What will happen to the Colorado River? What we know about looming water cuts

A houseboat sits anchored on the banks of Lake Powell.
A houseboat sits anchored on the banks of Lake Powell.

The seven states that rely on the Colorado River must come up with a plan to cut 2 to 4 million acre-feet of water use.

By mid-August.

And if they don’t, the federal Bureau of Reclamation will act for them.

It’s a massive amount of water to find in a short amount of time.

And there are more questions than answers about what this entails. But let’s walk through what we know.

Could the Colorado River dry up?

Maybe. Depending on how you define “dry up.”

It’s doubtful that all 1,450 miles of the Colorado River will turn to dust, even if we drain Lake Mead and Lake Powell, the nation’s two largest reservoirs. But larger stretches could go dry for all or parts of the year if the lakes tank, creating ecological disasters in places like the Grand Canyon.

The problem is one of supply and demand: We use far more water than the river now produces. Even though we’ve had close to normal snowpack in recent years, warmer temperatures, earlier runoff dates and dry soils parched by drought have left us with far less water flowing into the reservoirs.

Which is depleting them. Fast.

What if the lakes reach 'dead pool'?

Lake Mead and Lake Powell are now so low that there is risk of falling into what is called “dead pool” – meaning reservoir levels are too low to pass water through the dam. If Lake Mead were to reach dead pool, for example, no water would flow downstream past Hoover Dam – cutting off Colorado River water to anyone in Arizona or California for all or parts of the year.

But there are major problems to avoid long before we reach dead pool, particularly at Lake Powell. It involves a relatively higher lake level called “minimum power pool,” which is the point where turbines at Glen Canyon Dam can no longer generate hydropower.

The larger problem isn’t necessarily the loss of power – it’s that millions of acre-feet of river water must then be funneled through four smaller pipes that are encased in concrete within the dam.

Those pipes were not designed to handle this much water, particularly over time – which means that if any one of them is damaged, it can’t be easily repaired. And that would radically slash the amount of water that can flow downstream to keep Lake Mead (not to mention the rest of the Colorado River) alive.

That’s why Reclamation is requiring such quick and significant action. Trimming demand each year won’t restore lake levels, even if we luck out with a good runoff year or two. It simply provides a buffer to keep them from falling any lower.

How much less water must we use?

Reclamation did some modeling to show how much less water we’d need to use on average from 2023 to 2026 to provide that needed buffer. That’s where the range of 2 to 4 million acre-feet comes from (and keep in mind: That’s 2 to 4 million acre-feet above all the other cuts and water-balancing moves we’ve already made to keep the reservoirs afloat).

It’s a mind-boggling amount.

An acre-foot is the amount of water it takes to cover one acre in one foot of water. So, 2 million acre-feet is enough to flood the entire city of Phoenix ... with more than 6 feet of water.

We could cut off major cities in the Colorado River basin – Phoenix, Los Angeles, Denver, Las Vegas – and the savings still wouldn’t be enough to produce the kind of water we’re talking about here.

That’s why this is so tough.

If we’re going to produce this scale of water savings, and do it in a way that doesn’t completely cut off some users while others remain untouched, it’s also going to require sacrifices of the river’s largest users – the ones that also have the most senior water rights.

That includes farmers in California and Arizona, who have generally escaped cuts, even in the deepest levels of shortage for which we’ve planned.

What does this mean for states?

Reclamation has said that it expects all states and sectors to participate – which would mean this isn’t just something for a few junior users to figure out. Everyone’s in the pool.

But the bureau hasn’t said much more than that – other than if we fail to cut enough this year, it will mean even more drastic actions later.

For better or worse, Reclamation has declined to dictate parameters in hopes that the states can find a plan they can live with.

The bureau has shared how it arrived at the 2 to 4 million acre-feet, including charts that show what the average amount would need to be cut each year to maintain one of two buffer levels on the lakes.

But it hasn’t said, for example, whether it’s enough to cut 2.1 million acre-feet cut or 2.5 million acre-feet in 2023 – amounts that some groups appear to be targeting.

Why are there so few solid answers?

Reclamation is leaving it up to states to propose how the cuts will fall among junior and senior users in the upper basin states of Colorado, Wyoming, Utah and New Mexico that rely on Lake Powell and the lower basin states of Arizona, California and Nevada that rely on Lake Mead.

That’s not just tough. It may be downright impossible. We’re basically asking users to look past a century of entitlements and priority rights in hopes of finding something more equitable.

In just eight weeks.

Is it equitable for Central Arizona Project, which powers Arizona’s most populated areas, to lose most, if not all, of its water? And if not, is it equitable to fallow hundreds of thousands of acres of farmland, especially if we choose not to spend billions of dollars to compensate them?

What role will tribes play? And how will all of this impact water rates, food prices and life as we know it in the West?

All important questions. With no good answers yet.

Reach Allhands at joanna.allhands@arizonarepublic.com. On Twitter: @joannaallhands.

If you love this content (or love to hate it – hey, I won't judge), why not subscribe to get more?

This article originally appeared on Arizona Republic: Will the Colorado River dry up? What we know about looming water cuts