A deeper water shortage on Lake Mead is hardly the worst thing we're facing

·6 min read

The federal Bureau of Reclamation has declared a deeper level of water shortage for Lake Mead, the nation’s largest reservoir.

But that was not the most consequential thing Reclamation announced – or, more accurately, skirted – on Aug. 16.

It’s also not the gargantuan cut that some media reports make it out to be.

If anything, we got off easy.

What did Reclamation declare?

A Tier 2a shortage is the deepest mandatory cut we have made to date, one that entails 592,000 acre-feet – 21% – of Arizona’s apportionment from Lake Mead. Nevada must cut 25,000 acre-feet (8%) and Mexico 104,000 acre-feet (7%).

These are significant amounts of water.

But considering that Arizona has already left 800,000 acre-feet of water in the lake this year – a combination of mandated cuts and voluntary, compensated conservation efforts – it’s not exactly a “drastic” cut, as one headline suggested.

Nor is it something new or unexpected. We’ve been planning for this for years.

Where were we before?

A sign marks Lake Mead's 2002 water level -- with the current shoreline far in the background -- on July 9, 2022, near Boulder City, Nev.
A sign marks Lake Mead's 2002 water level -- with the current shoreline far in the background -- on July 9, 2022, near Boulder City, Nev.

Reclamation declared the first water shortage on Lake Mead last August – a Tier 1 shortage – which was created as part of a 2007 agreement that aimed to cut use when the lake hit certain low levels.

Arizona agreed to take the brunt of the cuts, and in a Tier 1 shortage, Arizona must trim 512,000 acre-feet of use. So, a Tier 2a ratchets that up for us by 80,000 acre-feet.

What's in Lake Mead? 5 bodies, sunken boats and a ghost town – so far

These amounts of water stem from the 2019 Drought Contingency Plan, which ratcheted up cuts when it became clear the 2007 amounts weren’t enough. California agreed to take cuts for the first time as part of that plan, but not until the lake reaches deeper levels of shortage (a Tier 2b shortage, to be exact, but more on that in a second).

Arizona also passed an internal Drought Contingency Plan in 2019 to help lessen the pain of cuts within the state. Pinal farmers – those with the lowest priority rights – were given a bit of water in 2022, plus some funding to help drill wells and transport that water to fields. That hasn’t produced the amount or quality of water that farmers had hoped, but that’s another blog for another day.

How will a Tier 2a shortage play out?

When the Tier 2a shortage goes live in 2023, Pinal farmers will receive no water from the Central Arizona Project, which delivers water to users from Phoenix to Tucson. They must now fully rely on groundwater to survive.

Then again, Pinal farmers were already in line to lose all of their CAP water in 2023, even if we remained in a Tier 1 shortage.

A Tier 2a shortage also will wipe out the next higher priority pool of CAP water – the so-called Non-Indian Agricultural pool. Most of that water goes to central Arizona cities and tribes.

Then again, they won’t necessarily be up a (suddenly dry) creek because the 2019 in-state plan mitigates 75% of their losses. In the grand scheme of things, it could be a lot worse.

Why did we get off easy?

This chart shows the key water levels in Lake Mead, which is used to determine water deliveries for Arizona, Nevada and California.
This chart shows the key water levels in Lake Mead, which is used to determine water deliveries for Arizona, Nevada and California.

Shortage declarations are tied to specific lake levels. But Reclamation decided to fudge that with a concept they call “operational neutrality.”

It stems from an emergency action this spring to help prop up Lake Powell. Reclamation kept 480,000 acre-feet in Lake Powell that should have flowed downstream to Lake Mead, then promised to pretend that water was in Lake Mead when determining shortage levels.

The lake has physically reached the threshold to be in a deeper – and more consequential – Tier 2b shortage, one that would ratchet up Arizona’s cuts to 640,000 acre-feet and would require California to cut for the first time, to the tune of 200,000 acre-feet initially.

That’s important because everyone that relies on Lake Mead would be making mandatory cuts, leaving larger, guaranteed amounts of water in the lake as it is rapidly tanking.

Relying on voluntary savings doesn’t always pan out, as we found this year with the 500-plus plan, a separate emergency action (notice that there are a lot of these?) to prop up Lake Mead. The goal was to pay people to leave 500,000 acre-feet in the lake each year, but users only volunteered a little more than half of that in 2022 – mostly from Arizona.

The benefits of those savings evaporated almost immediately once they hit the lake. Essentially, we spent millions on actions that did almost nothing for lake levels.

So, if anything, a Tier 2a shortage is an underreaction, and at a crucial moment when we need to be doing so much more.

Why is this the least of our worries?

We could make every cut we’ve already laid out, all the way down to a Tier 3 shortage, the deepest for which we’ve planned.

And Lake Mead would still be on a freefall to “dead pool” – the point where lake levels fall so low that water can no longer flow downstream through Hoover Dam to users in Arizona, California and Mexico.

Reclamation’s August 24-month study, which was released at the same time as the Tier 2a shortage declaration, projects the lake will fall below 1,000 feet of elevation in 2024 – more than 20 feet below the minimum protection level that Reclamation had hoped to maintain.

That’s why Reclamation said in June that the full Colorado River basin – all seven states that rely on the river – needed to cut an additional 2 million to 4 million acre-feet of water use in 2023.

Their modeling shows we need to cut at least 2.5 million acre-feet simply to maintain that minimum protection level on Lake Mead (and a similarly low protection level on Lake Powell, which also is tanking quickly).

And that’s on top of every water-saving action to which we’ve previously agreed.

So, what's the takeaway?

We could carry out the cuts in a Tier 2a shortage, or a Tier 2b, or the deepest Tier 3, and it still wouldn’t be enough to keep Lake Mead on life support. We must cut way deeper than that in 2023 – and sustain those deep levels until at least 2026 – if we have any chance of saving it and Lake Powell.

And no, there is no plan yet to do so.

The states couldn’t agree by Reclamation’s mid-August deadline, and while Reclamation promised on Aug. 16 to keep working with states on as many voluntary measures as possible, it did not offer any firm deadlines, water amounts or what exactly it might mandate if states still can’t do enough to fill the giant chasm between supply and demand.

That’s the whole reason we’re in this mess. Despite all that we’ve done so far to trim use, we are still consuming far more water than the Colorado River produces.

A Tier 2a shortage, though painful and consequential, is not enough to solve this problem. Yet it’s unclear how or when we’re going to do enough to keep the lakes from dying.

That’s the problem.

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

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This article originally appeared on Arizona Republic: Lake Mead has far deeper problems than a Tier 2a water shortage