Drying Rio Grande–Bravo Basin Threatens Water Security for 15 Million People

The binational Rio Grande–Bravo basin, once a dependable lifeline for Indigenous communities, farmers and cities, is facing a fast-escalating water crisis. A new, comprehensive analysis by the World Wildlife Fund, Sustainable Waters and university partners finds that current water withdrawals and evaporative losses are unsustainable and put drinking water, agriculture and ecosystems at serious risk across the United States and Mexico.

Scope of the crisis

The basin supplies roughly 15 million people and irrigates nearly 2 million acres of cropland. The study’s water "balance sheet" shows only about 48% of the water consumed in the basin is naturally replenished; the remaining 52% represents unsustainable use that is drawing down reservoirs, aquifers and the river channel itself.

“That’s a pretty daunting, challenging reality when half of our water isn’t necessarily going to be reliable for the future,” said Brian Richter, president of Sustainable Waters and a senior fellow with the World Wildlife Fund. “So we have to really address that.”

Key causes: irrigation and evaporation

Irrigation is by far the largest direct use of water in the basin, accounting for roughly 87% of withdrawals. Indirect losses — primarily evaporation from reservoirs and canals — make up more than half of overall consumption, a loss that grows more consequential as storage declines and surface deliveries shrink.

Impacts on farms, rivers and communities

Many irrigation seasons have shortened; in some places canals run dry as early as June even though the growing season extends into October. Some stretches of the river routinely go dry for months, and areas including Big Bend and sections near Albuquerque have seen riverbeds turn to cracked mud in recent years.

The analysis estimates that water shortages contributed to farmland losses between 2000 and 2019: about 18% of farmland in the Colorado headwaters, 36% along the Rio Grande in New Mexico, and 49% in the Pecos River tributary spanning New Mexico and Texas. Reduced irrigation has squeezed farm incomes and pushed many operators toward bankruptcy, while irrigation in the Mexican portion of the basin has increased in recent years.

Policy responses and cross-border solutions

Responses vary by jurisdiction. In Colorado, water managers have threatened to shut off groundwater wells if aquifers that support irrigated farms cannot be stabilized; some groundwater users pay fees that fund incentives for voluntary fallowing. New Mexico currently operates voluntary fallowing programs but has signaled it may need to curb pumping if proposed settlements in a long-running interstate dispute are approved. Meanwhile, New Mexico is behind on water deliveries owed to Texas under an interstate compact, and Mexico still owes water to the United States under a 1944 treaty — obligations made harder to meet as supplies shrink.

“Rebalancing the system also means maintaining those basic functions that the river and the aquifers and the groundwater-dependent ecosystems have,” said Enrique Prunes, manager of WWF’s Rio Grande Program and a co-author of the study. “That’s the indicator of resilience to a future of less water.”

The researchers and partner organizations emphasize that effective solutions require coordinated, large-scale action across state and national boundaries: reducing consumptive use where feasible, expanding incentives for fallowing and conservation, restricting groundwater overpumping, improving irrigation efficiency, and protecting environmental flows to sustain ecosystems that support long-term water resilience.

Without urgent cooperation and policy changes on both sides of the border, the basin’s declining water balance threatens the livelihoods of millions, the viability of regional agriculture, and the health of rivers and wetlands that communities and wildlife depend on.