Oil spills in San Francisco Bay are frequent news, but for those old enough to remember there is only one Great Oil Spill, the disaster of January 18, 1971.
In a predawn darkness thickened by heavy fog, two small Chevron tankers were maneuvering through the strait. At San Francisco’s Pier 45, Coast Guard technicians were just then testing a novel radar system. They watched helplessly as two blips threatened to fuse into one. Frantic calls to the captains failed to get through. The inbound Arizona Standard rammed its bow 40 feet into the outbound Oregon Standard, releasing more than a million gallons of heavy “Bunker C” fuel mixture — likely the worst spill in Bay history.
The San Francisco Bay Model in Sausalito ran tests predicting, correctly, where the slick would go next: up the Marin County coast. As official response sputtered, a ragtag army of volunteers appeared, determined to help but unsure how. Some capable locals worked through the night to install a boom across the mouth of Bolinas Lagoon, shielding the single most valuable habitat in the spill’s path. They did less well dealing with the oiled grebes, scoters, and loons.
“There were dying birds everywhere and no one knew what to do,” recalls volunteer Jay Holcomb. “It was as horrible as you can imagine.” The Point Reyes Bird Observatory (now Point Blue) estimated the loss of grebes, scoters, and loons at 20,000 birds. Of 7,000 collected, only 300 survived to be released. Effects on other biota — herring, eelgrass — were not even studied.
Weeks later, much of the goo seemed unaccounted for. Chevron asked the advice of John Conomos of the U.S. Geological Survey, who had tracked currents using drifters set at different depths. “Look in San Pablo Bay,” Conomos said. The oil was there, in the middle of the water column, trapped between opposing currents on the surface and along the bottom.
Coming less than a year after the first Earth Day celebration, the 1971 spill shocked public opinion, led to new laws and procedures, proved the value of Bay research, and seeded several important environmental organizations.
By early spring, some of the shell-shocked volunteers had incorporated International Bird Rescue, funded by the industry and later directed by Holcomb for a time. It is a leading group in the field to this day.
For its part, the Coast Guard greatly stepped up its supervision of Bay traffic, creating a new Vessel Traffic Service headquartered on Yerba Buena Island; it works like air traffic control though without an airport tower’s absolute authority. “Never again,” was the slogan of the day.
Of course, the spill of 1971 was neither the last nor the first in a series as old as the petroleum age and often involving fog.
In 1922, the tanker Lyman Stewart collided with a freighter in the Gate; its oil clogged the intakes of Sutro Baths near the Cliff House. In 1937, the Frank H Buck was rammed in the Gate by a passenger liner; the SPCA euthanized large numbers of hopelessly oiled gulls. 
In 1984, the Puerto Rican caught fire and broke up eight miles outside the harbor entrance, shedding about as much oil as the 1971 disaster, though with less dramatic (or visible) effect. In 1986, the coastal barge Apex Houston dribbled oil out of an unclosed hatch cover, killing common murres from the Golden Gate to Big Sur.
In 1988, Shell’s Martinez facility discharged some 400,000 gallons of oil into Suisun Bay wetlands. In 1996, the SS Cape Mohican spilled 96,000 gallons at San Francisco Pier 70, though most was contained at the site. 
Spread of oil in San Francisco Bay from Cosco Busan spill 2007 after 22 hours. Source: OPT
Then came November 7, 2007, when the Cosco Busan — in touch with Vessel Traffic Service, with bar pilot on board — nevertheless struck a tower of the fogbound San Francisco-Oakland Bay Bridge. The release was a comparatively small 54,000 gallons of heavy oil, but the site and season magnified its effect on birds. Despite advances in bird care and cleanup technology, nearly 7,000 seabirds and shorebirds were killed. Pacific herring suffered as well. A post-mortem report produced another long list of needed improvements, some of them familiar from 1971, and a new round of reforms.
Have things not improved since 1971 or 2007? Of course they have. “California now has one of the best oil spill response, preparation, and prevention systems in the world,” says Eric Loughlin of the state Department of Fish and Wildlife. And the relatively trouble-free span since 2007 is the longest yet.
Yet the recurrence of spills — and reported errors in response — reminds us just how difficult this job remains: what an achievement it actually is to move and process billions of gallons of hydrocarbons through and around this busy harbor, in any given year, without significant mishap.
This February, an oil spill was again in the headlines: 600 gallons of mixed water and diesel oil flowed from a punctured pipeline on Chevron’s Long Wharf in Richmond. The city issued a public health advisory. Nearby beaches and shorelines were closed. Estimates of spillage grew with each report. San Francisco Baykeeper criticized cleanup efforts as slow off the mark. A report is forthcoming. 
 U.S. Coast Guard, Fact Sheet: Vessel Traffic Service, San Francisco, Nov. 20, 2007; Carl Nolte, “Watching the Ships Roll In—and Keeping the Bay Safe,” San Francisco Chronicle, Feb. 13, 2011.
 Coast Guard, Incident Specific Preparedness Review, M/V Cosco Busan Oil Spill in San Francisco Bay: Report on Initial Response Phase, Jan. 11, 2008: I-2; John Hart, Don Stanley, Alice Yarish, “The Great Oil Spill,” Pacific Sun Jan. 27, 1971.
 Stephanie M. Carlson, remarks at State of the Estuary Conference, 2001.
 Burr Henneman, telephone conversation with author, March 6, 2021; International Bird Rescue site, consulted Mar. 1, 2021.
 Bill Davoren, telephone conversation with author, April 8, 2002.
 Harold Gilliam, San Francisco Bay (New York: Doubleday, 1957): 192-93.
 Incident Specific Preparedness Review, M/V Cosco Busan, I-2.
 Calif. Dept. of Fish and Wildlife, Oil Spill Prevention and Response, https://wildlife.ca.gov/OSPR/NRDA.
 CDFW, Oil Spill Prevention and Response, Cosco Busan Oil Spill: Final Damage Assessment and Restoration Plan/Environmental Assessment: Appendix D.
 Coast Guard, Incident Specific Preparedness Review, Cosco Busan, Part II and Final Report, May 7, 2008. 8
 George Kelly, “Bay Refinery Oil Spill Prompts Alert,” Bay Area News Group, Feb. 10, 202; telephone conversation Sejal Choksi-Chugh, San Francisco Baykeeper, Feb. 19, 2021.