An oil pipeline operated by Crimson Pipeline LLC in Ventura County, southern California has leaked an estimated 29, 400 gallons of crude oil in the surrounding hills. None of the oil has reached the Pacific Ocean, as an early warning from a local Ventura Country resident allowed officials to intercept the oil in a drainage basin a few miles inland.

The 10-inch underground pipeline was installed in 1941 and is up to date on state and federal inspections, according to Kendall Klingler, a spokeswoman for Crimson. However, the pipeline had been undergoing maintenance Wednesday and was not at its full rate of flow or pressure, Klingler said. The valve that had been replaced during maintenance was the source of the oil leak, she added.

Crimson Pipeline is responsible for the cleanup effort and deployed contractors to lay down large, absorbent booms in Prince Barranca, a gorge, to mop up the crude. On Thursday afternoon, workers in white haz-mat suits hiked down to the canyon with industrial pumps and vacuumed the pools of liquid that formed along the riverbed. This is being trucked away and properly disposed.

Thursday’s spill marked Crimson’s 11th pipeline spill or equipment incident since 2006, according to records compiled by the U.S. Department of Transportation’s Pipeline & Hazardous Materials Safety Administration (PHMSA). The regulator said it had sent investigators to provide assistance to the California state fire marshal, who is responsible for the investigation of the spill to determine the cause.