Hundreds of Chevron workers in California went on strike Monday after the company and the United Steelworkers union failed to reach a contract agreement. More than 500 workers at a refinery producing gasoline, diesel and jet fuel and lubricating oils in the San Francisco Bay Area city of Richmond began striking at 12.01am, the union said in an email. Workers recently voted down a contract offer from Chevron, and the company refused to return to the bargaining table. Refinery operations will continue as normal, Chevron said. But if the strike were to halt operations at the refinery, that could negatively affect fuel prices in California, which already has the highest gas prices in the US at $5.86 a gallon, according to the American Automobile Association. “It would be coming at a very unfortunate time because we already have a shortage of refinery capacity in California right now, and so losing even one or two percent of the state’s refinery capacity would probably result in a noticeable increase in gasoline prices,” Severin Borenstein, a UC Berkeley professor, told KTVU. Gas prices in the Golden State have continued to rise, even as they’ve started to fall elsewhere in the US. Lawmakers are calling for a $400 rebate for every taxpayer to help alleviate the burden of high prices at the pumps. Chevron, which is based in San Ramon, California, has said it does not expect the strike to cause any supply chain issues and told KTVU it would bring in trained workers to replace those on strike. In a statement on Sunday, Chevron said it has negotiated with the union for months, and believes the contract it offered was fair and addressed union concerns. The union said it had negotiated a national agreement for oil workers on wages and working conditions, but about 200 individual bargaining units still had to negotiate local issues. Chevron said that in Richmond, “the union’s demands exceeded what the company believes to be reasonable and moved beyond what was agreed to as part of the national pattern bargaining agreement.” Workers have said the company needs to do more. “We feel when a company can report $15bn profit and the highest profit since 2014, they can give the people whose backs they’re making these earnings off of, give them a little boost to help them out,” BK White, a worker who is involved in negotiations, told KTVU. The old contract with Chevron in Richmond expired 1 February and workers had been reporting to their jobs on a rolling 24-hour extension, the union said.