Sierra Nevada aerial view. (Credit: Jeffrey Pang/CC BY 2.0)
California has never experienced such severe water restrictions, and a recent article from National Geographic covers the reason behind it: the lowest Sierra Nevada snowpack in history. The current snowpack is only 6 percent of normal levels.
Although California receives rain, most of it runs off the land and into the ocean. For this reason, the snow, which gathers in the mountains and lingers, is the primary source of the state’s water in normal years. As it melts slowly in the spring and summer, it typically fills groundwater aquifers and reservoirs, providing water for people, wildlife, hydropower and industry.
But with such low snowpack levels currently, California has been resorting to using more groundwater, increasing its usage statewide to 60 percent. That’s up from 40 percent groundwater usage during years with normal levels of rain and snow fall.
The result of the low snowpack is an enormous loss of usable water for California. At the current reduced snowpack levels, about 75 to 80 percent of water from the Sierra Nevada is lost.