Las Vegas, look out: A bad year in the Colorado Basin hints at the system’s failure mode

Colorado River supply and demand, historical and projected, courtesy USBR

Colorado River supply and demand, historical and projected, courtesy USBR

In the work I’m doing now on the Colorado River Basin for my book, I’m trying to get beyond simply extrapolating supply and demand curves and then running around with my hair on fire. The hair-on-fire thing is easy to do, because the current supply and demand curves, as the Bureau of Reclamation frankly noted last December, are heading in a direction that’s physically unreal.

The question is what happens in the gap between the projected orange line veering upward and the blue line veering down. I’m interested in the specifics of that failure mode – who will come up short as the gaps between supply and demand become real, and how might we expect them to respond? It’s not enough to simply say “Phoenix (or Las Vegas or Los Angeles or Denver or the Imperial Irrigation District or Albuquerque) is screwed.” Because those water users will do something in response to try to minimize their screwedness. Who are they, and what will they do in response?

Buried in the tiny print of the US Bureau of Reclamation’s latest 24-Month Study (pdf) is a hint about what seems to me to be the most likely answer to my “who” question: Las Vegas, look out. (warning, wonkiness ahead, click through for more)

The Bureau doesn’t use red ink in its 24-month studies, a monthly compilation of stats on how much water there is in the basin now, where it’s sitting, and how much is expected based on the latest forecasts over the coming year. But red ink would be appropriate in this month’s edition. By this time in the spring, we’ve got a pretty good idea of what the current water year looks like, and it pretty much looks like a supply disaster:

Observed unregulated inflow into Lake Powell for the month of April 2012 was 0.764 maf or 72 percent of the 30-year average from 1981 to 2010. The forecast for May 2012 unregulated inflow into Lake Powell is 0.650 maf or 28 percent of the 30-year average. The forecasted 2012 April through July unregulated inflow is 2.36 maf or 33 percent of average.

Last year’s huge bounty of bonus water lifted total storage in the reservoirs behind Glen Canyon and Hoover dams by 5 million acre feet. 3 million of those acre feet will disappear this year.

The big picture Colorado Basin failure mode most often discussed is the “compact call”, the legal moment when the states of the Upper Basin fail to deliver their legally mandated 7.5 million acre feet (plus some spare water for Mexico) at Lee Ferry. Doug Kenney lays out a dandy failure mode in his discussion of the “climate change squeeze”, in which Upper Basin states, in order to meet that requirement, would have to curtail their uses of a Colorado River shrunk by climate change. I think Kenney’s argument is basically right (or at least, not obviously wrong).

But it is worth noting that even during the kick-ass drought of the ’00s, and continuing this year, the Upper Basin states have been able to meet their 7.5-plus maf delivery obligations (8.23 maf after water for Mexico is added to the ledger) and then some. From the perspective of the Lower Basin, there’s been no drought at all. They’ve continued to get all they’re legally entitled to, and then some.

And again this year, the 24-month study calls for delivery of another 9.5 million acre feet at Lee Ferry, more than enough to meet the Upper Basin’s legal requirements. And yet despite getting bonus water again this year, Lake Mead is projected to drop once again by the end of the 2012 water year, down 2 feet in elevation. That simple 2-foot drop is the number that I think matters the most, the tiny print I was referring to earlier. What’s going on here?

I’ve fallen back on this slide many a time on the blog to explain. Basically, the Lower Basin states – California, Arizona and Nevada – are legally entitled to use more water than flows their way each year under the minimum legally required scenario:

courtesy Paul Miller, USBR

Basically, what this simple water budget calculation suggests is that, given the minimum legally required inflow, there’s a 1.2 million acre foot per year shortfall among California, Arizona and Nevada, the states that use water flowing out of Lake Mead. That translates to a (roughly) 12 foot drop in the lake’s surface elevation. Mead’s projected to end the year at a surface elevation of 1,114 feet above sea level. When it hits 1,075, the reservoir’s operating rules, on which all seven basin states and the federal government agreed, call for Arizona and Nevada (basically Las Vegas) to face curtailment. (California stays fat and happy, having the senior-est rights on the Lower Colorado).

Arizona and, to a lesser extent, Nevada, have some room to move. Arizona is currently banking some of its surplus Colorado River water underground, along with a lesser portion for Nevada. But Arizona has a lot more room to move when it comes to agricultural usage. I’ve flown in and out of Phoenix a couple of times recently, and there sure is a lot of cotton still growing on the outskirts of town. I think it’s reasonable to think Arizona will figure out some equitable way of compensating farmers for some of that water when that shit hits the fan.

The Southern Nevada Water Authority, which serves Las Vegas, doesn’t have the ag cushion. It also faces a second problem. Independent of its legal rights to water from Lake Mead, it also has physical constraints. As the reservoir drops, its surface gets closer to Las Vegas’s water intakes, which are big pipes into the reservoir itself (Arizona takes is water downstream, so doesn’t face this problem). Vegas is hurriedly building a “third straw” – a new intake that is far deeper in the lake.

It’s reasonable to think that Vegas will get the new intake done ahead of the dropping lake. (If it’s doesn’t, the intake problem is the failure mode we all need to pay attention to). But it’s less clear that the Lower Basin states have the institutional mechanisms in place to sort out the question of who’s entitled to how much water if Mead keeps dropping despite the Upper Basin continuing to deliver its legally mandated 8.23 maf per year.

So my vote goes for the Lower Basin Crunch being the first failure mode we’ll see. And given Arizona’s flexibility in dealing with what comes next, it seems to me that Las Vegas is the place to watch for the first serious signs of trouble.


  1. ‘1.2 million acre feet per year shortfall’ …
    Would a million acre feet extra each year help or would another meeting/lawsuit & hair fire be better ?

    January 17, 2009
    Southern Nevada Water Authority
    Dear Ms. Mulroy and SNWA, (same info sent to Bureau of Reclamation at the same time)

    As we all know, Obama’s administration is investigating projects for the upcoming Stimulus Bill of $825 billion.
    Development of a non-tributary fresh water Source that, on average, could yield a million acre feet for the region and be utilized to keep Lake Mead reasonably FULL is worthy of consideration.

    Development of the Source is not outrageous, but I agree when Ms. Mulroy said, “Policymakers will need to become creative, even ‘outrageous’.”

    The SNWA should make the following known to the Obama administration:
    Lake Mead holds 28.5 million acre feet and when FULL can produce 2075 megawatts of renewable energy each year.

    By comparison, 21,000 desalination plants in 120 countries around the world produce 3.4 million acre feet a year. A $300 million dollar wind farm will only produce 150 megawatts !

    Lake Mead ’s Hoover Dam and 17 generators are already built, paid for and fully functioning!

    To appreciate a new Source solution to keep Lake Mead reasonably FULL, it is important to understand that all of the present tributary water flowing into and/or stored in Lake Mead already belongs to others and is subject to The Law of the (Colorado) River which is an accumulation of court decrees, compacts and case law stretching back to when the indigenous tribes first inhabited the desert Southwest.

    In other words, “don’t even think about touching one drop of the present Colorado River water supply; it already legally belongs to someone else” !

    Such non-tributary water must be fresh water which is under no circumstances any part of any tributary or groundwater that would drain into or possibly be connected to or eventually ever reach (and never has reached) any part of the Colorado River or any of its tributaries in any state.

    Delivery of non-tributary water from the new Source would not be subject to the provisions of the Law of the River because such water was never part of the Colorado River or its tributaries when the Laws of the River were set in stone.

    More importantly, non-tributary water from the new Source could be stored in Lake Mead WITHOUT DAMAGE to the existing water rights of those who already own and control all of the presently existing Colorado River water.

    If water from the new Source were to be stored in Lake Mead, the surface area of Lake Mead would increase. That surface area increase would cause more evaporation. The increase in evaporation would have to be subtracted off of the amount of non-tributary water stored.

    For example, Lake Mead presently has in storage approximately 15 million acre feet and has a surface area of 93,000 acres. If one million acre feet of non-tributary water were to be added, the surface area would increase to 97345 acres. The additional 4345 acres would cause the evaporation losses( +-7 ft/yr) to increase by 30,415 acre feet per year. In order to keep the non-tributary water in Lake Mead without damage to the water rights of others, 30,415 acre feet (3%) would have to be subtracted off of the million acre feet of non-tributary water accumulated. Each year, the evaporation loss would be re-evaluated and accounted for.

    The increase in renewable energy production due to the increase in reservoir depth could more than pay for the rental of the available air space in Lake Mead .

    If an extra million acre feet of non-tributary water could be accumulated in Lake Mead EACH YEAR, Lake Mead could, in a few years, be kept reasonably FULL and functioning rather than going DRY as predicted.
    Utilizing the million acre feet to keep Lake Mead full is only one option available. It may not be desirable to put all the fresh water in one shopping basket.

    Some of this million acre feet a year could be used by Las Vegas (SNWA) and the cities of California .
    Large instantaneous releases could be made to seasonally flood & restore the Colorado River Delta, worth $2.4 billion a year.

    75,000 acre feet a year could be released for diversion into the old All American Canal for groundwater recharge purposes to keep the 1.3 million people of Mexicali , Mexico from being without water in exchange for Mexico ’s cooperation with the drug and immigration issues.

    Non-tributary water in storage is rather amazing in that it can be utilized for exchanges. There are instances where owners of the non-tributary water can simply trade/exchange their non-tributary water for the natural flow water and thus put water to various beneficial uses in geographic areas where previously it would have not been allowed.
    All exchanges have to approved, properly measured and administered for by those in authority to avoid damage to existing water rights.

    The legal concepts associated with the movement and storage of non-tributary water are certainly not new to Bureau of Reclamation projects and private ventures throughout the west.
    Vast networks of diversion, storage, delivery and re-use of non-tributary waters enable the Colorado Big Thompson, Fryingpan-Arkansas, San Juan-Chama and scores of other projects to function on a daily basis in the desert Southwest.

    Being from Colorado , the new Secretary of Interior, Ken Salazar knows a great deal about these projects and can verify how they function.

    With communication, cooperation and coordination, exchanges may be possible which would help solve the issues surrounding Las Vegas , but also the Sacramento-San Joaquin River Delta .

    As an interesting example for evaluation, at times on a space available basis conveyance structures could receive the stored non-tributary water IN EXCHANGE for leaving an equal amount in northern California .
    Such an exchange could be a win-win trade.

    Point being that a water exchange can be made hundreds of miles away and can involve sometimes several totally separate river basins simultaneously without damage to anyone’s legal water entitlements.
    Nevada , Las Vegas and California need “WATER INSURANCE”.

    A totally versatile supply of millions of acre feet of non-tributary fresh water stored in numerous reservoirs may very well mean the difference between financial life or death for thousands of Nevadans & Californians in the event of severe drought, earthquakes, terrorism or even guagga mussel attacks.

    For all entities/agencies/municpalities/bureaus/states a readily available supply of fresh water for mitigation would certainly beat the millions of dollars spent for litigation, which never creates one new drop of fresh water !
    The best laid plans to mine the groundwater of the deserts for Las Vegas and the cities of Southern California may not turn out as designed.

    A water insurance policy to avoid the devastation & disappointment when all does not go well could avoid an avalance of cease and desist orders which might very well curtail the communities of the future.
    I would appreciate it if the SNWA would let me know that they have received this communique’.
    As always, I am open to all suggestions that enable a complete confidential disclosure to occur so that the SNWA and others can evaluate the merits of developing the Source and pass the information on to the Obama administration.

    Ray Walker (Retired Water Rights Analyst)

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