On 12 March 1928 there was a tall dam across this canyon from the high point on the left. Shortly before midnight, after leaks were inspected around noon, the dam collapsed catastrophically. Over 400 people were killed as the water rushed south towards LA and then west to the Pacific. While not as lethal as 19th century Johnstown, this was one of the worst man-made disasters of the 20th century.

The dam was built over an ancient landslide, so when enough water saturated deep enough, the dam broke. William Mulholland, who designed the LA Aqueduct, took responsibility for the disaster. There were some problems with the concrete, the height and the design, although it was likely impossible for him to know about the unstable geology beneath the site. He had inspected the dam at noon, saw leaks, but did not raise the alarm.

While folks sometimes complain about the lack of signs at this US Forest Service managed national memorial and monument, if you take the path up to the top of the hill, you’ll find 8 large plaques detailing the early history, LA’s water wars, Mullholland’s career, issues with the dam construction, descriptions of the flood, the aftermath, the lives lost, and the canyon geology. And you get the view above, plus a view of the wing wall. Park at the north end of the old San Francisquito Canyon road, where it’s closed to traffic, and hike back down the road along the pretty creek. Look for signs on your right for the trail up the hill to the viewpoint.

Here are my visitors to all NPS parks in California.