City officials in Ventura, Calif., said they're still investigating the cause of the release of 700 barrels of oil from a pump station run by Crimson Pipeline.

Ventura County Fire Captain Mike Lindbery said the release migrated about a half mile through an area canyon and associated waters before it was stopped.

"The pump station where the leak originated has been shut down, and any flow at this point is residual," he said in a statement.

The cause is underdetermined at this point and the spill is under investigation. The release ended in a catch basin and had not migrated outside the immediate area.

"The incident is currently in the containment and evaluation phase; and the flow has been stopped before it could reach the ocean, minimizing environmental impacts," the fire department said.

A message sent to community residents said air quality monitoring was underway and property owners in the area were advised to stay away.

The release in Ventura comes roughly one year after 3,000 barrels of oil were released on Refugio State Beach and along the California coast in one of the worst spills of its kind for the state in decades. A federal investigation completed last year identified external corrosion of the walls of a pipeline operated by Plains All American as the direct cause of the failure. Many of the indirect causes were considered preventable.

The California and Santa Barbara county attorneys general filed criminal charges in May against Plains and one of its employees, 41-year-old James Buchanan, for the release. The penalties could amount to $2.8 million for Plains.

A review of federal records by The Los Angeles Times finds Crimson Pipeline, the company behind the Ventura release, reported 10 spills resulting in more than $5.8 million in damage in the last 10 years. Since 2006, the company was tied to the release of about 7,500 barrels of hazardous liquids.

There was no statement from Crimson Pipeline on the Ventura release.