On October 28, 1996, at approximately 3:30 p.m., the SS Cape Mohican, a 725-foot Maritime Administration vessel, discharged an estimated 96,000 gallons of Intermediate Fuel Oil 180, a heavy bunker fuel oil, into a floating dry dock (Drydock #2) during routine maintenance at the San Francisco Drydock Shipyard. Approximately 40,000 gallons of fuel escaped from Drydock #2 and spilled into the Bay at Pier 70. The oil spill is believed to have occurred when an opened valve discharged stored fuel during the transfer of oil from a stabilization tank.

At the time of the discharge, the wind was blowing at 14 knots from the south-southwest; shortly after the discharge, the wind speed increased to 25-knot gusts and it began to rain heavily. Dispersed by an early-season storm, the discharged oil spread through portions of the Bay. Oil spread from Pier 70 south to offshore of Hunter’s Point and north into the central Bay to the Richmond-San Rafael Bridge, making landfall at Alcatraz, Yerba Buena, Treasure, and Angel islands. The Tiburon Peninsula and San Francisco waterfront were also oiled. The oil traveled outside the Golden Gate, oiling beaches as far north as Drakes Beach in the Point Reyes National Seashore and as far south as Pillar Point.