Snow surveyors report that water content in California’s snowpack is only 17 percent of normal.

After a record dry January and February in much of the state, the California Department of Water Resources projects it will only be able to deliver 35 percent of requested amounts from the State Water Project (SWP).

The 29 public agencies that purchase SWP water requested just over four million acre-feet of water for this calendar year.  Collectively, the agencies supply more than 25 million Californians and nearly a million acres of irrigated agriculture.

In addition to the light snowpack and extended periods of little rainfall, pumping restrictions to protect Delta smelt and salmon are another reason for the low water delivery estimate.

November and December were unusually wet, but between November 1 and February 28, fishery agency restrictions prevented DWR from pumping more than 550,000 acre-feet of water from the Sacramento-San Joaquin Delta to store in San Luis Reservoir.  Today San Luis – a summer supply pool for both the State Water Project and the federal Central Valley Project – is only 54 percent full.

“This is the kind of conflict we are working to resolve through the Bay Delta Conservation Plan,” said DWR Director Mark Cowin. 

The Bay Delta Conservation Plan would reduce harm to fish from altered stream flows caused by the south Delta pumps serving the SWP and Central Valley Project.  Pumping there at times causes reverse flows which may disorient or entrain fish.  The comprehensive plan's large-scale habitat restoration would also improve Delta conditions for fish and wildlife.

The November and December storms built California’s snowpack water content to 134 percent of normal by January 2, when DWR and cooperating agencies conducted this season’s first manual survey.  Manual surveys and electronic readings have recorded the water content decline since dry weather set in.  Statewide, the season’s second manual survey on January 29 found the snowpack water content at 93 percent of normal for the date.  On February 28, the season’s third manual survey found the snowpack water content at 66 percent of average On Mach 28, about the time the snowpack is normally at its peak, its water content was recorded at 52 percent of normal. 

Snow normally provides about a third of the water for California’s homes and farms as it melts into streams, reservoirs and aquifers.

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

Location

Elevation

Snow Depth

Water Content

% of Long Term Average

Alpha

7,600 feet

2.6 inches

1.2 inches

5

Phillips Station

6,800 feet

no snow

no snow

 

Lyons Creek

6,700 feet

7.1 inches

3.3 inches

15

Tamarack Flat

6,500 feet

 

 

not reported

 

Electronic readings indicate that water content in the northern mountains is 16 percent of normal for the date, and 11 percent of the April 1 seasonal average.  Electronic readings for the central Sierra show 23 percent of normal water content for the date and 18 percent of the April 1 average.  The numbers for the southern Sierra are 9 percent of average for the date and 7 percent of the April 1, full-season average.

DWR and cooperating agencies conduct manual snow surveys around the first of the month from January through May.  The manual measurements supplement and check the accuracy of the real-time electronic readings from sensors up and down the state.

Despite the dwindling snowpack, most key storage reservoirs are near normal levels for the date thanks to November and December storms, San Luis being an exception. 

Lake Oroville in Butte County, the State Water Project’s principal storage reservoir, is at 103 percent of its average level for the date (86 percent of its 3.5 million acre-foot capacity). Shasta Lake 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 (83 percent of capacity).

(An acre-foot is 325,851 gallons, enough to cover one acre to a depth of one foot.)

Reservoir storage will meet much of the state’s water demand this year, but successive dry years would create drought conditions in some areas.

The final SWP allocation for calendar year 2012 was 65 percent of requested deliveries. The initial delivery estimate for calendar year 2011 was only 25 percent of requested SWP water. However, as winter took hold, a near record snowpack and heavy rains resulted in deliveries of 80 percent of requests in 2011. 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 Delta fish -- was in 2006.

Electronic snowpack readings may be found at:

http://cdec.water.ca.gov/cgi-progs/snow/DLYSWEQ

Electronic reservoir level readings are available at:

http://cdec.water.ca.gov/cgi-progs/products/rescond.pdf

More from Western Farm Press

Farmers playing chess with nature in resistant weed fight

Killing cattle softly: slaughterhouse or gun?

Lettuce industry abuzz over automated thinner

Dirty Dozen pesticide list losing ground to science

PETA drones a trophy prize for US hunters

5 things moms get wrong at the grocery store

Water issues drive precision agriculture solutions in specialty crops