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Altadena’s Devil’s Gate Dam

Built in 1920 by the Bent Bros Company, the Arroyo Seco’s Devil’s Gate Dam, was the first flood control dam in L. A. County. Its construction followed the devastating 1914 flood that sent dozens of homes down the arroyo.

The dam under construction 

The Devil’s profile is downstream from the dam and
except for graffiti looks the same as in this photo.

The view before JPL was built
The dam soon after it was built in 1920.

The dam as it appears today.

Connecting Altadena to La Cañada Flintridge, the structure spans the narrowest place in the Arroyo Seco watershed at Devil’s Gate Gorge named after the shape of the rocks.

The watershed begins at Red Box Saddle in the Angeles National Forest near Mount Wilson in the San Gabriel Mountains. Although the dam was primarily built for flood control, the reservoir was used for recreation until the Sylmar earthquake compromised the integrity of the concrete structure in 1971.

Photo taken soon after the structure was completed.
When the first section of the 210 freeway opened in 1966, the road was largely circumvented. Today the old road is closed to motor vehicles and is enjoyed by recreational enthusiasts and dog-walkers.

A series of plans to manage the Arroyo Seco watershed near the dam have been established. The Los Angeles Times published an informative article about the controversy surrounding the cleaning out of the debris basin.

(Photos in this post are from the AHS archives, Los Angeles Department of Water and Power and Wikipedia.)