Conflict in the Borderlands

September 25, 2007

The history of U.S.-Mexico relations concerning water is one of barely contained, and sometimes open, diplomatic conflict. Within the United States, interstate water disputes over the Colorado River and the Rio Grande—known in Mexico as the Río Bravo—are complex and contentious. The tensions are only aggravated when these rivers and their tributaries cross the Mexican border. Despite some important successful examples of mutually beneficial bilateral negotiations, settlements regarding borderland water resources too often reflect the enormous asymmetries of wealth and power between the United States and Mexico.

For its water supply, the U.S.-Mexico border region depends on two major rivers—the Colorado River and the Rio Grande—both of which flow from north to south, and numerous smaller rivers that mostly flow from south to north. Rainfall amounts to less than eight inches a year along most of the 2,000 mile U.S.-Mexico border, making this one of the world’s most arid boundaries. Moreover, triple-digit temperatures cause surface water to evaporate quickly, resulting in a water deficit—more evaporates than is replenished through rainfall. Surface water availability is also highly undependable, varying enormously with dramatic swings in rainfall and run-off.

Under these conditions, groundwater is the principal source of supply for many border communities and a necessary resource for agriculture. However, these ancient underground water supplies are being rapidly depleted, especially along the stretch of the border flanked by the Colorado River and the Rio Grande. Indeed, devastating droughts of recent years have precipitated international conflict, particularly over the Rio Grande, and as droughts return so will the conflicts. Meanwhile, widely predicted global climate change promises to aggravate the situation.1

Prior to 1940, groundwater basins in many border areas were in hydrologic equilibrium—water inflow was approximately equal to outflow.2 Since then, water withdrawal has far exceeded recharge and has degraded water quality. Some aquifers along the border are at critical levels. Estimates show, for example, that in the Hueco Bolsón aquifer, which provides water to the cities of El Paso and Ciudad Juárez, only 20 years of usable supply remain. Also, in the borderlands of southern California and Mexico’s adjacent Mexicali Valley, annual groundwater overdraft is nearly two million acre-feet.3 The magnitude of this amount becomes apparent when compared to the 800,000 acre-feet used annually by more than five million people in southern California.4

Scarcity is especially worrisome considering the growing human population and rich natural environment along the border. The population of border cities in both countries is exploding. And as water infrastructure in Mexico has improved, the per capita use of water has increased. Additionally, irrigated agriculture uses a great deal of water along the border, where year-round sunshine facilitates the cultivation of everything from citrus to pecans. Cattle ranching—particularly important in the Mexican border-state of Sonora—has recently become even more water-intensive due to the introduction of buffelgrass and the need to irrigate this exotic fodder. Finally, in spaces not taken up by cities and farms there are water-dependent ecosystems that support more than 450 rare, endemic species.5

The struggles among water users within nations and across borders have left a string of winners and losers. Water serves as a kind of tracer element, identifying those who wield political and economic power and those who don’t. In many binational water disputes, powerful actors have sought to wrestle control from—and push risks onto—marginal communities and peoples unable to protect their interests. In general, Mexican water interests have taken a back seat to those of the United States, and in both countries urban expansion supersedes environmental health and the rights of indigenous people. The ruling tendency is to over-allocate available water supplies to those who win out, while ignoring ecological limits. The burden of risk is increasingly shifting from the present generation to the next, which will face much diminished and degraded water supplies, especially in terms of groundwater.

Like beads on a necklace that stretches along the entire border from Brownsville and Matamoros to Tijuana and San Diego, binational water problems are focal points for potential or existing conflicts.6 As mentioned, the sister cities of El Paso and Ciudad Juárez face a critical depletion of their aquifer, Hueco Bolsón. El Paso tried countering its shortage by buying up agricultural surface water as fast as the law allowed, but a severe drought hit the Rio Grande Basin, forcing the city to ration its water. Fierce competition for this scarce resource is straining relations between the two cities. El Paso residents blame Juárez for not building treatment plants to improve the Rio Grande’s water quality, and also complain that Juárez pumps water relentlessly without a long-term strategy.7

Ambos Nogales, the twin cities of Nogales—one in Arizona, the other in Sonora—face a unique problem arising from topography: the Sonoran city is much larger and sits higher than its U.S. counterpart. The two cities share the Nogales Wash, which sends a flood of water into the U.S. city when inundated. The water not only carries soil and refuse from the urbanized hillsides, but also industrial waste and sewage from broken lines.

For decades, San Diego and Tijuana have faced a problem similar to that of Nogales, albeit for slightly different reasons. Tijuana’s wastewater collection system has not kept pace with the city’s population boom.8 The topography and ocean currents are such that wastewater overflows find their way to southern California beaches. In the development of new wastewater facilities, controversy surrounds everything from their design to the question of who captures treated and reclaimed water and who should pay for upgraded facilities. San Diego has resisted significant cost-sharing, even though city residents will enjoy many of the benefits. San Diego officials maintain the problem is international in nature and thus should be dealt with by the federal government.

Settling these and other matters is no simple task. Like sedimentary rock, layers of binational institutions with partially overlapping jurisdictions have settled into place. The patchwork of organizations and jurisdictions reflects the piecemeal, incremental approaches taken by the two governments. Founded in 1889, the International Boundary and Water Commission (IBWC) is the oldest and most established of boundary institutions. The U.S.-Mexico Water Treaty of 1944 consolidated a variety of responsibilities into one commission divided in two parts—the IBWC in the United States and its Mexican counterpart, CILA. Investigation and dispute settlement are among the functions of the commission, addressing a wide range of water-related environmental problems including sewerage, salinity and other quality issues. It also interprets and implements water apportionment agreements. And although it has limited jurisdiction over groundwater, granted by Minute 242 of 1973—an addendum to the water treaty—the IBWC-CILA has been very slow to act in this area.9

Until the mid-1980s, the IBWC-CILA was the most important agency dealing with border water issues, but rising public concern about water quality and the perceived inadequacy of the commission has led to the establishment of other institutions. In 1983, the U.S.-Mexico Border Environmental Cooperation Agreement (the La Paz Agreement) provided a means for the environmental ministries of both countries to take the lead in water quality matters. The La Paz Agreement acknowledges the IBWC-CILA’s key role in addressing water functions specified in the 1944 treaty, but also provides a process for anticipating, assessing and receiving public input into the environmental aspects of transboundary water management. In the early 1990s, the Border Environmental Cooperation Commission (BECC) was created in partial fulfillment of the environmental side-agreements of the North American Free Trade Agreement (NAFTA). Its creation was a response to public concern that free trade would further degrade the environment in the already degraded borderlands. BECC consists of a Board of Directors representing many major stakeholders, including the commissioners of the IBWC-CILA, states, environmental ministries and the general public. BECC’s mandate is to provide technical and financial assistance for developing needed border infrastructure projects.10

The institutional arrangements for dealing with U.S.-Mexico transboundary water problems may be among the strongest in the world, but the performance of these institutions falls short of the high hopes of their designers. Key problems are the enormous power imbalance between the two countries and the related difficulty of directing high-level governmental attention to water issues in the United States. This means that rather narrow and parochial interests in the United States often hold national water policy toward Mexico hostage. Likewise, the IBWC-CILA has been disproportionately sensitive to the concerns of U.S. states, particularly California and Texas. The overall result is that despite their numbers, these institutions have not adequately addressed many problems.

Of the many interstate and international conflicts over water along the U.S.-Mexico border, some have flared far beyond others. Currently, the lining of the All-American Canal and the apportionment of the Lower Rio Grande waters are the most sensitive issues.

The All-American Canal near the western end of the U.S.-Mexico border became operational in the 1940s to provide surface water to the Imperial Irrigation District in southern California. Until recently, the canal, which for more than half of its 82-mile length parallels the border, has been partly earthen. The proposed lining of the canal would substitute the porous earth with an impermeable surface, greatly limiting groundwater recharge into Mexico. Without the lining, the All-American Canal’s proximity to the border, along with the prevailing groundwater gradient tipping southward towards Mexico, results in a steady percolation of water into Mexico’s sandy substratum. This water replenishes existing stocks and has served as a steady source for more than 50,000 acres of farmland in the Mexicali Valley and at least a half-million users just south of the border.11 The importance of this water for Mexico increased during the salinity crisis in the early 1970s, when the water the United States delivered to Mexico from the Colorado River was too salty to use.12

Mexico’s increased reliance on groundwater during the salinity dispute caught the attention of the United States, which then began exploring ways to retain the fugitive resource. Influencing the U.S. position were the powerful upstream interests of states that resented having to increase deliveries to Mexico because of the salinity settlement. In 1988, the U.S. Congress directed the Secretary of the Interior to proceed with the lining of the canal to end the seepage.13

Through the IBWC-CILA, Mexico pleaded a case for its ownership of the water in question under the provisions of Minute 242, which required mutual consultation over any future groundwater development.14 The U.S. countered that Mexico’s argument lacked legal merit since it was not groundwater at issue, but surface water belonging to the United States.15 The dispute, however, has never been part of the U.S.-Mexico diplomatic agenda. It has never been the subject of formal negotiations between the two countries.

Further exploration of the All-American Canal dispute illustrates how domestic political issues determine much of the U.S. water agenda with Mexico. The state of California has regularly exceeded its legal entitlement to 4.4 million acre-feet per year of the Colorado River’s water. In recent years, upper basin states and Arizona have strongly objected to California’s overuse, forcing the state to seek alternative means.16 The lining of the All-American Canal is one of the main strategies adopted. In 2003, as part of comprehensive agreements on the allocation of the Colorado River waters among the U.S. riparian states of the river and the water agencies of southern California, the San Diego County Water Authority became the agency in charge of lining the canal. The estimated cost of the mega-project is $325 million with a projected completion date of December 2008.17

The usual upper hand the United States has in water disputes is augmented in this case by the fact that it is the upstream party and can, therefore, take unilateral action. The U.S. contends that the All-American Canal’s seepage is actually surface water and that Mexico already receives its share of surface water from the Colorado River under the terms of the 1944 treaty. The treaty makes no explicit denial of Mexico’s right to seeped surface water, which in effect becomes groundwater. The negotiators were cognizant of the interaction of surface and groundwater as the process was well understood in 1944, yet they remained silent on Mexico’s use of such waters. In any case, since it is groundwater that is arguably in question, the United States should formally negotiate the issue with Mexico, as required by Minute 242 of 1973.

At the turn of the 20th century, agriculture began to flourish in arid areas along the eastern stretch of the Rio Grande. A web of irrigation canals transformed deserts into lush farmlands in southern Texas and the northeastern Mexican states of Chihuahua, Coahuila, Nuevo León and Tamaulipas. In just four Texas counties of the Lower Rio Grande Basin, an astounding 600,000 acres of irrigated land are in use.18 The diversion of water also has allowed the Lower Basin of the Rio Grande to sustain a population of 4.9 million people, although agriculture remains the primary consumer of water.

The main binational regulation of water resources in this area is also based on the 1944 Water Treaty. According to the treaty, Mexico receives 1.5 million acre-feet annually from the Colorado River, while the United States is entitled to an annual minimum quota from Mexico of 350,000 acre-feet, mainly from the Conchos River and other minor tributaries of the Rio Grande. The treaty provides for a decreased flow of water from Mexico to the United States in times of “extraordinary drought;” however, the treaty’s definition of “drought” is vague.

The drought that began in 1992 has made it difficult for Mexico to fulfill its delivery commitments. The Falcón and the Amistad Dams on the international reach of the Rio Grande, which, among other duties, store water for deliveries downstream to the United States, have not been full since 1992. The drought has left the reservoirs at only 30% of capacity since 1992, and in 2001 the Rio Grande’s flow failed to reach the Gulf of Mexico.19 Because of the delivery failure since 1992, the accumulated “water debt” Mexico owed the United States by 1997 was 1.5 million acre-feet.

Mexico uses the drought provision of the treaty to argue that it is permitted to repay the water over a five-year period. Alberto Szekely, Mexico’s Special Advisor on International Law to the Secretary of Foreign Relations, stated in May 2002 that Mexico “has only 19% of the volume of water behind its dams that it had a decade ago.” He claims that U.S. demands are “unreasonable,” since the water “does not exist.”20 The governors of the states of Chihuahua and Tamaulipas similarly confirmed that there is no water available for delivery to the United States. They also reject the notion that the central government should use “their” states’ water to repay a national obligation.21

The U.S. response to this current dispute over the allocation of waters of the Lower Rio Grande contrasts revealingly with the unilateral U.S. decision to line the All-American Canal. The issue of the water debt has rapidly made its way onto the bilateral diplomatic agenda. Presidents George W. Bush and Vicente Fox have discussed it at several meetings. At various points, the United States has put pressure on Mexico to fulfill its obligations. In October 2002, the State Department declared Mexico in violation of the 1944 treaty, although it did not specify any sanctions.22 The mobilization of those U.S. interests affected by the lack of water delivery focused public attention on the problem in the United States. Farmers in southern Texas publicized their plight and lobbied their congressional representatives, asking for compensation from Mexico or the imposing of sanctions, or both.23

Under pressure from the U.S. government, Mexico committed itself to paying the water debt. The IBWC-CILA played a critical role in negotiating a compromise that led to the signing of an agreement in March 2002, which commits Mexico to pay the debt it had accumulated since 2000. By early 2004, Mexico was again allocating its annual quota of 350,000 acre-feet of water to the United States, but the 1.5 million acre-feet of water debt accumulated between 1992 and 2000 remained unresolved.24

A long-term solution lies in the conservation of water on both sides of the border. President Fox stressed that Mexico needed $400 million dollars to install drip-irrigation systems—designed to conserve water—in the Rio Grande area. The project is under review by the North American Development Bank for funding, but farmers in southern Texas strongly oppose the loan, claiming it would reward Mexico for violating the 1944 treaty.25

Water conflicts along the border have the potential to become more heated, considering the enormous demand for limited resources. The persistence of significant institutional gaps does not help the situation. For example, in the case of the All-American Canal, although a groundwater working group exists, there is no groundwater treaty and a formal agreement is unlikely. Groundwater is not highly ranked among the many issues that crowd the bilateral agenda. Unfortunately, without such a treaty, problems of transboundary resources will likely worsen. Aquifers are being over-drafted in many parts of the border, and without an agreement there is little incentive to avoid a race to the bottom.

Existing institutions have also failed to fully address problems resulting from prolonged drought. The 1944 treaty, governing both the Rio Grande and the Colorado River, was agreed upon when little was known about the long-term affects of prolonged drought. And there was no awareness of global climate change, which now threatens both the amounts and timing of precipitation and run-off in the two international rivers. Bilateral talks on this subject are necessary, as is a clear definition of drought provisions in treaties.

Nations are seldom willing to engage in treaty discussions unless a situation of mutual interest and reasonable trust exists. The enormous asymmetry of power between the United States and Mexico hinders the achievement of such a climate. As the world’s sole superpower, the United States rarely focuses attention on its relationship with its far weaker and often compliant southern neighbor. Mexico, on the other hand, is acutely aware of its relative powerlessness and is hesitant to engage in treaty-making from a position of disadvantage.

In the past, Mexico has offered the U.S. State Department something in exchange for being heard on these matters. This was the case in 1944 when, during negotiations for the comprehensive water treaty, Mexico pledged its full support for the cause of the United States and the Allies during World War II. But such opportunities for leverage do not exist at this time.

Meanwhile, Washington’s reluctance to deal with water issues bilaterally encourages parochial interests in California and Texas to dominate the agenda. Demand for this finite resource in towns and cities on both sides of the border continues to grow exponentially along with the population. Urban and industrial development try to keep pace with the demographic upsurge with little regard for the fragile ecological balance of most border habitats. These problems, and their political eruptions, will only worsen as water supplies are increasingly diverted to more powerful U.S. interests.

About The Authors:
María Rosa García-Acevedo is assistant professor of political science at California State University, Northridge. She has published work on U.S.-Mexico transboundary links. Helen Ingram is Warmington Endowed Chair in Social Ecology and has published books and articles on border water problems.


1. John Hernandez, “Long Term Climate and Streamflow Records on the Rio Grande.” Paper presented to the Binational Conference, Coping with Scarcity in the Rio Grande/Río Bravo Drainage Basin: Lessons to be Learned from the Droughts of 1900-1996, Cuernavaca, Mexico, October 1997.
2. T.W. Anderson et. al., “Geohydrology and Water Resources of Alluvial Basins in South-Central Arizona and Parts of Adjoining States” (U.S. Geological Survey Professional Paper 1406-B, 1972).
3. Jason Morrison, Sandra Postel and Peter Gleick, Sustainable Use of Water in the Colorado River Basin (San Francisco: The Pacific Institute, 1996).
4. Testimony by Maureen Stapleton, General Manager, San Diego County Water Authority, at Oversight Hearing on “Implementation of the California Plan for the Colorado River,” U.S. House of Representatives: Subcommittee on Water and Power, December 10, 2001, p. 1.
5. Luis Villa, “Acaparan ganaderos el agua en Guaymas, miles de campesinos en las miseria por la sequía,” El Financiero, May 14, 1998, p.6.
6. As a sample of the wide array of border water issues, see the articles included in Natural Resources Journal, Spring 2000, Vol. 40, No. 2.
7. Octavio E. Chávez, “Mining of Internationally Shared Aquifers: the El Paso-Juárez Case,” Natural Resources Journal, Spring 2000, Vol. 40, No. 2, p. 247.
8. For a recent update, see “Obstacle Removed for a Major New Plant,” San Diego Union-Tribune, February 29, 2004, p. G-2.
9. Much of this section is based on research by Stephen P. Mumme, particularly his “Institutional Framework for Transboundary Inland Water Management in North America: Mexico, Canada, the United States and their Binational Agencies,” report submitted to the Commission on Environmental Cooperation, Montreal, Canada, December 1996.
10. Pamela Doughman and María Rosa García, “Visiones contrastantes del agua y su impacto en el manejo del agua, la equidad social, y la cooperación transfronteriza,” in Alfonso Cortez Lara (ed.), Seguridad, agua y desarrollo en el futuro de la frontera México-Estados Unidos (Tijuana: El Colegio de la Frontera Norte, forthcoming).
11. For a discussion on the impact in Mexico of lining the All-American Canal, see Vicente Sánchez (ed.), El revestimiento del Canal Todo Americano: competencia o cooperación por el agua en la frontera México-Estados Unidos (México: El Colegio de la Frontera Norte/Plaza Jones, forthcoming).
12. Stephen P. Mumme, Apportioning Groundwater Beneath the U.S.-Mexico Border (La Jolla, California: Center for U.S.-Mexican Studies, University of California, San Diego, 1988).
13. See U.S. Congress Public Law 100-675, 1988, http:/
14. Albert E. Utton, “Mexican International Waters” in Robert Beck (ed.), Waters and Water Rights, Vol. 5 (Charlotteville, Virginia: Michie Co., 1991).
15. All surface water of the Colorado River had been allocated through the U.S.-Mexico Water Treaty of 1944, by which Mexico was entitled to receive 1.5 million acre-feet of this water annually. Stephen P. Mumme, “Revising the 1944 Water Treaty: Reflections on the Rio Grande Drought Crises and Other Matters,” Journal of the Southwest, Vol. 45, No. 4: Winter 2003, p. 649.
16. Lisa Snedeker, “Interior Secretary Announces Plan for the Colorado River Water,” Associated Press, December 14, 2000, pp. 1-2.
17. SDCWA, “Four Agencies Sign Historic Colorado River Deal,” News Release, 10/10/2003; José Luis Jiménez, “County Water Authority Approves Imperial Deal,” Los Angeles Times, September 26, 2003, pp. B2-B3. See also the 1998 California legislation that allocated funds for the lining of the All-American Canal (SB 1765),
18. Robert W. Gee, “Dry Fields Threaten Way of Life for Valley Farmers,” Cox News Service, March 17, 2002, p. 1; Robert W. Gee and Susan Ferriss, “U.S., Mexico Share an Urgent Thirst,” Cox News Service, March 17, 2002, p. 1.
19. Ismael Aguilar-Barajas, Mitch Mathis and Jurgen Schmandt, “Water Security and Economic Development in the Binational Lower Rio Grande/Rio Bravo Basin,” paper presented at the Stockholm International Water Institute Seminar, Stockholm Water Symposium, Stockholm, Sweden, August 18, 2001.
20. Susan Ferriss, “Fox Vague on Water Deliveries Owed U.S.” Cox News Service, June 24, 2002, pp.1-2.
21. Ferriss, “Fox Vague on Water Deliveries Owed U.S.”
22. Chuck Lindell, “Texas at Odds with Mexico over Water Crisis,” Cox News Service, October 2, 2002, pp. 1-2.
23. Lindell, “Texas at Odds with Mexico Over Water Crisis”; Mary Jordan and Paul Duggan, “Water Dispute Divides Texas and Mexico,” The Washington Post, May 25, 2002, p. A-3.
24. Asher Price, “U.S. Gets Annual Payment of Water. But Fox says Mexico doesn’t Have Enough Reserves to Tackle Backlog,” The Austin American Statesman, March 10, 2004, p. B1.
25. Ferriss, “Fox Vague on Water Deliveries Owed U.S.”; Susan Ferriss, “U.S., Mexico Reach Pact to Release Reservoir Water,” The Washington Post, June 30, 2002, p. A17.

Tags: water, Colorado, environment, inidgenous activists, US-Mexico border

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