SAN JOAQUIN VALLEY CRUDE OIL SPILL INTO A FRESHWATER STREAM: A CASE STUDY1

ABSTRACT In April 1993, a pipeline rupture occurred adjacent to a primary California freeway on the north slope of the Tehachapi/San Emigdio Mountains leading into the San Joaquin Valley. An estimated 6,200 barrels of blended San Joaquin Valley crude oil (27° API gravity) sprayed on the freeway, and flowed downslope and into Grapevine Creek. The crude oil flowed 12 kilometers terminating at a containment dike constructed during the initial response. Cleanup activities were completed and approved by the lead regulatory agency within 21 days of the release. The release occurred at an elevation of 730 meters above sea level, spraying oil on to the northbound lanes of the freeway and closing it for 36 hours. After passing through engineered freeway drainage, the oil entered Grapevine Creek and flowed through 1,525 meters of riparian habitat and 8,500 meters of grassland habitat. Elevation at the terminus was 300 meters. Upper Grapevine Creek supports dense riparian vegetation that may have contributed to sign...