In August 2026 the nation’s two largest reservoirs, Lake Mead and Lake Powell, both on the Colorado River, hit their lowest levels since they first began to be filled in 1936 and 1963, respectively.

The federal government and the seven Colorado River basin states – Arizona, California, Colorado, Nevada, New Mexico, Utah and Wyoming – have been unable to reach an agreement about who should reduce water usage by how much to avoid catastrophic declines in lake levels.

And the existing plans and commitments, including a federal outline announced in late July 2026, don’t get close to achieving what’s needed to keep the river flowing. Here’s a look at the key issues making an agreement so hard to reach.

To stabilize the Colorado River system, seven states and Mexico need to reduce annual consumption of Colorado River water by at least 3 million acre-feet (980 million gallons), and probably more like 4 million acre-feet (1.3 trillion gallons), each year.

The Lower Basin states – Arizona, California and Nevada – have been using less water, even as their populations have grown.

They have proposed to further reduce water use in 2027 and 2028, and Mexico has, too. Those decreases, coming only from the Lower Basin states, would be the biggest-ever reductions of Colorado River water use, but they would amount to only about 3.7 million acre-feet over two years, about half what is likely needed.

Unless more water is conserved, the reservoirs that have stored surplus water over the decades could shrink to the point that only the water that naturally flows into the river each year would be released downstream. That’s a condition called “run of river,” which could result in drastic cuts to the Lower Basin’s water supply.

If the winter of 2026-27 is like the winter the West had in 2025-26, the river and reservoirs........

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