A study has revealed that Colorado’s West Slope water basins may be approaching a critical tipping point, where maintaining traditional water delivery levels to Lake Powell and other vital areas could become unsustainable, even under modest climate change scenarios.
The research, published in Earth’s Future on November 9, represents the most extensive exploratory modeling analysis ever conducted on drought vulnerability in the Colorado West Slope basins—six watersheds within the Colorado River Basin on the western side of the continental divide.
These watersheds, which feed into Lake Powell and support a $5 billion annual agricultural economy, are crucial water sources for seven western U.S. states, as well as Mexico.
“Our work shows that even relatively middle-of-the-road climate change and streamflow declines in these basins flows can threaten to put the system at risk of breaching a tipping point,” Patrick Reed, the study’s senior author and Joseph C. Ford Professor at Cornell Engineering’s School of Civil and Environmental Engineering, said in a statement.
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At such a point, the river basins would be “no longer able to maintain the levels of deliveries to Lake Powell that we’re accustomed to over recent history,” he continued.
The research team employed an innovative approach, combining Colorado’s StateMod water planning model with a new modeling framework.
This methodology generated hundreds of thousands of streamflow scenarios under both historical and climate-change conditions.
Their findings suggest that traditional drought vulnerability analyses, which rely solely on historical streamflow records, may significantly underestimate both the magnitude of potential drought events and their impacts on water storage, agriculture and municipal water supply.
The study’s timing is particularly significant as state and federal policymakers prepare to negotiate water-sharing agreements that are set to expire in the coming years.
The research builds on recent historical events, including the unprecedented 2021 water shortage when Lake Powell reached record low levels.
Levels have rebounded somewhat since then thanks to heavy snowfall in recent years, though the lake remains far from full. The study shows also that even without climate change, severe shortages can emerge from the basins’ inherent variability.
Combined, climate change and natural variation could have devastating effects for the crucial reservoirs in the region which serve some 40 million people.
“This finding highlights the need for advanced drought analysis methods that can capture these widespread and interconnected impacts,” the study’s lead author, David. F. Gold, an assistant professor of physical geography at Utrecht University, said in a statement.
“With increasing pressures on water resources, integrated management approaches that are scientifically informed and consider interconnected sectors are critical to preserving resilience.”
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Reference
Gold, D. F., Gupta, R. S., & Reed, P. M. (2024). Exploring the Spatially Compounding Multi-Sectoral Drought Vulnerabilities in Colorado’s West Slope River Basins. Earth’s Future, 12(11), e2024EF004841.
