Manual and electronic readings show that California's near-record snowpack is slowly melting with warming spring weather. But snowpack water content is still 144 percent of the April 1 full season average.
Tuesday’s readings will help hydrologists forecast spring and summer snowmelt runoff into rivers and reservoirs. The melting snow supplies approximately one-third of the water used by Californians.
"All indications are that we're moving toward summer with a good water supply for our farms and cities," said DWR Director Mark Cowin. "We must be aware, however, that California can quickly turn from wet to dry, and we can't afford to forget the lessons of conservation that we learned in the 2007-2009 drought."
Snowpack water content is measured manually on or near the first of the month from January to May, and in real-time by electronic sensors.
Electronic readings indicate that water content in the northern mountains is 159 percent of the April 1 seasonal average. Electronic readings for the central Sierra show 144 percent of the April 1 average. The number for the southern Sierra is 127 percent. The statewide number is 144 percent.
The first of April is normally when snowpack water content is at its peak. California's reservoirs are fed both by rain and snowpack runoff.
A majority of the state's major reservoirs are above normal storage levels for the date. Lake Oroville in Butte County, the State Water Project's principal reservoir, is 112 percent of average for the date (93 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 108 percent of average (94 percent of capacity).
DWR estimates it will be able to deliver 80 percent of requested State Water Project (SWP) water this year.
In 2010, the SWP delivered 50 percent of a requested 4,172,126 acre-feet, up from a record-low initial projection of 5 percent due to lingering effects of the 2007-2009 drought. Deliveries were 60 percent of requests in 2007, 35 percent in 2008, and 40 percent in 2009.
The last 100 percent allocation — difficult to achieve even in wet years due to pumping restrictions to protect threatened and endangered fish — was in 2006. The SWP delivers water to more than 25 million Californians and nearly one million acres of irrigated farmland.
Statewide snowpack readings from electronic sensors are available at http://cdec.water.ca.gov/cgi-progs/snow/DLYSWEQ