Dry winter may portend water rationing in Bay Area

Rainfall this winter is far below historical averages and water districts all over California are considering rationing.  So far, two dozen California water districts have extended rationing imposed last year, and more is like to be on the way, reports the Chron.

In the Sierra Nevada, where ice and snow turn into about 60 percent of the water flowing out of the state’s taps each year, snowpack is about two-thirds of normal.

"Projections for the state’s water supply continue to look poorer as the water hasn’t come down," said Elissa Lynn, the state’s chief meteorologist. ...

In San Francisco, water managers have asked customers to voluntarily cut use by 10 percent, resulting in a 12 percent reduction.

The hydrological gods also have been kind to the city. The watershed draining into the Hetch Hetchy reservoir is at a much higher elevation than the watershed that supplies the East Bay water district, and is on the runway for many major storm systems.

"Our reservoirs are in pretty decent shape," said Michael Carlin, assistant general manager of water at the San Francisco Public Utilities Commission. "But over the next couple months, we’ll be watching the storms coming through, the trajectories, the reservoirs. ...

Based on that, we’ll see if we can make it on voluntary conservation or if we have to go mandatory."

Hetch Hetchy, which is owned by the SFPUC, supplies water for the County Coastside Water District, which serves Half Moon Bay and El Granada.

Half Moon Bay resident Dennis Paull reports that he has measured the rainfall in December and January of 3.75 inches, only 40% of his 9.25 average since 2001.