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Snow and Water in the Roaring Fork Valley

The winter of 2016-17 is off to a great start here in the Roaring Fork Valley! 2017 kicked off with two big storm cycles, each dropping feet of snow on our mountains bringing smiles to the faces of skiers across town. But more importantly, these recent storms have significantly bolstered our snowpack.

Other than skiing, why do we care about what the snowpack is doing? To begin with, monitoring the snowpack over the course of a year and comparing it to prior years on record allows us to get a handle on changes in climate in this region. Secondly, snowpack data allows water managers to predict spring and summer river flows, which is crucially important for agriculture and outdoor recreation interests. Given that much of the annual precipitation in this area falls as snow, a healthy snowpack is key to avoiding drought during the drier summer months.

Let’s take a closer look at our current snowpack, via data from a network of automated backcountry monitoring stations known as SNOTEL. These stations measure the snow water equivalent (SWE), which is the amount of water that would result if you were to melt the entire snowpack. There are currently six operating SNOTEL stations in the high elevations of the Roaring Fork watershed (Fig. 1).

Figure 1. Map of the Roaring Fork watershed with individual SNOTEL sites marked with red stars.

The closest SNOTEL station to Aspen is located near Independence Pass at 10,600’. For this date, the current snowpack is tied with that of 2008-2009 winter for the highest SWE since the year 2000 (Fig. 2). The Independence Pass snowpack SWE is currently at 146% of the median to date, already having accumulated an impressive 74% of the seasonal median SWE with several months of winter remaining. 

Figure 2. Graph showing SWE from the Independence Pass SNOTEL site for individual winters going back to the year 2000. Smoothed purple line is the average SWE from 1981-2010. The current position of the snowpack is circled in red on the graph.

Another SNOTEL station in the Roaring Fork watershed is located near Marble, CO by McClure Pass at 9,500’. For this date, the current snowpack here has the second highest SWE since the 1999-2000 winter (Fig. 3). The SWE is currently at 146% of the median to date, already having accumulated 77% of the seasonal median SWE, similar to the Independence Pass site. 

Figure 3. Graph showing SWE from the McClure Pass SNOTEL site for individual winters going back to the year 2000. Smoothed purple line is the average SWE from 1981-2010. The current position of the snowpack is circled in red on the graph.

A third SNOTEL station of interest in the Roaring Fork watershed is Schofield Pass, located near the drainage divide between Aspen and Crested Butte at 10,700’. For this date, the current snowpack here has by far the highest SWE since 2000, an astonishing 4.4 inches more than the next highest year (Fig. 4). In fact, the 30.2 inches of SWE at Schofield Pass right now is the most ever recorded at this site for this date since observations began there in 1986! The Schofield Pass snowpack SWE is currently at an amazing 189% of the median to date, already having accumulated a whopping 89% of the seasonal median SWE with several months of winter remaining. Schofield Pass tends to be a snowier site than other observation locations in the Roaring Fork watershed, and has received the brunt of the last two storm cycles to impact the region. 

Figure 4. Graph showing SWE from the Schofield Pass SNOTEL site for individual winters going back to the year 2000. Smoothed purple line is the average SWE from 1981-2010. The current position of the snowpack is circled in red on the graph.

In summary, all SNOTEL stations in the Roaring Fork watershed are reporting well above average SWE measurements, with the Schofield Pass site showing historically high snowpack SWE (Fig. 5). Taken together, the six SNOTEL sites are at 175% of the median SWE to date, already having accumulated 89% of the seasonal median SWE. 

Figure 5. Graph showing SWE from all six SNOTEL sites in the Roaring Fork watershed for the current winter (solid lines) versus the 1981-2010 average for each station (dotted lines).

So, it’s clear that we’re having an excellent winter so far here in the Roaring Fork valley. But other than making for some great skiing, why is does this matter? It all comes back to the importance of the Roaring Fork watershed as a whole. The watershed, which is approximately the size of Rhode Island, provides 279 billion gallons of water annually to the Colorado River (Roaring Fork Conservancy), equivalent to roughly 400,000 Olympic-sized swimming pools. Furthermore, although the Roaring Fork watershed comprises only 0.5% of the total land area of the Colorado River watershed, it supplies 8-12% of the total flow for the Colorado River downstream of the confluence (Roaring Fork Conservancy). This is crucial because over 40 million people in the arid southwest rely on the Colorado River for water. And everyone wants a piece of the pie. 

We have a unique situation here in Colorado – roughly 80% of the water is found on the Western Slope but roughly 80% of the people live on the Front Range (CO Water Conservation Board). To supply enough water to the millions of people living on the Front Range, 24 tunnels have been drilled through the Continental Divide to transport water from west to east (Fig. 6). Two of the five largest diversions are located here in the Roaring Fork watershed. The Boustead Tunnel diverts water from the upper Fryingpan and Hunter Creek drainages to Turquoise Lake near Leadville, and the 4-mile-long Twin Lakes tunnel diverts water from the upper Roaring Fork drainage to Twin Lakes on the east side of Independence Pass. During the spring and summer, these two tunnels will divert an average of 40% the water in these headwater regions to eastern Colorado (water that therefore is not ultimately flowing into the Colorado River). These diversions have led to numerous legal conflicts pertaining to who owns the water and how much of it do they own. In recent years, Pitkin County and the city of Aurora have been engaged in a very expensive multi-year legal battle over how much water the municipality can divert. More information about these diversions can be found at www.roaringfork.org.     

Figure 6. Map of the 24 transmountain water diversions in Colorado.

Benjamin Franklin once said “When the well is dry, we learn the worth of water.” The Roaring Fork watershed is one of the biggest wells in the West as far as individual watersheds go, and now more than ever, there is a lot to lose if the well runs dry. As competition for water resources intensifies, it will become more important than ever to monitor our snowpack to better manage our precious liquid resource. The big wildcard for the future is climate change; we know that long-term average temperatures are warming in the Roaring Fork Valley, but what remains to be seen is how quickly and it what ways it will affect our snowpack and the water it holds.

~ Josh Johnson, Winter Naturalist