RICHMOND — Bakken crude oil from North Dakota is part of the mix of increased crude-by-rail shipments into Contra Costa County, raising concerns from local leaders about whether current regulations are sufficient to minimize risks of transporting the volatile fossil fuel.

“There’s a lot more to be learned, but Bakken (crude) is coming in now,” said Contra Costa County Hazardous Materials Division Director Randy Sawyer. “How much, I don’t know.”

Kinder Morgan Inc., at 1140 Canal Blvd. in Richmond, secured a permit last month to transfer crude from rail cars to trucks, said county Supervisor John Gioia, of Richmond, and is the only facility in the Bay Area that receives crude shipped on Burlington Northern Santa Fe trains, according to the California Energy Commission.

Domestic oil harvesting has increased in recent years, most notably in North Dakota, where drillers use hydraulic fracturing, or “fracking,” to fracture rock and extract oil. As the haul has increased, more oil is coming by rail to California refineries for processing.

Northern California volume of crude by rail increased 57 percent during 2013, from 74,332 barrels in January to 116,657 barrels in December, according to California Energy Commission statistics. But the bulk of the increase statewide went to Southern California refineries, as total state volume spiked from 155,841 barrels in January to 1,180,662 barrels in December. Only about one tenth of all crude-by-rail imports came to Northern California.

About 85 percent of the crude by rail delivered to Northern California in 2013 came from North Dakota, followed by 12.5 percent from Colorado, according to the commission. Four of the five Northern California oil refineries listed by the commission are in Contra Costa County, with the other in Benicia.

The city of Benicia is considering local resident concerns about Valero’s proposals to ship crude by rail.

Local officials say they may need to revisit the county’s Industrial Safety Ordinance to see whether modifications should be made to ensure safety in dealing with Bakken crude, which is more volatile and susceptible to explosion than heavier crude blends.

What local agencies can do to regulate the rail cargo, which is typically covered by federal interstate commerce laws, is limited.

The changes come as popular resistance to increased refining of continental oil has been building.

In the past month, critics hosted town hall-style meetings in Richmond, Martinez and Pittsburg decrying planned increases in crude-by-rail shipments into the Bay Area. Activists drew attention to rising accident numbers, with particular emphasis on a train explosion in July in Lac-Mégantic, Quebec, where 47 people were killed. Other derailments and explosions have occurred in the past year in Alabama and North Dakota.