Glen Canyon Dam

The federal government will cut back Arizona, California and Nevada's water allocations after years of state-level negotiations. Cities in the Phoenix and Tucson areas will be the hardest hit.

Powell reached the new low on Aug. 15. The two lakes on the Colorado River are the country's largest reservoirs and provide water and electricity for millions of people, as well as farms and wildlife.

In an email obtained by The Associated Press, the Bureau of Reclamation told various groups that water from Glen Canyon Dam in northern Arizona would not be released “due to significant hydropower generation concerns under already strained system conditions.”

Environmental advocates argue that new water-sharing rules can and should keep the river flowing for plants, animals, people and infrastructure.

If water levels drop much lower than they are now, hydropower generators inside Glen Canyon Dam could be forced to shut down.

The Bureau of Reclamation is expected to announce a decision in the next couple of weeks, and said it is weighing several factors, including the Colorado River's ecological health and Glen Canyon Dam's hydropower production.

The three Western states say their proposal would save 3.2 million acre-feet of water through 2028. That’s enough water to serve more than 25 million people a year.

Trial runs are happening in some of the nation's most remote and sensitive ecosystems. Dinosaur National Monument recently set up an eDNA autosampler to detect signs of invasive rusty crayfish in the Green River.

Lake Powell is at just 23% capacity and approaching the point where water won't be able to flow into its hydroelectric turbines without air causing damage.

Drought and steady demand along the Colorado River are draining the nation's second-largest reservoir. Land that was once submerged is now full of beavers and thriving ecosystems.

A group of nonprofits is calling for reductions to water demand, changes at Glen Canyon Dam and more transparent negotiations.

The mountains that feed the Colorado River with snowmelt are strikingly dry. Many ranges are less than 50% of their average snow for this time of year.