A section of the St. Francis Dam, known as the "tombstone," remained standing after the dam broke on the night of March 12, 1928. To the consternation and embarrassment of Los Angeles water officials, it became a tourist attraction. In May 1929, more than a year later, it was dynamited into oblivion after an adventurous young man fell from the top of it and died.

Remarks from J. David Rogers, St. Francis Dam engineering expert:

Nice detailed view of the standing monolith (Block 1) after the dam failure. Some effervescence salts can be seen precipitating around the seeps oozing from the monolith's jagged face. A few form imprints can also been seen near the upstream and downstream faces of the block, which are only five feet high. The downstream face of the dam has been cleaved off (about 12.5 vertical feet) just below outlet No 3 at elevation 1685 feet.

The only steel reinforcement in the dam was for the crest roadway across the 11 spillway slits, which were only 18 inches below the dam's finished crest elevation of 1836.5 feet (the slits were at elevation 1835 feet and can be seen in the [inset] image). The solid section near the dam's central axis was for the four outlet works (30-in dia pipes) and for the Stevens Reservoir Stage Gage (on the upstream side). The solid deck slab was only 6 inches thick and was reinforced by square deformed rebars, typical of the mid-1920s. Note how large portions of the reinforced road deck are hanging from either side of the monolith. These were cut off a few weeks after the failure because of safety concerns.

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.