Robert Gabriel Varady, University of Arizona; Andrea K. Gerlak, University of Arizona, and Stephen Paul Mumme, Colorado State University
The United States and Mexico are vying for shrinking shared water supplies after years of unprecedented heat and insufficient precipitation.
A prolonged drought on the lower-middle Rio Grande since the mid-1990s means less Mexican water flows to the United States. The Colorado River Basin, which feeds seven US states and two Mexican states, is also at record levels.
A 1944 treaty between the United States and Mexico governs water relations between the two neighbors. The International Boundaries and Water Commission that she created to manage the 450,000 square mile Colorado and Rio Grande basins did so deftly, according to our research.
This competent management has kept the water relationship between the United States and Mexico mostly conflict-free. But it masked some well-known underlying stresses: a population boom on both sides of the US-Mexico border, climate change and aging water facilities.
1944 to 2021
The predominantly semi-arid US-Mexico border region receives less than 18 inches of annual precipitation, with large areas reaching less than 12 inches. That’s less than half of the average annual precipitation in the United States, which is predominantly temperate.
The 1940s, however, were a time of unusual water abundance on treaty rivers. When American and Mexican engineers drafted the 1944 Water Treaty, they did not foresee today’s prolonged mega-drought.
They also did not anticipate the region’s rapid growth. Since 1940, the population of the 10 largest city pairs that straddle the US-Mexico border has grown almost twenty-fold, from 560,000 to some 10 million today.
This growth is fueled by a booming, water-dependent manufacturing industry in Mexico that exports products to US markets. Irrigated agriculture, ranching and mining compete with growing cities and expanding industry for water scarcity.
Today, there is simply not enough to meet demand in the border areas governed by the 1944 Treaty.
Three times since 1992, Mexico has failed to meet its five-year commitment to send 1.75 million acre-feet of water across the border to the United States. Each acre-foot can supply an American family of four for a year.
In the fall of 2020, a crisis erupted in the Rio Grande Valley after years of mounting tensions and prolonged drought that endanger crops and livestock in the United States and Mexico.
In September 2020, Texas Governor Greg Abbott declared that “Mexico owes Texas a year of water from the Rio Grande.” The following month, Mexican workers released water from a dyked portion of the Rio Conchos in Mexico, intended to cross the border to partially repay Mexico’s 345,600 acre-foot water debt to the United States. United.
Frustrated farmers and protesters in the Mexican state of Chihuahua clashed with Mexican soldiers sent to protect workers. The wife of a 35-year-old farmer and mother of three was killed.
Mexico also agreed to transfer its water stored at the Amistad Dam to the United States, fulfilling its obligation just three days before the October 25, 2020 deadline. The move satisfied its water debt to the United States by under the 1944 treaty, but compromised the supply of more than one million Mexicans living downstream from the Amistad Dam in the Mexican states of Coahuila and Tamaulipas.
The United States and Mexico have pledged to review the rules of the Rio Grande Water Treaty in 2023.
Equally serious is the drought dilemma on the Colorado River. The water level in Lake Mead, a major reservoir for communities in the Lower Colorado River Basin, has fallen nearly 70% in 20 years, threatening water supplies to Arizona, California and Nevada .
In 2017, the United States and Mexico signed a temporary “scarcity-sharing solution”. This agreement, forged under the authority of the 1944 treaty, allowed Mexico to store part of its treaty water in American reservoirs upstream.
Save a tense treaty
Water shortages along the US-Mexico border also threaten the natural environment. As water is channeled to farms and cities, rivers are deprived of the flow necessary to support habitats, fish populations, and the overall health of rivers.
The 1944 water treaty was silent on conservation. Despite all its strengths, it simply allocates water from the Rio Grande and Colorado rivers. It does not take into account the environmental aspect of water use.
But the treaty is reasonably elastic, so its members can update it as conditions change. In recent years, conservation organizations and scientists have promoted the environmental and human benefits of restoration. The new Colorado River agreements now recognize ecological restoration as part of treaty-based water management.
Environmental projects are underway in the lower Colorado River to help restore the river delta, with an emphasis on native vegetation like willows and poplars. These trees provide habitat for endangered birds such as the Yellow-billed Cuckoo and the Yuma Flying Rail, as well as many species that migrate along this desolate portion of the Pacific Flyway.
Currently, no such environmental improvement is planned for the Rio Grande.
But other lessons learned about Colorado are now being applied to the Rio Grande. Recently, Mexico and the United States created a permanent binational advisory body for the Rio Grande, similar to the one created in 2010 to oversee the health and ecology of Colorado.
Another recent agreement allows each country to monitor each other’s water use in the Rio Grande using common diagnostics like Riverware, a dynamic modeling tool to monitor water storage and flows. Mexico has also agreed to try to use the water more efficiently, allowing more to flow to the United States.
Newly created joint teams of experts will study compliance with the treaty and recommend other changes needed to manage the climate-threatened waters along the US-Mexico border in a sustainable and cooperative manner.
Gradual treaty changes like these could tangibly reduce tensions from the past year and revitalize a landmark US-Mexico treaty that is crumbling under enormous pressure from climate change.[This week in religion, a global roundup each Thursday. Sign up.]
Robert Gabriel Varady, professor-researcher in environmental policy, University of Arizona; Andrea K. Gerlak, Professor, School of Geography, Development and Environment, University of Arizona, and Stephen Paul Mumme, professor of political science, Colorado State University
This article is republished from The Conversation under a Creative Commons license. Read the original article.