It has been raining. Drought in large portions of California is endangered.
But going by the U.S. government Drought Monitor 100 percent of California remains in drought. Soaking rains and heavy snows, according to the government, have done essentially nothing to attenuate the extent or even the severity of drought.
Compared to the January 12 Monitor (left hand map) only a tiny portion of California is experiencing less severe drought this week (see the extreme northwest corner of the January 19 map on the right). Yet the news on the ground has been nothing but good.
The following graph depicts water storage at Lake Shasta (a good benchmark because it is the largest reservoir in the state) in northern California. The January improvement is dramatic.
The graphs are on an October 1 to September 30 water year basis. This year's water storage in Lake Shasta has spiked to 2.1 million acre feet, which beats last year's and the previous year's storage for the same time of year. Current water storage is substantially greater than the 1.5 million acre feet January, 1977 low experienced during the worst previous drought. The trajectory of storage recovery is moving sharply upwards towards the long-term average (the solid blue shaded area) of about 2.9 million acre feet for this time of year.
The recent news is similar for Lake Folsom, a more centrally reservoir located down near Sacramento. We highlight Lake Folsom here because it received substantial press mid-November for falling to record lows.
Folsom Lake’s water level sank to its lowest level in history Saturday, a vivid reminder of California’s epic drought even as a new winter storm moved into the region.
The 60-year-old reservoir held 140,501 acre-feet of water at midafternoon, or roughly 14 percent of capacity, according to California Department of Water Resources data. The lake fell below the old record of 140,600 acre-feet, a mark seen during the 1977 drought, around midnight Friday and continued falling through the day.
“Certainly a milestone we didn’t want to see happen,” said Eric Kurth, a forecaster with the National Weather Service in Sacramento. An acre-foot is 326,000 gallons.
Storage at Lake Folsom has jumped up from about 140,501 acre feet to 388,656 acre feet. It is now well above the 1976-77 drought year floor and headed towards normal. We will get to the sustainability of that rebound (and Lake Shasta's) in a bit.
The reason for increased water is simple. It rained and it rained a lot. Here are 30 day precipitation charts.
During the last month the Mount Shasta area received 12 inches of rain which is 5.8 inches more than, or about 190 percent of, normal.
Rainfall was also abundant in Sacramento, near Lake Folsom which is the state capitol city's municipal water source.
The snow conditions at California ski resorts last weekend were as follows:
|Snow condition||Last snowfall||Summit depth||Weather||Open trails||Open lifts|
Both Lake Shasta and Lake Folsom are fed by rivers in Sierra Nevada Mountain drainages. The key as to whether the reservoir storage will continue to surge during this water year lies as much in their respective snowpacks as in continued rain showers. Here are the current year favorable snowpack readings. Shasta is Northern Sierra. Folsom is Central Sierra.
By comparison the last years' snowpacks were pathetic. The following compares current year snowpacks with the last two years and the drought year of 1976-77.