The governor's office released confidential documents on hazardous crude oil that travels through California communities via train.
The information is critical for emergency responders to better prepare in case of a major accident along the train tracks.
The trains carrying tanks of crude oil have been seen going through Sacramento.
"This actually comes right through downtown Sacramento," Deputy Director for Governor's Office of Emergency Services Kelly Huston said. "So, if there's a derailment, or worst, an accident, where this ruptured and caught fire, you could have some real problems."
The office released confidential documents from BNSF Railway that transports bakken crude oil. The sensitive information pertains to trains carrying more than a million gallons of bakken oil. That's about 33 rail cars or more.
"Bakken crude is particularly dangerous because it's more volatile. It will ignite at a lower temperature and it's been coming through in big volumes," Huston said.
The railway's data is useful for emergency responders.
"We know there's going to be an increase in these shipments and it's helpful for first responders, your local fire chief, the police chief, others along the route to know how much of the bakken crude is actually coming through a community," Huston said.
Based on the data, on average, one bakken crude oil train passes through Sacramento every two weeks.
"That to us is helpful information because it gives us, at least right now, a base line of how much of this is coming through," Huston said. "But we still don't know what's to come and that's really the most important question."
That's a main concern for emergency responders and for people who live by the train tracks.
Officials said they expect to see a significant increase in crude oil being transported through trains because of the high production levels coming from refineries in North Dakota. The high volumes can't be pushed down the pipeline to California refineries.