California drought: Sierra Nevada snowpack falls to 500-year low

Last winter's snow accumulation in the mountains that provide state's most important natural water system was just 5% of what is normal, study finds

The Sierra Nevada snowpack that is a critical water source for California fell to a 500-year low last winter - far worse than scientists had estimated and underlining the severity of the current drought, according to new research.

The snow accumulation in the mountains was just 5% of what is normal, inflating the risk of wildfires, drying up wells and orchards, and pushing communities into water rationing.