On the evening of September 26, 1998, the T/V Command left San Francisco Bay bound for Panama. As it traveled in the southbound traffic lane off San Francisco and San Mateo County coasts, it released an estimated 3,000 gallons of Intermediate Bunker Fuel (IBF) 380, also known as Fuel Oil No.6. Due to light winds and fair weather, the oil moved little in the first few days, primarily staying in the vicinity of the southbound traffic lane. On September 30, oil began to wash ashore, largely in the form of scattered tarballs, over 15 miles of beaches, primarily in San Mateo County. A tarball sample collected as far away as the Salinas River mouth in Monterey County, however, matched the source sample from the tanker.