U.S.-Mexico Groundwater Diplomacy: Lessons from the Historical Record

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• U.S.-Mexico Groundwater Diplomacy:Lessons from the Historical Record
• Stephen P. Mumme (bio) and Elia M. Tapia-Villaseñor (bio)

Among the enduring challenges and, some would argue, the unfinished business of elaborating a comprehensive regime for managing shared waters along the U.S.-Mexico boundary, the problem of reaching bilateral agreement on groundwater looms large. The desirability of, indeed the compelling need for, such an agreement if transboundary aquifers are to be managed sustainably has long been recognized, initially addressed in the deliberations that produced the landmark 1944 Water Treaty, and formally established by binational agreement in 1973. And yet, nearly 50 years since the International Boundary and Water Commission's Minute 242 of the treaty obliquely raised the need for a comprehensive treaty on groundwater, that goal remains unrealized.

This paper aims to advance understanding of both the causes of this diplomatic impasse as well as emerging opportunities for progress toward binational management of these essential, even critical, water resources for the U.S.-Mexico border region. We first consider the history of binational diplomacy on groundwater, from the deliberations leading to the 1944 Treaty through the protracted binational dispute on salinity that generated the concerns expressed in Minute 242 in 1973. We then look at the binational discourse on groundwater since the salinity dispute to ascertain what limited progress has been made since Minute 242 was signed. We observe that a long diplomatic hiatus is broken with a few focused studies on aquifer quality and with a 2006 initiative, the U.S. Transboundary Aquifer Assessment Act (TAA-Act), and the subsequent binational engagement through the U.S.-Mexico Transboundary Aquifer Assessment Program (TAAP). We then review the diplomatic progress that is evident in Minute 242's formal commitments, the diplomacy that [End Page 362] produced the agreement, and such diplomacy as has followed in the post-1973 period, particularly that related to TAAP. These incremental and cumulative gains, we argue, have now set the stage for binational engagement on joint management of transboundary groundwater along the border.

Groundwater Diplomacy: Origins and Concerns

Binational concern with groundwater is a relatively modern affair, driven by the advent of electrically powered pumps that became available to border farms and communities in the 1930s (Mann, 1963). Groundwater is unmentioned in either the Treaty of Guadalupe Hidalgo or the Gadsden Treaty establishing the basic contours of the U.S.-Mexican boundary, nor is it referenced in subsequent boundary and water agreements prior to 1944. Rapid expansion of electricity grids on both sides of the border after 1920, powered by new hydroelectric dams and coal-fired power plants generating cheap electricity, facilitated agricultural resort to underground aquifers.

Recognition of the value of border groundwater at the diplomatic level may be dated to deliberations on the 1944 Water Treaty, which commenced in earnest in 1943. To better focus on the principal surface water concerns, U.S. and Mexican diplomats deliberately set groundwater matters aside when formulating the 1944 Treaty. However, the treaty adapts to water-related challenges via interpretations or modifications (Minutes). The International Boundary and Water Commission (IBWC) oversees the application of such Minutes, the 1944 Water Treaty, and any other issue or treaty regarding boundary demarcation and water resources in the U.S.-Mexico border region, including the contentious dispute over the salinity of Mexico's Colorado River water allotment that threatened to derail national commitment to the treaty.

Groundwater in the 1944 Water Treaty Negotiations

It is plain enough from the treaty record that the negotiators were little concerned with such groundwater pumping as existed in various localities near the international boundary with the singular exception of groundwater extraction and utilization in the lower Colorado River [End Page 363] region (Hundley, 1966; Ward, 2003). Attention focused specifically on groundwater use in two locations, near San Luis Rio Colorado and along the stretch of the recently completed All-American Canal (AAC) proximate to the international boundary. The AAC conveyed Colorado River water to the agricultural valleys of Imperial, Coachella, and Yuma and was originally built as an earth-lined canal by the United States Bureau of Reclamation (USBR), the federal U.S. agency in charge of infrastructure...