A clam, stranded by Lake Mead’s decline.

Walking the newly appearing shoreline of Lake Mead in December, I picked up the above clam.

After I used the picture yesterday to illustrate a blog post and my water newsletter, I got a note from Karl Flessa, one of the founders of Centro de Estudios de Almejas Muertas – the Center for the Study of Dead Clams – and a member of the Inkstain Colorado River Brain Trust, to whit:

It’s Corbicula fluminea or Asian clam, first recorded in North America in the 1930s. Occurs thru most drainages in the US . Invasive and unpopular. Tends to clog up pipes and canals.

Occurs in soups in Japan.

The decline of the Colorado River has contributed to the death of many clams.

Re soup, I see an opportunity.

“Close is not done.” – Brenda Burman

New plan: a temporary tattoo that reads, “CLOSE IS NOT DONE.”

That was Commissioner of Reclamation Brenda Burman’s talking point during a press call this morning explaining what happens next now that we all turned into DCP-less pumpkins last night at midnight.

The Arizona legislature gave its last-minute approval late yesterday (hilariously, as I was in the middle of lecturing to UNM Water Resources Program students about DCP – went into the lecture  – no DCP vote – logged in to the Arizona Republic to check during a class break – DCP vote approved screaming headlines and excited #azwater tweetage). But with final signatures still needed from Arizona and the Imperial Irrigation District’s last-gasp effort to get the state of California to live up to its promises to protect the Salton Sea mean CLOSER IS STILL NOT DONER. Or something. My tattoo gets complicated. But it’s only gonna be a temporary one.

the background

DCP, the Drought Contingency Plan, is a voluntary effort by Nevada, California, Arizona, and sorta kinda Mexico to slow the decline of Lake Mead by reducing water use among the three U.S. states and two Mexican states as Lake Mead declines. Mead, the big reservoir that stores water for farms and cities in those five downstream states (NV, CA, AZ, Sonora, and Baja), currently is two feet lower than it was last year at this time, despite receiving surplus inflows over the past year. This is because USERS ARE TAKING TOO MUCH WATER OUT OF THE LAKE. A more empirical and value-free way of phrasing it might be USERS ARE TAKING MORE WATER OUT OF THE LAKE THAN FLOWS IN, but I’m comfortable the normative “too much” here.

DCP, at its heart, is pretty simple. It’s an agreement among the users to take less water out of the lake so it doesn’t get empty.

ah, but it is not actually that simple

Using less comes down to allocation rules, and there are two ways to set them. Down Path One, to borrow from Burman’s “fork in the path” metaphor from this morning’s press briefing, is that the users, represented by their respective state governments, agree on the terms of the deal. Path Two involves the the federal government stepping in and imposing some sort of new allocation schemed.

Path One is preferable (my normative judgment) because when everyone agrees on the steps to be taken, we have institutional stability in river management. Path Two depends on the authority granted to the Secretary of Interior under the U.S. Supreme Court’s decision in 1963 resolving Arizona’s big lawsuit against California. What exactly is that authority? It is not entirely clear, because lawyers and participants from the various states and interests don’t agree on whether the federal government has the authority to intervene early to reduce the lake’s decline, or whether the it has to wait until it’s physically impossible to get the water through Hoover Dam because Lake Mead is functionally kinda empty.

“Not entirely clear” is a terrible way to manage a river. Down Path Two there be dragons.

Hence a widespread preference for Path One.

what happens now that we’re all DCP-less pumpkins

Interior today announced that, despite Arizona’s big step forward, we don’t have a DCP by the agency’s Jan. 31 deadline. So we’re preparing the steps that might be needed to start heading down Path Two. In particular, Burman and Interior are asking the governors of the seven U.S. basin states what they think Interior should down if it needs to head down Path Two. Importantly, Burman left Interior with an escape route to keep things on Path One. She asked for the states’ input by March 4, but said that if the final DCP signoffs are in hand by that time, she’ll rescind the request for comments and we can all think no more about Path Two.

so really we’re not all pumpkins after all

So really, the deadline is March. But close is not done, I’m still getting the temporary tattoo.

what’s the deal with the pumpkin thing?

See here.

E.C. LaRue at Diamond Creek. Photo by R.C. Moore. 1923. Courtesy USGS

USGS hydrologist Eugene Clyde LaRue’s December 1925 testimony before the U.S. Senate Committee on Irrigation and Reclamation set my storyteller’s nerves tingling.

It was a critical moment in the history of the West, as Congress deliberated turning the abstract water allocation rules of the Colorado River Compact into appropriations and concrete.

Y’all probably know the conventional telling of the story of the allocation of the Colorado River’s waters, a story I told this way myself in what I now call “my last book“.

At the time the Colorado River Compact was negotiated, streamflow data was sketchy, based primarily on a single gauge at Yuma, Arizona, near the bottom end of the river system. But twenty years of data was sufficient to give the compact’s negotiators confidence that they had at least 17 million acre-feet per year on average to work with, and likely more.

At the time I wrote that line in 2015 in Water is For Fighting Over, I had a copy of LaRue’s 1916 USGS Water Supply Paper No. 395, The Colorado River and Its Utilization, on a shelf above my computer. But until I began collaborating with Eric Kuhn back in 2016, I didn’t fully grasp the importance of LaRue’s work. As early as that 1916 report, LaRue had raised cautions about the sufficiency of the Colorado River’s supplies. By 1925, they had moved from cautions in dense USGS report tables to full-throated Senate testimony. “For many years,” LaRue told the Senators, “it has been reported that there was plenty of water for all.” LaRue then turned picked up a copy of WS395, his 1916 report, quoting a passage that could or should have been known to the Compact’s negotiators when they gathered in 1922 to carve up the Colorado River’s waters. “The flow of Colorado River and its tributaries,” LaRue told the Senators, “is not sufficient to irrigate all the irrigable lands lying within the basin.” LaRue’s cautions came fully three years before Congress ratified the Compact and plunged us headlong into decades of dam and canal building that overshot the amount of water the Colorado River had to fill them.

The University of Arizona Press will publish Science Be Dammed: How Ignoring Inconvenient Science Drained the Colorado River, by Eric and myself, this fall. We’ll tell you the story of LaRue and others who followed in his wake, and the important ways in which the use and misuse of science is now embedded in the problems of 21st century Colorado River governance as we try to untangle the knots left by the river’s overallocation.

As a writer, I love Congressional hearings – little theatrical set pieces where policy dramas play out. As a numbers nerd, Eric is drawn to the tables embedded in those hearing transcripts, the graphs, the empirical dramas as those measurements played out across the Colorado River Basin over the last century. Eric, who recently retired as general manager of the Colorado River Water Conservation District on Colorado’s west slope, is one of the river’s smartest people. He sees things in the numbers that I cannot until he shows them to me. For a Colorado River nerd like myself, the chance to collaborate with Eric these last three years has been a blast.

We look forward to sharing with y’all what we found.

Here is some data about Lake Powell, the big Colorado River reservoir straddling the Arizona-Utah border.

• Since 2005, the average estimated “natural flow” of the Colorado River at Lee’s Ferry has been 13.5 million acre feet per year, well below the 14.8maf average since 1906.
  • So yes, it’s been dry.
• Since 2005, releases from Lake Powell have exceeded the Upper Basin’s Colorado River Compact and Mexican treaty obligations by 9.4maf.
  • So despite the fact that it’s been dry, we Upper Basin residents have had enough extra to deliver a bunch of “bonus water” to downstream water users.
• Since 2005, the total volume of storage in Lake Powell has risen, from 9.169 million acre feet at the end of 2004 to 11.028 million acre feet at the end of 2018.
  • So despite being dry, and delivering extra water downstream, Lake Powell’s elevation has been relatively stable.

This is straightforward empirical stuff.

Brian Maffly has a great piece in the Salt Lake Tribune about the challenges of Colorado River management, with a focus on Lake Powell.

But Maffly weakens an otherwise excellent survey of the river’s issues with the alarmist assertion that “without a change in how the Colorado River is managed, Lake Powell is headed toward becoming a ‘dead pool.'”

It is important when doing journalism about phenomena over time (and any other sort of analysis) to choose periods of record that accurately capture the thing you’re trying to understand and explain. Maffly, and the sources on whom he relied for the story, have cherrypicked a time window that supports the “OMG POWELL DOOMED” argument, but that is misleading.

In support of his argument, Maffly notes that Powell “has shed an average of 155 billion gallons a year over the past two decades.” That is correct, but it’s a troubling choice of time frame. Since 2000, Maffly writes, Lake Powell “has been steadily dropping.” This is false.

The entire loss Maffly describes happened during the first years of the 21st century, the driest five-year stretch on record. Yowza, Lake Powell dropped a lot during the drought!

From 2005 to the present, Lake Powell’s elevation has been relatively stable, not steadily dropping.

Lake Powell storage since the turn of the century

It certainly would be correct, and is important to note, that a repeat of the drought of the early ’00s would be disastrous. Absent changes in management, it would lead us to dead pool. It is important to have policies in place that are ready for that. Increased withdrawals from the basin increase the risk should that happen. But the years that followed the drought of the early ’00s, in which Lake Powell’s levels have been stable despite a river flow depleted by climate change and the crazy policies that continue to ensure excess downstream deliveries, also are important if we’re to assess the impact of current Colorado River operating policies on the risk of Lake Powell reaching dead pool.

The reservoir that seems to be headed far more inexorably toward disaster is Mead, not Powell. That’s a lot closer to what I imagine when I hear “steadily dropping”. Remember that Mead is declining despite deliveries since 2000 of more than 9 million acre feet above the Compact-Mexico obligation of 8.23maf per year.

Lake Mead storage since the turn of the century

To be clear, I believe the Colorado River faces serious challenges. I agree with Doug Kenney, who told Maffly, “At some point, you can’t ignore reality anymore, and the reality is we need to use a lot less water in the Colorado Basin.” Yup. Doug’s right. This includes the Upper Basin. The Lake Powell pipeline and other efforts to take more water from the system seem ill-advised, guaranteed to increase the risk to existing users in both the Upper and Lower basins.

Much of the challenge right now, though, is in the Lower Basin. The ability to maintain Lake Powell’s elevations over the last ten-plus years despite drought and “bonus water” releases from Powell suggests the Upper Basin is in a far better position.

Much of Maffly’s discussion of the overall challenges is excellent. It’s important, especially for Utah water users to hear. But selling that message with “OMG LAKE POWELL DEAD POOL” is at odds with the facts, and undercuts the otherwise important stuff the story has on offer.

A note on data sources:

• Lake Powell storage data is here from USBR, I’ve posted a slightly easier to use summary here.
• Data on Powell releases can be found in the annual USBR accounting reports.
• Average annual flow at Lee’s Ferry is in the USBR Natural Flow Database, with estimates for more recent years via personal communication with USBR.

Crashing Lake Mead

Sunday afternoon, I crashed Lake Mead.

This was not difficult.

Each spring, UNM Water Resources Program students do a case study of a river basin as they’re learning dynamic simulation modeling, linking hydrology, economics, and rules. This year, we’re doing the Lower Colorado River Basin.

In the WRP curriculum, we’re big on understanding the rules by which we manage water as a resource – where they come from, and how they work.

The model results above are a perfect example of George Box’s famous dictum that “all models are wrong but some are useful.” The Goldsim model, which I wrote really fast because I needed something for tomorrow’s lecture, is a super-simple simulation of the water allocation hydrology and rules in the classic Bureau of Reclamation “structural deficit” slide, combined with a Monte Carlo simulation of some reasonable assumptions by me about 21st century inflow hydrology from the Upper Colorado River Basin.

Within a decade in my model, Lake Mead is kinda unusable, doing little more than passing through whatever water comes down from upstream. Under some scenarios, my simulation quickly throws an error, informing me that you can’t have negative water in a reservoir.

The rules here, which govern now much water gets released from the reservoir, are encoded in the Colorado River Compact and the Boulder Canyon Project Act, as interpreted by the U.S. Supreme Court in the 1963 Arizona v. California decision.

Obviously this is the “all models are wrong” part of Box’s dictum. This is a realistic view of the system if we don’t do anything. It’s not a realistic view of the system because it assumes people won’t say “OMG Lake Mead is almost empty we’ve gotta do something!” Which is what they’re now saying, which is why new and better rules are being written.

This spring’s assignment to our water resources students is to experiment with ideas about what those new rules might look like, how they might work.

I’m very much looking forward to this. I think it will be useful.