Come Rain or Shine

Drought, Snowpack, and Streamflow

May 05, 2021 USDA Southwest Climate Hub & DOI Southwest Climate Adaptation Science Center Season 2 Episode 7
Come Rain or Shine
Drought, Snowpack, and Streamflow
Chapters
Come Rain or Shine
Drought, Snowpack, and Streamflow
May 05, 2021 Season 2 Episode 7
USDA Southwest Climate Hub & DOI Southwest Climate Adaptation Science Center

In this continuation of our special series on drought, we interview two water and climate scientists to learn what streamflow forecasts are predicting for the upcoming summer, and to learn more about an emerging area of research, termed snow drought. Dr. Adrian Harpold is a hydrologist with the University of Nevada, Reno, and is also a SW CASC funded researcher. Dr. Brad Udall is a Senior Water and Climate Scientist with the Colorado Water Center at Colorado State University, and is a co-principal investigator with the SW CASC. Here they share with us insights such as why 100% of the historic snow-pack doesn’t always translate to 100% of the historic runoff, the challenges of “weather whiplash”, options for water management on the watershed scale, and what gives them hope for the future even in the face of some pretty grim predictions.

Links to organizations and events mentioned during the interview

Center for Weather and Water Extremes https://cw3e.ucsd.edu/

Blue Forest Conservation Initiative https://www.blueforest.org/

Information on the Oroville Dam incident https://damfailures.org/case-study/oroville-dam-california-2017/

To learn more about atmospheric rivers, check out Season 1 Episode #1 Atmospheric Rivers 

If you’re enjoying this podcast, please consider rating us and/or leaving us a review on Apple Podcasts, Podcast Addict, or Podchaser. Thanks!

Follow us on Twitter @RainShinePod

Have a suggestion for a future episode? Please tell us! https://forms.gle/3oVDfWbjNZs6CJVT7


Affiliate links:

DOI Southwest CASC: https://www.swcasc.arizona.edu/

USDA Southwest Climate Hub: https://www.climatehubs.usda.gov/hubs/southwest

Sustainable Southwest Beef Project: https://southwestbeef.org/


Show Notes Transcript

In this continuation of our special series on drought, we interview two water and climate scientists to learn what streamflow forecasts are predicting for the upcoming summer, and to learn more about an emerging area of research, termed snow drought. Dr. Adrian Harpold is a hydrologist with the University of Nevada, Reno, and is also a SW CASC funded researcher. Dr. Brad Udall is a Senior Water and Climate Scientist with the Colorado Water Center at Colorado State University, and is a co-principal investigator with the SW CASC. Here they share with us insights such as why 100% of the historic snow-pack doesn’t always translate to 100% of the historic runoff, the challenges of “weather whiplash”, options for water management on the watershed scale, and what gives them hope for the future even in the face of some pretty grim predictions.

Links to organizations and events mentioned during the interview

Center for Weather and Water Extremes https://cw3e.ucsd.edu/

Blue Forest Conservation Initiative https://www.blueforest.org/

Information on the Oroville Dam incident https://damfailures.org/case-study/oroville-dam-california-2017/

To learn more about atmospheric rivers, check out Season 1 Episode #1 Atmospheric Rivers 

If you’re enjoying this podcast, please consider rating us and/or leaving us a review on Apple Podcasts, Podcast Addict, or Podchaser. Thanks!

Follow us on Twitter @RainShinePod

Have a suggestion for a future episode? Please tell us! https://forms.gle/3oVDfWbjNZs6CJVT7


Affiliate links:

DOI Southwest CASC: https://www.swcasc.arizona.edu/

USDA Southwest Climate Hub: https://www.climatehubs.usda.gov/hubs/southwest

Sustainable Southwest Beef Project: https://southwestbeef.org/


Emile Elias: Welcome to Come Rain or Shine podcast of the Southwest Climate Hub and the Southwest Climate Adaptation Science Center or CASC. I'm Emile Elias, Director of the Southwest Climate Hub.

Sarah LeRoy: And I'm Sarah LeRoy Science Communications Coordinator for the Southwest CASC. Here we share recent advances in climate science, weather and climate adaptation and innovative practices to support resilient landscapes and communities.

Emile Elias: We believe sharing this information will strengthen our collective ability to respond to impacts of climate change in one of the hottest and driest regions of the world.

Sarah LeRoy: Welcome to the third episode of the special series, focusing on the impacts of drought. If you haven't already be sure to check out our previous episodes on this topic. We'd also like to say thank you to rrjaunty for leaving us a review on Apple podcasts. rrjaunty writes, "Fun and informative. I'm already learning a lot from this podcast. Keep up the good work." Thanks, rrjaunty We appreciate the feedback and to all our listeners, we do read every review and we appreciate your ratings and feedback to let us know how we're doing and help us to grow. You can rate and review us on Apple podcasts, Podchaser, or Podcast Addict, or drop us a line on Twitter.

Our handle is @RainShinePod. Now on with the show.

As we move into late spring and temperatures get warmer around the Southwest region, water managers are looking forward to anticipate how much water supply may be available in stream flow through the summer. Today, we're speaking with two water and climate scientists to learn what streamflow forecasts are predicting for the upcoming summer, and to learn more about an emerging area of research termed snow drought. Adrian Harpold is a hydrologist with the University of Nevada Reno and is also a Southwest CASC funded researcher. Brad Udall is a senior water and climate scientist with the Colorado Water Center at Colorado State University, and is a co-principal investigator with the Southwest CASC.

Thank you both for speaking with us today. I'd like to start by talking a little bit about your research. Adrian, I quickly mentioned in the intro here, this term, snow drought. Could you define snow drought for us and then describe some of your snow drought research? 

Adrian Harpold: Sure. And it's a pleasure to be here talking about a somewhat unfortunate topic, but important.

I'll give you the very simple definition first, which is snow drought is a lack of snow. For a time of year when you would expect to see a certain amount of snow on the ground for that place and climate, you're not seeing that snow. There are some pretty different reasons that you can end up in a snow drought.

And I think that's where some of the science we've been doing is useful. You can have your typical drought where you're not receiving precipitation. And we think of that as a dry snow drought. It's just dry. There's no precipitation coming in. It's hard to form a snowpack. There's also snow droughts that arise really out of sort of temperature and energy controls where you're getting precipitation, but maybe it's falling as rain, and so you're not getting a snowpack or maybe you're getting precipitation and it's falling as snow, but it's melting or sublimating, or somehow going away before that time of year when you expect it to be there, which is often sort of this time of year. You know, March and April. So that's how we've begun to think about it.

And we have a long record now of snow conditions across the Western U.S. We're, we're lucky in many ways, and we can show how extreme some of these droughts can be. How, little snow, compared to similar times in the past. 

Emile Elias: Thanks Adrian. And thank you both for being here today. As you know, this is a topic that is close to my research interest, and really, I think one of the most critical topics to talk about, and you're both doing some really interesting research on this topic and pulling information together.

So Brad, I'll start with you. Can you describe some of the recent things you've investigated and things that you're finding that you'd like to share? 

Brad Udall: So Sarah and Emile, terrific to be with you. And I appreciate your efforts on these podcasts to inform folks about some of the pressing science issues in the American Southwest.

So my work has focused heavily on the Colorado river system and how and why it has been changing, especially since the year 2000. And in 2017, I put out a paper with Jonathan Overpeck formerly of the University of Arizona, that looked at what we called the millennium drought. And what we found was that from 2000 to 2014, the paper's old now from 2000 to 2014, the river was down approximately 20%. And if you looked at precipitation, you actually could not explain that flow decline completely. And you had to then go look at some other facts, including especially temperature to explain the decrease in flows. And what we found was that somewhere between a third and a half of the flow decline in the Colorado river, since 2000 was due to these higher temperatures.

And I want to note that that study built on prior work by Connie Woodhouse, who the year earlier in 2016 had found that since 1988 for a given amount of precipitation, runoff in the Colorado river system was not what you would expect, that they were seeing declines in runoff efficiency. And then I'll also note that Overpeck and I built on work by Julie Vano during her PhD dissertation, where she attempted to quantify what's called the temperature sensitivity, which is to say how much the flow declines per degree increase in temperature.

And also what we call precipitation elasticity, how the flow changes if precipitation goes up or down. So that's one study and there's another study. I can also get into that I did a year later with Dennis Lettenmaier and his grad student, if you like. 

Emile Elias: Absolutely. Let's go ahead and hear about that, that second study.

Brad Udall: So the second study was a modeling study and Lettenmaier's a long time hydrologist formerly at University of Washington now at UCLA and his graduate student, Mu Xiao and I got together. And what we did was we ran a well-known hydrology model that takes inputs like temperature and precipitation and wind and produces river flow for an effectively the entire Colorado river basin.

And we ran that for a hundred year period from about 1914 to roughly 2014 using historical data. And you get outputs that look like what you would expect or hope for in that the model faithfully reproduces the flow of the Colorado river during that time period, then you do a really simple experiment, which is you take out the temperature increase that occurred during that time though, over or roughly a degree Celsius, 2 Fahrenheit temperature increase, and your rerun the model. And instead of getting a 20% decline like you do using the historical temperatures, all of a sudden you only get a 10% decline in flow. And it's a really simple deductive process to then say, Hey, that flow decrease was due to the, the temperature increase that occurred during the, there mostly during the 21st century, but started roughly back in 1980 or so.

So that study effectively attributed about half of the flow decline in the Colorado river due to these higher temperatures. 

Emile Elias: Yeah. Thanks Brad. Thanks for that, and also the background. Highlighting how all of this research that's done builds on other research and that, you know, we're really learning together as a community about what's happening and also about the importance of temperatures specifically.

And that's especially important since we have a lot more knowledge about what temperature will we believe what temperature will do in the future. So, Adrian, I'm curious about some of your recent findings or other studies that you might like to discuss.

Adrian Harpold: Sure, I think I'll pick up in Brad's large scale Colorado river basin footprint, even though that is not really my field, but there's an interesting study recently by Chris Milly at the USGS, I believe it is in Science or Science Advances, looking at trying to attribute these effects that Brad mentioned and for declining flows in the Colorado river basin, and they do a similar sort of modeling game where they turn on and off different parts of the model to try to attribute causation, again around temperature to a large degree, because if you think about the effects of temperature there sort of multi discipline, where they come and affect the vegetation and the biology and those effects are quite complicated.

The way that trees use the water early in the season, how much water they use, how they do their photosynthesis. You have a effects on the rain and snow, the phase of the precipitation as it falls is temperature sensitive among other things. You have overall sort of water demand by the atmosphere being very temperature sensitive.

And then the snowpack processes are, are complex themselves, but, the point of the Milly paper is actually to attribute some of the effects to the snow albedo feedback, which the idea is that as your snow line moves up in elevation you have a smaller snow covered area, more of the incoming solar radiation, like the sunlight that is really the primary incoming energy to our surface of the Earth is, is absorbed by the land surface. It's not reflected off of the snow surface. And they showed that among some of the other temperature effects that, that I mentioned, and Brad was discussing that they think in their sort of modeling world, that, that snow albedo feedback is, is an important reason why some of the declines are, are occurring.

Brad Udall: I could build on that. I'd like to just for a second. So Chris and his coauthor, Kristen Dunn, said that we're losing about 9% of the flow of the Colorado river, per degree Celsius increase. And that's at the upper end of what Overpeck and I suggested the number might be, we went from about 3% to 10%, again, based on Julie Vanos work. Both these studies did two other things.

So Overpeck and I used global climate model projections to take future temperatures and using this temperature sensitivity number, then project out what we might lose by 2015 to 2100. And we suggested by 2050 using these very solid global temperature increases that are projected, that the for the Colorado river could lose 20% just due to temperature alone.

And if you combine that with the recent modest precipitation declines, you'd have an overall decline of about 30% by mid century. Chris Milly did similar projections and came out with numbers that looked a lot like ours as well. These sort of eye-popping flow reductions due to temperature increases.

So it's, it's worthy to note that Chris duplicated work and confirmed, I should say more importantly, confirmed work done by lots of other people. And that study got a lot of press in various national publications. 

Emile Elias: Yeah. Thank you, Brad. Thanks for adding on to that. And also highlighting the fact that there are different research groups out there asking similar questions and coming up with similar answers.

And so I feel like that's You know, corroborating and increasing our strength in, in what we know in terms of what we, we believe will happen in the future. On this podcast, we often ask folks, we take a step back and we ask folks how they began to study this topic. What was it about looking into this that was important or interesting, intriguing to you?

And so go ahead and start with Adrian on this question. How did you start investigating this research topic? 

Adrian Harpold: I like this question, although I'm always, it's always slightly awkward, but since I did have a bit to prepare, I'll give you my, my, my story is playing in creeks in Washington state as a child, and really being encouraged by my parents to be outdoors and sort of have that connection with, with those places.

And then going to engineering school, but having summers as a raft guide on the Snake River, I think locked in some kind of connection again. And just saw a pathway forward and in life as a hydrologist, which really was all on the East coast through graduate school. And it wasn't until I moved to Arizona, and then later Colorado that I really saw, you know, like, wow, snow drives everything in these systems. And on top of that, I realized, we don't actually know, you know, how these systems work. You know, from a hydrological standpoint, we don't know how the snow melts and where, when and where that water goes into the watershed, how it becomes streamflow.

These questions are still pretty open in a lot of ways. And so critical when you think about really short-term when, you know, in my lifetime, now I have a child, certainly in her lifetime. The changes they're going to see in the snowpack and the water resources are, are profound. So, that kind of drove me to, to a career.

And now as a professor, you know, teaching and, you know, just sort of sharing that love of water and, and water resources. 

Emile Elias: Yeah. I mean, I think it's one of the most fascinating careers, certainly. So I concur with your choice, the same question to you, Brad, how did you get into studying this topic? What was interesting?

Brad Udall: You know, what's fascinating to me is Adrian and I, in some ways had a similar path. I actually have two years of my life spent in the bottom of the Grand Canyon as a river guide. That's 45 two week-long trips down there that I did through college when I was studying engineering. And then later as well, whenever I could convince an employer that it was really important for me to go do another trip.

Yeah. I studied engineering as an undergraduate and ran a consulting firm and was part of a consulting firm here in Boulder for almost 10 years. Went and did some work in the NGO world actually ran a land trust for a few years. Very untypical, frankly, that's also been very useful to me in my career path.

Just understanding why and how ranchers use water in the American West. In 2003, I was actually hired by the University of Colorado to run the NOAA-RISA, Regional Integrated and Sciences Assessment program, they're called the Western Water Assessment. And it was at that point in time that I actually was able to connect the climate part of this into the hydrology part, which I'd previously done.

And since that time I've, I spent 10 years at the University of Colorado, a year at their law school running their environmental program there and then moved up to Colorado State University in 2013 where I've been since. And I'll tell you it's been a pleasure to be in this field. It's, there are great people working in it.

There there's to my mind, no more pressing topic than water resources in the American West and climate change and what we're going to do about it. 

Emile Elias: So Brad, your response really ties into my next question so well, because you hit on recreation, you talked a bit about agriculture and ranchers and, and law and land trusts.

And so my question really is ties into that. And that's, what are some of the implications of your research for Southwestern ecosystems and communities? And of course they're tied together. 

Brad Udall: Yeah, huge, huge question, Emile. And I'll tie back into Adrian's answer a little bit about, this new evaporative load that we're all experiencing.

Right? And so Overpeck and I, and others have talked about this increase in evaporation in all its forms because of these warmer temperatures, any given day is likely to be warmer. Throughout the year we have a longer warm season. The atmosphere now holds more moisture as it warms 7% per degree Celsius, roughly.

So there's a bigger suck above our head to try and draw water out of natural systems in the Colorado river system and many systems, in the American West, something like 80% of what falls from the sky actually ends up going back up to the sky through direct evaporation and through plant transpiration, and many scientists are now saying what's going on in the American West isn't a drought, because the drought implies we'll go back to non drought and we need another term for it. If it's not a drought, what is it? That term is a mouthful, it's a term called aridification. So this drying and warming of the land surface, and I'm less capable of talking about what happens to ecosystems, but more about communities.

Because my work around the Colorado river gets into lots of where this water goes and, very clearly, we're going to get used to using less water. We have to, if these projections are anywhere near close to being right, these river systems are going to have less water in them. Currently in the Colorado River supply and demand are balanced.

And if supply goes down, guess what? Demand has nothing to do, but to follow that decrease in supply. So, I mean the implications and ramifications of this are going to get felt throughout Arizona, for example. In the Colorado River system has now been in what are called Tier Zero shortages for the last two years.

And has received less Colorado River water. And with this year's runoff where we're looking at going for the first time ever into what's called a Tier One shortage in Arizona, which means their big canal, the biggest canal, the Central Arizona Project which can carry 1.6 million acre feet is going to lose a third of that.

They're going to lose over 500,000 acre feet with enormous implications for ongoing farming in Pinal County, between Phoenix and Tucson. So, I mean, I think every major Southwestern city, all of whom rely on Colorado River water is going to get to deal with less. And we're now kind of in the process of trying to figure out what that new future looks like. 

Emile Elias: Thanks, Brad. There's a lot of work to be done there. And was talking with a rancher in that area was really concerned about not having the water resources available, not just for his own production, but he was concerned about dust in the area and what was going to happen to those fallow lands.

And so there are some broad implications of this that aren't even necessarily considered at the moment. So I want to ask you Adrian, the same question. Do you have some examples of the implications for Southwestern ecosystems and communities?

Adrian Harpold: Yeah. I'll point to another wicked problem. In addition to aridification, which is really concerning because that's just a lack of water and a sort of a perpetual drought.

The idea of weather whiplash in the future, where we're oscillating between very dry periods, maybe even multi-year droughts and then very wet periods is concerning, especially in a place like California and parts of Nevada where winter flooding is a real concern because it puts water managers in a bind where they have to manage for winter time floods, especially as snow turns to rain. Scientific evidence suggests precipitation intensity will increase because as Brad was saying, the atmosphere can hold more water vapor. So when it's very dry, that's a problem for being a giant suck from the land surface. But when you're picking up water from the tropics and transporting that over the coastal and sort of inland coastal areas that can deliver more water and water more intensely. So the water managers are forced to leave space in the reservoirs as a flood flood precaution, but then we face these periods of drought where we need all the water we possibly can because in parts of the state of Nevada that I live in, in California, we really receive no summer precipitation. So the spigot turns off in about May about this time of year, and that's all the water we have for the year. So it's a real dilemma. You think about the Oroville Dam disaster. We were coming out of a drought of record.

I'll talk a second about that. And received this 2017 year that was really exceptional because not only did it deliver some of the largest AR (atmospheric river) events, they were back to back and just very difficult to predict. And that's when you know, the failure on the, on the spillway occurred at Oroville Dam.

And just, I think it was a wake up call for the flood challenges that are probably in our future. The weather whiplash effect also has ecosystem implications that, I think we're still trying to fully grasp. But in these really water limited and fire prone systems, the vegetation can respond very quickly to wet years and then face trouble in the following dry years.

And the idea of structural overshoot, where the vegetation grows very quickly to make use of water in wet years, and then turns around and has to maintain all those leaves and branches, and new growth in the dry years. And there's pretty good evidence from the 2012 to 2015 drought by Roger Bales and colleagues in California that, that was a big driver of why we saw so much mortality, where we saw the mortality and weakens the, the trees to other pathogens and, and beetles and such. And in my part of Nevada, that that rapid growth becomes fire fuel. And so we in the lower elevations of sagebrush, pinyon juniper, we tend to have worse fire years after wet years.

And have to, may have to manage that slightly different. So these are new sort of paradigms that really are going to require us thinking about our management infrastructure in these systems, I think a little more holistically. 

Sarah LeRoy: Thanks, Adrian. And I can definitely say that in Arizona, we witness that too right. We see those really wet years. We get really excited and then we turn around and we're dry again. And those fires are really, they pick up. So it's tough. So I wanted to shift gears just slightly. Brad, you started talking about this a little bit when you were mentioning the Tier One shortages in Arizona, but I want to shift a little bit and talk about current conditions for this year.

And I know that April 1st snow water equivalent numbers just came out. So thinking about the snowpack levels as we talk now in mid April, I mean, what does this mean for stream flow forecasts for this year? I guess I'll start with Brad. 

Brad Udall: So they're grim in a word. You know, this year right now, Colorado basin snowpack's somewhere around 80%, it was a little higher not too long ago, but we're looking at 45% of expected runoff out of 80% of snow pack and this discrepancy and significant part traces back to these really dry soils that happened last year in the June, July, August period, which in the four corners states was the driest and hottest period going back the entire amount that NOAA keeps records, 126 years. And I'll note, there's a really interesting study back in 2012, by Tapash Das and some really well-known coauthors that looked at how soil moisture deficits affect rivers around the West and the Colorado River function very uniquely in this regard.

In that, using models, what Das and others showed is that soil moisture deficits in one year in the summer of one year actually reduce the flow all the way into the next year. And that finding, I think ties in really nicely what we're seeing this year in terms of these really low forecasts and I'll note last year too, we had something similar.

Where we had a hundred percent of snowpack on April 1 in the Colorado river system, and we got 52% of runoff. So this disconnect between runoff and, and snowpack is, should be really disconcerting for people. And it's yet one more implication of what's going on under our very eyes as it warms. 

Sarah LeRoy: Thanks, Brad. Yeah, that is very scary to think about. You know, in the past we would get really excited if we had a hundred percent of our snowpack, right. And so it's scary to think that we need much above that if we want to get the runoff levels that we're looking for. Adrian, did you have anything you wanted to add?

Adrian Harpold: Yeah, I think Brad, you know, gave you the bad news, so maybe I don't have to, to that way, but I'll, I'll put it in the context of how we predict the stream flow and really the flows into our reservoirs. That's, that's one of the main sort of water management metrics is like how much water is coming in into our up Upland reservoirs.

And then down into our big reservoirs, like Lake Mead, Lake Powell and it's, it's actually a real challenge. If you think about the way that we've historically done this, we've used the past observations and the snowpack and the past observations of streamflow to make predictions. And hat tip to my, you know, long deceased colleague, Jay, James Church here at the University of Nevada.

This has proved incredibly reliable for a hundred years, we've been able to go up in the mountains, we can basically have a precipitation measurement device, which is the snow pack, and we can measure that and we can predict really well how much water will come down and come into our streams. But as the system becomes what we call non-stationary, which just means that it changes over time, those tools are not as strong as they used to be, because one, the past is not necessarily now a great predictor of the future. So that's the main, the main trouble we have is using past years. Maybe we never had a soil moisture deficit, the way that we do this year, and maybe these are extreme conditions or extreme combinations of conditions that we haven't experienced before.

And the other is that our measurement network was designed for a historical snowpack its extent, sort of where, where we have deep snow packs and we're losing in some, some ways our measurement accuracy as the snow line recedes. And we, we receive more rain in the winter. So these tools, again, sort of shout out to, you know, hydrology as a career.

We, we still use in many ways, the tools from the early 20th century to make a lot of these predictions and we're going to, we're going to really need to lean on to a new and better ways of doing this, given how important these resources are. 

Sarah LeRoy: Thanks, Adrian. Brad, I wanted to talk a little bit more about the shortage on the Colorado river you mentioned earlier. So normally, right, we look at the water levels at Lake Mead. You know, there's thresholds that the water level passes and that, you know, triggers different tiers of shortages in different States. So, are we looking at that for this year?

Brad Udall: We sure are. And we're going to see reservoir levels that are unprecedented since the initial fillings of both Lake Mead, the nation's largest reservoir and Lake Powell, the nation's second largest reservoir this year. Both of those reservoirs are hovering around 40% of full and they're going to go even lower. And as you correctly know the delivery the delivery amounts in the lower basin for Arizona, California, and Nevada are based on Lake Mead's levels. And because those levels are now going to drop below some of the trigger thresholds Arizona, and to a lesser extent Nevada are going to receive pretty substantial shortage cuts coming in 2022 and likely continuing into 2023. They're very large that Arizona, to its credit has planned for this, although some aspects of that planning are slow to get in place, including some funding to handle reductions in water for Pinal County farmers in Arizona.

I, I mean, these are enormous. And for the last two years we've been in, what's called a Tier Zero shortage, which is a really frankly tiny little shortage. This isn't, will not be tiny. We're looking at the loss of 20 to 30% of the farmland in Pinal County over the next several years for a variety of reasons, but mostly around what people think are large-scale extended cuts in water to these farmers because of these flow reductions. 

Sarah LeRoy: So not good news. Let's try and think a little bit more positively with this next question, which is thinking about some promising solutions and adaptation efforts with regard to Western water scarcity. So, Adrian, let's start with you on this question.

Adrian Harpold: I'll try to be positive here. You know, I work with a lot of young people and I think it both keeps me positive and forces me to stay positive on their behalf. I, I think going back to where I pointed at with a real wicked problem of this weather whiplash and I, I suggested there's really two challenges I was pointing to with that reservoir management and sort of the vegetation management aspects of fire and vegetation health. I'll take opportunistic look at those where I'm involved a little bit, really an effort led by the Center for Weather and Water Extremes in the West at SCRIPPS, have been involved in a, in a effort that I don't think they named it this, but a Forecast-Informed Reservoir Operations, or FIRO.

And this work has mainly focused on the Russian River basin, which is a more rainfall dominated system. And they've really shown that what they can do in the Russian is. In a nutshell, keep more waters in the reservoir and still reduce flood risk and therefore end up with more water supplies and managed winter flood risk.

So they're expanding this effort into the Sierra Nevada, and I think up into the Cascade Range and maybe other places I can't keep track of that group. And, thinking about the challenges of, of snowpack and in particular, the big extreme events that we get in the Sierras like rain on snow flooding.

What we need is observation networks that let us react. Well, even going back a step, let me be careful. We need, we need the hydrometeorology. I don't wanna sell that short, right? We need the the predictions of how much precipitation is going to happen. And they're flying aircraft into these atmospheric rivers.

They have just state-of-the-art supercomputer level models predicting that, then the system comes in. We need to be able to observe what's happening. The precipitation, the snowpack, the streamflow response. Then obviously we need the models to somehow take that information and make predictions sort of medium and short-term timescales.

And I think that's a challenge for scientists, it's a challenge for the water managers to adapt, it's a challenge for the policy folks to adapt and sort of encourage this, but also maybe an opportunity to, I wouldn't say solve, but we'll say adapt or mitigate some of these, these challenges that are on the horizon, whether we like it or not. Another opportunity and really again, something I think we have to do which I've seen the whole debate change in the last few years is vegetation management with a particular focus on forest management. We know that fire suppression and overstocking of mountain forests in particular, some invasive species issues and other ecosystems are changing fire dynamics.

And that is made much worse by climate change effectively the aridification concept of just drier systems. So we have very few tools. If you think about it, we have very, very few ways to manage these water resources because they drain from giant sort of natural areas. Vegetation is one of the only things that we could realistically change in these systems without what I'll say is unrealistic sort of engineering solutions. Although I will say that the scope of these vegetation projects are, you know, bigger than most engineering things of the 20th century. We can adapt to this. We can pull vegetation out that reduces fire risk. Some of the work I'm doing is trying to show how we can promote snow retention in that removal of vegetation.

How, how do we keep that snow around longer? Provide more to our streams, reduce fire risk, the following dry, dry season. So I think a real paradigm shift in how we think about you know, cutting down trees in our forests. How we think about burning prescribed fire, where we have smoke in the shoulder seasons of the fall in the spring, where yeah, you know, we'd like to be outside, but I also dealt with months and months of pretty extreme, I'll say extreme fire smoke this summer from fires that, that nobody wanted. So I think that these trade offs are really profound. They're really sort of societal, but they're also opportunities because these are some of the few ways that we can adapt and not, not fall victim to some of these changes.

Sarah LeRoy: Thanks, Adrian for highlighting some, some opportunities there. And Brad, I'll ask you the same question. What do you see as some of the most promising solutions or adaptation efforts with regard to Western water scarcity? 

Brad Udall: So I sometimes it's referred to myself as the skunk in the room. But I actually am a bit of an optimist on our ability to come up with new ways to manage the Colorado River.

And I want to put my answer in that context. There's a series of really important agreements that expire in 2026 on the Colorado River. And we now have an opportunity to put in place another agreement for roughly the next 25 years until mid century. And there's a whole series of really difficult problems to solve like overuse of water in the lower basin.

Within the 1922 Colorado River Compact, there's a clause that no one's really sure what it means. Is it a delivery obligation by the upper basin or is it a non-depletion obligation because the two mean very different things in a climate change world, there are places in the upper basin right now where people want to actually increase demands like Utah.

There are 29 tribes in the basin and then I think 10 have quantified water rights. So 19 have Supreme Court what are called Winters Rights that were granted to them way back in 1908, yet have no quantity of water associated with them. So they're real equity issues here. So that's sort of the, the stage setting that we're going to get to solve with this new agreement.

How do you get to solutions? Well, I mean, clearly you get to put economics and environmental values and societal values all informed by science. I think in places you're going to have what we call in Colorado and the state of Colorado, demand management. So voluntary dollars for reductions in water use.

And there's a lot of work underway right now in my state around this topic. There's some kind of far out ideas that might actually work, but would require a real rethinking of the compact. One idea is a notion of caps on water use by the upper basin in exchange for a better interpretation of what that delivery obligation or non-depletion obligation means. 

In the lower basin you know, these cuts that are falling on Arizona, can't continue to fall on Arizona if the reservoirs drop. Other States have got to share and by that I mean, California, especially the state with the largest, right in the whole basin. And you know, in the lower basin we've never charged evaporation actually, it's been a freebie and maybe we need to think about charging States for that.

I was recently part of a study at the Utah State where we suggested that expanding demands just makes no sense. And clearly in the realm of with the tribes were going to kind of need to think long and hard about how to deal with their issues with non-expansion of dominions. You know, one area that I've done some work on in ag is this notion of crop switching. Can ag producers switch to less consumptive crops and yeah, there's certainly lots of possibility there, but everybody needs to understand, it's actually quite complicated to do. Ag producers might need new labor, they might need new equipment and new markets, new processing, new transportation. They can't do this on their own. And if we're really going to promote this, we need to actually support them in this.

Clearly, we're going to need some adaptive measures through time that either crank down water use or allow it to increase a little bit, if the future isn't quite as bleak as some of us think it might be. But let me say, despite all of these challenges, I'm actually pretty optimistic because of the people who run these big water systems in the West know each other, they meet regularly, they talk to each other, they like each other.

They understand the other person's problems. And within that, I think, are really good opportunities for some good outcomes here. And I'll point to the 2019 agreement. This what's called Drought Contingency plan in the Colorado river where the lower basin States really came together and figured out how to, how to plan for a pretty dire future.

So I'm optimistic despite being in a skunk. 

Adrian Harpold: And picking up on Brad's point, this is Adrian, I think the coordination by agencies and, you know, people on some level, right. It really is people, it's really the optimistic sort of piece here. And there's been some, some pretty good evidence of that in the Colorado River basin in terms of solving these problems.

Although I do think the future problems will be unprecedented. I will point to a challenge though, that I've sort of picked up on recently in that vein, which is we have massive open federal land and a real federal management of a lot of the water resources. And these agencies were built a long time ago.

You know, when the Forest Service was mostly about you know, board feet and you know, forestry, and the Bureau of Reclamation was mostly about building canals for agriculture and don't get me wrong. Those things remain important, but we live in a world now where we don't have extra water necessarily for more irrigation and, and that, and you know, a lot of those Southwestern forests are just not really productive enough to compete, you know, with forestry in other parts of the world. And so I think we need more coordination between these agencies. There's a recognition that the forests that drain into these reservoirs are, you know, managed you know, the reservoirs are managed by one group.

The forests are managed by another group. They all kind of have the same goals. And some rethinking of that coordination, I think there's really good examples in some places. But as these problems become pressing sort of everywhere, I think we're going to, those kinds of issues are going to be required for solutions and thinking a bit outside the box, maybe even bringing in private investors. One of the examples I've seen here in California is a group called the Blue Forest Conservation Initiative, which I'm on their science advisory board. And I think I finally can sort of explain their model simply, which is that they put out water bonds and make an investment ahead of time with the expectation of forest management, forest restoration work creating additional water resources that have an economic value. So there's a feedback between restoring the forest, treating the forest, having more water available and that sort of paying for itself in some capacity. And, I think those kinds of efforts really do again, take coordination between water authorities, water management agencies, agencies like the forest service to really on the ground make them happen.

But it's exciting to see them as a possibility.

Emile Elias: Yeah, thank you. Thanks for highlighting some of those collaborative solutions and creativity and different ways of thinking about doing things as we move forward with different people, right? Highlighting the need for, for those engaged and knowledgeable people.

And really our thanks for those people, thinking of creative ways to move forward. Just yesterday, someone asked me about their declining groundwater levels and having to drill deeper wells and what are we going to do about it? And for me personally, it, it brings about a lot of stress, right? It makes me personally feel tied into this and obligated and wanting to do something.

And then I start to think, actually, we all have a personal responsibility in responding to, to what we see coming in the future. And we talked about some age old, timeless topics. Fires and floods and droughts. And then some new topics like the anticipation that the Colorado River flow will decrease by about 30% in the future, or this disconnect between runoff and snowpack.

And so we're touching a lot of topics within this topic, and it reminds me of two things. One, drought and stress, and we just recently did a podcast on that topic. And that certainly ties in for a lot of us. And also climate hope, this new idea or this concept of broadening our understanding and the work that you do that broadens our understanding of what's happening in the future so that we can respond appropriately.

And even if we're tired and we see what's coming and we can even be scared, we can also fall back on these people doing this great work and a broadened understanding that for me personally, it gives me some more climate hope. So thank you for the work that you do, for helping us understand more deeply what's coming, what's happened in the past. Some of the creative solutions. And I wanted to give you a chance to share any last comments or thoughts that you have on this conversation. And we'll start with Brad. 

Brad Udall: Emile, Sarah, thanks for the opportunity to chat with you and Adrian, too. I've always admired your work. You know, I never do one of these without saying we also got to solve the root cause here. Right? We got to pursue net zero emissions as soon as we possibly can. The cool thing about that is every time I studied the technologies around these, you actually do get pretty excited about what's going on here. Capitalism is working in that sphere and fabulous things are headed our way, including price decreases in technologies that don't emit greenhouse gases.

So, while that won't solve this more immediate problem of water related and climate warming issues in the longterm, it's a solution we gotta have on, on the table. And it's actually pretty exciting and that we're going to change the world almost always for the better here with these new technologies.

So that, that excites me. I trust the people in the American West to talk and resolve these issues. When I look at American water issues, it's actually governance working the way it should be, where people compromise and they talk and they learn about their neighbors and their other States and, and incorporate their needs into their own actions.

And, and I feel actually pretty good about what's going to come out of this despite some real challenges ahead. 

Emile Elias: Thanks, Brad. Thanks for ending on that optimistic note. And Adrian, anything else you'd like to add? 

Adrian Harpold: Just that I appreciate being here, Emile and Sarah and Brad. I appreciate a conversation and learning from you.

And I'll just point to, you know, being at a university and working with the next generation, that's really going to have to solve these problems and in a lot of ways and remaining optimistic because they're you know, if we're clear-eyed and working towards solutions and educating the next generation.

They're going to be able to solve some of these challenges, I think that we find very daunting. We just might need to give them the space to think outside the box in ways that we haven't been able to do before. But you know, we live in a great part of the world and I think that we will work through these challenges, but we need to again be clear-eyed about, about what they are and what's coming for us. 

Emile Elias: Thank you both for speaking with us today. Really appreciate your insight and look forward to seeing what you do next.

Thanks for listening to Come Rain or Shine podcast of the USDA Southwest Climate Hub

Sarah LeRoy: and the DOI Southwest Climate Adaptation Science Center. If you liked this podcast, don't forget to subscribe like or follow for more great episodes. If you want more information, have any questions for the speakers, or would like to offer feedback, please visit climatehubs.usda.gov or swcasc.arizona.edu

Emile Elias: Our sincere thanks to USDA Agricultural Research Service, the Sustainable Southwest Beef Project. And the U.S. Geological Survey for supporting this podcast.