Growing up in the shadow of the Rocky Mountains, Andrew Schwartz never missed an opportunity to play in – or study – a Colorado snowstorm. During major blizzards, he would traipse out into the icy wind and heavy drifts of snow pretending to be a scientist researching in Antarctica.  

Decades later, still armed with an obsession for extreme weather, Schwartz has landed in one of the snowiest places in the West, leading a research lab whose mission is to give California water managers instant information on the depth and quality of snow draping the slopes of the Sierra Nevada.

The University of California, Berkeley’s Central Sierra Snow Laboratory at Donner Pass near Lake Tahoe has provided daily snowfall and snowpack measurements for more than 75 years, but it is taking on a heightened role helping drought-stressed water managers plan and react to shortened snow seasons and shifting runoff periods caused by climate change. Schwartz and the lab are testing new sensors and other technologies with the aim of improving the accuracy of runoff models and giving water agencies a better understanding of how much water may end up in their snow-fed reservoirs.

Snowmelt from the Sierra helps sustain millions of people in cities such as Sacramento, San Francisco and Los Angeles and more than $40 billion worth of California-grown crops each year. The growing demand for the precious snowmelt is making the lab – which is the only continuously monitored snow outpost in the West – a key source of information for water managers.

Schwartz, who has managed the lab over the last year and a half, talked with Western Water about the lab’s ongoing renaissance, the effects climate change and wildfires are having on snow patterns and snowmelt, and new developments in snow science. This printed interview was edited for conciseness, but you can listen and watch a video of the full Q&A here.

WESTERN WATER: You’ve described the Central Sierra Snow Lab as the “pinnacle of snow science.” What makes the lab different from others and why is it so important for local, state and federal water managers?

SCHWARTZ: We have one of the longest snowfall records in the world, beginning all the way back in water year 1879, so technically in 1878. So we have that record that started with the [Southern] Pacific Railroad out here and then we picked up in 1946 when the lab was built and continue that. So that’s a wonderfully long record.

One of the things that sets us apart is that we have a full-time staff on site 24/7, 365 (days of the year). So we always have somebody out in these snowy conditions, we’re constantly getting manual measurements in addition to the automated measurements. In the lab’s 76 years, it’s played a vital role in shaping what we understand about snow and our climate and meteorological processes as well because of all the amazing research from different organizations that has occurred here.

WW: Annual temperatures are rising in the Sierra. A recent federal study estimated the American River watershed in the winter could warm by another 5 degrees by the end of the century. How is climate change altering snow patterns in the West?

SCHWARTZ: We are seeing warming temperatures throughout the Sierra Nevada, but particularly here at the snow lab with our records. Something that we’ve seen in our data is that our season is getting shorter, we are seeing more rain events in the middle of winter.

That warming and that rain really creates issues because it is going to melt the snow (sooner) and that’s more snowpack that we don’t have in the peak season in the late spring and going into the summer.

WW: Predicting the timing of Sierra snowmelt and the amount of runoff that will flow into reservoirs is becoming harder for water managers as the climate warms. How is the lab helping water managers update their modeling and improve their understanding of shifting runoff periods?

SCHWARTZ: We are definitely seeing more complex runoff patterns. We had last winter this very warm mid-winter event where we saw melt in January, February and March, periods when ordinarily we’d be getting the bulk of our snow. And as a result, we’re finding it harder to predict these types of things and manage our water.

Now, we’re working on process-based models where a lot of them in the past for various agencies may have been statistical. You know, very simple regression models: X amount of snow plus maybe a meteorological condition is going to equal Y amount of water in terms of runoff.  

I think across the board right now there’s a large movement towards physical modeling and process-based modeling, which is something that we engage in here and are also big proponents of doing. That’s really, I’d say, probably the primary way that we’re learning to deal with the lack of averages that we could have depended on in the past.

WW: California wildfires are increasing in frequency and size in watersheds that are critical to the state’s water supply. You’ve studied fire and snowpacks in Australia. How do wildfire burn scars affect the snowpack and timing of snowmelt?

SCHWARTZ: These massive fires can affect an entire catchment or maybe multiple catchments, and realistically, one of the biggest issues – for multiple reasons – is that they remove the tree canopy. When you’re removing the tree canopy, you’re introducing all this additional solar radiation on your snowpack, which speeds up the snowmelt. And you’re also really, really increasing wind speed and temperature in those areas, which adds to evaporation.

We also see reductions in snow-water equivalent a lot earlier and shorter snowfall seasons in these areas because they are not conducive to keeping snow on the ground and protecting it in the way that maybe an undisturbed forest might be.

WW: So the watersheds are essentially not producing as much water in areas that have been ravaged by wildfire?

SCHWARTZ: That’s correct. We also see differences in our streamflow and we see differences in runoff because a lot of times, with these fires, they can change the soil properties. So we see all that water, rather than soaking in, just sliding right off the hill.

And then of course there’s water quality issues that arise as well with black carbon, occasionally heavy metals and things like that. So, wildfire is a big problem and one of the things that we’re really pursuing as snow hydrologists and any hydrologist, really, going into the future because of how prevalent it is and the impacts that it has.

WW: On the tech side, the lab is currently testing 3D-printed snow depth sensors in conjunction with the University Corporation for Atmospheric Research (UCAR) in Boulder, Colo. How do these sensors work and who will benefit from the technology?

SCHWARTZ: These sensors are part of what’s called the 3D-PAWS system. This one particularly uses what we call a sonic snow depth sensor. It emits a pulse of sound that travels down to the snowpack surface and bounces back, and then we can calculate the distance from the sensor to the snowpack based off the speed of sound and the time it took for that pulse to travel down and back.

Now, that’s not a new technology. But what’s new is these sensors being so low cost and being able to be manufactured very easily, meaning they can go into developing countries or maybe countries that don’t have the same infrastructure that we do but still need to manage their water resources.

WW: You’re also developing small, inexpensive snow sensors that can be operated by anyone with an internet connection. Can you give us an update on the “citizen science project”? How many are there?

SCHWARTZ: The point of having these sensors is to have something that’s relatively low cost, maybe $100-$200, that people can install at their homes. Because for one, a lot of people in these areas are fascinated by snow — I certainly am — granted they’re not all snow scientists but a lot of their livelihoods depend on it.

We have up here around the [Donner] Summit near the snow lab probably 50 to 75 people that want to try one. So we’re going to do kind of a case study to figure out how they all work, how we can tweak them and then deploy them largely hopefully around the region if not the country and even the world if we can get to that point.

WW: Sierra Nevada is a Spanish name that translates to “snowy mountain range.” What trends have you seen in the Sierra over the last decade or so in terms of snowpack? 

SCHWARTZ: As far as the last decade, we’ve had our ups and downs for sure, but we are trending down a little bit. However, if you widen things out a bit to maybe 20 or 30 years, it doesn’t look quite as severe. We are still losing snow and a lot of that is transitioning to rain, but it’s not quite as severe as maybe the last 10 years.

The window of the snow season is definitely closing. It’s getting a lot shorter. We are seeing less snow overall and more rain coming in.

WW: In addition to testing new technologies, the lab is helping to train California Department of Water Resources staff on how to use the new tools. How has the lab been able to assist DWR, which of course manages and allocates water?

SCHWARTZ: DWR is actually the lab’s largest collaborator and has been involved realistically at this site since the mid-1950s. So they’ve been involved up here for a very long time and we’re doing a number of different things with them.

Recently, we’ve also taken on testing a lot of the sensors they’re interested in, seeing how feasible it is for potential large-scale deployment. And so we’ve become kind of a testing bed for DWR as well, which has been really rewarding because there’s a lot of these technologies that are hard to get a really solid handle on unless you can stick them out in the field. Luckily, we’re able to afford them with that luxury.

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Reach Writer Nick Cahill at ncahill@watereducation.org, and Editor Doug Beeman at dbeeman@watereducation.org.

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