Shortly before midnight on 12 March 1928, the St Francis Dam, a concrete wall holding back a reservoir in San Francisquito Canyon, collapsed. A wall of water swept down the canyon and the Santa Clara River valley to the sea, killing hundreds of people. It was one of the worst civil engineering disasters in American history, and it ended the career of William Mulholland, the engineer who had built the aqueduct that brought water to Los Angeles. The ruins of the dam lie a few kilometres north of this stop, broken blocks of concrete scattered in the canyon.
This stop lies in the hills north of Santa Clarita, between Castaic and Bouquet Canyon, where the suburbs meet the chaparral and oak woodland of the Angeles National Forest. San Francisquito Canyon Road and Bouquet Canyon Road are popular with bikers, winding up through the hills with tight bends and views over the valleys.
For a swim, Castaic Lake, to the west, is a large reservoir with a smaller lagoon below the dam, where swimming is allowed in summer at a designated beach. The water is warm, and the lagoon is popular with families.
The riding is good but demanding. The canyon roads are narrow and winding, with variable surfaces, and the heat in summer can be intense. Wildfires are a constant threat, and roads can be closed at short notice. Watch for cyclists, wildlife and debris on the road.
Santa Clarita and Castaic have every service along the I-5 corridor, so fill up there before heading up the canyons, where there is nothing. And stop for a few minutes at the dam site if you ride San Francisquito: the silence of that canyon, knowing what happened there, is something you do not forget.