
variety of cost-sharing mechanisms in the
Grand Valley of Colorado, with the net
social cost per ton of salt removed as a
common measuring stick. These social
costs are net of the value of irrigation la-
bor saved and do not include the cost of
administering the program.
We found the economic efficiency of
cost-sharing mechanisms to vary with the
degree to which an economic incentive is
directed toward salt discharges. As econ.
omists would predict. an effluent tax on
the salt discharged by each farm achieves
salinity control at the lowest social'"cost.
Unfortunately, it is not practical to meas-
ure the amount of salt or any other non-
point-source pollutant coming from every
irrigated field. Average discharges could
be estimated given soil type, crops, and
irrigation techniques, but even this ap-
proach is an administrative nightmare.
A more feasible alternative is to tax
production inputs whose use correlates di.
rectly with the level of pollution. For sa-
, tinity, the influent tax should be placed on
irrigation water. This cost-sharing mech-
anism is not as efficient as an effluent tax-
the relationship between. reduced water
use and lower salt loads is not exact-but
a tax on water would be much easier to
administer because charges for wat~r. al-
ready are assessed. In addition, subsidies
for conserving water will have essentially
the same effect on salinity control as taxes
on wateL consumption.
Subsidizing irrigation system improve.
menlS .moves the cost-sharing mechanism
one step farther from the goal of reduced
salt loads. Capital.inrensive investments
in water-conserving technologies are en.
couraged, hut this type of subsidy ignores
irrigation management options. This re.
suits in an increased social cost per ton of
salt removed. Property faxes are the least
efficient cost-sharing mechanism of all.
Raising property taxes creates no incen-
tive to change salt loads. but it could raise
revenues for the local cost share.

I

Who pays?

In assessing the worth of a project Or pro~
gram. economists tend to focus almost ex-
clusively on the investment's efficiency.
but [he equity question-how costs and
benefits are distributed-is equally 1m.

SPRING 1985 j 11