Department of Water Resources (DWR) hydrologists announced March 30 that water content in California’s mountain snowpack is 165 percent of the April 1 full season average.
“Recent storms have significantly contributed to the above-average snowpack, helping to stabilize California’s water supply for the year,” said DWR Director Mark Cowin. “While this is beneficial for California’s farms, businesses and communities, we remind residents to practice sensible water use and conservation as we transition to warmer weather.”
After the snowpack readings were in, Gov. Jerry Brown officially rescinded former Governor Schwarzenegger’s emergency proclamations and executive order issued in 2008 and 2009 relating to water shortage associated with the drought, but urged Californians to keep conserving water as they move into the spring and summer months.
“While this season’s storms have lifted us out of the drought, it’s critical that Californians continue to watch their water use,” Brown said. “Drought or no drought, demand for water in California always outstrips supply. Continued conservation is key.”
Snowpack water content is measured both manually, on or near the first of the month from January to May, and in real-time by electronic sensors.
Last week’s manual survey and electronic readings are the most important of the year, since April 1 is when the state’s snowpack normally is at its peak before it melts into streams and reservoirs in the spring and summer months.
March precipitation has helped register 2011 among the top years in snowpack water content, despite dry weather conditions in January and early February.
The mountain snowpack provides approximately one-third of the water for California’s households, industry and farms as it melts into streams and reservoirs.
Electronic readings indicate that water content in the northern mountains is 174 percent of the April 1 seasonal average.
Electronic readings for the central Sierra show 163 percent of the April 1 average.
The number for the southern Sierra is 158 percent. The statewide number is 165 percent.
On March 1, the date of this winter’s third manual survey, percentages of the snowpack’s normal water content were 109 percent of the full season average, 103 percent for the northern Sierra, 106 percent for the central Sierra and 119 percent in the south.
On this date last year, snowpack water content readings of the April 1 average were 123 percent in the north, 88 percent in the central ranges, 102 percent in the south and 102 percent statewide.
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 (SWP) principal reservoir, is 104 percent of average for the date (80 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 111 percent of average (91 percent of capacity).
DWR estimates it will be able to deliver 70 percent of requested SWP water this year. The estimate likely will be adjusted upward as hydrologists make adjustments for snowpack and runoff readings.
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 – 09 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 1 million acres of irrigated farmland.