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Chairmanâs Summary Henry Vaux, Jr. University of California, Berkeley The Symposium participants expressed concern about the adequacy and availability of water resources world-wide in the face of continued population and economic growth. It was noted that groundwater will be particularly important in the future because it will account for about 65% of the available supply. Despite the importance of groundwater, in the future the failure to manage much of the worldâs groundwater effectively raises concerns about the sustainability of groundwater resources. These concerns are raised at a time when the sustainability of water supplies is seen as one crucial determinant of the earthâs ability to support projected levels of population and economic growth. Continued lack of effective management will expose large segments of the worldâs population to unacceptable levels of economic and public health risk. Economic risks arise because of the prospect that water supplies (particularly groundwater) will be insufficient to support anticipated economic growth. Public health risks arise because the continuing deterioration of groundwater quality worldwide will expose substantial numbers of people to a broad range of disease-causing organisms and toxic chemicals. These concerns about the adequacy of water generally and the importance of groundwater specifically extend to Mexico. A number of Mexicoâs most important aquifers are now subject to severe overdraft. Significant numbers of people depend upon this overdraft for domestic supplies and overdraft supports key industries. The severe overdraft problem in the Valley of Mexico has been characterized and possible alternative measures for addressing it have been identified in a joint report between the National Academy of Sciences and the Academia Mexicana de Ciencias (NRC 1995).The overdraft problem extends beyond the Valley of Mexico. Groundwater is the only permanent source of water in the arid and semi-arid regions which cover nearly 50% of the country. Groundwater satisfies almost all of the rural water uses and accounts for 70% of the water supply in urban areas where 55 million people live. Yet 50% of the groundwater is withdrawn from aquifers where rates of extraction persistently exceed rates of recharge. It appears that groundwater overdraft may account for as much as 20% of total annual water use in Mexico. Concerns were also expressed about the progressive and continuing deterioration of groundwater quality in Mexico. Continuation of the current trends of groundwater quality degradation will likely lead to severe public health problems in the future. During the pre-conference field trip to northeastern areas of the Yucatan Peninsula participants observed the contamination of water wells with human and animal wastes. Presentations at the Symposium documented the fact that groundwater quality in the Yucatan is being degraded by wastes from hog farms and waste from the City of Merida which has no central sanitation systems and relies instead on some 80,000 septic tanks. Concerns about groundwater quality are especially serious in the Yucatan where groundwater is the only permanent source of water supply. Since state and federal level agencies have limited 1
capacity to regulate water quality, it seems likely that deterioration of groundwater quality is widespread in Mexico. Participants were asked to identify the circumstances which, in their opinions, represented the most significant barriers to effective groundwater management. The most important barrier cited by the participants was that necessary information was not getting to water managers. Critical data are not available and existing data are not effectively communicated to decision-makers. For example, data and information about both groundwater quantities and groundwater quality are fragmented and there is no comprehensive picture of groundwater trendsâboth in the Yucatan and elsewhere. There is a significant need for data and information characterizing groundwater quantity and quality both in real time and over the long term. Another problem is that sources of groundwater contamination are both very dispersed and very concentrated. Hog farms are an example of the latter. The groundwater quality management problem is caused by both point and non-point sources and resolution will require that a large number of persons and institutions participate in measures to remediate and enhance water quality. Moreover, the sheer number of actors and the dispersion of those actors mean the private industry will have a very important role in devising and executing groundwater protection strategies. In addition, there is little public awareness or understanding of the problem. Action is not likely to be forthcoming unless the broader public understands what is at stake if groundwater is not managed in a sustainable fashion and encourages local government officials to take action. The fact that groundwater is not highly visible complicates the problem of developing public support for science-based management. Participants considered next the question of how science and scientific input can best contribute to the resolution of the problems identified above and how to secure the buy- in/involvement of the water managers. Thus, for example, local managers will have difficulty in managing groundwater in a proactive and far-sighted way without information on the rates of aquifer recharge and extraction, which would enable them to better understand whether they will have sufficient water supplies in years to come. Similarly, information such as accurate estimates of levels of various contaminants at key sites, the travel times of soil-borne contaminants, and dispersion rates of contaminants within aquifers would help managers devise effective, targeted management and remediation plans in a timely fashion. Most workshop participants agreed that there are significant opportunities to improve the stewardship of groundwater resources in Mexico and thereby minimize the risks to the economy and to public health. They also emphasized that with the aid of science significant strides can be made in the development of science based strategies for managing and protecting groundwater resources in Mexico. The first need is for fundamental data and information about the nature of groundwater resources and how the quantities and qualities are changing over time. Part of this effort should include a careful assessment of what is known and what is not known. Priorities can then be attached to the development of needed new scientific information. The development of adequate 2
scientific information will be absolutely essential not only for the creation of management schemes but for the public education necessary to build public support. The second need is for some credible economic analyses that delineate the costs of alternative forms of groundwater management and the costs of failing to manage groundwater. This analysis should focus on a long term time frame (20 years) and should include findings on the incidence of both benefits and costs from groundwater management and from no management. A third need, in conjunction with and as part of the economic analysis, would be an analysis of the potential public health outcomes of alternative management regimes as well as the no management regime. The fourth is to develop science based strategies for establishing and maintaining sustainable systems of groundwater extraction and for protecting groundwater quality. Scientific information will need to be developed in an interdisciplinary fashion and groundwater should be viewed in terms of its position and role in the overall hydrologic cycle. Finally, participants discussed possible next steps to be undertaken in an effort to address groundwater problems. It was argued that the groundwater resources of the Yucatan ought to be the focus of the next effort because of their extreme vulnerability to contamination. Results of that effort could then be transferred elsewhere in Mexico as needed and as appropriate. Many participants suggested that two activities should occur in parallel with each other. First, a scientific commission should be established and charged with assessing what is known about the groundwater resources of the Yucatan and what needs to be known. Part of this effort would entail the creation of a systematic, long term data collection effort. The commission would then proceed to develop a science based water management plan for the region, making clear note of where additional science is needed to undergird the plan. Given adequate data, existing science could go a long way towards informing the effort to make a general water management plan. Second, and in parallel with the scientific effort, many participants suggested that there should be an effort to inform the public, raise public awareness and involve the public in formulation of groundwater management plans. Some of the group thought it would be helpful to establishâin parallel with the scientific commissionâa multidisciplinary steering committee that would convene a series of public workshops focused on the health and availability of water sources in the Yucatan. Those workshops might have the goal of defining what the water situation should look like 20 or 30 years hence. Their thinking was that this steering committee might evolve into an NGO which would enjoy a high degree of credibility and trust. Most participants consider the current circumstances surrounding the quantity and quality of groundwater in the Yucatan and elsewhere in Mexico as unsustainable. This raises questions about the capacity of Mexicoâs water resources to sustain projected economic and population growth. There are significant opportunities to improve the stewardship of groundwater resources in Mexico which can be pursued at relatively modest cost utilizing 3
existing scientific information. The development of needed additional scientific information and the creation of a long term data gathering network should be high on the list of priorities, however. There was strong support for the proposition that development and implementation of science-based strategies for the management of groundwater would enhance the welfare of all Mexicans. 4
References National Research Council. 1995. Mexico Cityâs Water Supply: Improving the Outlook for Sustainability. National Academies Press, Washington, D.C. 5