Hydrologists with the California Department of Water Resources are getting ready to head into the Sierras for the benchmark April snowpack survey on Tuesday, but don't expect the measurements to bode well for the state's ongoing drought.
The annual April 1 survey is the most comprehensive of the season, with measurements taken at hundreds of locations. It's an important indicator of future water supplies, because early April is typically the high point of annual snow accumulation. Automated readings show that statewide snow levels are currently at around 30 percent of average for this time of year.
Though storms have been forecast to hit the state soon, officials said that they were unlikely to significantly change snowpack levels.
"Even though we'll probably be up there surveying in the storm, we just haven't had the number of storms that would make any appreciable difference in the situation regarding water supply," said Frank Gehrke, chief of the California Cooperative Snow Surveys Program.
The state receives about a third of its water supply from snowmelt that trickles down from the Sierra Nevada. Gehrke said that storms that dumped rain and snow on the state in late February provided some relief but were far from enough to end the ongoing drought.
“We probably have crawled out of the driest [year] on record that we were tracking back in January and February, but it’s still a very serious situation in terms of water supplies this summer,” Gehrke said.
Teams take readings at hundreds of snow courses throughout the Sierras, but many of the courses are only measured during the April survey. Gehrke said manual readings are necessary, because many watersheds lack automatic measuring equipment. Also, the remote measurements only provide a general idea of range wide snow levels.
“We make a forecast based upon individual watersheds,” Gehrke said. "A generic forecast of the Central Sierra really doesn’t do much good. You have to do it watershed by watershed.”