Oil spills, large and small, blot the history of San Francisco Bay, but for old-timers there is just one Great Oil Spill: the disaster of January 18, 1971. Two small Standard Oil tankers locked hulls in the foggy Golden Gate, releasing over a million gallons of heavy “Bunker C” fuel mixture to foul shores from Ocean Beach to Point Reyes. As official response sputtered, local volunteers rallied to de-oil birds and keep the goo out of Bolinas Lagoon. Still, 20,000 grebes, scoters, and loons are thought to have died. Safety systems and spill response were revamped after that, but couldn’t prevent or contain the next big spill, the Cosco Busan accident of 2007. It’s good to report that the Bay has not been oiled on this scale since then. Half a century ago I helped cover the big spill for the Pacific Sun newspaper; this spring I revisit it for Estuary News.