Overview of the St. Francis Dam (full view, center) and reservoir (full view, right) after the break. The view is to the west.

According to J. David Rogers, St. Francis Dam engineering expert, this (LW2642g) is an "oft-reproduced image taken of the dam failure from the Bee Highline Road, with the prominent knob of the Vasquez Sandstone in the distance, overlooking San Francisquito Canyon. This image shows the deep shear key afforded the right abutment dike, about 18 feet deep, excavated by steam shovel into the Vasquez conglomerate/sandstone. Towards the bottom of the image one can also discern the remnants of the old San Francisquito Canyon Road, which was about 13 feet above the dam's left abutment, on the southeast side of the canyon. Look closely and you will also see the white timber and wire mesh guardrails that were placed along this roadwhere the drop-offs were dangerously precipitous" (see Rogers' image of the road and guardrails, inset; click to enlarge).

Photograph shot on or shorly after March 13, 1928. The dam collapsed at 23:57:30 on March 12 and it took about 72 minutes for the 12.5-billion-gallon reservoir to empty (Outland 1977).

About the image: One of seventeen 5x7-inch glossy photographs found in a box in the Photography section of the San Francisco Public Utilities Commission's Engineering Archives in 2013.^[1] There was no record of the origin of the photographs and no writing on the back to identify subjects or dates. Current SFPUC staff members did not know the reason for their inclusion in the archive.

Ownership transferred via email communications (on file) from SFPUC to SCVTV-SCVHistory.com. Prints received July 11, 2014; subsequently transferred to the Santa Clarita Valley Historical Society.

1. A hand-written notation by current San Francisco PUC staff indicates the images were emailed Aug. 8, 2013, to someone who identified them as the St. Francis Dam. SFPUC staff alerted us to their existence in the Spring of 2014.

Construction on the 600-foot-long, 185-foot-high St. Francis Dam started in August 1924. With a 12.5-billion-gallon capacity, the reservoir began to fill with water on March 1, 1926. It was completed two months later.

At 11:57:30 p.m. on March 12, 1928, the dam failed, sending a 180-foot-high wall of water crashing down San Francisquito Canyon. An estimated 411 people lay dead by the time the floodwaters reached the Pacific Ocean south of Ventura 5½ hours later.

It was the second-worst disaster in California history, after the great San Francisco earthquake and fire of 1906, in terms of lives lost — and America's worst civil engineering failure of the 20th Century.