LAURA: Angus Goodbody, thank you  so much for joining me today.

ANGUS: Thank you for having  me.

It's a pleasure being here.

LAURA: Thanks.

So, the NRCS, that's the Natural  Resources Conservation Service issues spring   forecasts for Western rivers, including the Rio  Grande.

How does the Rio Grande look this spring?

ANGUS: This spring, we're looking at below median  stream flow for most of the of the watersheds in   the Rio Grande.

It depends a bit on which part  we're talking about.

As a whole, the main stem   down in Central New Mexico is expected to have a  little less than 70 percent of median.

And that,   that would be for the April through July runoff  period.

But, there is quite a bit of variability.

The good news is that the the headwaters  in Colorado probably are in the best shape   right now, so still not at median or  typical values, but not so far below.

LAURA: So, when you're compiling  these forecasts, what are, like,   what are the different factors you consider?

ANGUS: So, our forecast modeling system is,   it's a statistical method that we use.

We also  work in conjunction with NOAA, National Weather   Service.

And they use a process simulation  model.

So, we actually have a few different   sources of information available to us.

I'll talk  about the NRCS modeling system, though again,   we really rely mostly on historical and current  observations of snowpack and precipitation.

And, we collect most of those data through the  SNOTEL network, which is our high elevation   mountain ground-based observing system.

LAURA: And so, can you talk   about how snowpack relates to streamflow   and also how that has, kind of, changed?

ANGUS: Sure.

So, you know, in a lot of the Western   U.S., we depend on water from the mountains and  that water is largely sourced as snowpack.

So,   you know, accumulating through the winter, we tend  to have deep seasonal snowpacks through a lot of   the upper Rio Grande basin and also in New Mexico  and the higher peaks of the Sangre de Cristos   and other high mountains in that area, locally.

So, the whole premise for being able to forecast   is the fact that we do accumulate this snowpack  high up in the mountain, ahead of time, so we're   able to assess exactly how much is up there or at  least an index of how much is up there.

And then,   we know, that that is going to run off later in  the springtime once the temperatures warm up,   etc.

So, it's really based on that natural  snowpack reservoir that can be measured in advance   to give us an indication of what to expect  later in the spring and summer runoff season.

LAURA: One of the things that we've  talked about a bunch on our show   is how even a normal or above average snowpack  doesn't necessarily translate to robust   downstream flows.

Can you explain why that is?

ANGUS: Sure.

So and this gets… You asked a little   bit about the change too in the previous question,  so there's no question that, you know, the amount   of snow we have in our mountains is changing and  has changed, you know, considerably in the last   few decades.

We can detect that just with our  ground-based measurements.

There's also a feedback   between how much snow is in the mountains and  what actually runs off and it's not just simply,   “Oh, there's less snow, so we have less water.”  There's other processes in play here, related to   forest transpiration and evaporation and soil  moisture conditions coming into a season,   that seemed to be exhausted exacerbated  recently with, you know, multiple years of dry   conditions.

So, we have deficits entering the  season that may be larger than what we're used to,   even in the more recent historic record.

So, I will say, yeah… so, if you think about   less snow in the mountains, obviously that's  going to mean less volume.

It also can mean   different timing of the runoff as well and this is  an issue, because we've built our systems around   an expectation of runoff at certain times of the  year.

So, potentially, as we have warming and   maybe more of the storms in the winter transition  to more liquid precipitation rather than snow,   we can actually have a similar amount of runoff.

But, coming at different times of the year,   now, that is not what we've been seeing most,  in the most recent decade.

In the Rio Grande,   in general, it's been just quite dry.

So,  overall, the main force for runoff is going to   be how much precipitation of any variety that we  get throughout the year.

And so, as long as that   remains low, we'll continue to have low runoff.

I guess, to talk more about the stream flow and   we do see… we have seen a significant reduction.

Every 10 years we update our stream flow normals   and, basically, that is a 30-year average in  median that we calculate for the seasonal target   periods that we forecast for.

So, again that's  typically either April, July or March, July, or   the standard target periods in the Rio Grande.

And  what we did see across the board in this recent   update was less total volume of water running off  during that time period.

So, our actual normals   have lowered, which means that our interpretation  of, you know, 100 of normal is actually   less than it was for the previous 10 years.

LAURA: So, I'm interested in talking a little bit   more about that.

You've noted in your forecasts,  earlier in the year, that people should understand   that 100 of normal might not mean the same  thing as it did last year.

Can you explain that?

ANGUS: Yeah, so it's, it's basically… it feeds  off of what I was just talking about, in the sense   that, if we have, let's say, we have a watershed  where the 30-year normal is 100,000 acre feet.

And for the 1981 to 2010 period was, which was our  previous normal period, it might have been 120,000   acre feet.

So, there's been a twenty thousand,  you know, twenty thousand acre foot reduction,   which is actually close to twenty percent  reduction.

And so, it's important, if people are   just looking at the percent of normal values, to  realize that that is scaled to the new normal.

So,   if what we used to consider normal was a 100,  was 120, we need to refocus and understand that   a hundred percent now actually means  a hundred thousand not a hundred and   twenty thousand.

So, it's important to rescale.

LAURA: Right, so I wanted to jump back a little   bit to some of the factors that you talked  about, like dryer forests, for instance.

I'm also thinking about soil moisture and  relative humidity and these sorts of things.

When we're looking at these sort of cumulative  impacts to a watershed, like, how do we ever   catch up?

Do we ever catch up on some of these  things, or how long does it take to catch up?

ANGUS: Yeah, it's a great question.

I'm not  sure I have a decisive answer.

It depends.

It   depends what happens in the future also, always.

And, of course, we're not… one thing in water   supply forecasting, I think sometimes people  think we have a better view of what the actual   future weather is going to be like and that's not  really the basis for our forecast.

Our forecasts,   right now, are still really based on historical  relationships between snowpack and runoff.

And,   you know, that's one of the concerns in the  current environment, as the climate potentially   changes, some of those relationships may not be  as strong as they once were.

So, we still don't   have a great alternate method.

So, we still  proceed with that, you know, using history   to understand what's going to happen.

And there  still is a robust connection.

It's not like those,   the, you know, we still measure snow in the  mountains and we still see a reasonable runoff   based on those predictions.

But, I guess could,  you could, you ask the last part of your question?

I was trying to remember what else you asked… LAURA: Yeah, I guess, I guess I'm asking a   question that's not fair to ask anybody, but I  think so many of us want to know, or understand   how many good years would  we need to ever catch up?

ANGUS: You know, honestly, if things were wetter  in the Rio Grande, it wouldn't necessarily take   that long to catch up.

I mean, the big question  is, is that actually going to happen?

And I,   and again, I do tend to look to history.

I know  we're in a time of greater uncertainty with   what the climate will be doing, you know, in the  next decade or decades.

However, we can look back,   particularly at our stream flow records, which in  the, in the Rio Grande area, honestly, go back 100   years or more in some cases, and get an idea of  what have things been like in the past?

So, as I   mentioned, we update our normals every 30 years.

I've actually gone back 80 years and looked at   30-year increments through time, to see what those  cycles have looked like.

And, the reality is,   the Rio Grande has always gone through, you know,  long cyclical periods of wetter and drier periods.

So, in a sense, what we're experiencing now  is not unprecedented.

Of course, the reasons   we may be experiencing may be unprecedented.

So, of course that's the concern right now,   right?

And, of course, we have so  much more demand than in the past.

LAURA: Absolutely, yeah.

So, you know,  we talk on our show a lot about how   sort of the climate change impacts over the past  few decades, in particular since the 70s, when   we've seen a couple degrees rise in temperature,  we've certainly seen longer wildfire season   things like that.

I'm curious, you've been doing  forecasting in the Rio Grande basin since 2009.

What are some of the biggest  changes that you've seen and maybe,   you know, are you surprised by any of these  changes, or the pace of these changes?

ANGUS: You know, I mean, honestly, the Rio Grande,  since I started forecasting in the late 2009,   I think was when I first operationally  began forecasting in the Rio Grande, it has,   it's really been consistently dry for the  last 10-plus years.

I mean, there's been an   odd year here or there, where we've gotten to  median or above, but that's been the anomaly.

There's also been a lot of impacts to  the watersheds, particularly in Colorado,   but other places too.

And this has manifested  in whether it be wildfire impacts or there's   been a beetle kill situation as well.

So, we have  places where the vegetation is being impacted on   a broad scale and we know conceptually that that  has an impact on the hydrology of those basins.

Unfortunately, modeling that is difficult and so  we still, we still are using, you know, general   relationships of snowpack to run off and it's hard  to say exactly what those impacts are.

We can look   at a lot of research and understand that, “Well,  when we remove canopy, there's actually multiple   competing impacts and forces, like, we actually  might get more snow accumulating in certain areas   but we also might melt that snow more rapidly  in the springtime.” So, that gets back to the   impacts on both volume and timing of  the snowpack and runoff in the streams.

LAURA: So, I'm curious your final thoughts.

What  is one thing that you would like everyone to, kind   of, keep in mind this spring and looking forward?

ANGUS: So, there's a lot of effort right now   to improve our modeling.

And so, one of the  things that I would mention, as we transition   to new technologies, whether that's, you  know, remote sensing of snowpack or other   hydrologic variables, that we don't  have great ground-based measurements of   is, that it's going to take some time to integrate  these new ideas and new modeling approaches   into operational forecasting.

I know, you know,  everybody wants an immediate response to the,   to the issues and I mean it's certainly worth  a lot of attention right now.

But, the fact is   that some of these changes take time.

And, it  also one thing I really want to mention here,   we do have some emerging technologies  that are very promising.

And   in the long run absolutely will improve our  ability to forecast runoff.

But, in the meantime,   we need to continue to support our legacy and  ground-based systems, because there's a lot,   there's a lot of information, as we transition to  new systems, that's still going to be needed.

And,   in fact, the ground-based measurements  are still critical for the research and   development of many of those new systems.

LAURA: All right.

Well, Angus Goodbody,   thank you for helping keep us all informed.

I look  forward to your forecasts whenever they come out.

Thanks for joining me today.

ANGUS: All right.

Thank you.

Take care.