You’d think that, given how dangerously low Lake Mead is getting, we’d have a good idea of what life might look like without that water.
Yet few major players are modeling for a future without Colorado River water – or even a future in which we are asked to live on markedly less of it.
Ironically, the deeper the lake plunges, the more reluctant water managers seem to be about fleshing out the worst-case scenario.
That’s a mistake.
Reclamation is focused on the near term
There is virtually no chance that Lake Mead or the upstream Lake Powell that feeds it could hit “dead pool” – the point where water levels are so low that none flows downstream – in the federal Bureau of Reclamation’s most recent five-year forecast.
But the forecast also suggests that both lakes could hit what’s called “minimum power pool” – the point at which all hydropower generation stops – by 2026.
We’ve taken unprecedented, emergency actions to keep the power on at Lake Powell, because if we don’t, the alternative means taking the risky step of flowing a ton of water through smaller pipes that weren’t designed to handle it, particularly for an extended period.
But those actions are just a temporary prop.
We are still facing a nearly 1 in 4 chance of Lake Powell returning to “minimum power pool” by 2024 – a risk that remains steady through 2026, the latest year for which Reclamation has forecast.
Even though the rules for operating the reservoirs expire in 2026, and we should be knee-deep in negotiations for how we manage Lake Mead and Lake Powell for the next 20 years, Reclamation’s modeling remains focused on the short term.
“Reclamation is very concerned about the ongoing drought, the possibility of continuing low-runoff conditions, and the implications for the Colorado River Basin system,” Lower Basin spokesperson Patti Aaron said via email, “but at this time we are focused on near- term actions and not exploring modeling of specific long-term future scenarios.
“Additionally, we are not making assumptions about how Reclamation or our partners and stakeholders may respond to low system conditions beyond current policies … .”
Southern Nevada is one of the few to go there
Problem is, few of the other major players – the state and regional water agencies that will negotiate the next 20 years of operating rules – are making those assumptions, either.
Southern Nevada Water Authority is one of the few to have done this sort of modeling and publicly share the results.
The authority, which relies heavily on Lake Mead to sustain the Las Vegas area, modeled how a Colorado River that produces 11 million acre-feet of water annually might impact its long-term supplies. That’s on the low end of what the river has flowed in recent years, and far less than the 15 million acre-feet assigned to states decades ago.
The analysis is part of its annual water resource plan and wasn’t meant to determine how dwindling runoff might impact other users or the wider river. But it predicts that Lake Mead will continue to plummet through 2025 and dip into “dead pool” territory multiple times over the next 50 years.
The water authority used those assumptions to model how its water supplies might fare under various use scenarios, which also helped to inform its plans to curb outdoor use, particularly through turf removal. It concluded that existing water supplies should be sufficient if users meet a lower demand target, but that it would need additional supplies if they don’t.
All signs point to significantly less water
It’s a pity that more major players aren’t doing similar work.
The last 20 years suggest that Lake Mead and Lake Powell will be unlikely to refill once they drain. We’ve had more than twice the number of years where the Colorado River flowed less than 10 million acre-feet since 2000 than we did in the last century, according to data presented by climate researcher Brad Udall.
Most scientists also agree that the Colorado River basin is only going to get hotter and drier.
Consumptive use would have to fall markedly and permanently, and the trend lines on runoff would probably have to reverse (and stay that way for years) to begin building back the storage we’ve lost in the nation’s largest reservoirs.
By how much? Good question.
No one appears to have modeled that specifically, though a recent analysis from the Future of the Colorado River suggested that to stabilize the lakes, the Lower Basin states, including Arizona, would need to make even deeper, permanent cuts while the Upper Basin states would need to give up their long-promised dream of growing use.
We need to know what’s at stake
Modeling is hard work. There is a lot of uncertainty. Even the most revered experts are unsure exactly where we’re headed, though a new study from the Los Alamos Federal Laboratory suggests that Colorado could lose half or more of its snowpack by 2080.
There are also touchy politics involved.
Few major players like publicly talking about the possibility of little to no Colorado River water because they fear it will be perceived as a tacit embrace of that future, as if modeling for an 11 million acre-foot river (or less) means they’re ready to throw out decades of water law and appropriations.
We need to get over that.
All signs point to major trouble for Lake Mead and Lake Powell, and it’s high time to help everyone understand what’s at stake.
Reach Allhands at joanna.allhands@arizonarepublic.com. On Twitter: @joannaallhands.
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