The California Department of Water Resources will conduct this winter’s third snow survey on Tuesday, Feb. 28.

The agency said it's expected that manual measurements of snowpack water content will corroborate the low electronic readings from remote sensors up and down the state’s mountain ranges.

Electronic readings today indicate that statewide, water content in the snowpack is only 30 percent of normal for the date, and 25 percent of the average April 1 measurement when the snowpack is normally at its peak before the spring melt.

Surveyors from DWR and cooperating agencies will fan out to numerous sites for the third of five manual snow surveys made each winter to forecast the amount of frozen water that will trickle into streams, reservoirs and aquifers when the snow melts this spring and early summer.

Persistent dry weather this winter caused DWR on Wednesday to reduce its estimate of the amount of water the State Water Project will deliver this calendar year.

The reduction was from 60 percent to 50 percent of the slightly more than four million acre-feet requested by the 29 public agencies that distribute water to more than 25 million Californians and nearly a million acres of irrigated farmland, the agency reported. An acre-foot is 325,851 gallons, enough to cover one acre to a depth of one foot.

The 50 percent allocation is not severely low, and could be increased if stronger hydrologic conditions develop, according to DWR. Last year, an unusually wet year, the final allocation was 80 percent of the slightly more than 4 million acre-feet requested.

The final allocation was 50 percent in 2010, 40 percent in 2009, 35 percent in 2008, and 60 percent in 2007. DWR said the last 100 percent allocation – difficult to achieve even in wet years because of fishery agency restrictions on Delta pumping to protect threatened and endangered fish – was in 2006.

This winter’s unusually dry conditions to date have principally been caused by a high pressure ridge along California’s coast that has diverted most storms to the north.

One bright spot this year is the state’s good reservoir storage, due to conserved runoff from last winter’s storms.

Lake Oroville in Butte County, the State Water Project’s principal storage reservoir, is at 102 percent of average for the date (72 percent of its 3.5 million acre-foot capacity), Lake Shasta north of Redding, the federal Central Valley Project’s largest reservoir with a capacity of 4.5 million acre-feet, is at 95 percent of its normal storage level for the date (69 percent of capacity).

San Luis Reservoir in Merced County, an important storage reservoir south of the Delta, is at 104 percent of average for the date (89 percent of its capacity of 2,027,840 acre-feet).

San Luis is a critically important source of water for both the State Water Project and Central Valley Project when pumping from the Delta is restricted or interrupted.

Statewide, reservoir storage is 110 percent of normal for the date.

Electronic snowpack readings are available on the Internet at: http://cdec.water.ca.gov/cgi-progs/snow/DLYSWEQ.

Electronic reservoir level readings may be found at: http://cdec.water.ca.gov/cdecapp/resapp/getResGraphsMain.action.

See DWR’s new Water Conditions page at http://www.water.ca.gov/waterconditions/.

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