My coverage of the St. Francis Dam is "broken" into two parts. This first part concerns the physical aspects of the dam, and the second part (the next post) concerns the geology of the site.
This photograph, upstream view, (also from Wikipedia.com) shows the remnants of the dam after its collapse on March 12, 1928. Only the central part and most of the wing dike (on the west side of the dam) remained intact. This dam, which was part of the Los Angeles Aqueduct system, collapsed just before midnight. The wall of water was initially 125 feet high, and its initial velocity was 18 mph. The 12 billion gallons of water roared down the Santa Clara River Valley to the city of Ventura, which is as the coast. The water traveled a total of 55 miles, and it took 5.5 hours to reach the ocean. The debris was a deadly mixture of mud, barbed wire, wood, etc. Nearly all the victims never knew what hit them.
All the subsequent photographs (in both of the posts) were taken by me in January, 2011 and in April, 2017.
This is all that is remains today of the main part of the dam. Although the central part did not collapse during the failure of the dam (see first picture), it was eventually dynamited in order to prevent climbers from attempting to climb it and possibly fall (i.e., liability issues).
|Remnants of the "steps"which were on the downstream part of the face of the dam.|
|Rebar sticking out of large chunks of the concrete rubble. The staff is 1.5 m (in 10 cm increments). The flat surfaces were once part of the "steps," mentioned above.|
|Other sides of the same blocks shown in previous slide.|
This is the floodplain about 0.25 mi. downstream from the dam site. As you can see, there are building-size chunks of the dam that were broken up and transported by the wall of water suddenly being released from the reservoir behind the failed dam. Most of these chunks, some weighing as much as 10,000 tons came from the western side of the dam. Most of the eastern side collapsed in place and remained near the dam. Some of the transported chunks moved as far as 3,000 ft. downstream. For scale: Notice the cars on new highway along the left side of picture.
San Francisquito Creek once again flows freely, right through the middle of the collapsed dam.