A new Sierra Nevada snow survey on Thursday puts hard numbers on what is already plain to the eye: Winter has turned bone-dry in California.
Measurements by the state Department of Water Resources show that the water content of the snowpack is 66 percent of average for the date, a steep drop from a 134 percent reading on Jan. 2. The two months since then will rank as the driest January-February period in the Northern Sierra since record-keeping began in 1921, with just 2.2 inches of precipitation compared an average of 17.1.
The Northern Sierra region runs from Lake Shasta in the north to the American River basin in the south. It is the state's most important region for water supply because the snows that melt there during summer feed the state's largest reservoirs and its largest river, the Sacramento.
Thanks to big storms in November and December, most of the state's major reservoirs hold near-average water supplies as of Thursday. That is not likely to remain the case throughout summer, however, as the depleted snowpack may not hold enough water to keep them full and also meet the water demands of a thirsty state.
One early exception is San Luis Reservoir near Los Banos, which is filled by water pumped out of the Sacramento-San Joaquin Delta to serve farms and cities farther south. It holds 69 percent of average capacity for the date, partly because of pumping cutbacks imposed over the past two months to protect the threatened Delta smelt, a native fish.
"Near-record dry weather combined with pumping restrictions to protect Delta smelt are making this a gloomy water supply year," DWR Director Mark Cowin said in a statement.
DWR estimates it will be able to deliver 40 percent of the approximately 4 million acre-feet of water requested by the 29 public agencies it serves. They supply more than 25 million people and nearly a million acres of farmland. The U.S. Bureau of Reclamation, which also pumps water from the Delta, estimates it will be able to deliver 25 percent of contracted water supplies to its customers south of the Delta.
The city of Sacramento has its own water rights in the Sacramento and American rivers and is not effected by these estimates. Some suburban communities in the Sacramento metro area, however, rely on water stored by Reclamation in Folsom Reservoir, and they were told to expect 75 percent of normal water deliveries.
These delivery estimates may improve if wetter weather returns.