Native vegetation in the hills includes coastal sage scrub , grasslands , oak/walnut woodland , and various riparian habitats . Climate is Mediterranean , with warm summers and cool , moist winters . Runoff from the field is to the south and southwest , either down Carbon Canyon to the Santa Ana River , or southwest down various drainages to the San Gabriel River . Wildfires are a frequent occurrence in the summer and autumn ; the point of origin of the Landfill Fire , part of the 2008 Freeway Complex Fire , was on the eastern portion of the field owned by BreitBurn Energy near the landfill
Freeway Complex Fire
Freeway Complex Fire
Brea-Olinda Oil Field