The ruins of the St. Francis Dam stand in a remote canyon off San Francisquito Canyon Road, an eerie reminder of the worst American civil engineering disaster of the twentieth century. On the night of March 12–13, 1928, the dam failed catastrophically, releasing its entire reservoir in a matter of minutes. The flood wave swept through the Santa Clara River valley at thirty miles per hour, destroying farms, towns, and oil camps all the way to the Pacific Ocean near Ventura.
Massive chunks of concrete still lie in the canyon, unmoved since the flood. The site is accessible by a rough trail from a roadside pullout, and the scale of the wreckage makes the power of the escaping water viscerally imaginable. There is a small historical marker at the road and interpretive panels. The surrounding canyon is beautiful in its own right, with rugged terrain and native vegetation that has recovered over a century.