Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
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
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
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
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
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
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
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
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
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,
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.