Can continental transboundary compacts hold water?

Abstract

The growing number of threats facing continental-scale transboundary water treaties warrants contemporary evaluation of not only the political and climatological conditions under which they were constructed, but also of how different management strategies for accommodating changes in those conditions can lead to treaty success or failure. We assess these threats by highlighting key attributes and vulnerabilities of water treaties across North America that frame a diverse set of future water management priorities. While these threats are ubiquitous globally, they are particularly pronounced in North America where water-abundant basins along the border between the United States (US) and Canada contrast with arid basins along the border between the US and Mexico. We propose addressing these needs through a three-step call to action for management agencies, politicians, and the public at large to embrace a holistic perspective on transboundary water agreements.

Fig. 1. Map of central North America identifying transboundary basins (dark blue) of the Colorado River, the Rio Grande, and the Laurentian Great Lakes; states and provinces (light blue) within the US, Mexico, and Canada intersecting these basins; and the areal extent of both the Ogallala (red) and Cambrian-Ordovician (green) aquifers.

Locations of the Lees Ferry (AZ) and Laredo (TX) flow monitoring stations (see Fig. 2) are also shown. North American political boundaries were obtained from: the Commission for Environmental Cooperation (CEC). 2021. “North American Atlas—Political Boundaries”. Statistics Canada, United States Census Bureau, Instituto Nacional de Estadística y Geografía (INEGI). Available at www.cec.org/north-american-environmental-atlas/political-boundaries-2021/.

Fig. 2. Annual average flows and water elevations from 1918 to 2022.

On A the Colorado River at Lees Ferry (AZ), B the Rio Grande at Laredo (TX), and C Lake Michigan–Huron (Lakes Michigan and Huron are commonly considered one lake from a long-term hydrological perspective). Lake Michigan–Huron water elevations are relative to the International Great Lakes Datum (IGLD). Accurate flow records at Laredo began in 1923. Blue/red bars indicate years above/below the average over the period shown.