California’s highly productive farmland, population of 38 million, and major economy depend on water, and Sierra snow is a critical part of that supply because it acts as a frozen reservoir that slowly releases water in spring to streams and rivers downstream. Knowing how much snow is in the Sierra and the snow’s water content helps reservoir managers and farmers plan for snowmelt runoff. The Central Sierra Snow Lab was established in 1946 to gather accurate information and conduct snow research. It was built by the U.S. Weather Bureau and the Army Corp of Engineers, then taken over by the U.S. Forest Service in 1952, with the University of California at Berkeley assuming responsibility in 1995. Donner Summit is especially suited to snow research because long-term snowfall records there, first gathered by the railroad, reach back to 1881, and the Pacific Ocean’s maritime influence produces an average of 34 feet of snowfall each winter, the highest snowfall of any residential area in the continental U.S. The snowpack typically lasts seven months and ranges from six to sixteen feet deep. The lab also sits in a large watershed draining terrain north of Boreal and west of Castle Peak, making it ideal for studying runoff and streamflow, especially as the snow-rain line moves higher each year. Snow water equivalent is measured efficiently with the Federal Snow Sampler, which is pushed into the snow to extract and weigh a core, since depth alone does not indicate water content. Developed by Dr. James Church, the "Father of Snow Surveying," the sampler helps determine the extent of the snowpack and how much water to expect downstream during snowmelt.