The weekend oil leak along the Southern California coast happened not far from the site of the catastrophe more than a generation ago that helped give rise to the modern environmental movement itself: the 1969 Santa Barbara spill.

That still ranks in the top tier of human-caused disasters in the United States and is the nation's third-largest oil spill, behind only the 2010 Deepwater Horizon and 1989 Exxon Valdez calamities.

During a 10-day period in early 1969, between about 3.5 million and 4.2 million gallons of crude spilled into the Santa Barbara Channel after a blowout six miles offshore...