Access to this collection is generously supported by Arcadia funds., The Devil's Gate Dam was the first flood control dam constructed in Los Angeles County. Designed by the flood engineers from the Los Angeles County Flood Control District and completed in 1920 Bent Brothers company, it formed the Hahamongna flood basin. The dam is located in La Cañada Flintridge at Devil's Gorge, the narrowest point on the Arroyo Seco. The Arroyo Seco is a seasonal river and watershed that begins at Red Box Saddle near Mount Wilson in the San Gabriel Mountains and ends at the confluence with the Los Angeles River near Elysian Park, north of Downtown Los Angeles., View across Devil's Lake (Hahamongna Lake, Hahamongna Basin Watershed) with the San Gabriel Mountains visible in the distance. The lake was formed by the Devil's Gate Dam in 1920., Text from negative sleeve: Devil's Gate Dam