Survey: More Sierra snow, less water equivalent

Survey: More Sierra snow, less water equivalent

The first manual snow survey of the Sierra snowpack conducted Dec. 30 found more snow than last year at the same time yet the snow water equivalent as measured statewide remains far below average for the date.

The first manual snow survey of the Sierra snowpack conducted Dec. 30 found more snow than last year at the same time yet the snow water equivalent as measured statewide remains far below average for the date.

The Department of Water Resources (DWR) conducted the survey about 90 miles east of Sacramento on a plot along Highway 50 near Echo Summit.

There, snow covered the ground at a 21.3 inch depths, says DWR’s Frank Gehrke, chief of the California Cooperative Snow Surveys Program who conducted the survey.

The snow water equivalent was four inches at that particular location, or 33 percent of average.

Statewide, 105 electronic sensors in the Sierra detected a snow water equivalent of 4.8 inches - 50 percent of the multi-year average for the same time period. This compares favorably with last winter’s first survey when the snow water equivalent statewide was 20 percent of normal, which tied with 2012 as the driest readings on record.

In response to the findings, DWR Director Mark Cowin said, “Although this year’s survey shows a deeper snowpack than last year, California needs much more rain and snow than we’ve experienced over the past two years to end the drought in 2015.

“The department encourages Californians to continue their water conservation practices.”

Depleted reservoirs

The state’s surface and groundwater reservoirs have been severely depleted during the drought, which now is in its fourth consecutive year, Cowan says. A snowpack built up significantly during the winter months is needed to recharge the reservoirs to historical averages as the snow melts during the late spring and summer months.  

Generally, California’s snowpack supplies about a third of the water needed by the state’s residents, agricultura, and industry as it melts in the late spring and summer.

The electronic readings suggest that water content in the northern mountains is 57 percent of normal for the date and 20 percent of the average on April 1, when the snowpack normally is at its peak before the spring melt.

Electronic readings in the central Sierra show 45 percent of normal for the date and 16 percent of the April 1 average. The numbers for the southern Sierra are 48 percent of average for the date and 15 percent of the April 1 average.

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

DWR estimates it will deliver only 10 percent of the slightly more than 4 million acre-feet of State Water Project (SWP) water requested for calendar year 2015 by the 29 public agencies that collectively supply more than 25 million Californians, and nearly a million acres of irrigated farmland.

DWR hopes the initial 10 percent delivery estimate will increase as winter storms develop.

Reservoir totals 

Lake Oroville in Butte County, the State Water Project’s (SWP) principal reservoir, today is at 38 percent of its 3.5 million acre-foot capacity (61 percent of its historical average for the date).

Shasta Lake north of Redding, California’s and the federal Central Valley Project’s (CVP) largest reservoir, is at 41 percent of its 4.5 million acre-feet capacity (66 percent of average for the date).

The San Luis Reservoir, a critical south-of-Delta reservoir for both the State Water Project and Central Valley Project, is at 39 percent of its 2 million acre-foot capacity (58 percent of average for the date) due both to dry weather and Delta pumping restrictions to protect salmon and Delta smelt.

Delta water is pumped into the off-stream reservoir in winter and early spring for summer use in the Bay Area, San Joaquin Valley, Central Coast and Southern California.

Governor Ed Brown Jr. declared a drought emergency on Jan.17, 2014. 

Electronic snowpack readings: http://cdec.water.ca.gov/cdecapp/snowapp/sweq.action

Electronic reservoir readings: http://cdec.water.ca.gov/cdecapp/resapp/getResGraphsMain.action

Electronic precipitation readings: http://cdec.water.ca.gov/snow_rain.html

Water conditions page: www.water.ca.gov/waterconditions/waterconditions.cfm

Drought page: www.water.ca.gov/waterconditions/index.cfm

Hide comments

Comments

  • Allowed HTML tags: <em> <strong> <blockquote> <br> <p>

Plain text

  • No HTML tags allowed.
  • Web page addresses and e-mail addresses turn into links automatically.
  • Lines and paragraphs break automatically.
Publish