USC Dana and David Dornsife College of Letters, Arts & Sciences

The Sierra Nevada mountain range is one of the prized natural wonders of the West Coast, as well as a hotbed of countless types of outdoor activities. Many environmentalists fear that changes in the snowpack (accumulation of snow) of these mountains reflect a permanent decline, stirring much alarm. As environmental enthusiasts, one does not disagree with the consciousness certain activists are attempting to bring to the issue. However, historic trends as well as present-day measurements—while low at cer

tain points—do not indicate any alarming decrease in snow content in the region. There’s plenty!

This graph from a Sacramento newspaper illustrates some trends among the snowpack content over the years. As you can see, very wet years like 82-83 happen just as easily as do dry years like 66-67.

From 2012’s Western Snow Conference, researchers Maruice Roos and Sunny Sahota find Northern Sierra Nevada snowpack to be decreasing the last 60 years–Southern Sierras have shown an increase, however. While the North Sierra Snowpack (Water Content) is at 18 degrees below average, South Sierra is at 20 percent above average, some places nearly 22 percent (Roos, Sahota 21).  This bodes well for us in Southern California—but also more seriously for the fate of the range in general. Further evidence can attest to this variability. That same study finds ENSO variability to produce patterns, sometimes with serious anomalies, though a periodic oscillation. 1950-1994 saw almost 45 years in an overall (while oscillating) decrease from maximum snow water equivalent, until a large spike in 1997 reached the highest point in 50 years. The variability is immense in its timescale.

Even within a year or a season, measurements can be sporadic. Typically measurements are gathered intermittently throughout the winter months.  This year’s initial measurements taken December 31^st, 2012 showed that precipitation, runoff and reservoir storage all measured significantly above the average and well above the previous 2011 measurements. Currently, measurements show that we are on track to receive 155% of the average this year versus 49% last year (Ca. Dept Water Resources 2013). This can be seen by the graph below

*;  although the Mammoth Snow Pass Snowpack is not much higher than the annual average it has exceed far above where it was last year at the same time. However, as we have learned, this does not indicate that the entire year or season will necessarily remain this truly optimistic. Take Lake Tahoe’s 2000 season in which snowpack went from a dismal 22% low to over 100% of its usual rate in just a matter of a week-long storm.

So what does this mean?  First of all the snowpack is not only important for water supply as much of California’s water resources come from the Sierra Nevada region, but also the annual snowpack largely determines how well tourism and snow sports will be on the local mountains -particularly Mammoth and Big Bear. Thus, media outlets will be touting the success of the current seasons’ snowpack to market to visitors, whether or not it is slightly below average. However, a good year of snow does carry huge economic benefits for the region– in 2010 California’s ski resorts had an increase of almost 1 million tourists during the annul ski year because of a snowpack 143% of their usual illustrating the importance of maintaining this regions snowpack levels not only for environmental but for economic and social reasons (Martin, H , 2010).

However, there will never be a completely predictable or (yet) fully understandable pattern of snowfall and thus snowpack in this region. Even areas where April 1 snowpack measurements are optimistic, those same regions often see the season end sooner as snow accumulation decreases and melts more quickly (Harpold).  As far as 2013 goes, it is still too soon to tell where the seasons’ end will fall in terms of shortcomings or exceeding expectations of snowfall and snowpack. Many, though, are impressed by its immensity so early in the season. Statements released by both the California Department of Water Resources and the Los Angeles Department of Water and Power (LADWP) show little concern for the upcoming snow year (LADWP 2013). Already the region shows levels of precipitation well above average from previous years. Media particularly newspapers such as the Los Angeles Times and the San Francisco Tribune were quick to relay this information promising their readers a good snow season and a plentiful water supply predicted for the upcoming months.

Snowpack plays a leading role by supplying water to more than 25 million people and almost one million acres of farmland

This post was authored by Meghan Hennegan, a junior double majoring in Environmental Studies and International Relations, and Jennica Wragg a sophomore double majoring in Environmental Studies and Cinematic Arts Critical Studies.

Works Cited:

Harpold, A., P.Brooks, S.Rajagopal, I.Heidbuchel, A.Jardine, and C.Stielstra (2012), Changes in snowpack accumulation and ablation in the intermountain west, Water Resour. Res., 48, W11501, doi:10.1029/2012WR011949

Roos M, Sahota S. Contrasting Snowpack Trends in the Sierra Nevada of California. 80th Annual Western Snow Conference [Internet]. 2012. Available from: sites/westernsnowconference.org/PDFs/2012Roos.pdf

SHAW, G. (1979, May 27). Rise in sierra snowpack possible. Los Angeles Times (1923-Current File). Retrieved from http://search.proquest.com/docview/158838686?accountid=14749

How are California’s reservoirs – How are California’s reservoirs? (1993, Sunset, 190, 28-28. Retrieved from http://search.proquest.com/docview/203298754?accountid=14749

Abundant snowfall a big lift for state’s ski resorts- Martin, H. (2010, May 15). Abundant snowfall a big lift for state’s ski resorts. Los Angeles Times. Retrieved from http://search.proquest.com/docview/276824521?accountid=14749

From mountaintop to tap HOW MELTED SIERRA SNOWPACK BOOSTS VALLEY WATER SUPPLY. (1995, May 07). Los Angeles Times (Pre-1997 Fulltext). Retrieved from http://search.proquest.com/docview/293073842?accountid=14749

Los Angeles Department of Water and Power, (2013). Eastern sierra precipitation conditions. Retrieved from website: https://www.ladwp.com/ladwp/faces/wcnav_externalId/a-w-laa-cond-rprt;jsessionid=mcv7RTfpTyGrZyTCrtFWhGd9Q4217Lnv5hkBcyGGspd656ZjKfXS!-1241156102?_adf.ctrl-state=1dud0gky71_63&_afrLoop=305873035374000&_afrWindowMode=0&_afrWindowId=null

California Department of Water Resources, (2013). First snow survey of 2013 shows wet conditions. Retrieved from website:  http://wwwdwr.water.ca.gov

http://www.sierrawave.net/16006/ladwp-snowpack-report/