Taking climate change seriously: the Colorado River “stress test”

Courtesy Dave Kanzer and Eric Kuhn, from Eric’s 2013 Colorado River Water Users Association presentation


The Bureau of Reclamation Colorado River team did something remarkable in yesterday’s release of its new 5-year reservoir levels analysis – the “stress test”, a methodology pioneered a decade ago by an Upper Colorado River Basin technical team that included John Carron of Hydros and Eric Kuhn and Dave Kanzer of the Colorado River District is now the “new normal”, to borrow a terrible phrase. From the “5-year projections approach tab” here:

The method used to generate future inflows in the current projections includes resampling a subset of the historical natural flow record (1988-2019) using the Index Sequential Method (ISM), referred to here as “Stress Test” hydrology. In the past, the full historical record (1906-2019), known as the “Full” hydrology, was used to provide 5-year probabilistic projections. The Stress Tests hydrology scenario applies ISM to a shortened period of the natural flow record, 1988-2019, which removes the earlier portion of the natural flow record and focuses on the recent (approximately 30 years) hydrology. This period has a 10% drier average flow than the Full hydrology. Use of the Stress Test scenario is supported by multiple research studies that identified a shifting temperature trend in the Colorado River Basin in the late 1980s that affected runoff efficiency and resulted in lower average flows for the same amount of precipitation (McCabe et al. 2017Udall and Overpeck 2017Woodhouse et al. 2016).

The idea is that the traditional approach – using the entire period of record to model the probabilities of future river flows – is not longer valid because climate change is changing the river.

John, Eric, and Dave reasoned nearly a decade ago that using a shorter record, focused on our climate-changed Colorado, might better help managers think about and plan for what to expect next. (Dave also famously provided the memorable Homer Simpson image for Eric’s CRWUA presentation).

The “stress test” has been creeping into basin management discourse for a while, and Reclamation had already begun publishing stress test scenarios alongside. But the new 5-year flow and reservoir level estimates now are all in on the stress test.

The stress test may not be stressful enough, which was one of the implicit messages in the editorial Brad Udall and I published in Science magazine in May, and which Brad and I made more explicit here. But this use of the stress test is nevertheless hugely important, kudos to the Reclamation technical and management team for this important step.

Dry in all my river basins

odds favor a dry autumn 2021 in the watersheds that matter to me

Getting ready for class class discussion this afternoon about “drought” (“I get to see my students in person!” he exclaimed nervously.), I had occasion to check the latest Climate Prediction Center long lead forecast. It’s a few weeks old, but I don’t expect it’ll have changed much.

The brownest blob captures both river basins I care most about – the Rio Grande and Colorado, with odds tilted toward drier than average conditions through November. (And it doesn’t get any better if you look at the longer leads.)

Today’s class teaching goal: there’s no one thing called “drought”, it has many different definitions depending on who and where you are. For me, the most important measure is soil moisture (now) and snowpack (over the coming winter). Those are the things that determine available water supply for the communities of interest to me. There’s some overlap between my “drought” and a forest’s, or a fish’s, but they’re not necessarily the same thing. (If any of my students are listening in here, that’s a clue to the “what did Prof. Fleck leave out of the recorded lectures” discussion question.)

After some time last week in the mountains of northern New Mexico and southern Colorado, where Albuquerque gets its water, I had occasion to pull the latest soil moisture modeling from the Colorado Basin River Forecast Center. CBRFC only does the Colorado River Basin side of the continental divide, but there’s no reason to think it’s any different on our side of that line.

I cringed:

Dry soil moisture heading into fall 2021 in the Colorado River Basin





On the importance of gathering stones

Round rocks of the San Juan-Chama project

I had the joy of sharing a goofy group text thread yesterday evening with a couple of friends exchanging pictures of the round rocks we each collected yesterday morning on a field trip to see the plumbing of the San Juan-Chama Project, which diverts Colorado River Basin water beneath the continental divide to bring drinking and irrigation water to New Mexico’s parched middle Rio Grande Valley.

The San Juan-Chama Project’s 25 miles of tunnels are the thread that connects us in central New Mexico’s Rio Grande Basin to water and its management across the Colorado River Basin. That makes the tunnels the thread that holds together the work I’ve been doing for the last decade trying to understand the relationship between the water in my little town of Albuquerque, New Mexico, and the water challenges of the greater West. But I’d weirdly never actually visited this vital bit of plumbing.

So when a friend invited me to tag along Thursday and Friday on a workshop and facility tour for San Juan-Chama Project water users to talk about infrastructure management and governance, I said “yes”.

We hung out Thursday afternoon at a lovely picnic shelter along the Rio Chama talking about concrete maintenance priorities and the crazy-sounding Law of the Colorado River governance rules. (The concrete discussion was fun, but I didn’t understand a lot of it. There were a lot of totally legitimate “What, what? Why did they do it that way?” questions about the crazy governance structures.)

Friday we toured the dams and diversions.

the mouth of the Azotea tunnel

When I told WT, one of my former students, that I was headed up to Chama for a facility tour, he told me I had to pick up some round rocks at the Azotea Tunnel. Azotea is where the water emerges from beneath the continental divide after miles of concrete tunnel. Rocks that make it through the intakes have been skittering and rolling for a good long while, like time in a multi-million dollar rock tumbler, before they emerge to be deposited as the water slows and begins its trip down Willow Creek and into the Rio Chama on its way to my Albuquerque faucet.

The group had swollen to about 30 by the time we got to Azotea, with about a dozen mostly white government rigs parked on the apron above the tunnel. And within moments of our arrival, the senior managers from central New Mexico’s largest municipal water agencies had scampered like kids down the rocky channel embankment to begin hunting for the best round rocks.

The headwaters snow is long gone, and the tunnel’s been dry save for a couple of late summer rainstorms since the second week in August, which sucks for water management purposes, but was great for round rock hunting!

The rocks were cool, but the real value was the earnest goofiness of the endeavor.

I write a lot about the importance of “social capital”, the personal bonds among the water management community’s problem solvers. That’s what this was about.

We sat out by the Rio Chama Thursday evening until well after dark, long after the grill had cooled, talking water until it was so dark you could see the Milky Way and the evening star (Venus?) next to a setting sliver of a moon. We artfully arranged the car-sharing arrangements so we had time to talk during the shuttling from one tunnel and diversion dam tour stop to the next. We clustered in the shade eating our salads and PB&J talking about the Green Book and water bypass rules and Sec. 11 of Public Law 87-483, the San Juan-Chama Project’s 1962 authorizing legislation.

We collected round rocks. And then gleefully texted pictures of them with one another after we got home.





This morning’s operations missive from the federal-state-local Middle Rio Grande operations group (by “Middle” here we mean central New Mexico) notes a release of ~100 cubic feet per second of imported San Juan-Chama Project water for environmental flows, an effort to help the struggling Rio Grande silvery minnow.

SJC water is removed from the Colorado River Basin in the San Juan mountains of southern Colorado, through a series of tunnels beneath the continental divide, for use in the Rio Grande Basin.

So – water from one troubled basin (the Colorado) to provide environmental benefits in another (the Rio Grande).

The driest on the Rio Grande since….

One measure of dryness on the Rio Grande

I’ve been thrashing about this year thinking about ways of visualizing and measuring how dry this year has been on my home river, the Rio Grande through Albuquerque. Above is my latest stab at it.

A flow of 100 cubic feet per second at the USGS gage at Albuquerque’s Route 66 bridge in the middle of town has always been a threshold I watch. That’s in part because for a time it was used as a criteria for Endangered Species Act compliance (no more), and in part because when it drops that low it just looks dry – a shallow braided channel meandering through muddy sand.

This particular bit of code counts the days each year below a specified threshold, and the graph above was created by setting that to 100 cfs.

The flows here are a combination of climate-driven inflows and human management. All those dry days back in the 1960s, ’70s, and ’80s were driven in significant part by river management – much larger diversions from the river for irrigation. The relative lack of dry days across much of the 21st century was also driven by river management – an ESA requirement to keep the river wet here.

In both cases that combines with hydrology.

Unfortunately we only have data for the Route 66 bridge gage since 1965. I’ve got some more work I’m doing (back later for that, gotta get to the day job) looking at other gages with longer records, but the interplay of gage history and diversion points makes that more complicated than I have time for this morning, still ingesting first coffee.

Yesterday was the 14th day this year with a daily average flow less than 100 cfs. Last year we had 14 such days. The last time we had more was 1989.

Flow this morning, as I write this, is < 80 cfs.

Brad Udall on Upper Colorado River Basin climate change risk

By Brad Udall, posted with permission, from his Aug. 18, 2021 presentation to the Colorado Water Conservation Board

Colorado State University’s Brad Udall has been doing some really interesting thinking about how to conceptualize and communicate climate change risk to water supplies in the Colorado River Basin.

Shown above (and shared with permission) is one of Brad’s “selected averages” graphs. The horizontal lines show the average river flow value for a period of interest – the entire period of record, for example, or the 21st century. (It’s from a presentation Brad gave to the Colorado Water Conservation Board earlier this month.)

While the general pattern will likely be familiar to people working on Colorado River issues – wetter in the long run, drier in recent decades – the value being graphed may not be. It’s “unregulated inflows”, which is the number calculated by the Bureau of Reclamation and the Colorado Basin River Forecast Center to estimate the actual inflows into Lake Powell, minus the impact of upstream reservoir operations.

It’s the best number to use if you want to look at the the actual water flowing into Lake Powell, and therefore available to meet compact-driven Upper Basin commitments to deliver water downstream to the Lower Basin at Lee Ferry. It combines both natural flows, and Upper Basin consumptive uses.

The key number to look at here is the one in the blue box. Since 2000, the average unregulated inflows have been 8.38 million acre feet per year. The Upper Basin’s Lee Ferry compact delivery “obligation” (lawyers please don’t subpoena me on this point, I ) is 8.23 maf, which means that we’re right on the edge of trouble even now, in terms of the Upper Basin’s ability to meet the expected deliveries to users in the Lower Basin. Increased Upper Basin use, or decreased flow (see Brad’s 6.66maf for 2018-2021) would cross that trouble threshold.

What this means is that, based on 21st century hydrology, the Upper Basin is already caught in what Doug Kenney and colleagues dubbed “the Upper Basin climate change squeeze”.

This is what Brad and I were getting at in our May editorial in Science. Lower flow scenarios are entirely credible based on the best available climate science and the hydrology we are seeing. We need analyses – modeling runs – that consider them as we prepare for the next round of river management negotiations, so that we know what will do if Brad’s scary “6.66” is a harbinger of our future.

Now out in paperback (and perhaps timely given the chaos?): Science Be Dammed – How Ignoring Inconvenient Science Drained the Colorado River

Our friends at the University of Arizona Press have kindly printed a bunch of new copies of our book Science Be Dammed, this time in paperback so it’s cheaper!

Eric and I did a fun Q&A with Abby Mogollon at the press to accompany this second launch:

Q: Why did you embark on this project?

A: We wanted to provide a resource that would contribute to better decision making. In the next few years, the Colorado River basin water managers and other stakeholders will be facing difficult decisions, including renegotiating the river’s fundamental operating rules – questions about who gets water, and how much. We recognized that the river has been legally overallocated for decades. We wanted to understand how this happened–how science was used/misused in the decision-making process and how that misuse of science has become embedded in the river’s governance structure. We believed that with the impacts of climate change adding a new level of deep uncertainty and complexity to an already overused river, it was important to understand how we got here.

Why don’t they redo the Colorado River Compact?

Koda, co-author with Bob Berrens and John Fleck, of the forthcoming book The Rio Grande and the Making of a Modern American City, to be published as soon as we can write it and find a publisher.

My co-instructor Bob Berrens and I added a slide this morning to our welcome lecture for first-year students in the University of New Mexico’s Water Resources Program, hoping to foreshadow two questions we’ll be asking the students over and over and over and over this semester:

Bob: That sounds great, how are you going to pay for it?

John: X sounds great, why don’t they just do X?

The welcome lecture includes all the usual “read the syllabus”, and “no this won’t be on the quiz, we don’t have quizzes”, and such, as we shove aside the bureaucratic detritus of academia so we can get down to the business of talking about water.

The headline for this year’s class (yes, I am an inkstained wretch, see blog title, our syllabus has a headline) sums up the dilemma:

There’s less water. What do we do?

There’s less water. What do we do?

It’s the ninth or tenth time we’ve taught the class together, depending on how you count, and we love doing it because we are good friends who have spent the better part of that decade talking about water in and out of class, we still don’t really understand all the things, and teaching helps us sort through our own confusions.

We have our lists of things we hope to share with the students – the challenge of market and non-market values of water, the strange land of municipal pricing, the even stranger land of agricultural water use in its many forms and flavors, the tools of water measurement, the wisdom of Elinor Ostrom and Ronald Coase in analyzing water governance structures, the story of the orange groves of Upland, California, where I grew up.

Through it all, as we’re building the scaffolding, we’re also asking the students to use that same scaffolding to begin to analyze a question. A month or so back, while walking with Bob’s dog Koda around Altura Park (which sits midway between our two houses), we settled on this year’s question.

There’s less water. What do we do?

As the reservoirs behind Hoover and Glen Canyon dams on the Colorado drop to record lows, as irrigators in central New Mexico struggle to water crops after an early start and early end to their irrigation seasons, as I spend countless hours with reporters from across the country looking for help understanding all of this, as my own river goes dry, it remains the central question. And I do not know the answer.

I’ve got some schtick involving case studies I’ve written over the years about successful conservation and collaborative water-sharing agreements, and about the importance of being attentive to science, however inconvenient. I will happily share all of this with our students over the coming semester. I really believe it, and I think it’s all important, and I feel so privileged that students want to sit and listen to me yammer on about it for hours on end!

But I’m mindful of Bob’s and my questions, which really are important – how are we going to pay for the things that need to be done, and why haven’t they been done already?

Let’s assess the farmers to to pay for it.

The point of Bob’s question is the more obvious – many solutions we might contemplate are costly, and understanding how we pay for them (or fail to come up with a mechanism to pay for them) are at the heart of many of our dilemmas. We need to think through these questions carefully. This is central to the new book Koda, Bob, and I are beginning to write. Bob’s insights about financing mechanisms are one of his most important gifts to my thinking.

Why don’t they build a pipeline/canal to the Mississippi?

My question – why don’t they do “X” – is more obscure, because in one common usage it isn’t really even meant as a question. Often, a person posing it really means “X should be done“. But I’ve found it incredibly useful, going back to a long career in journalism, to really try to pose it as a question – to really understand the reasons X has not been done.

In some cases, upon closer inspection, I find they haven’t done X because it’s a really bad idea for reasons I hadn’t thought through. In other cases, I find that X has costs, or downsides, that I hadn’t thought through. In other cases I find obstacles that, however good an idea X is, must be overcome.

Sometimes (see above), X hasn’t been done because we have no way to pay for it. I’m pretty sure it was Koda who pointed out that Bob’s question is really a particular case of my more general formulation.

I pretty much never find that they haven’t done X because it never occurred to them.

Darkness at the park

At Bob’s suggestion (I have found these to be useful), I was rereading this morning a 1959 essay by Charles Lindblom called “The Science of ‘Muddling Through’“. It provides a great framework to explain why, the more time I have spent in the study of water policy and governance, the less clear the answers have become.

Lindblom suggests that our desires for an omnisciently rational policy making process, while widely expected, is impossible – because of bounded rationality, and lack of clarity about how to weigh relative values (shared and unshared). So we end up muddling.

During the pandemic’s darkest last winter, Koda, Bob, and I were walking around the park in the cold dark of night. Halfway down the park’s north side, Koda alerted – there was something in the park. We couldn’t see it, but we have come to understand that Koda is far smarter than we.

I guess that’s my hope for the semester, that Bob and I might walk down the side of the darkened park and get some help from our students in seeing what is there.

The Magic of Radio

When I was a little kid, the Fleck family had a big box with a radio and a record player and speakers in the family room.

Radio was always magical to me, and when I was at my littlest I imagined a man inside the box, scrunched up and holding a guitar, talking and singing to us. I dreamed of becoming that man, and while I never did learn to play the guitar or scrunch down inside the radio box, I did launch my life as a communicator more than four decades ago by talking to people over the radio.

Live radio remains, for me, a great joy.

Tomorrow at 10-11 a.m. eastern time, 8 a.m. Albuquerque time (Aug. 25, 2021, remembering the permanence of this blog post) I’ll be live on NPR’s On Point out of WBUR in Boston talking about the Colorado River.

If you’re not in Boston, WBUR streams over the internet. It’ll be boxed up for later distribution as one of these newfangled podcast things so popular with kids today.

But I would be so very happy if you would join me live.