The California Department of Water Resources (DWR) first snow survey of the 2009/2010 winter season indicates snow water content is 85 percent of normal for the date, statewide. This time last year, snow water content was 76 percent of normal statewide. Despite some recent storms, the season’s first snow survey shows that “we’re still playing catch-up when it comes to our statewide water supplies,” said DWR chief deputy director Sue Sims. “Looking at the real possibility of a fourth dry year, we must prepare now, conserve now and act now, so that we have enough water for homes, farms and businesses in 2010 and in the future.”
While the first snow survey determined that the water content is higher than last year at this time, it’s too early to ascertain whether improved figures will translate into a better water year than the state experienced last year. Electronic sensor readings show northern Sierra snow water equivalents at 77 percent of normal for this date, central Sierra at 85 percent, and southern Sierra at 99 percent. The sensor readings are posted at http://cdec.water.ca.gov/cgi-progs/snow/DLYSWEQ.
Storage in California’s major reservoirs is low. Lake Oroville, the principal storage reservoir for the State Water Project (SWP), is at 29 percent of capacity, and 47 percent of average storage for this time of year. DWR’s early estimate that it will only be able to deliver 5 percent of requested State Water Project water this year to the Bay Area, San Joaquin Valley, Central Coast and Southern California reflects low storage levels in the state’s major reservoirs, ongoing drought conditions, and environmental restrictions on water deliveries from the Sacramento-San Joaquin Delta to protect endangered fish species. Increased precipitation this winter could increase this allocation level. DWR estimates that fishery agency restrictions on Delta pumping adopted in the past year to protect Delta smelt, salmon and other species could reduce annual deliveries of State Water Project water by up to 30 percent.
Snow water content is important in determining the coming year's water supply. The measurements help hydrologists prepare water supply forecasts as well as provide others, such as hydroelectric power companies and the recreation industry, with needed data. Monitoring is coordinated by the Department of Water Resources as part of the multi-agency California Cooperative Snow Surveys Program. Surveyors from more than 50 agencies and utilities visit hundreds of snow measurement courses in California’s mountains to gauge the amount of water in the snowpack.