Introduction

This article examines the contemporary consequences of anthropogenic modifications and climate-induced environmental changes on the Colorado River and the Rio Grande—two critical transboundary rivers along the U.S.–Mexico border—highlighting their growing social, economic, and public health impacts on surrounding populations.

Among the findings of the study are the following:

• • The southwestern U.S. and northwestern Mexico are experiencing their driest period in at least 1,200 years, also known as a “megadrought”
  • Due to climate change, as well as the manipulation and over-extraction of the Colorado River and Rio Grande, water quantity and quality are declining, threatening both ecological and human health at the U.S.-Mexico border
  • Water shortages and restrictions are challenging the production capacity of agricultural and livestock sectors, leaving farmers and consumers with less

The Colorado River and Rio Grande have experienced a long history of human manipulation. At the expense of the basins’ natural flow regimes, development along the two rivers and the U.S.-Mexico border has soared, resulting in low water levels and poor water quality. Such drastic changes have threatened ecological and human health, as well as the agricultural industry, in the border region. Climate change has only exacerbated the situation.  

Causes of Water Decline 

1. Human manipulation and over-extraction:

• • Significantly altered through dams, diversions, and other water management practices
  • Overallocated, meaning that the amount of water promised to users exceeds the amount available  

 2. Climate change 

• • Warming temperatures drive below-average snowpack and rainfall, leading to water decline in a reinforcing cycle
    • Snowpack [1], or the amount of snow that accumulates on the ground, feeds both rivers in their respective mountains. In a warmer climate [2], more precipitation falls as rain rather than snow, resulting in reduced snowpack. Higher temperatures also cause snow to melt earlier, affecting the timing and availability of water
    • Periods of drought [3] are becoming more prolonged and intense. Warming temperatures speed up the water cycle, increasing the rate at which water evaporates from soil and transpires from plants

Experts warn that climate variability makes governance even more difficult. Adriana Reséndez Maldonado, Mexico commissioner of the International Boundary and Water Commission, noted precipitation in the Rio Grande basin is “unpredictable,” a reality echoed by Dr. Maria Elena Giner, former U.S. commissioner of the International Boundary and Water Commission, who highlighted how overlapping treaties and human activity further complicate the system. Dr. Giner highlighted the nexus of water agreements at multiple levels as a reason for this, ranging from the local scale up to the international scale.

What’s at Risk 

1. Ecological health

• • Worsening habitat conditions for plants and wildlife due to megadrought, aridification, and over-extraction of water
    • Megadrought [4]: persistent, multi-year drought events that are extreme in terms of severity, duration, or spatial extent when compared to other droughts of the last two thousand years.
    • Aridification [5]: a gradual, but permanent, transition of the climate and hydrology of a region to drier conditions
  • Despite these signs of distress, improving environmental flows has not been a priority
  • Environmental flows [6]: the water flows necessary to sustain river ecosystems and human activity

2. Human health  

• • Unpredictable rainfall and severe flooding have contaminated transboundary waters with industrial pollutants, sediment, and sewage overflow, threatening [7] already inadequate water infrastructure and exacerbating sanitation concerns
  • The unincorporated communities in rural areas along the border, also known as colonias [8], are highly at risk due to their location outside city limits, far from main water and sewer lines
  • At least one-third of colonias lack secure access to water services, wastewater services, or both

3. Agriculture 

• • Water shortages and restrictions, as well as increasing salinity, have led to reduced crop yields [9] and the death of cattle [10], negatively impacting productivity and profitability. 
  • Some farmers have begun to allocate fewer acres to their traditional water-intensive, but high-value crops

Other experts have observed that climate change does not recognize political boundaries. Vianey Rueda, a Ph.D. candidate at the School for Environment and Sustainability at the University of Michigan, explained that just as entire agricultural sectors in Texas are shutting down due to a lack of water, the same phenomenon is occurring in Mexico. Because everyone depends on precipitation, when it does not fall, all are equally affected.

Looking Towards the Future 

By 2050 [11], water demand for municipal and industrial use is expected to increase by 100 percent and 40 percent, respectively. This prediction does not bode well for water users at the border, as declining water quantity and quality continue to exacerbate habitat conditions and socioeconomic inequities, as well as domestic and bilateral tensions.  

The presence of an international border can hinder localism and immediacy [12]. Pushing for a more regional approach while balancing both large and small-scale efforts will continue to be a challenge for border communities and their asymmetric institutional capacities. When fragmented institutions leave behind such governance gaps, local participation must be prioritized if the region hopes to address infrastructure failures and build resiliency.  

ENDNOTES

[1] https://watercalculator.org/footprint/importance-mountain-snowpack-water/

[2] https://www.epa.gov/climateimpacts/climate-change-connections-new-mexico-rio-grande#ref3

[3] https://www.epa.gov/climateimpacts/climate-change-connections-new-mexico-rio-grande#ref3

[4] https://www.drought.gov/news/megadroughts-common-era-and-anthropocene-2022-11-15

[5] https://www.climatehubs.usda.gov/hubs/southwest/topic/megadrought-and-aridification-southwest-united-states

[6] https://ecologyandsociety.org/vol27/iss1/art20/

[7] https://www.wilsoncenter.org/publication/next-president-united-states-challenges-and-recommendations-us-mexico-relationship

[8] https://www.aljazeera.com/features/2016/11/5/living-on-the-edges-life-in-the-colonias-of-texas

[9] https://www.vox.com/the-highlight/23648116/colorado-river-lake-mead-agriculture-leafy-greens

[10] https://www.reuters.com/sustainability/land-use-biodiversity/northern-mexico-farmers-fight-drought-amid-water-dispute-with-us-2025-04-24/

[11] https://www.wilsoncenter.org/publication/next-president-united-states-challenges-and-recommendations-us-mexico-relationship

[12] https://ecologyandsociety.org/vol29/iss4/art35/