The California Department of Fish and Wildlife said the impact from a petroleum product leak Tuesday at the Chevron refinery long wharf in Richmond appears to be centered near the city’s Keller Beach, but no oiled wildlife or public health impacts have been found.

About 12 to 18 barrels (500 to 750 gallons) of a low-sulfur diesel fuel and flush water mix was released in the leak, according to lab analysis and technical review announced late Wednesday.

The leak started about 2:40 p.m. Tuesday and was stopped about two hours later, according to Contra Costa County Supervisor John Gioia.

While environmental effects appeared limited, public access sites on Western Drive and Keller Beach in Richmond remained closed while on-water response crews focused on cleanup and analysis.

Richmond Mayor Tom Butt joined a U.S. Coast Guard helicopter crew that flew over the area Wednesday morning and found sheening from Point Molate to Brooks Island, and response teams went to shorelines in the area to do further assessments, fish and wildlife officials said.

“A patchy sheen from Point Molate to Brooks Island was observed during the overflight,” according to the spill Unified Command that includes Chevron, the state wildlife agency’s Office of Spill Prevention and Response, Contra Costa Health Services and the U.S. Coast Guard.

“Sheens remain visible in some areas along the southeast side of Point Richmond,” the Unified Command said. “Boom was preventatively placed in sensitive areas and there has been no reported impact in those areas.”

A total of 3,500 feet of boom was deployed in the Richmond eel grass beds north of the spill and 2,500 feet at Brooks Island south of the spill, with more in place in other sites to proactively protect sensitive areas, officials said.

“At this time, the only shoreline area known to have been affected is immediately adjacent to the Chevron wharf,” the Unified Command said in an update late Wednesday.

People who spot potentially oiled wildlife are asked to report them at 877-UCD-OWCN.

Dan McMenamin, Bay City News

Dan McMenamin is the managing editor at Bay City News, directing daily news coverage of the 12-county greater Bay Area. He has worked for BCN since 2008 and has been managing editor since 2014 after previously serving as BCN’s San Francisco bureau reporter. A UC Davis graduate, he came to BCN after working for a newspaper and nonprofit in the Davis area. He handles staffing, including coaching of our interns, day-to-day coverage decisions and management of the newswire.