Water reserves in Mexican dams are running low: 113 of the 210 dams that hold more than 90 percent of Mexico’s storable water recorded levels below the average they had managed to retain over the past three decades.
Catalisis, the technological application unit of Quinto Elemento Lab, analyzed data from Mexico’s 210 main dams reported by the National Water Commission (Conagua) between 1991 and 2025, and compared their recorded volumes on the last day of October of each year, when most should have their maximum storage capacity.
The data show that dams in the northwest, a region encompassing the state of Sonora and seven municipalities in Chihuahua, have been the most affected, with a decrease of between 45 and 100 percent of stored water. The Abelardo Rodríguez Luján dam, which supplied Hermosillo for decades, had virtually no water at the end of the rainy season. Its reservoir has not exceeded 20 percent of its storage capacity since 2015.
Furthermore, 12 dams have never stored so little water at this time of year. Among these is the Andrés Figueroa or Las Garzas reservoir, located in the municipality of Ajuchitlán in Guerrero. On average, every October 31, Las Garzas reservoir yielded about 100 cubic hectometers (one cubic hectometer is equivalent to one million cubic meters), but this year it barely reached 64.12. This reservoir provides water for approximately 11,000 hectares of crops and for the daily needs of residents of that and other neighboring municipalities.
The country has been experiencing a drought that has lasted for five years and will reach a record high in 2024: 98 percent of the municipalities, 2,428, recorded at least one day of drought during the year. Among other reasons, this has meant that, since 2019, 7 out of 10 dams have recorded relatively less storage.
“It’s been since 1990 that we’ve begun to notice (the climate change). If we compare (the data) with precipitation, droughts are becoming increasingly frequent. At the national level, they have extended in duration, geographic extent, and intensity,” warns Sandra Guido, director of the environmental organization Conselva, Costas y Comunidades, based in Sinaloa, one of the states that has suffered the most from the lack of rainfall in recent years.
According to a study by the National Institute of Ecology and Climate Change (INECC), 126 of these dams have less water than required, meaning they are vulnerable to water stress. The Institute made a series of projections, and the least encouraging estimate indicates that by 2040, not 126 but 139 dams will be unable to provide the required water.
Although there is widespread water scarcity, the drought has placed extraordinary pressure on the country’s state and municipal governments. In response, the federal government has planned the construction of new infrastructure.
President Claudia Sheinbaum’s National Water Plan includes nine projects that seek to improve the water capture capacity of dams and its transfer to supply centers, but their construction will take up to three years.
Building more hydraulic works will not resolve the water shortage if water supply to industries continues to be prioritized over the needs of the population and the production of food for national consumption under non-agroindustrial schemes, says Francisco Peña de Paz, a researcher at the Colegio de San Luis Potosí.
The specialist adds that, in addition to the environmental impacts—recognized in an exhaustive report by the World Commission on Dams—“the concentrated management of large volumes of water means that a political group of experts, sometimes not even experts, but only politicians, defines how that water is used, making it easier to monopolize it. For example, agricultural production is growing, but it is the responsibility of large agricultural companies.”
In this sense, the researcher asserts that more than a meteorological problem that presents itself as water scarcity, it is an issue of injustice in the distribution of water and the hoarding of water by certain actors with economic and political power.
Regional crises
Conagua divides the country into 13 hydrological regions. Since 2010, 11 of these have less water stored. In the case of the Southern Border and Northwest regions, all the dams monitored by the Commission ended the rainy season with less water than their historical average.
In Sonora, part of the Northwest region, the Plutarco Elías Calles Dam, known as El Novillo, supplies water to Lake Oviachic. It provides water to agricultural producers in Irrigation District 041 and to Ciudad Obregón, within the Yaqui River basin, home to more than 329,000 people. In April of last year, the Oviachic reached such a low level that the local diocese called for a mass to pray for abundant rains.
This dam also supplies water to Hermosillo—home to around one million people—through the Independencia Aqueduct, a 135-kilometer pipeline that crosses five municipalities. On the last day of October 2024, its reservoir reported a decrease of 51.7 percent compared to the same date in 2023.
The lack of water is already having an impact on the economies of the regions. For agricultural production, it has caused “million-dollar losses,” as Ariel Monge Martínez, head of the Sonora State Water Commission, points out: “We have two of the main agricultural valleys at 25 percent land use (…) most of it could not be irrigated due to lack of water.” The impact is significant given that Sonora is the fourth largest agricultural producer in the country.
In the Río Bravo region, which includes municipalities in Chihuahua, Coahuila, Nuevo León, and Tamaulipas, 15 of the 23 main dams are below the average volume of the last 30 years, including the international dams of La Amistad and Falcón, which store the water that Mexico is obligated to deliver to the United States every five-year cycle as part of the Water Treaty.
The international agreement, signed in 1944, regulates the exchange of water from two basins shared by both countries and commits Mexico to delivering 431,721 cubic hectometers of water from the Rio Grande every five years in exchange for 1.85 billion cubic meters of water from the Colorado River.
Mexico has had to negotiate extensions in several five-year cycles over the past three decades to fulfill its part, precisely because of the lack of water. October 25th is the deadline for Mexico to deliver approximately 75 percent of the outstanding volume for this cycle.
The water debt has already begun to generate demands on the other side of the border: Texas senators approved a resolution requesting that the United States Department of State and the United States Section of the International Boundary and Water Commission pressure Mexico to deliver the outstanding volumes. Texas Governor Greg Abbott also posted on his X account that “Mexico’s blatant disregard for its water obligations must not be allowed to continue.”
The pressure is also internal. The water commitment is being fought over in the Mexican border region.
“What they’re demanding here in Tamaulipas is for water from the Conchos River (in Chihuahua) to come in to replace the water that’s going to the Monterrey metropolitan area (and that comes from the San Juan River), (…) but that’s water that actually has to be delivered to the United States,” explains Xavier Oliveras González, coordinator of the Mexico-United States Border Studies specialty at the Colegio de la Frontera Norte.
In contrast, seven dams in the country surpassed their historical records on October 31, 2024. These are the Gonzalo N. Santos Dam in San Luis Potosí, which underwent major intervention in 2023 to rehabilitate its dam wall and cushion the impact of Hurricane John, and the Canseco Dam in Veracruz, which mitigated the flooding caused by Tropical Storm No. 28 last October.
Why is there less water in dams?
Year after year, more water is being allocated from surface sources such as dams. Between 2001 and 2022, the volume allocated increased from 44,000 cubic hectometers to 54,000 cubic meters, roughly 6.8 times the size of Lake Chapala, the largest in Mexico. Furthermore, since 2019, rainfall has decreased in the country, and drought has increased. This has led to increasingly less water being retained in the reservoirs of the country’s main dams, although these are not the only causes.
In Sonora, the demand for water has dried up the Abelardo Rodríguez Luján Dam, which has alleviated the dry season for more than seven decades. The state government announced that it will replace it with the El Molinito Dam, located 25 kilometers from Hermosillo, and three new dams on the Sonora and San Miguel rivers, at a total cost of 7.5 billion pesos. But the strategy fails to address one of the main problems: water waste.
“Hydrologically, there is no justification for building these dams, because right now the Sonora River has no water (…) and climate change has caused and will cause rainfall to decrease,” warns Rolando Díaz Caravantes, a research professor at El Colegio de Sonora. The specialist asserts that more than 50 percent of the water that reaches the Sonoran capital is wasted through leaks in the water system and poor water usage measurements.
The director of the Sonora Water Commission, Ariel Monge Martínez, says the problem is rather the lack of dams that can store excess water during the rainy season. This is the case with the El Molinito dam, which is intentionally kept empty to prevent flooding after heavy rains. In the last 15 years, according to the official, this reservoir has “dumped” more than 746 million cubic meters of water. “That’s the big problem with inefficient management of the Sonora River basin: when we have significant water withdrawals, we have to release them.”
In the Northern Pacific region—which includes Sinaloa and some municipalities in Durango, Chihuahua, Nayarit, and Zacatecas—93 percent of the water allocated is used for agriculture, a sector severely affected by the drought.
Activist Sandra Guido explains that, in addition to the lack of rainfall to replenish reservoir storage, each drought leaves “scars” on ecosystems by affecting “green infrastructure”—the vegetation and soils that absorb and retain water. This loss of permeable soils and flora means that when it does rain, less water is retained: “So what happens? It rains on degraded soils, and this turns into water erosion (…) and this soil is deposited in the rivers, silting them up (that is, filling them with mud or garbage that can clog the channels). This silt is also deposited in the dams. So the dams have less capacity to store water.”
For researcher Peña de Paz, the problem lies in the fact that large hydraulic projects are not designed to meet the population’s water needs. “Here in San Luis Potosí, we were told that if they didn’t build the El Realito dam, we would start dying in the streets of thirst. It’s been 10 years since it was officially completed, and that company has never been able to deliver the cubic meter, one thousand liters per second, that was the commitment. I say that large projects don’t provide water; in the neoliberal period, large projects only provide money.”
Addressing the water crisis
Sheinbaum’s strategy to guarantee the right to water is based on organizing concessions, modernizing 200,000 hectares of irrigated land, rehabilitating and building treatment plants, water treatment plants, and wells, cleaning up three rivers, and implementing 17 infrastructure projects.
One of these projects will be carried out in Coatzacoalcos, Veracruz, where two Development Hubs for the Well-being of the Isthmus of Tehuantepec Interoceanic Corridor are already under construction. These areas have been defined by the federal government as having the necessary conditions to attract investment. According to Hildeliza Díaz Calafell, director of the Municipal Drinking Water Commission of the city council, Conagua’s proposal is to take water from the Uxpanapa River, which arrives through an aqueduct to the La Cangrejera dam, and from there, through a pumping plant, pump water into the city.
La Cangrejera has reported a slight decrease of 183,000 cubic meters, just 0.82 percent, between October 31, 2023, and the same date in 2024, but this dam has historically reported its best storage figures in December. Comparing their levels on December 31, 2023, and 2024, the decrease reaches 35 percent.
“According to what the National Water Commission has informed us, the supply offered to Coatzacoalcos is a possibility. It does not affect its distribution with the rest of the water they provide to industry, and above all, there is also an issue of aqueduct maintenance, which is why we have some [water] losses,” says Díaz Calafell.
Sandra Guido, from Conselva, Costas y Comunidades, believes that a national water audit should be conducted to measure how much water actually exists. This is because Conagua only measures water in dams and indirectly estimates availability in rivers and aquifers, without knowing the volume actually used by concessionaires or the volume extracted from irregular wells.
Francisco Peña de Paz, for his part, has three criticisms of the National Water Plan. The first is the focus on technological development for agricultural irrigation, which prioritizes agribusiness production over food sovereignty.
“This logic of technological development is oriented toward commercial agriculture […] rather than the production of, for example, corn, beans, squash, and vegetables like tomatoes and chili peppers, which are staples of the Mexican diet and have been abandoned for a long time. We produce asparagus as if we were dedicated to eating asparagus.”
The second is Conagua’s proposal for two laws: one that guarantees the human right to water and another that regulates its management and concession, given that water is the same. Finally, Peña de Paz notes that Sheinbaum’s strategy fails to recognize water as a key resource for ecosystem conservation.
“Just as the poet [Ramón López Velarde] said that the devil deeded the oil fields to Mexico, it seems as if God had deeded water only to humans, but the truth is that water also sustains the life of animals and plants, and many unicellular beings. It’s not possible to ignore this issue because we are part of an ecosystem,” the researcher points out.
Source: proyectopuente
