Water has been a godlike force determining life and death for centuries across Mexico’s arid Baja California Peninsula. And today, climate stressors, a boom in tourism, and urban growth are making water an extra precious resource in Mexico’s driest state.
“The effects of climate change are serious here in Baja California Sur,” said María Z. Flores López, a hydrologist and director of the Integrated Water Management Program at the Autonomous University of Baja California Sur, speaking in Spanish.
In many ways, Baja offers an extreme snapshot of a globally intensifying aridification crisis, where landscapes are permanently drying up. But the state’s situation also offers an opportunity: If an arid, fast-growing peninsula can stabilize its water supply, it could share those lessons across the country – and even beyond Mexico.
“If we learn how to conserve water, it can be a prime example of sustainable conservation,” Flores López said.
The stress of growth, drought, and water demand
Mexico’s groundwater system is under stress from both excess demand and environmental degradation.
Approximately 114 of Mexico’s 653 aquifers are already overexploited, and nearly half are operating at a deficit, according to the country’s water authority. The most stressed aquifers tend to lie beneath arid regions and population centers – a pattern that’s true in Baja Sur, where a surging population depends on seasonal rains filtering into deep aquifers.
Forty years ago, La Paz – the capital of Baja Sur – was a small city. Today, it is one of the fastest-growing urban areas in northwestern Mexico, fueled by tourism, migration, and real estate development. Los Cabos, the tourism mecca roughly 100 miles south of La Paz, is growing even faster. This Baja Sur destination has tripled its population since the year 2000, and annual visitor counts top 4 million – many staying at sprawling new resorts.
The growth has shifted water demand sharply, according to Enrique Troyo Diéguez, a water expert at the Center for Biological Research of the Northwest.
“Water availability is very limited, and the population is growing so much,” Troyo Diéguez said in Spanish. “This carries a truly catastrophic level of consumption.”
One sobering report from federal authorities revealed that in 2022, La Paz was annually extracting 39% more water than its aquifer could recharge over the course of the year, signaling that consumer trends must change and alternative sources must be explored to prevent the aquifer from drying up.
During drought periods, which are becoming more frequent and harsh, the demand on aquifers is especially costly.
“When we have drought periods, then there is no recharging of the aquifers,” Troyo Diéguez said, recalling the latest major dry spell. “Up until the beginning of August in 2025, we had 18 months of drought. It hardly rained at all during 2024.”
A relatively rainy and wet end of 2025 brought some reprieve to many aquifers that had been depleted during the drought. But sometimes, the water is no longer safe to drink.
Freshwater lost to the sea
As sea level rise pushes ocean inland, saltwater is contaminating freshwater stores in some coastal aquifers.
This phenomenon, known as saltwater intrusion, has been documented in Mexican coastal aquifers since the 1970s, but recent research shows the problem is intensifying. The Baja California peninsula is a hot spot, and overpumping, reduced recharge, and rising seas are driving salty water into wells.
“Those wells that are very close to the coast start pumping brackish water. That water might be usable for bathing, but not for drinking or cooking,” Troyo Diéguez said.
The peninsula’s geography and climate compound the water problem. Rain falls infrequently and unevenly, mostly in summer storms or tropical cyclones between July and September.
When rain arrives, most of it falls in the mountains. From there, the water rushes down and collects in rocky washes known as arroyos. Then much of it flows into the Gulf of California to the east, or the Pacific to the south or west.
“Most of the time, that water runs off and reaches the sea and is wasted. It’s gone. It’s not used,” Flores López said.
Creative efforts on both small and large scales are beginning to crop up to slow and retain this flow of water.
But two other climate factors add related stressors: Higher temperatures are increasing evaporation rates of water on the ground. And longer droughts are reducing aquifer recharge.
Measuring what matters
After years of studying these many layers of water vulnerability in Baja Sur, Flores López in 2025 launched the Center for Innovation, Technology and Water, or CITA, at the Universidad Autónoma de Baja California Sur with collaborator Jesús Hernández Cosío.
CITA’s biggest project, which it inherited from an effort Hernández Cosío began several years prior, has been deceptively simple: Measure water use.
Over the past five years, a team has been installing smart water meters at university facilities and municipal sites to monitor real-time consumption and variables. That work has helped identify behavior, leaks, and other important data points.
“When we saw the data, it hit us like cold water,” Hernández Cosío, a digital systems expert, said in Spanish. “We didn’t realize how much was being wasted.”
The daily readings revealed patterns that are now changing behaviors and water management decisions at the university. For example, campus landscapers now avoid watering at the hottest times of day when the sun evaporates water faster than ornamental plants can use it.
For Flores López, the implications extend far beyond the campus.
“This is a huge problem across all of Mexico: There isn’t sufficient water measurement,” she said. “It isn’t measured; it isn’t known.”
These invisible losses add up in big ways.
One striking example in La Paz emerged several years ago after local water studies probed the aging water distribution network: Nearly half the municipal water extracted never reaches consumers. Instead, it’s lost to countless underground leaks and other connection problems.
Aging pipes leak underground for months or years unnoticed. Many homes lack water meters altogether. And in a region where every drop matters, that invisibility is too costly.
“That’s why we say that CITA has to be very much oriented toward water measurement,” Flores López said.
The desalination dilemma
As groundwater availability grows more precarious, desalination, or the removal of salts and minerals to make salty water drinkable, increasingly enters the conversation – and the controversy.
“Desalination will become a necessity,” Troyo Diéguez said. “But it’s not a single solution.”
Desalination is already part of water treatment in many places in Baja and beyond, including the purification of brackish groundwater. And it can also be done on a larger, more extensive scale with seawater.
Flores López also expressed caution. “Yes, desalination is an option,” she said. “But it has risks.”
Those include high energy demand, brine waste that can damage marine ecosystems, and long distribution pipelines, which are especially problematic when nearly half the water may be lost in the distribution system before reaching consumers.
Energy dependence adds another vulnerability in Baja Sur.
Water pumps require electricity. And when hurricanes in Baja Sur knock out power, wells and desalination pumps go offline. Power outages are also frequent during the hot summer seasons when many residents are cranking air conditioning.
“We depend on energy to extract water,” Flores López said. “When cyclones arrive, the power goes out, and the wells stop working. They don’t draw out water.”
A proving ground
Despite the challenges, she sees Baja Sur not just as a cautionary tale but as a proving ground ripe with possibilities.
“We’re the worst state in Mexico for water,” Flores López said. “Water is the No. 1 problem in this state, plain and simple.”
The desperate circumstances demand experimentation, investment, and innovative efforts.
For now, the emerging solutions are not silver bullets. They are layered, local, and often modest in scale, according to Troyo Diéguez. The solutions look like measuring leaks and updating pipes, slowing runoff, growing different crops, and rethinking landscaping.
But the mindset can be embraced around the world: treating water as the vulnerable, priceless necessity that it is.
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