May 13 (Bloomberg) -- California's East Bay Municipal Utility District is set to vote today on a proposal to ration water to customers near San Francisco, including two oil refiners, because of a drought.

A seven-member board will vote on the plan to reduce supplies to industrial customers by 5 percent, Charles Hardy, a utility spokesman, said in a telephone interview. Residential, commercial and irrigation customers would also be affected by the plan.

A vote for rationing would limit water supplies in the region for the first time since the draught of 1991 and 1992, Hardy said. Refineries use water to cool units that process oil into products including gasoline and diesel fuel.

``It's pretty certain we are going to do something,'' Hardy said. The vote is scheduled for a meeting at 1:15 p.m. local time today.

Chevron Corp. and ConocoPhillips have refineries in the water district, according to Hardy. The majority of the water used by the Chevron refinery is recycled, which will not be affected by the rationing, Hardy said. The ConocoPhillips refinery also uses recycled water.

Lloyd Avram, Chevron's Spokesman, didn't immediately return a voice mail for comment. Bill Graham, a ConocoPhillips spokesman, said he couldn't immediately comment on the plan.

There are no power plants in the district, Hardy said.

The utility serves 1.3 million customers in an area that includes Oakland, Richmond and San Leandro, Hardy said.

Customers that use water for irrigation, including golf courses and cemeteries, would have supplies reduced by 30 percent, Hardy said. Commercial customers would have a 12 percent reduction and single family homes would have a 19 percent reduction.

The utility wouldn't say how they would reduce usage.

To contact the reporter on this story: Robert Tuttle in New York at rtuttle@bloomberg.net

Last Updated: May 13, 2008 14:18 EDT