Manual and electronic readings show that California’s drier than usual mountain snowpack is steadily melting with warming spring weather.

Statewide, snowpack water content is only 40 percent of normal for the date, and was only 55 percent of normal the first of April, the time of year when it is historically at its peak.    

"The fact that we just had a dry winter right after an unusually wet season last year shows that we must be prepared for all types of weather,” said DWR Director Mark Cowin.  “Reservoir storage will mitigate the impact of dry conditions on water supply this summer, but we have to plan for the possibility of a consecutive dry year in 2013, both by practicing conservation, continuing to develop alternative local water supplies, and working toward improved water storage and conveyance.”

The Department of Water Resources (DWR) will analyze the snow survey results to forecast runoff into the state’s streams and reservoirs as the snowpack continues to melt through spring and into summer.  The winter snowpack – often called California’s “frozen reservoir” – normally provides about a third of our water supply.

Snowpack runoff this year obviously will be less than normal, but above average reservoir storage due to wet conditions last winter will mitigate the impact on water supply.

With Lake Oroville in Butte County -- the State Water Project’s principal storage reservoir 97 percent full (116 percent of average for the date), DWR expects to be able to deliver 60 percent of the slightly more than 4 million acre-feet of SWP water requested this year.  This is not an unusually low delivery projection, or allocation.  Wet conditions last year allowed the DWR to deliver 80 percent of amounts requested by the 29 public agencies that supply State Water Project water to more than 25 million Californians and nearly a million acres of irrigated agriculture.  The final allocation was 50 percent in 2010, 40 percent in 2009, 35 percent in 2008, and 60 percent in 2007.  The last 100 percent allocation – difficult to achieve even in wet years because of pumping restrictions to protect threatened and endangered fish – was in 2006.

Today’s manual snow survey was the fifth and last of the year. Surveyors from DWR and cooperating agencies trek into the mountains on or about the first of the month from January to May to take the vital water content measurements that signal how much runoff will be available for hydropower, homes, farms, industry and other uses.

Manual snow surveys complement and check the accuracy of real-time electronic sensors placed up and down the state’s mountain ranges. 

Results of manual readings by DWR snow surveyors off Highway 50 near Echo Summit are as follows:

Location

Elevation

Snow Depth

Water Content

% of Long Term Average

Alpha

7,600 feet

26.5 inches  

12  inches

45

Phillips Station

6,800 feet

0  inches

0  inches

0

Lyons Creek

6,700 feet

37  inches

15  inches

66

Tamarack Flat

6,500 feet

18.4  inches

7.9  inches

43

These results, combined with readings from other locations, will produce the accuracy-checked water content readings as well as forecast spring and summer runoff.

Electronic readings indicate that water content in the northern mountains is 70 percent of normal for the date. Electronic readings for the central Sierra are 35 percent of normal.  The number for the southern Sierra is 20 percent.  The statewide number is 40 percent.

On May 1 last year, after an unusually wet winter, water content in the statewide snowpack was 190 percent of normal.  It was 217 percent or normal in the north, 180 percent in the central Sierra, and 177 percent in the southern Sierra. 

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 Water Conditions page at: http://www.water.ca.gov/waterconditions/

DWR will hold a webcast at 10 a.m. on May 9 to provide a wrap-up of winter 2011-2012 water conditions and their water supply implications for California.  The webcast will summarize seasonal weather and climate conditions, provide forecasted runoff for the major snowmelt-driven river basins, and describe how residents can help save water this summer.