Six gallons of creosote and 10 gallons of asphalt emulsion spilled into Sorrento Valley Creek on Monday afternoon after a 4 1/2-ton truck lost its brakes on Sorrento Valley Road and rolled into the creek, according to Fire Department spokesman Ron Davis.
Neither the truck driver nor his passenger was injured.
Because creosote is a known toxic substance, the county Hazardous Materials Team dammed the creek to prevent the chemicals from flowing downstream.
The truck had been traveling north on Interstate 5 about 12:40 p.m. and lost its brakes after turning off on Sorrento Valley Road. The truck rolled three or four times down into the creek after the driver failed to negotiate the turn onto Roselle Street, Davis said.
The Helix Wholesale Co. owns the truck and will clean up the spill.