CALIFORNIA BRIEFING / SANTA BARBARA

A mixture of oil and water leaking from an ExxonMobil platform has spread across a mile of ocean off the Southern California coast, federal and state officials said.

Initial reports indicated the leak came from a deck drainage tank where rainwater, lubricants and fluids drain into a sump unit, said Coast Guard spokeswoman Stephanie Young. She said the company reported the leak Monday and was still working to stop the mixture from seeping into the Santa Barbara Channel.

It was unclear how much oil -- which Young described as a light lubricant, not crude oil -- had spilled.

The U.S. Minerals Management Service, the federal agency that owns Platform Harmony and leases it to ExxonMobil, said the spill was 10 feet wide and stretched for about a mile.

Margaret Ross, a spokeswoman with ExxonMobil Corp., said less than five gallons of a “water-soluble product” had leaked into the ocean since the company discovered the problem Monday.

Assemblyman Pedro Nava (D-Santa Barbara) said oil companies are responsible for monitoring their equipment for leaks and discharges and ExxonMobil could face a “significant penalty” if it did not report and repair the leak promptly.