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.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter.
Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.
OCR for page 1
Executive Summary
In 1982, scientists made an unexpected discovery at Kesterson Na-
tional Wildlife Refuge (NWR) in California's San Joaquin Valley. They
determined that irrigation drainage water was increasing selenium concen-
trations in the refuge's ponds and causing reproductive failures and deaths
in some species of aquatic organisms and waterfowl.
The rapidity of the contamination was without precedent. From the
time the ponds were built in 1971 until 1978, Kesterson's inflow was entirely
fresh water. It was exclusively irrigation drainage water by 1981. Barely 2
years later, in 1982, the first problems were noted.
The contaminant involved selenium also was unprecedented. In the
past, water quality degradation resulting from irrigated agriculture usually
was associated with salinity, although residues from fertilizers and pesticides
also sometimes caused problems. No one had anticipated contamination by
the trace element selenium. Thus the discovery of Kesterson's very visible
selenium contamination attracted national attention, and it set in motion a
widespread effort to identify causes and remedies.
The refuge's contamination was caused by a combination of natural
and human factors including soils rich in soluble selenium and other trace
elements, increased irrigation development with subsequent installation of
subsurface drains, and the failure to install an adequate disposal system for
the drainage water. Nevertheless, the contamination at Kesterson NWR
should not be dismissed as an aberration. Selenium is just one example of a
trace element being concentrated as a consequence of irrigation practices.
1
OCR for page 2
2
IRRIGATION-INDUCED WATER QUALITY PROBLEMS
The toxic effects caused by selenium are only symptoms of the range of
effects that can be caused by elevated salt concentrations.
The underlying issue is clear: irrigation, like many other uses of water,
degrades water quality for later users. The contaminants of concern and
the severity of impacts may vary, but the phenomenon of irrigation-induced
water quality contamination can no longer be ignored. The degradation at
Kesterson NWR and throughout the San Joaquin Valley not only serves as
a warning of potential, similar contamination that might occur elsewhere,
but it also offers insights about how to study and solve such problems.
In undertaking this report, the National Research Council's Commit-
tee on Irrigation-Induced Water Quality Problems sought to provide a
discussion of the insights gained from the San Joaquin Valley experience
and to highlight some lessons that should not be overlooked when similar
environmental problems arise in the future. The committee attempted
to focus on questions of a long-term, interdisciplinary nature ones that
address the national public interest-and it wishes to remind scientists,
resource managers, politicians, and citizens of the importance of this broad
perspective.
This committee was established in April 1985 with the principal pur-
pose of providing the U.S. Department of the Interior and the State of
California with assistance in structuring and evaluating a comprehensive
research program on irrigation-induced water quality problems in general
and the San Joaquin Valley in particular. The committee was charged to
(1) review and advise the overall research strategy being conducted by the
U.S. Department of the Interior and the State of California; (2) review the
research program in progress; and (3) assist in identifying conceptual alter-
natives available to deal with irrigation drainage problems. The committee
met frequently with program managers and researchers from both the San
Joaquin Valley Drainage Program and the National Irrigation Water Qual-
ity Program (Appendix B) and transmitted advice through formal National
Research Council letter reports (Appendix C). The committee elected to
publish this report to leave a permanent record of its thinking.
KESTERSON AS AN EXAMPLE OF
A BROAI)ER PROBLEM
The National Research Council's Committee on Irrigation-Induced
Water Quality Problems was created as a result of the damage caused
by selenium at Kesterson NWR, but it was charged to look beyond the
San Joaquin Valley. Kesterson NWR may have become a symbol of this
type of water quality problem, but it is not an isolated incident. The
U.S. Department of the Interior through its National Irrigation Water
Quality Program- has conducted reconnaissance-level evaluations at more
OCR for page 3
EXECUTIVE SUMMARY
3
than 20 other sites in the western United States where drainage water
from federal irrigation projects flows into wildlife refuges. As of spring
1989, this evaluation process had identified four additional sites that show
potential contamination problems and warrant more extensive research.
These sites are Stillwater Wildlife Management Area, Nevada; the Salton
Sea area, California; Kendrick Reclamation Project area, Wyoming; and
the Middle Green River basin area, Utah. Additional sites with similar
problems, whether associated with federal water projects or private irriga-
tion development, may be discovered in the future. The potential for such
contamination problems elsewhere in the world is also great.
What happened at Kesterson NWR provides one more illustration of
the long-known fact that irrigation projects without adequate outlets for
drainage create unacceptable levels of salinity. The unexpected part of the
scenario was that, given the right soils and geology, the process of drainage
on irrigated lands can also concentrate trace elements to levels that can
cause real harm to the biota.
UNDERSTANDING THE SCIENTIFIC DIMENSIONS OF
AN ENVIRONMENTAL PROBLEM
Decisionmakers must have a basic understanding of the general pro-
cesses by which irrigation degrades water quality before they can resolve
irrigation-induced problems. Hydrological, chemical, geological, and eco-
logical factors all affect and are affected by irrigation. These factors set
the stage for the development of problems and are critical to any attempt
to select potential solutions, because no solution can be successful unless
it reflects some knowledge of the underlying natural processes.
Irrigation causes water quality degradation and salinity problems be-
cause all water contains dissolved salts. The concentration of these salts
varies depending on the origin of the water. When irrigation water is
applied to a field, it moves away by various routes. Some water evaporates
from the soil surface; much more is taken up by plants and returned to
the atmosphere by plant leaves through transpiration. As both evaporation
and transpiration occur, the mineral salts remain behind in the soil. If the
salts are not flushed from the root zone by the application of additional
irrigation water, the increased salinity will slow plant growth, and in time,
agricultural productivity will suffer or cease.
Thus irrigated agriculture will always be short lived unless the salts
accumulating in the root zone are flushed or precipitated out. Drainage-
whether natural or provided by installing drainage systems is a necessity
to maintain irrigated agriculture over time. In most unaltered ecosystems
the common path for soluble salt removal is through the natural drainage
provided by rivers and creeks to the ocean. Although the ocean is the
OCR for page 4
4
IRRIGATION-INDUCED WATER QUALITY PROBLEMS
ultimate sink for all dissolved salts in the surface drainage system, not all
areas drain to the sea in a human time frame. Drainage water sometimes
collects in closed basins, as happens in the Dead Sea on the Jordan-Israel
border, the Salton Sea in southern California, the Great Salt Lake in Utah,
and in the reservoirs at both Stillwater NWR, Nevada, and Kesterson NWR,
California.
These natural or human-made low points accumulate both water and
salts. The water leads to the growth of wetland vegetation, and this attracts
waterfowl and other wildlife. When such enclosed water bodies are used
to dispose of irrigation drainage water, they may, through evaporation
and other processes, quickly become saline and can ultimately lose their
capacity to support biological productivity and diversity. The accumulation
of trace elements, some of which are toxic in low concentrations, and of
agricultural pollutants, such as pesticides or nitrates and phosphates from
fertilizers, can accelerate the deterioration of water quality.
The adverse effects of salinity from irrigation have long been known.
The dominant dissolved salt species involved in these processes include
the carbonates, bicarbonates, sulfates, and chlorides of sodium, calcium,
and magnesium. What has only recently been understood, however, is
that potentially serious impacts can be caused by trace elements such
as selenium, molybdenum, and arsenic. In most cases, these elements
are not carried in by irrigation water but instead originate from in situ
geological materials. This has added a new dimension to the problem
of irrigation water management. Drainage must now be managed not
only to reduce salt accumulation in the root zone and salt disposal in
streams, but also to limit the toxic effects of selected trace elements.
Given the nation's increased awareness of the values of wetlands, and the
increased commitment to environmental values in general, decisionmakers
must be prepared to address these irrigation-related problems effectively
and equitably.
UNDERSTANDING THE INSTITUTIONAL DIMENSIONS OF
AN ENVIRONMENTAL PROBLEM
An array of economic, social, legal, political, and other institutional
factors also affects society's perception of i'rrigation-related problems and
their solutions. These factors, however, cannot be considered in isolation
because institutional and scientific considerations often are entwined, and
effective programs to solve such problems require an understanding of the
complex interactions that occur between social and physical components.
The term "institutions" is used broadly in this report to encompass
much more than the few government bodies that are directly involved
OCR for page 5
EXECUTIVE SUMMARY
s
in irrigation-related activities. The concept includes administrative or-
ganizations, social customs, regulations, policies, laws, and many other
elements. Institutional factors contribute to the creation and continuation
of irrigation-induced water quality problems, and they sometimes impede
appropriate responses.
The most pervasive economic issue contributing to irrigation-related
water quality problems and affecting the choice and success of solutions
is the cost of water. The use of subsidies to support the high cost of
water projects has brought many benefits to the West, but it has also
brought problems. The subsidized low cost of water results in more water
being used, encourages farmers to cultivate less desirable lands, and leads
to increased agricultural runoff. The difficult question of who will pay for
whatever responses are adopted to combat irrigation-related problems must
also be addressed. Demographic trends are also important: the West is
becoming increasingly urbanized, and this is bringing a shift in priorities for
water use. Current water use patterns also diminish the amount of fresh
water left in streams to dilute contaminants and carry them to the sea.
The political setting has played a critical role in creating situations
conducive to irrigation-related problems. The decision to irrigate the West
was, of course, primarily a political one. Policymakers chose to promote
social goals the settlement of the West through the Reclamation Act of
1902. This occurred at a time when there was great belief in the ability of
technology and engineering to overcome almost any natural obstacle. The
importance of political, economic, and social factors cannot be overstated.
In short, the institutional setting in the West created many of the problems
now being faced, it created a structure that prevented the problem from
being addressed effectively early on, and it will ultimately determine what
solutions will be implemented.
The environmental and social impacts both positive and negative-
associated with irrigation and irrigation drainage water can be exacerbated
or ameliorated by the institutional setting. This setting involves a maze of
sometimes competing interest groups, agencies, laws, mandates, and social
patterns. In many ways, the solutions to irrigation-induced water quality
problems are hindered less by scientific and technical uncertainties than
they are by conflicts in the social, economic, and legal realms. Thus it will
prove impossible to solve these types of problems unless a combination of
scientific and institutional means is brought to bear on the process.
RESOLVING PROBLEMS: ESSENTIAL STUDY ELEMENTS
Science now plays a critical role in mediating the conflicts that arise
among parties with different perceptions of a problem and its potential
resolution. Finding solutions to irrigation-related problems can require
OCR for page 6
6
IRRIGATION-INDUCED WATER QUALITY PROBLEMS
difficult choices. Thus the equity and effectiveness of the process used
to seek, evaluate, and implement potential solutions become critically
Important. Sound study design is essential.
A well-conducted problem-solving endeavor should employ, in order,
the elements of problem recognition; problem definition; data assessment,
collection, and interpretation; identification of alternative responses; and
evaluation of those alternatives. In structuring any problem-solving en-
deavor, explicit attention should be paid to quality assurance and quality
control, data and information management, monitoring, risk and exposure
assessments, public participation, and conflict management. The complexity
of irrigation-related problems should be recognized but should not be used
as an excuse for paralysis. And in light of the inherent complexity of such
problems, it should be recognized from the start that no environmental
problem is solely technical or solely institutional.
A broadly acceptable definition of a recognized problem must be
negotiated early in any research effort because different participants will
have different perspectives, focus on different symptoms, and have different
goals. How a problem is defined ultimately determines the nature of the
solutions that are examined and implemented. Obtainable goals can be set
only if the problem to be solved is clear and agreed upon by all parties.
All potential responses have costs money, resources, energy, and social
costs so that who will pay becomes an essential consideration. Rarely, if
ever, is it possible for all parties to be fully satisfied, and some judgments
and compromises will have to be made. If the problem-definition process
is adequate, in the end local, regional, and national interests should be
appropriately balanced.
Public participation should be incorporated throughout all problem-
solving endeavors, but it is particularly necessary when defining a problem
and assessing the alternative responses. Public participation brings compet-
ing interests together, communicates information, identifies research needs,
and helps people understand the nature of scientific uncertainty. In fact,
the success of any proposed solution will ultimately depend in large part on
the public's confidence that the decision process was open and complete.
A wide range of alternative responses needs to be analyzed formally. This
not only avoids the pitfall of overlooking important possible solutions, but
it also provides a basis for establishing the costs of preferred alternatives
compared to the costs of others.
RESOLVING PROBLEMS: IDENTIFYING AND
EVALUATING ALTERNATIVES
The goal of all the steps in any problem-solving endeavor is to select
and implement successful responses to the defined problem. The process
OCR for page 7
EXECUTIVE SUMMARY
7
discussed in this report is broadly applicable, whether the problem is
caused by irrigation drainage or other influences. Regardless of the specific
circumstances, however, one step in this process merits special emphasis:
identifying and evaluating the full range of alternative responses available.
1b identify appropriate responses ones that adequately and fairly re-
spond to the stated goals of the problem-solving endeavor requires careful
analysis. Technical, ecological, economic, legal, social, and political criteria
all should be evaluated in an attempt to weigh the relative advantages and
disadvantages of each proposed approach.
This committee has consistently emphasized the need 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. All options need to be assessed so that
the costs and benefits can be compared and so that innovative ideas are
not eliminated prematurely. 1b ignore certain options is to jeopardize the
credibility of the overall analysis. Obviously, in the latter stages of any
study the time, money, and energy spent assessing the various options will
begin to be weighted in favor of the more appropriate choices (after all,
this is the objective of the study and evaluation process), but this should
never preclude the importance of studying all options before beginning to
eliminate unacceptable ones.
The identification and evaluation process should ask and seek answers
to difficult questions. These might include the costs and benefits of the
option, whether it involves a proven technology, how difficult the option
might prove to implement, the time frame of the option, and, importantly,
who pays and who benefits. What will emerge from a constructive ques-
tioning process will not be one "right" solution but instead a combination
of institutional initiatives and technical measures. In the process of for-
mulating this mix, trade-offs associated with different options will become
more clear. Legal or political constraints will emerge.
The evaluation of alternatives will involve careful assessment to deter-
mine each alternative's role, effectiveness, and incidental impacts in solving
a particular environmental problem. Some of the elements to be considered
include technical soundness, economic viability, institutional soundness, so-
cial acceptability, political feasibility, and ecological appropriateness.
The array of technical and institutional alternatives is formidable.
Technical options for salt management, for example, fall generally into
three categories (transport and disposal of the drainage water, source con-
trol, and treatment of the drainage water) and may include retirement of
land from irrigated agriculture, better irrigation management, onsite evap-
oration ponds, desalinization technologies, chemical and biological removal
techniques, ocean disposal, and deep-well injection. Institutional options
OCR for page 8
8
IRRIGATION-INDUCED WATER QUALITY PROBLEMS
are particularly diverse. Changes in pricing policy, subsidies, taxation, or
water transfer policy will each have impacts. Regulatory approaches can
be used, or institutions can be changed to reduce the conflicts caused by
convicting responsibilities.
RECOMMENDATIONS
This committee sees the sometimes negative environmental impacts
associated with irrigation in arid regions as a generic problem that the
nation must be better prepared to address. In undertaking this report,
the National Research Council's Committee on Irrigation-Induced Water
Quality Problems sought to help foster awareness of the problems that
can be caused by irrigation drainage and to guide decisionmakers in seek-
ing equitable, effective responses. It is virtually inevitable that additional
irrigation-related water quality problems will appear in the future, as will
other environmental problems of a similar nature, and it would indeed be
unfortunate if the insights gained from the San Joaquin Valley experience
were to go unrecognized and unheeded.
The recommendations presented here focus on two different levels
of activity. The first set of recommendations focuses on planning issues
and study design; these recommendations suggest methods that should
be used by scientists, resource managers, public officials, citizens, and
other decisionmakers when formulating effective responses to irrigation-
induced water quality problems wherever they arise. The second set of
recommendations addresses policy issues and the opportunities for national
action to minimize the negative impacts associated with irrigation.
Planning Issues
Related to Irrigation-Induced Water Quality Problems
· Federal and state agencies should strive to use sound study design
when trying to resolve irrigation-induced water quality problems. Sound
study design should emphasize a formal systems approach, be responsive
to change, and recognize the dynamic properties of the hydrologic system.
· Federal and state agencies responding to irrigation-related prob-
lems should develop an action plan that carefully evaluates the alternative
responses available and that reflects increasing scientific understanding of
ecosystems. They must work to promote public participation, reconcile
competing societal needs, balance economic and non-economic costs, and
consider the possibility of institutional and legal changes.
· Federal and state agencies should choose a course of action only
after all the identified alternatives have been examined and displayed
openly. There must be a clear understanding that `'win-win" solutions
OCR for page 9
EXECUTIVE SUMMARY
capable of satisfying all parties are rare and that options often need to be
site- or region-specific. All options present economic trade-offs and value
choices, so that judgments are necessary.
· Federal and state agencies should pay particular attention to the
feasibility of implementation. Adequate and stable funding, coordination
among agencies and levels of government, effective enforcement, competent
personnel with clear responsibilities, and well-defined channels for citizen
input are necessary.
Federal and state agencies need to be actively involved in some type
of interagency program to regularly monitor the impacts of irrigation on
water quality at all major irrigation projects. This program should contain
elements devoted to anticipating future problems and to monitoring water
quality over the long term. The National Irrigation Water Quality Program,
or some equivalent, could perform these functions indefinitely. Components
of the San Joaquin Valley Drainage Program also will need to be continued.
.
Policy Issues
Related to Irrigation-Induced Water Quality Problems
If any major irrigation projects are planned in the future, at the
onset federal and state agencies should calculate the costs of drainage for
irrigation return flows and should commit funds to build and maintain the
system.
· Federal and state agencies should design and implement manage-
ment strategies that minimize the adverse impacts of irrigation, and they
must acknowledge the inevitable ecological trade-offs involved.
.
Federal and state agencies should systematically monitor all major
irrigation projects for substances that could cause water quality problems.
Federal and state agencies that facilitate or regulate irrigation
should periodically calculate and publicize the associated environmental
costs as well as the agricultural benefits, and should work to accommodate
the nation's increasing commitment to protecting environmental values.
· Irrigation return flows should not be exempt from federal and state
water quality regulations, and such regulations should be enforced.
· Federal and state agencies should increase their efforts to provide
water supplies for wildlife, enhance wildlife habitats, and protect the bi-
ological and recreational values associated with in-stream flows and good
water quality.
Federal and state agencies should acknowledge all external costs-
including social and environmental costs when calculating the costs and
benefits of agricultural subsidies.
· Federal and state agencies should identify irrigated lands that are
degrading water quality significantly and should implement cost-effective,
OCR for page 10
10
IRRIGATION-INDUCED WATER QU^I~PROBLEMS
environmentally sound actions to correct or minimize the degradation. Such
a program would incorporate a range of alternative approaches for pre-
venting, mitigating, and treating irrigation drainage problems. This would
include, if necessary, phasing out production on particularly problematic
lands.
Responding to Irrigation-Induced Water Quality Problems:
A Shared Responsibility
One fact made clear during this committee's oversight of the San
Joaquin Valley Drainage Program is that finding a solution to the valley's
drainage problem, and any such situation anywhere in the West or the
world, is not a purely technical question. Indeed, the more difficult issues
are often political, social, and economic. In all cases, however, the various
components are intimately interrelated. Only by defining and addressing
the system as a whole, and realistically assessing its complexity, can progress
toward real and lasting solutions be made.
The U.S. Bureau of Reclamation, which has received considerable at-
tention in this report because of its primary role in the Kesterson NWR
experience, is not alone in facing the significant challenges arising from
irrigation-induced water quality problems. The problems are not all caused
by federal and state activities, nor can they necessarily be solved at those
levels alone. The federal and state agencies involved in irrigation are man-
dated to carry out the will of the public, and so the ultimate responsibility
for solving these types of problems is one that the public shares.
Representative terms from entire chapter:
drainage water
