OPINION

PART 6

Sixth in a seven-part series

By ERIK MARQUEZ and ANDREW I. RUDMAN

Water insecurity on both sides of the 2,000-mile U.S.-Mexico border has long been a strain on the bilateral relationship. Today, increasing climate threats, higher agricultural and industrial demand, poor infrastructure and a rapidly growing population will exacerbate the insecurity if steps are not taken to reconcile available supply with growing demand.

Water Insecurity in Mexico

Mexico faces an imbalance between regions in terms of availability of and demand for water. Central, north and northeast Mexico have access to roughly 33 percent of the nation’s renewable water, while the southeast has access to the remaining 67 percent. In terms of demand, the disparity is reflected in the reverse as the south represents only 22 percent of Mexico´s territory and 23 percent of its total population.

Supply

According to data from Mexico’s National Water Commission (Conagua), the country’s average per-person water supply reached its lowest level in at least 24 years in 2020, with the average person receiving only 240 liters per day – a 31.1 percent decrease over the 1996 level of 348.3 liters per day. In fact, only 58 percent of Mexico’s population has daily access to water. Additionally, there are 6 million people with no access to potable drinking water and 11 million people lacking access to basic sanitation. The border region presents additional water supply challenges given the differing approaches and regulations between the United States and Mexico. Groundwater in Mexico is managed by Conagua as a public good, while in the United States, groundwater can be publicly or privately owned. In Texas, uniquely, groundwater can be privately owned under the “rule of capture,” meaning that any owner with groundwater on their property is free to extract it at the expense of their neighbors.

Furthermore, much like almost all international water agreements, groundwater is not addressed within the 1944 Water Treaty or any of its minutes.

A recent study from geologists at Texas A&M confirmed the existence of 72 hydro- geological units (HGU — subterranean water sources) that span across the border. Of these, 60 percent are within the United States and the remaining 40 percent are within Mexico; additionally, only 50 to 55 percent are considered to be of “good to regular quality.”

Consumption

Roughly three-quarters of Mexico’s water consumption is allotted to its vital agricultural sector. Yet the efficiency (and likely some illicit use) of the infrastructure required to provide water to fields (and for urban consumption) is such that roughly 50 percent of the water carried does not reach its intended recipient. Conagua projects that to feed Mexico’s growing population (projected to increase by 25 percent by 2050), food production will need to increase by 70 percent, requiring a 55percent increase in water demand. An increase of this magnitude is completely unsustainable, with extraction rates quickly resulting in complete depletion. Out of Mexico’s 653 groundwater aquifers, which account for 20 percent of Mexico’s renewable water, at least 157 are already overexploited. The remaining 80 percent of Mexico’s renewable water comes from the 757 surface-level basins where rivers and streams converge to create bodies of water, eight of which are shared with the United States.

It is important to note that renewable water does not signify an infinite water source; overextraction diminishes the potential for replenishment. Renewable water within surface bodies of water and subterranean aquifers naturally recycles itself through the water cycle. Therefore, high rates of overextraction will prevent the replenishment of surface and groundwater at its natural rate, inevitably leading to a permanent depletion of Mexico’s aquifers.

Within Mexico, 60 percent of these surface-level basins have had a long history of contamination due to agricultural, industrial, urban and residential runoff. This reduces the supply of clean water for urban use, especially for drinking as the water will carry a multitude of bacteria and viruses.

Likewise, shared watersheds in the border region suffer from a similar pollution issue. Storm water runoff filled with garbage, sediment and other bacterial matter moves downhill through the Tijuana Valley watershed, which is shared by both countries. This threatens key infrastructure and creates environmental, as well as public health concerns. Causes vary from lack of heavy metal pre-treatment and inefficient or deteriorating sewage infrastructure/maintenance within Mexico and the United States. As of August 2022, the /International Boundary and Water Commission (Comisión Internacional de Límites y Agua) reached an agreement to allocate $474 million in sanitation improvements to be carried out in San Diego and Tijuana, which, according to the U.S. Environmental Protection Agency (EPA), will reduce transboundary wastewater flows by up to 90 percent. The projects seek to address the large quantity of untreated sewage that flows through the Tijuana River.

The 1944 Water Treaty

The Treaty Between the United States of America and Mexico for the Utilization of the Waters of the Colorado and Tijuana Rivers and of the Rio Grande, more commonly known as the 1944 U.S.-Mexico Water Treaty, created the International Boundary and Water Commission (IBWC), or the Comisión Internacional de Límites y Agua (CILA), which forms a single international body headed by two engineer commissioners, with foreign policy oversight from the U.S. Department of State and the Mexico’s Foreign Relations Secretariat (SRE), respectively.

The joint authority is responsible for management and conservation of the Rio Grande and Colorado rivers, construction, operation and maintenance of storage dams, reservoirs and hydroelectric generation, as well as preservation and resolution of border water quality issues — all for the mutual social and economic welfare of both countries.

Water from the Rio Grande is shared between the countries. Each year, Mexico must deliver to the United States one third of the flow reaching the main channel of the Rio Grande, meeting an average minimum volume of 350,000 acre-feet (431,721,000 cubic meters) per year over a five-year water delivery cycle. Under the treaty, the United States must reciprocate by providing Mexico with 1.5 million acre-feet of water each year from the Colorado River. The five-year cycle for Mexico’s Rio Grande water deliveries provides flexibility to reflect the greater flow variability of a monsoon-fed river versus the snow-fed Colorado River.

Stressors Exacerbated by Climate Change

Strains on Mexico’s access to water — more formally described as hydrological scarcity —have been caused by several intertwined issues:

First, Mexico’s national urban population growth has skyrocketed in the past five decades. By 2030, 86.2 million Mexicans will be living in large metropolitan zones, approximately 62.7 percent of the national population. By 2050, this figure is expected to reach 70 to 80 percent of the population as metropolitan zones continue to expand and eventually connect. More specifically, the population at the border has more than quadrupled, totaling about 11 million Mexican citizens. When added to the 19 million American citizens living on the U.S. side of the shared border, this growth increases demand for water.

Second, Mexico’s hydrological infrastructure is simply outdated and inefficient. Agriculture and urban use generate significant water losses with leaking water pipes nationwide accounting for the loss of 40 percent of total volume of water that would have been used for drinking. Additionally, only 50 percent of water collected by sewage systems receives any sort of treatment. Not only is there a lack of potable tap water — especially at the border — but Mexicans also face exposure to raw wastewater discharges which carry pathogens and viruses producing infectious diseases which disproportionately impact vulnerable and impoverished communities.

Third, Mexico’s hydrological inefficiency lies in its city planning and unnatural gray infrastructure. Urban zones across Mexico, especially in the north, are sprawling concrete masses; according to Mexico’s National Autonomous University (UNAM), 50 percent of the nation’s territory has lost its vegetational coverage and suffered damage to natural and hydrological systems as a result. Impervious surfaces such as highways, parking lots and roofs contaminate and lose rainfall runoff while continued expansion eliminates natural systems and runoff patterns. Consequently, these urbanized areas experience high-velocity stream flows due to a lack of natural buffer zones. These high-velocity flows can overwhelm streets and pumping systems which cause severe floods, property and infrastructure damage, social disruption and even lead to loss of life. Erosion and sewage overflow of human, industrial and other toxic waste seeping into groundwater are other consequences of gray infrastructure.

To make matters worse, Mexico’s unique geographical location is a breeding ground for incredibly varied climate phenomena such as hurricanes, floods and, most importantly, droughts. These disastrous events are amplified by global climate change, leaving Mexico to manage reduced supply and poorer water quality. The northern and northeast regions of Mexico are the most vulnerable to the effects of climate change, particularly droughts and decreased rainfall.

There are roughly 4.5 million Mexican citizens living in the five Mexican border states of Sonora, Chihuahua, Coahuila, Nuevo Leon and Tamaulipas that currently live under drought conditions. These droughts further undermine the natural efficiency of the hydrological cycle upon which the replenishment of Mexico’s surface water and groundwater sources rely. Another way in which climate change counterintuitively impacts the arid border is the threat of intermittent severe flooding that ravages urban areas, showing undeniably that the consequences of climate change are exacerbating the stressors and subpar infrastructure.

RECOMMENDATIONS

1944 Water Treaty

Conserve existing water sources under Minute 323 of the Treaty.

Promote additional relationships in the academic, scientific, private and public sectors to support more effective solutions for binational water efforts.

Incorporate additional individuals with expertise in the use of water technology and those with specialized water knowledge to strengthen the data/reasoning behind solutions and proposals.

Continue establishing a science advisory group to enhance IBWC/CILA’s efficacy.

Climate Change

Allocate sufficient additional resources to Conagua, including and as appropriate, from the North American Development Bank (NADBank) to fund necessary infrastructure upgrades to enhance resilience in response to climate change.

Implement a recovery of water rights program to balance supply and demand.

In IBWC/CILA, prioritize incorporation of scientists with climate change expertise to foster the design and implementation of climate-based water-management strategies.  

The above article is part of a seven-part series first published by the Wilson Center Mexico Institute and is being republished in Pulse News Mexico with express prior permission