This program focused on the Sierra Nevada snowpack, which supplies about one-third of California’s water and serves as a vast winter reservoir. We spoke with Sean de Gusman of the Department of Water Resources. He is chief of DWR’s Snow Supply and Water Forecasting Section and is responsible for measuring the Sierra snowpack and figuring out how much water it contains. We asked him how he measures the snowpack. He told us about the extraordinarily complex process that involves physical, on-the-scene measurements at Phillips Station in the Sierra, 120 electronic sensing sites, airplane and satellite determinations, and more. At the close of the program, we read excerpts from a Wikipedia article on the great flood of 1862, when above average snowpack coupled with spring rains turned the Sacramento valley into a vast lake. Read the press release that sparked this interview: https://water.ca.gov/News/News-Releases/2020/Dec-20/December-2020-Snow-Survey    See the actual data at cdec.water.ca.gov.