Thursday, March 28, 2013

Snow survey confirms dry conditions

The state Department of Water Resources' final snow survey this morning confirmed what officials already knew: Despite the deluge in November and December, this has turned out to be a dry year.

From the DWR:
Snow surveyors today reported that water content in California’s snowpack is only 52 percent of normal, with the spring melt season already under way.

“With most of the wet season behind us, this is more gloomy news for our summer water supply,”
said DWR Director Mark Cowin.

After a record dry January and February in much of the state, DWR on Friday decreased its water delivery estimate, or allocation, from 40 to 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.

Pumping restrictions imposed this winter 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 63 percent full.

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

Today’s survey – finding snowpack water content at only 52 percent of normal -- is particularly significant because this is the time of year the snowpack normally is at its peak before slowly melting with warming weather. The season’s final survey on or about the first of May will check the rate at which the snowpack is melting. Snow normally provides about a third of the water for California’s homes and farms as it melts into streams, reservoirs and aquifers.
For my complete story on the water year and the weather expectations for April, check CapitalPress.com soon.

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