Snow surveyors reported that water content in California's mountain snowpack is below average for the date.
Manual and electronic readings record the snowpack's statewide water content at 93% of average for this time of year. That is 55% of the average April 1 measurement, when the snowpack is normally at its peak before the spring melt.
The snowpack normally provides about a third of the water for California's homes, farms and industries as it slowly melts into streams, reservoirs and aquifers in the spring and early summer. "We're still seeing decent snowpack conditions due to storms in late November and early December," says DWR Director Mark Cowin. "Those early season storms also erased the deficit in our reservoir storage, but relatively dry weather this month is once again a reminder that the weather is unpredictable and we must always practice conservation."
Results of manual readings by the Department of Water Resources (DWR) off Highway 50 near Echo Summit are as follows:
Alpha location at 7,600 feet elevation, 64% of long-term average
Phillips Station at 6,800 elevation, 66% of long term average
Lyons Creek, at 6,700 foot elevation, 75% of average
Tamarack Flat at 6,500 feet elevation, 78% of long term average
Electronic readings indicate that the water content in the northern mountains is 97% of normal for the date and 59% of the April 1 seasonal average. Electronic readings for the central Sierra show 90% of normal for the date and 54% of the April 1 average. The numbers for the southern Sierra are 91% of average for the date and 51% of the April 1 average. DWR and cooperating agencies conduct manual snow surveys around the first of the month from January to May.
The manual measurements supplement and check the accuracy of real-time electronic readings from sensors up and down the state.
DWR currently estimates that it will be able to deliver 40% of the slightly more than 4 million acre-feet of State Water Project water requested for this calendar year by the 29 public agencies that supply more than 25 million Californians and nearly a million acres of irrigated farmland. The delivery estimate may increase as more winter storms develop. The final allocation of State Water Project water in calendar year 2012 was 65% of requested deliveries. The allocation was 80% in 2011, 50 5% in 2010, 40% in 2009, 35% in 2008, and 60% in 2007. The last 100% – difficult to achieve even in wet years because of restrictions on Delta export pumping to protect sensitive fish species – was in 2006.
Lake Oroville in Butte County, the State Water Project's principal reservoir with a capacity of 3.5 million acrefeet, today is at 75% of capacity, 113% of average for the date. Shasta Lake north of Redding, the federal Central Valley Project's principal storage reservoir with a capacity of 4.5 million acre-feet, today is at 76% of capacity, 111% of normal for the date.
(An acre-foot is 325,851 gallons, enough to cover one acre to a depth of one foot).