On November 7, 2007, the freighter Cosco Busan struck the Bay Bridge as it attempted to depart San Francisco Bay. The accident created a gash in the hull of the vessel, causing it to spill 53,569 gallons of oil into the Bay, according to US Coast Guard calculations. Wind and currents took some of the oil outside of the Bay, where it impacted the outer coast from approximately Half Moon Bay to Point Reyes. Inside the Bay, the oil primarily impacted waters and shoreline within the central portion of the Bay, from Tiburon to San Francisco on the west side and from Richmond to Alameda on the east side.

The spill precipitated widespread beach closures, fishery closures (both commercial and recreational), and the cancellation of many activities associated with boating or use of the Bay waters. A large-scale response ensued, with clean-up crews active for several weeks. The response was organized through a Unified Command, which was made up of several federal and state agencies as well as the responsible parties.

Portions of the response were completed as beaches were inspected and determined to have met cleanup criteria. The US Coast Guard officially declared the response to be complete on November 9, 2008, one year and two days after the spill.