A research team at the Autonomous University of Baja California (UABC) has identified significant regulatory gaps in Mexico’s approach to seawater desalination, including no dedicated legislation, no brine disposal standards, and no formal process for public input. The findings come as the federal government pushes forward with a desalination plant in Rosarito despite a failed bidding process earlier this year.
Mariana Villada Canela, a senior researcher at UABC’s Institute of Oceanological Research in Ensenada, leads the project. Her team reviewed 110 technical and regulatory documents along with international case studies from Spain, Israel, and Saudi Arabia. The study focuses on two high-vulnerability zones: Tijuana-Playas de Rosarito and San Quintín, both of which face chronic water shortages.
“There are important areas without clear regulation,” Villada Canela said in a UABC press release. “We want the results to contribute to more transparent, inclusive, and sustainable public policies.”
Rosarito Desalination Plant Moves Forward Without Clear Rules
The UABC research lands at a critical moment for Baja California’s water infrastructure. President Claudia Sheinbaum announced in early 2025 that a failed public bidding process would not stop construction of a major desalination plant in Playas de Rosarito. The federal government has treated the project as a priority since at least 2023, when CONAGUA, Mexico’s national water commission, flagged the Tijuana-Rosarito corridor as one of the country’s most water-stressed urban areas.
CESPT, Tijuana’s municipal water utility, has struggled with aging infrastructure and population growth that outpaces supply. Tijuana’s population exceeds 2 million, and the city relies heavily on water piped from the Colorado River through a system that is both oversubscribed and politically vulnerable to decisions made in the United States. Rosarito, which has grown rapidly with both Mexican families and foreign residents, shares much of that same supply chain.
The Rosarito desalination plant, if built, would be one of the largest in Latin America. But the UABC study raises a basic question: under what rules? Mexico has no specific desalination law. There are no national standards governing how plants should dispose of brine, the concentrated salt byproduct that can damage marine ecosystems when discharged into the ocean. And there is no formal mechanism requiring public participation before a desalination project is approved.
By contrast, Spain requires environmental impact assessments that include brine dispersion modeling before any desalination plant begins operation. Israel, which desalinates roughly 80% of its drinking water, regulates discharge concentrations at the outfall point. Saudi Arabia has invested in zero-liquid-discharge technology at several newer facilities. The UABC team studied all three models.
Water Costs and Marine Ecosystems at Stake in Tijuana and Rosarito
Desalinated water is expensive to produce. Reverse osmosis, the most common technology, requires large amounts of electricity to force seawater through membranes. In Israel, production costs run between $0.50 and $0.60 per cubic meter. In Mexico, where energy subsidies are less predictable and infrastructure costs are higher, estimates for the Rosarito plant have ranged from $0.80 to $1.20 per cubic meter.
Those costs will eventually reach consumers. CESPT’s current residential water rates in Tijuana start at roughly 90 pesos (about $5 USD) per month for basic usage tiers. A desalination-fed supply could push rates significantly higher, though no official projections have been published. The UABC study identified rate increases as a top concern among residents surveyed in the Tijuana-Rosarito corridor.
Environmental risks are also real. Brine discharge raises salinity near outfall points and can harm fish, invertebrates, and seagrass beds. The Rosarito coastline supports commercial and artisanal fishing. Villada Canela’s team identified fishers, rural communities, and indigenous groups as particularly vulnerable populations who could benefit from improved water access but also suffer from marine ecosystem damage or unaffordable rate hikes.
“It is not only about guaranteeing supply,” Villada Canela said. “It is about building solutions that are socially just and environmentally responsible.”
Preliminary results from the study show divided public opinion. Many residents view desalination as a necessary response to the water crisis. But distrust of institutional management runs deep, especially after years of intermittent service, broken infrastructure promises, and rate disputes with CESPT.
San Quintín Faces Its Own Water Emergency
The study’s second focus area, San Quintín, sits roughly 300 kilometers south of Tijuana in a farming valley that produces much of Mexico’s tomato and strawberry exports. Groundwater in the San Quintín aquifer has been critically overdrawn for years. Saltwater intrusion has already contaminated wells in several communities. A smaller desalination facility has been discussed for the area, but no concrete timeline or funding has been announced.
San Quintín’s population includes a large indigenous Triqui and Mixtec workforce. Many families lack reliable piped water and depend on trucked deliveries that cost several times the municipal rate. For these communities, desalination could provide genuine relief, but only if the water reaches them at a price they can afford.
The UABC project will produce governance recommendations, proposed regulatory frameworks, and public education materials. Villada Canela’s team is also training graduate students through applied fieldwork in both study areas. No timeline has been set for a final report, but the research is active and ongoing. The story was first reported by La Jornada Baja California.