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Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
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OCR for page 94
as
Resolving Problems:
Identifying and Evaluating Alternatives
1
The ultimate goal of the problem-solving process discussed in this re-
port is to select and implement responses to help reduce or solve irrigation-
induced water quality problems. The problem-solving process described is
one that can be applied broadly to the nation's environmental problems.
Regardless of the specific circumstances, however, one step in this pro-
cess merits special emphasis: identifying and evaluating the full range of
alternative solutions available.
Chapter 4 outlined the generic systems approach necessary to assess
any complex environmental problem and discussed the first steps of such
a process. This chapter concentrates on the final steps- identifying and
evaluating the range of responses available to decisionmakers.
This committee has emphasized just how important it is for decision
makers to display and debate openly the full range of available alternatives
before filtering this broad group to a subset of most appropriate options.
No potential option should be dismissed a priori, even if intuition judges it
to be impractical or unpopular.
In conceiving alternatives, there is a tendency to restrict the range of
alternatives considered for two reasons: first, the people developing the list
may have backgrounds that steer them to consider approaches within their
expertise and leave them biased against "unconventional" solutions, and
second, some obvious alternatives may be rejected a priori because they are
assumed to be impractical, legally difficult, or politically unpopular. This
tendency to prejudge or to fail to recognize" a number of alternatives
must be overcome. As with problem definition, the judgment of a team
94
OCR for page 95
IDENTIl;YING AND EVALUATING ALTERNATIVES
95
of outside experts without vested interests can be useful in providing fresh
insights and ideas.
A few examples may illustrate the issue, even if their simplicity appears
to overstate the point. The mission of the U.S. Bureau of Reclamation has
been to develop water resources for irrigation. In searching for solutions
to irrigation-induced problems, its personnel historically have not been
likely to seriously consider reducing or eliminating the use of irrigation.
Ocean disposal of irrigation drainage water, as another example, has been
restrained by laws and regulation. Those accustomed to operating within
the rules may not appreciate that laws can be changed; an academic
scientist, on the other hand, is likely to see ocean disposal as a natural
process, only accelerated by irrigation. This outside vision might recognize
the value of assessing the costs, benefits, and disadvantages of various
means of ocean disposal. Fish and wildlife specialists are accustomed to
being last in line when it comes to water resource allocations. They may
not appreciate that water for wildlife purposes might be provided at the
upper end of an irrigation scheme, prior to use for irrigation, rather than
at the lower end, after degradation.
Thus, a wide range of alternatives structural and nonstructural, tech-
nical and institutional-should all be displayed and openly debated. These
also should consider shifts in priorities or shifts in the end use of the
resource. Identifying and evaluating a full range of options should ensure
that innovative ideas are not prematurely eliminated and that the true costs
and benefits of each of the options can be assessed.
To ignore certain options whatever the reasons for doing so- is to
jeopardize the credibility of the overall analysis. Obviously, in the latter
stages of any study the time and energy spent on the various options will
begin to be weighted in favor of the more appropriate options (after all,
this is the point of the study and evaluation process), but this should never
preclude the importance of giving all options equal consideration in the
early stages of an analysis.
Using irrigation-induced water quality problems as a focus, the two
sections below list selected classes of options to demonstrate the range
that must be considered. One section discusses technical responses and
the other discusses institutional responses, even though it is clear that
successful strategies will need to combine elements from both categories.
No attempt is made to be exhaustive or to advocate any particular option.
Specific action packages from this range can only be chosen deliberately
on a case-specific basis, and they must incorporate the essential elements
of good problem solving described in Chapter 4.
OCR for page 96
96
IRRIGATION-INDUCED WATER QUALITY PROBLEMS
TECHNICAL OPTIONS
The irrigation of arid lands brings about major changes in land use and
in the distribution and use of water. This in turn leads to a redistribution of
salts, with unintended and sometimes unanticipated consequences. These
impacts of redistribution often are minor initially, but they tend to become
increasingly important over time.
The primary and long-recognized adverse effect of irrigation is the
generation of drainage water that carries substantial amounts of salts. The
more acute and less common effect, vividly illustrated in the San Joaquin
Valley, is the mobilization of specific trace elements in relatively small,
but potentially toxic, concentrations. In evaluating drainage options, this
distinction between types of problems must not be lost. A response that
may be feasible for selenium removal may not be applicable for boron or
nitrate removal. A treatment for a specific trace element may have no
application for total salt load management.
The redistribution of salts is a universal feature of irrigation in arid
lands, and many of the problems associated with irrigation are due to
excessive salt concentrations. Thus the long-term viability of irrigated
agriculture becomes a matter of "salt management"-devising strategies to
prevent salts from accumulating either in the irrigated area or downstream.
The basic approaches available for this task include transporting the
salts out of the system and storing salts where they will do no harm,
leaving the salts in place, or treating the drainage water. Retiring problem
lands from irrigated agriculture is an example of an approach directed at
leaving salts in place. Deep-well injection is an example of storing salts,
while building drainage canals to take the salts to the ocean is a means of
exporting them. The following sections explore these classes of options in
more detail.
Through most of history, the most common approach to salt manage-
ment on irrigated lands has been to discharge drainage water into streams.
In the process, the often highly concentrated drainage waters are diluted by
mixing with the river flow so that no adverse environmental effect is noted
immediately. While this process has been used many times in many places,
the cumulative effect can be severe, especially if it is combined with water
diversions from the river. In fact, in principle, concentration is desired to
reduce the cost of handling the waste stream and to reduce the volume of
water dedicated to the disposal process.
Transport and Disposal of Drainage Water
The primary objective of draining irrigated lands is to remove excess
water and salts in order to maintain a root environment suitable for crop
OCR for page 97
IDENTIFYING AND EVALUATING ALTERNATIVES
97
growth. However, once the drainage water has been collected, the salts must
be transported and disposed of in some acceptable manner-by dilution or
by storage in a location where they will cause little damage. Treatment of
the drainage water may also be necessary to facilitate either transport or
disposal.
Ocean Disposal
One direct way to dispose of drainage water is to discharge it to
the ocean. The challenge is to avoid adverse effects in transit. In some
cases, salts in the discharged water can be sufficiently diluted with other
water so they do not create a water quality problem during transport. This
traditional approach has often been carried out by constructing drainage
canals to carry drainage water either back to a river with enough dilution
water in it, or directly to the ocean. If the salts do not ultimately reach
the ocean, however, the water quality problem is only being postponed or
moved elsewhere. For instance, the disposal of the return flows from the
New Lands Project into the Mucked River in Nevada has only served to
cause severe water quality problems in the Stillwater basin.
Studies assessing disposal of the San Joaquin Valley's drainage water
by discharging it into San Francisco Bay or directly into the ocean have
shown these options to be expensive and controversial. As indicated in
Chapter 1, the San Luis Drain originally was to extend to the bay, but its
high construction cost and public opposition resulted in its being terminated
in the ponds at Kesterson National Wildlife Refuge (NWR). Although the
planners had hoped that additional funds would be allocated to complete
the drain, such a solution is probably no longer socially or politically
acceptable because of concerns over possible adverse impacts on water
quality at the point of discharge.
Another ocean disposal option would be to transport the San Joaquin
Valley's drainage water directly to the ocean through closed conduits con-
structed over the Coast Range. This approach would be expensive and also
has generated substantial opposition.
Eking the analysis beyond the example in the San Joaquin Valley,
it must be recognized that ocean disposal generally involves transporting
drainage water in natural channels (e.g., the Colorado River). The question
to be answered regardless of site is whether a management plan can be
devised that avoids or reduces adverse effects associated with transport and
discharge.
Deep-Well Injection
Another technology undergoing study is deep-well injection, when
excess salts are disposed of by injecting them into abandoned deep wells
OCR for page 98
98
IRRIGATION-INDUCED WATER QUALITY PROBLEMS
(Lee et al., 1988b). Deep-well injection has long been used by the oil and
gas industry to dispose of oil field brines. The application of this technology
for agricultural drainage water is a relatively recent modification, however,
and it faces a variety of technical, financial, and institutional constraints.
For instance, because of the great volume of drainage involved, it
may not be feasible to inject the entire return flow, requiring first that the
drainage be treated to reduce the volume and as a consequence concentrate
the salts. This would be an expensive undertaking. If the entire return flow
were injected, substantial amounts of water would be removed from possible
use by downstream residents or to support in-stream flows. Furthermore,
it is difficult to establish with certainty that the injected water will not have
long-term negative effects on regional water quality. Also, there is some
concern that large volumes of injected water could destabilize the region
tectonically.
Source Control
Source control can be described as those salt management activities
that are undertaken at the farm level, the source of the drainage water.
Salt management approaches that rely on source control essentially rely on
leaving the salts on the land.
Retirement of Land from Irrigated Agriculture
One way to manage salt loads is to retire the most problematic lands
from irrigated agriculture. Land retirement eliminates the need for salt
and water disposal on those lands retired. As a result of reducing the
number of acres irrigated, the rate of export of salts offsite through ground
water and surface runoff also is reduced. Alternate land uses chosen for
the retired acreage must be assessed to ensure that water use and drainage
volumes would be reduced.
Managen~ent of Iwigai'on
Another approach to managing salts at their source is through irrigation
management. The quantity and quality of irrigation drainage water can
be affected significantly by increasing the efficiency of irrigation by better
management of existing systems or by introducing more advanced irrigation
technology (van Schilfgaarde et al., 1974~. One example of a technologically
advanced system enabling precise control of water application is subsurface
trickle irrigation with automatic feedback control for determining the timing
and amount of water application. Such systems are designed to reduce
drainage while increasing water use efficiency and crop yield, but at a
relatively high cost of capital investment and management skills (Phene et
OCR for page 99
IDENTIFYING AND EVALUATING ALTERNATIVES
_.....
. ~.~. ~ ,',:
~-4 L. .
99
_ 3~ _
:: I
One technical approach for managing salts at their source is through improved irrigation
management. Drip irrigation, used here on furrowed cotton in California, conserves water
and energy and reduces the threat of erosion. Such systems can reduce drainage but are
expensive and require increased management skills. Inset: close-up of an "in-line" emitter.
CREDIT: Soil Conservation Service, T. McCabe.
al., 1988~. Such techniques can reduce drainage volumes well below 10
percent of the amount of irrigation water applied.
One approach is to recycle drainage water and use it directly, perhaps
diluted and supplemented with additional irrigation water, to grow salt-
tolerant crops. Rhoades et al. (1988) demonstrated that as much as 50
percent of the water used to irrigate crop rotations that included cotton,
alfalfa, melons, and sugar beets could be supplied from a drainage source
containing over 3000 mg~l total dissolved solids. This option, however, may
simply transfer increasing salinity problems to smites downstream.
Irrigation management alone will not provide a long-term solution
to salt management but can delay the onset of a problem until other
approaches become more feasible. It can retard the rate of salt discharge
in the drainage water and, at a steady state, often reduce the total mass of
salts discharged. In addition, irrigation management simultaneously reduces
the amount of drainage water that ultimately needs to be removed. Unlike
land retirement, irrigation management allows agricultural production to
continue. However, source control activities generally require more careful
OCR for page 100
100
IRRIGATION-INDUCED WATER QUALITY PROBLEAdS
Throughout history, the main challenge for irrigated agriculture has been salt management.
Evaporation ponds are a commonly used means to deal with saline subsurface drainage
water, but the potential for adverse environmental impacts is significant. The light-colored
areas in cropped fields are due to high soil salinities resulting from poor drainage.
CREDIT: Jim Oster, University of California, Riverside.
management than is necessary with more traditional irrigation techniques,
and they result in higher salt concentrations in the drainage water.
Onsite Evaporation Ponds
The major mechanism available to concentrate salts is evaporation,
a process seen throughout the arid West in naturally formed salt lakes
and dry salt beds. The construction of onsite evaporation ponds to collect
and concentrate salts from irrigation water drainage is an attempt to use
this natural process to store salts temporarily or permanently at a selected
location. Evaporation ponds are a commonly used means to deal with
saline subsurface agricultural drainage water (Lee et al., 1988a). Although
many drainage dischargers view ponds as a viable means of disposal, the
potential for adverse environmental impacts is significant.
One disadvantage of evaporation ponds is that the area devoted to
the ponds is removed from agricultural production or other uses for the
OCR for page 101
IDENTIFYING AND EVALUATING ALTERNATIVES
101
foreseeable future. Typically, 15 percent of the land area farmed must be
sacrificed to the pond (Tanji et al., 1985~. Another is that evaporation
ponds remove water from the system and thus reduce the amount available
to downstream users and for in-stream How.
Evaporation ponds can be biologically productive and attractive to
waterfowl. The biological productivity can be expected to decrease, how-
ever, as the salt concentration increases. Also, unless specific measures
are taken to prevent the seepage of saline waters into ground water, evap-
oration ponds also can contaminate local ground water. However, after
evaporation ponds have been in use for some time, the ponds tend to seal,
substantially reducing saline water intrusion into the ground water.
The presence in the drainage water of trace elements, even in relatively
small quantities, changes the situation drastically. Concentration through
evaporation can lead, in short order, to levels that are toxic to fish and
fowl. In fact, in the San Joaquin Valley, excessive levels of arsenic, boron,
molybdenum, and selenium have been noted in some evaporation ponds
(Schroeder et al., 1988~. Such ponds are no longer just evaporation ponds,
but need to be considered as potentially hazardous waste disposal sites,
subjecting them to stringent regulations.
Extensive studies of both the biological and chemical characteristics
of evaporation ponds where trace elements are a problem have led to
design recommendations intended to reduce the ponds' use by biota. Mul-
ticell ponds with a minimum water depth of 1 m, with steep sides, and
with banks and levees cleared of vegetation will reduce use by waterfowl,
shore birds, and macroinvertebrates. Aquatic plants can be controlled with
herbicides, and other pesticides may be needed to control invertebrate
populations (Parker and Knight, 19894. In short, this presumably simple
solution to a waste disposal problem can readily grow into an expensive
and environmentally hazardous endeavor that may no longer be called a
solution.
Thus onsite evaporation ponds can offer only an interim service that
can be useful while other, permanent solutions are sought. They will also,
however, create a neat range of problems in the long run.
Drainage Water Treatment Technologies
Scientists and engineers have developed a number of water treatment
technologies that might be applied to irrigation-related problems. Some
are applicable to specific substance removal; others remove all salts. These
technologies are, in general, an expensive approach to salt management.
They also add the problem of disposal of the removed salts.
OCR for page 102
102
Desalinization Technologies
/
IRRIGATION-INDUCED WATER QUALITY PROBLEMS
Desalinization technologies usually are used to create high-quality
water, usable for drinking or other purposes, from a saline source. The
primary technologies used in desalinization are reverse osmosis and flash
evaporation. Both are capital and energy intensive, and thus the cost of
separating the salt from the water tends to be high. A desalinization plant
is being built near Yuma, Arizona, to remove salts from the Wellton-
Mohawk Irrigation and Drainage District before the drainage water is
released to the Colorado River. However, analyses show that this is a very
expensive option (van Schilfgaarde, 1982~. The use of such technologies
also creates the problem of disposing of the highly concentrated salt-rich
waste. Thus these technologies only provide ways of concentrating the
mixture to be disposed of; they are not a solution to the problem itself.
Desalinization plants need to be part of an integrated strategy for residual
salts management.
Chemical and Biological Removal
Chemical and biological approaches can also be used to address some
salt management issues. In the San Joaquin Valley, for instance, high
concentrations of selenium are of special concern; Studies have shown that
ferrous ions or iron filings can be used to create selenium-rich sludges
that can be separated from the drainage water (Lee et al., 1988a; Murphy,
1988~. However, even if one of these processes were perfected and made
economically attractive, it would still leave two problems. First, the total
salt concentration would not be affected and the need would remain to
dispose of the selenium sludge. Second, these approaches are specific to
selenium and do not address the wider question of other trace elements.
One biological approach investigated in the San Joaquin Valley uses
fungi to remove selenium. Certain fungi, when provided with a source
of energy and maintained in a favorable (anaerobic) environment, will
metabolically convert selenium compounds to volatile dimethyl selenide
(Lee et al., 1988a). This process shows potential to remove selenium from
contaminated soils (Frankenberger and Karlson, 1988~. Again, however,
this approach is selenium specific.
Another proposed biological approach that deals specifically with sele-
nium involves using organisms that facilitate selenium accumulation in biota
without causing toxic responses (Lee et al., 1988a). In small pilot projects,
bacterial filters have demonstrated some success, but the feasibility of this
approach at a large scale is uncertain, and it is doubtful that the technology
can be worked out in the short time frame necessary for remediation.
The biologically oriented technologies that show some promise have
OCR for page 103
IDENTIFYING AND EVALUATING ALTERNATIVES
103
not advanced past the research or pilot stage. If found to be feasible, they
would need to be evaluated as part of an overall management strategy.
INSTITUTIONAL OPTIONS
Finding a solution to the complicated water quality problems caused
by irrigation requires a careful review of institutional as well as technical
options. Although the two options are addressed separately in this chapter,
they cannot be dealt with separately in actual practice. As was discussed
in Chapter 3, the social and scientific aspects of a problem are inextricably
intertwined. In many cases, an institutional option would be used to
bring about the use of a preferred technical option. Ultimately, the finest
technical option is of little value if there is no institutional way of assuring
its implementation and continuing operation.
Situations exist where institutional change alone might bring about
desired improvements. Even if no specific technical option is preferred,
adopting certain institutional changes can encourage irrigators to adopt one
or more of several beneficial options. The choice is left to the individual
decisionmaker, depending on the particular circumstances.
The strategies ultimately chosen to cope with irrigation-related prob-
lems will undoubtedly involve a mix of various institutional options. This
section discusses four types of institutional options: price adjustments, legal
changes, organizational changes, and political and social changes.
Price Adjustments
Chapter 3 discussed the various economic factors that contribute to
the water quality problems associated with irrigation drainage water. Many
of these problems occur because the prices irrigators pay for their resources
or receive for their products do not reflect actual social costs. Thus one
way to correct these discrepancies is to adjust the relevant prices.
Accurate Market Prices
The most obvious discrepancy is in the price that irrigators pay for
irrigation water. Adjusting the price of water so that irrigators pay the
full cost of providing it would make those farmers served by government
irrigation facilities operate more efficiently. In situations where irrigation
proved to be an uneconomic operation, it would reduce the amount of
irrigated acreage. Irrigators would tend to use less water, thus leaving
more to serve other social purposes. Even a relatively small reduction in
demand would free significant water supplies for other uses because of the
substantial amount of water consumed by irrigated agriculture in western
states.
OCR for page 104
104
IRRIGATION-INDUCED WATER QUALITY PROBLEMS
Similarly, removing price supports for surplus crops would induce
irrigators to grow fewer of these products, again resulting in an increase in
efficiency and a reduction in government price support payments.
However, such changes, as much as they might improve the system's
general efficiency, are unlikely to correct drainage problems fully. They
might reduce the amount of drainage generated, but they would not neces-
sarily reduce it in those areas causing the most serious problems. Making
such major price changes could also significantly worsen the financial condi-
tion of many farmers and cause other unwanted social repercussions. Many
of the people affected would not be causing downstream water quality prob-
lems. Others would find it more difficult to invest in alternative actions
to reduce drainage problems. Finally, as simple as such price adjustments
appear in theory, they would be difficult to implement. Many irrigators ob-
tain their water under long-term contracts in which the prices already have
been established. For irrigators who provide their own irrigation supplies,
the only way to adjust the cost of water is for the state to charge for the
right to use water. Although such charges are not unknown, they would
represent a radical change and would be hotly resisted.
Similar implementation problems affect proposals to remove price sup-
ports from irrigated crops. There would be no effective way to implement
such a policy unless the supports were eliminated for all farmers. Nor
would such a change necessarily have a significant impact on irrigation
drainage problems.
Truces and Charges
One way to adjust costs in a manner more closely focused on drainage
problems is to impose taxes or charges on the irrigators responsible for
these problems to pay the costs of ameliorating the damages. Special
drainage taxes could be instituted for problem lands or inputs such as
water, fertilizers, or pesticides in problem areas. Economic theory suggests
that increasing the eRective price of these inputs would induce some farmers
to conserve them.
Practical problems arise, however. It may not be legal or possible
to focus taxes on inputs used only in specific drainage problem areas.
Furthermore, input taxes are not necessarily an efficient approach to solving
environmental problems caused by output (e.g., drainage). However, this
approach has the benefit of providing a source of revenue that could be
used to fund mitigation programs.
Alternatively, irrigators could be charged on the basis of the amount
of drainage they generate or the amount of contamination in that drainage.
Such charges (or effluent fees) might act to induce irrigators to take actions
OCR for page 107
IDENTIFYING AND EVALUATING ALTERNATIVES
107
Constraints on Drainage
Existing water law also could be modified to make it pertain to the
quality of the drainage water as well as to the quantity withdrawn and
consumed by irrigators. At the federal level, abolishing the section of the
Clean Water Act that exempts irrigation return flows from the pollution
control provisions governing other dischargers might be the most direct
approach. Similar changes could be made in state water quality laws. Such
changes, however, would retain the existing separation between the legal
structure governing water quantity and that governing water quality.
Incorporating water quality concerns directly into the legal structure
governing the allocation of water would probably require states to modify
their existing legislative doctrines. Conceivably, the reasonable use doctrine
could be expanded to include a water quality dimension, for instance by
declaring that reasonable use requires that any unused water or waste water
be of sufficiently good quality that it causes no damage to downstream users
or to the environment. Such a concept is at least implicitly incorporated in
the riparian doctrine of water use but historically has had little influence
on the quality of water discharges in areas where that doctrine prevails.
Another approach might be to expand the concepts incorporated in
the public trust doctrine to include water quality concerns. This doctrine
was used by the California Supreme Court to control the amount of water
that Los Angeles could remove from the Mono Lake basin because of the
impacts these withdrawals were having on the water quality in Mono Lake
and on the viability of the ecosystem. This doctrine, however, is not clearly
defined, and how it might be applied to any particular circumstance is very
uncertain.
Regulatory Approaches
The most direct legal approach would be to adopt new regulatory pro-
grams that would require the implementation of desired technical solutions
in those areas causing significant water quality problems. These programs
could control any or all stages of the irrigation and farming process: the
use of inputs, irrigation management, or the quality of the drainage.
Controls on inputs could limit which lands are irrigated, restrict the
amount of irrigation water applied to the land, or restrain the types or
quantities of agricultural chemicals used (if these are the cause of the water
quality problem). However, controls on inputs may not solve the problems
and are likely to be inefficient. One method proposed to control agricultural
use would be to define soils containing trace elements in problem-causing
quantities as "geologic hazard areas" and restrict agricultural use that
would cause leaching and deep percolation. This could be legally similar
to existing floodplain management strategies.
OCR for page 108
108
IRRIGATION-INDUCED WATER QUALITY PROBLEMS
Controls on irrigation management could include any of the techniques
described previously in the "Technical Options" section of this chapter.
Again, adopting such a regulatory approach implies that the regulator
knows how to solve the problem as well as or better than the individual
farmer. In some cases, it can be difficult to enforce this type of approach
because of the difficulty of determining whether the farmer is in fact using
the required management practice.
Controls on the quality of the drainage water or on the ambient quality
of the receiving water focus most directly on the problem of concern and
allow the irrigator the most flexibility in choosing how to solve the problem.
However, enforcing such an approach can be a problem because of the
difficulty and cost of monitoring drainage flows., Controls on ambient
quality also raise questions about allocating responsibility for the problem
among the various dischargers.
One possibility might involve raising the level of control from the
individual irrigator to the water district. This could reduce the need for
intensive monitoring and quantitative source determination at the farm level
by passing the responsibility of allocation to the members of the district.
This issue is addressed further in the section "Organizational Changes" in
a somewhat different context.
Organizational Changes
Implementing effective and efficient solutions to the problems being
experienced in the San Joaquin Valley may require modifications in certain
administrative organizations because of the conflicting responsibilities of
the different agencies and institutions involved in water management.
Broadening and Redefining Responsibilities
One way to reduce the institutional problems caused by conflicting
responsibilities would be to broaden the responsibilities of existing institu-
tions. For instance, water supply institutions such as the USER and the
water (and irrigation) districts could be made responsible for the quality
of drainage water as well as the provision of water for irrigation. Alter-
natively, water pollution control agencies could be given responsibility for
supplying water as well as controlling the amount of pollution in water
discharges. The geographic jurisdiction would have to be defined along
hydrologic boundaries rather than political ones.
If a major effort were made to broaden some agency responsibilities,
some conflicts and confusion would likely result because several different
agencies could then have responsibility for dealing with the same problem.
Thus there would need to be a concurrent redefining and consolidating
OCR for page 109
IDENTIFYING AND EVALUATING ALTERNATIVES
109
of agency responsibilities. These changes would probably be very diffi-
cult to implement. They might, however, help significantly to prevent
future problems such as the contamination of Kesterson NWR. They also
might improve the nation's capability to respond to those problems that
have already occurred if they ultimately helped improve coordination and
communication among the nation's water resource and water management
agencies.
Correcting Other Insi~tutzonal Impediments
In the process of attempting to deal with the problems at Kesterson
NWR and similar sites throughout the West, numerous other institutional
constraints will undoubtedly be discovered. Problems involving the length
of irrigation contracts and the question of who actually owns water rights
have already been mentioned.
Another institutional impediment in some parts of the San Joaquin
Valley is that water often is delivered to irrigation districts and individual
farmers on a fixed schedule, regardless of whether it is needed. This can
result in the farmer applying excess water to the land, thus causing increased
drainage. Such a system also precludes the farmer from adopting efficient
irrigation systems that apply low volumes of water on an almost continuous
basis. A water delivery system set up to make water available when
it is needed would reduce these problems and would probably increase
production and improve water use efficiency. Such a change, however,
would require investments to increase the capacity of water supply systems
and to provide nearby storage facilities.
The types of changes needed to resolve such institutional constraints
will depend on the technical solutions that are selected. For some techno-
logical choices, institutional constraints may be very important; for others,
the significance may be less.
Finally, the search for the best solution must recognize that different
agencies and institutions are governed by different legal standards and
follow different administrative procedures. Some of these standards and
procedures may be too ponderous to allow an agency to respond effec-
tively to the problems associated with irrigation drainage water. Thus the
institutional procedures governing the institution itself can constitute an
important consideration when an institutional response is selected.
Political and Social Changes
No technical or institutional solution, no matter how elegant, is likely
to be implemented successfully if it does not have adequate political and
social support from all sides of the controversy. This is one reason why
the entire process of identifying and evaluating alternative solutions should
OCR for page 110
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IRRIGATION-INDUCED WATER QUALITY PROBLEMS
be open and should involve substantial public participation. Active efforts
need to be made to build support for the desired changes in the state and
federal legislatures as well.
One primary consideration in developing social and political support
for a proposed solution is how the costs and benefits are distributed
among the affected populations. If this distribution is seen as inequitable,
significant opposition can develop. Finding the "right" balance can be one
of the trickiest parts of deciding on a solution. If it offers powerful political
interests too few benefits, or if they are expected to pay what they perceive
as an undue portion of the costs, they may be able to block a proposed
solution politically. However, significant opposition also can result if less
powerful interests such as small farmers or minorities are unfairly affected,
or if the general taxpayer is expected to pay a major portion of the bill
for investments that will benefit a small group of already heavily subsidized
irrigators.
EVALUATING ALTERNATIVES
The final step in the study process is to evaluate the technical and
institutional options that have been identified and select those that appear
to be most attractive. Although this is the final step in the study process,
the criteria and procedures that will be used need to be clearly thought
out and made explicit at the beginning of the study. If this is not done,
the prior steps may not provide the information necessary to conduct solid
evaluations, and the evaluations and ultimate decision may be considered
suspect.
Thus much of the planning for the evaluation phase should be con-
ducted early in the study, most appropriately at the time that the problem
is being defined. Like the problem-definition process, this planning should
incorporate substantial public input and discussion. All segments of the
public need to have confidence that the decision-making process is legit-
imate and that it will reflect their values. Making an effort to build this
confidence at the beginning of the process should help the entire study
proceed more efficiently and should result in the final recommendations
being broadly supported. It is an investment that is usually very profitable,
but all too rarely made.
Thus the committee cannot overemphasize the importance of defining
the problem clearly and comprehensively. How the problem is defined-
whether explicitly or implicitly-will determine what solutions are explored
and implemented. Obtainable goals can be set only if the problem to be
solved is clear and agreed upon by all parties. All responses have different
impacts on the affected interest groups. A response at the local level
may aggravate the problem at the state or national level. The simplest
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IDENTIFYING AND EVALUATING ALTERNATIVES
111
engineering response may be an environmental mistake. A quick fix may
preclude a future, permanent cure. The benefits of each alternative for
all affected parties must be carefully assessed, and decisionmakers must
remember that all responses have costs money, resources, energy, and
social costs. Who will pay becomes an essential consideration, and, like the
other questions raised, the answer depends very much on the perspective
from which the question is asked. It may be that no answers are possible
in which all the parties win, so that compromise is more often than not the
only realistic goal.
Evaluation Criteria
The principal evaluation criterion is, of course, the extent to which
the proposed option will help solve the problem the study is addressing.
Again, this emphasizes the importance of defining the problem accurately
and early. The link between problem definition and the ultimate choice
of options can be solidified by including in the definition explicit mea-
sures for determining how success will be measured. For instance, if the
problem is defined to be deteriorating water quality, the definition of the
problem should indicate which particular contaminants are of concern (e.g.,
selenium alone, other specific salts, all salts, all agricultural chemicals, all
contaminants for which water quality standards are in place, or some other
specific list of substances). The definition should also indicate whether im-
provement would be measured by the average concentration of pollutants
in the receiving water, the maximum concentration of pollutants in the
receiving water, or some other criterion.
Success in solving the defined problem is not, however, the only crite-
rion for evaluating alternative options. Various other technical, economic,
institutional, and environmental criteria must also be considered.
In the water resources field, substantial effort has been spent over the
past 40 years developing criteria and procedures for project evaluation.
These were first compiled and published in the Federal Register in 1973
(Water Resources Council, 1973~. This landmark discussion of principles
and standards set forth four "accounts" national economic development,
environmental quality, social well-being, and regional development that
are to be evaluated when analyzing the advantages and disadvantages of
proposed water resources projects supported by any federal agency. An
update published in 1983 provides additional principles and guidelines (Wa-
ter Resources Council, 19834. The regulations implementing the National
Environmental Policy Act's requirement that environmental impact state-
ments be prepared for such projects, and Executive Order 12291, which
requires that cost benefit analyses be conducted for many federal activities,
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IRRIGATION-INDUCED WATER QUALITY PROBLEMS
also influence the structure and content of evaluation processes carried out
for federal actions.
Regardless of the particular requirements or emphases of these specific
evaluation procedures, any comprehensive evaluation should consider four
general categories of criteria-technical, environmental, economic, and
other institutional. Again, the way in which these evaluations will be
conducted and the specific criteria and measurements that will be used in
the evaluation process should be spelled out early in the study process.
Technical Criteria
Any proposed response to an irrigation-induced water quality problem
needs to be technically and scientifically sound. Where the technology has
been proven and widely demonstrated to be effective in real applications,
the primary concern is whether there is anything different about the pro-
posed application that might disrupt the technology. For new technologies,
however, the evaluation will need to consider whether the technology acts
in concert with scientific principles, whether it is consistent with existing
engineering practice, whether it is likely to have any adverse side effects,
and whether there are any characteristics of the proposed application that
might interfere with its functioning properly.
Any technology ought also to be evaluated on the basis of whether it
truly resolves or only changes the problem, and whether the solution is long
term or short term. A technical approach that simply removes the salt from
the drainage water (e.g., using a membrane desalinization process) has a
disadvantage; although it may remove the contaminants from the water, it
creates another waste stream of high salt concentration that still requires
disposal. Some solutions, such as the original proposal to use Kesterson
NWR to evaporate irrigation drainage water, may work in the short term
but be ineffective or even create more serious problems in the long term.
Environmental Criteria
Although the environmental and ecological viability of proposed ac-
tivities often was not given significant consideration in the past, this has
now become a primary concern. At the least, the proposed action should
have little adverse impact on the stability and functioning of existing nat-
ural ecosystems. Beyond being environmentally nondamaging, however,
responses that help restore degraded ecosystems and increase the provision
of environmental amenities are generally to be preferred over those that
do not.
Evaluating the absence of negative impacts and the provision of en-
vironmental benefits needs to be closely tied to the technical analysis and
evaluation of the option. Otherwise the technical analysis may miss some
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IDEN1:~IFYING AND EVALUATING ALTERNATIVES
113
potentially significant impacts, and the project design may miss some im-
portant opportunities to generate environmental benefits.
The environmental evaluation is often difficult for two reasons. One
is the often substantial uncertainty involved in efforts to assess and predict
environmental effects. The second is the problem of developing good,
unambiguous measures of these effects.
Economic Criteria
The third set of criteria relate to the economics of the proposal.
Economic efficiency is usually a major consideration. Is the proposal
cost-effective that is, does it represent the least-cost way of achieving
the benefits it provides? How efficient is it that is, by how much do
the expected benefits exceed the expected costs? These are the standard
questions regarding the proposal's economic efficiency.
But economic efficiency is only one aspect of the economic evaluation.
A second is the financial question is the proposal affordable? Particularly
in times of tight government budgets, very expensive projects are unlikely
to be funded even though they appear to be very efficient. No matter how
efficient a proposal may appear in theory, the concept has little meaning if
the project is never implemented.
Another important economic consideration is how the benefits and
costs of the proposal are likely to be distributed. Who will end up paying
for, and who will end up receiving, the benefits? Is this distribution
equitable? Is there any way of getting the beneficiaries to pay more of
the costs? This distribution question will be closely tied to the financial
question of how the proposal will be funded.
Other Institui'onal Criteria
All proposed alternative responses also must be evaluated in light of
various other institutional criteria such as social and political acceptability,
whether the responses are in accord with existing laws and court interpre-
tations, and whether they fit into existing institutional responsibilities.
The more congruent the proposal is with existing practices, the more
likely it is to rate well according to these criteria. On the other hand,
however, environmental problems are often caused by existing practices;
when that is the case, any effective solution will have to change those
practices. The questions then become how much the practices have to be
changed, how difficult these changes will be, and what incentives can be
created to encourage them.
The fundamental question in this part of the evaluation is whether
the proposal can actually be implemented. The most effective and efficient
approach is of little value if it cannot (or will not) actually be put in place.
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IRRIGATION-INDUCED WATER QUALITY PROBLEMS
In this case, the evaluation phase may involve significant effort to develop
effective implementation strategies. An assessment of the likely success of
these options should then be fed back into the technical, environmental,
and economic evaluations to develop improved estimates of how well the
proposal will in fact address the problem.
Clearly there are very few ways of quantitatively measuring these
institutional criteria. That fact, however, does not diminish the importance
of their evaluation.
The Evaluation Process
Evaluation the analysis and interpretation of data-is required for
understanding. Careful thought is necessary to turn data into informa-
tion. The interpretive activities that facilitate the conversion of data into
information are seldom given sufficient attention in study design.
Programs of the magnitude required to solve environmental problems
must establish a specific plan to evaluate and interpret the data. Re-
searchers should not expect that some obvious answer will emerge on its
own or that the measurements acquired by the individual disciplinary team
members will be integrated for effective interdisciplinary problem solving
without pointed efforts. Serious effort is necessary to transform data into
relevant information.
Although the evaluation process is the last to be completed, it should
not wait until all the other study elements are accomplished. Instead,
the evaluation process should be ongoing. Nor should every proposed
response necessarily receive the same thorough analysis. Relatively simple
evaluations conducted early in the study may demonstrate that some options
are clearly undesirable, for instance because they are technically infeasible
or prohibitively expensive. Thus the evaluation process may be a series of
evaluation filters, with increasingly rigorous analyses being conducted as
the study progresses.
Another reason for beginning these analyses early is that they may
demonstrate that some important questions are not being asked or necessary
information is not being collected. Thus there should be feedback from the
evaluation phase to the information-collection phase. The feedback can
also occur in the opposite direction if information- collected in other phases
of the study indicates a need for modifying evaluation criteria for instance,
by adding additional contaminants or considering additional environmental
effects.
The process of investigation, analysis, and evaluation of alternatives is
dynamic. Judgment must be exercised in a process that weighs criteria, con-
straints, and opportunities and that uses comprehensive, interdisciplinary
analysis to generate a variety of possible appropriate responses.
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IDENTIFYING AND EVALUATING ALTERNATIVES
115
~ determine the appropriate responses, decisionmakers should as-
sess how the various actions respond to the goals articulated early in the
problem-solving endeavor. In most cases, a combination of approaches will
be necessary.
Four sources of input need to be weighed in the decision-making
process, including:
1. technical input and scientific standards;
2. legal mandates and administrative guidelines;
3. political input; and
4. public desires (which sometimes can differ dramatically from polit-
ical input).
In the past, professionals with relevant technical expertise tended to
make most resource management decisions. Over time, however, the U.S.
legal system has evolved to provide broader guidance, and the public has
become increasingly involved. Also, it was assumed in the past that the
public view was represented by the political input, but that perception has
now become more realistic.
The identification and evaluation process must consider questions such
as the following:
Does the option involve proven technology?
What are the costs, and what are the benefits?
Who pays, and who benefits?
· How difficult is it to implement the option?
· What is the time frame is the option a temporary or a permanent
solution?
What emerges from a constructive consideration of these questions
will not be one "right" solution but rather a combination of institutional
initiatives and technical measures. In the process of formulating this mix,
trade-offs associated with different options will become evident. Legal or
political constraints will emerge that might interfere with the implementa-
tion of some options that may appear technically attractive.
The final decision will involve a difficult process of weighing competing
and conflicting demands and developing procedures to alleviate or manage
the conflicts. ~ade-offs must be recognized and compromises negotiated.
Each stage in a problem-solving endeavor should involve some effort to
consider equity questions-basically, who pays and who benefits. An effec-
tive solution cannot be implemented without weighing the trade-offs that
are inherent in any judgments and choices. Resolving disputes early in
the process reduces the probability that the courts will need to play a role
later in the process. In the end, the ultimate decision on what actions to
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IRRIGATION-INDUCED WATER QUALITY PROBLEMS
take to reach the stated goals will be a compromise blending technical and
institutional components.
CONCLUSIONS
Chapter 4 introduced five basic functions that characterize problem
solving: (1) recognizing a problem, (2) defining the problem, (3) assessing
the data base and collecting data, (4) identifying alternative responses, and
(5) evaluating those responses. Although these discussions have focused
on independent system components, the importance of an interdisciplinary
approach cannot be overemphasized. The ultimate task in problem solving
is to evaluate the information gained for each component in relation to
the others and to integrate that information for interpretation. Thus the
final function to consider in any problem-solving endeavor is how to use an
iterative process incorporating these basic steps.
As data are gathered and evaluation proceeds, a series of possible
responses will evolve some with less certain outcomes than others. While
some types of uncertainty can be dealt with explicitly and quantitatively
through good quality control, other types of uncertainty can only be han-
dled through the adoption of compromise. The goal of using an iterative
problem-solving process is to provide feedback for midcourse corrections,
so that control can be exercised even when the events cannot be predicted.
In the management of natural resources, the ecosystem processes
that are being managed occur on time scales longer than the design of
most experiments. The areas being managed typically are large. It follows,
therefore, that knowledge from experimental science at these scales is likely
to be sparse. Monitoring can be thought of as the straightforward data-
collection phase of long-term, large-scale experiments. Monitoring plays a
crucial role in evaluating and assessing the success (or lack of success) of
management in meeting stated goals.
Because a system's response to management at these scales is not likely
to be perfectly predictable, and because, as a system changes in response
to management, predictability may be even less certain, it may be necessary
to alter management strategies as data become available. A mechanism
for continuously reevaluating the data and information base in light of
emerging alternative responses needs to be formalized. This evaluation
should determine how well management goals are being achieved so that
alterations in the whole problem-solving and data-gathering process can be
implemented.
Another crucial aspect of the iterative process involves analyzing the
full range of possible alternatives, including those that appear to warrant
further attention as well as those that appear flawed. This is helpful to
the long-term success and eventual public acceptance of the chosen option.
An analytical methodology to identify the diverse and often conflicting
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IDENTIFYING AND EVALUATING ALTERNATIVES
117
environmental and economic considerations can be developed through iter-
ative reevaluation. It aids in identifying and quantifying diverse elements.
Iteration also provides a process for presenting relevant information and
mechanisms for compromise (making the necessary trade-off. The public
Is more likely to have confidence in the final decisions if they are made
in a logical and open manner, following a process that has been carefully
thought out and subjected to public review.
REFERENCES
Colby, B. G. 1988. Economic impacts of water law-state law and water market development
in the southwest. Natural Resources Journal 28, 721-749.
Frankenberger, W. T., Jr., and U. Karlson. 1988. Dissipation of Soil Selenium by Micro-
bial Volatilization at Kesterson Reservoir. Final report, Project 7-FC-20-05240. U.S.
Department of the Interior, Washington, D.C.
Lee, E. W., G. H. Nishimura, and H. L. Hansen. 1988a. Agricultural Drainage Water
Treatment, Reuse, and Disposal in the San Joaquin Valley of California, Part I:
Treatment Technology. Technical report, San Joaquin Valley Drainage Program, 2800
Cottage Way, Rm. W-2143, Sacramento, California.
Lee, E. W., G. H. Nishimura, and H. L. Hansen. 1988b. Agricultural Drainage Water
Treatment, Reuse, and Disposal in the San Joaquin Valley of California, Part II:
Reuse and Disposal. Technical report, San Joaquin Valley Drainage Program, 2800
Cottage Way, Rm. W-2143, Sacramento, California.
Murphy, A. P. 1988. Removal of selenate from water by chemical reduction. Ind. Eng.
Chem. Res. 27, 187-191.
Parker, M. S., and A. W. Knight. 1989. Biological characterization of agricultural drainage
evaporation ponds. Water Science and Engineering Paper No. 4521. Department of
Land, Air, and Water Resources, UC-Davis. 51 pp.
Phene, C. J., K. R. Davis, R. L. McCormick, and D. Heinrick. 1988. Subsurface Drip
Irrigation: Management for Maximizing Yields and Reducing Drainage. Proceedings
of Drip Irrigation Symposium, San Diego, California, pp. 34-54.
Rhoades, J. D., F. T. gingham, J. Letey, A. R. Dedrick, M. Bean, G. J. Hoffman, W. J.
Alves, R. V. Swain, and P. G. Pacheco. 1988. Reuse of drainage water for irrigation:
Results of Imperial Valley study I. Hypothesis, experimental procedures and cropping
results. Hilgardia 56~5), 1-16.
Saliba, B. C., and D. B. Bush. 1987. Water Markets in Theory and Practice: Market
Transfers, Water Values, and Public Policy. Westview Press, Boulder and London, pp.
64-65.
Schroeder, R. A., D. U. Palawski, and J. P. Skorupa. 1988. Reconnaissance investigation
of water quality, bottom sediments, and biota associated with irrigation drainage in
the ll~lare Lake bed area, southern San Joaquin Valley, California, 1986-87. U.S.
Geological Survey, Water Resources Investigations Report 88-4001. U.S. Geological
Survey, Books and Open File Reports Section, Denver, Colorado.
Tangi, K. K., M. E. Grismer, B. R. Hanson. 1985. Subsurface drainage evaporation ponds.
California Agriculture 39~9 and 10), 10-12.
van Schilfgaarde, J. 1982. The Wellton-Mohawk dilemma. Water Management and Supply
6~1/2), 115-127.
van Schilfgaarde, J., L. Bernstein, J. D. Rhoades, and S. L. Rawlins. 1974. Irrigation
management for salt control. J. Irrig. Drain. Div., ASCE 100(IR3), 321-338.
Water Resources Council. 1973. Establishment of principles and standards for planning water
and related land resources. Federal Register, Vol. 38, No. 174, Part III, September 10.
Water Resources Council. 1983. Economic and environmental principles and guidelines
for water and related land resources implementation studies. U.S. Army Corps of
Engineers, Department of the Army, Circular No. 1105-2-115. 137 pp.
Representative terms from entire chapter:
water quality
