Although both seasonal and fleeting, snowpack is a valuable natural resource. The snow at Lassen Volcanic provides superb winter recreation and creates a winter habitat to which park animals and plants are well-adapted.
How Much Water is in Snow?
Not all snow is equal when it comes to water content. Snow is composed of frozen water crystals, but because there is so much air surrounding each of those tiny crystals in the snowpack, most of the total volume of a snow layer is made up of air.
There are three main measurements for snowpack: depth and density, which combined determine snow water content equivalent. At Lassen, the records for each of these individual measurements have occurred in different years. The deepest snowpack of 331 inches (27.6 feet) occurred in 1983. The highest density of water in snow (55%) occurred in 2017 and the highest snow water content equivalent of 145 inches occurred in 1995. This means the largest amount of water to result from a park snowmelt occurred when the snowpack was both deep (287 inches/23.9 feet) and dense (51%).
2020 Snowpack Surveys
Forecasting Water from Snow
Data from the Lower Lassen Peak snow measurement site is used to produce monthly forecasts from January to May. Forecasters use average density and depth for each snowpack to estimate spring and summer snowmelt runoff into rivers and reservoirs. Measurements taken on or around April 1 at established sites are generally the most significant as this is when the snowpack is normally at its greatest depth and density.
Snow Measurement Sites
Today in California, more than 50 state, national, and private agencies pool their efforts in collecting snow data. At Lassen Volcanic, park staff and partners work together to record data at Manzanita Lake and Lower Lassen Peak. Visitors to the Lake Helen picnic area may have spotted the 36-foot-tall snow sensor that collects and transmits real-time data to specialists at the California Department of Water Resources. Data from the Lower Lassen Peak remote station is manually verified four times each winter by a surveyor.
Lassen's Snowpack over TimeCalifornia Department of Water Resources has been recording snowpack measurements at Lower Lassen Peak since 1930. Data shows normal variations in snowpack over time. However, rapid changes in climate over the last few decades have resulted in warmer and drier conditions overall. The most recent drought cycle in California continued for 376 weeks, or seven years, until March 2019. Reduced snowpack leads to reductions in melted snow that is available to the state's water supply.
Even with normal snowpack depth and density, warmer spring temperatures can result in earlier spring melt. This early melting can stress the capacities of man-made reservoirs that are designed to store and gradually release water during California's long, dry summers.
Learn more about the effects of climate change and drought in the park.
Last updated: December 4, 2020