This is a re-post from 2019 with updated links for pictures and further readings.
by Jay Lund
Collapse of Los Angeles aqueduct pipeline through Antelope Valley from a major flood in February, 1914 (3-months after the aqueduct’s official opening)
“In February, 1914, the rainfall in the Mojave Desert region exceeded by nearly fifty per cent in three days the average annual precipitation.
Where the steel siphon crosses Antelope valley at the point of greatest depression, an arroyo or run-off wash indicated that fifteen feet was the extreme width of the flood stream, and the pipe was carried over the wash on concrete piers set just outside the high water lines. The February rain, however, was of the sort known as a cloud-burst, and the flood widened the wash to fifty feet, carried away the concrete piers, and the pipe sagged and broke at a circular seam. The water in the pipe escaped rapidly through the break under a head of 200 feet, and the steel pipe collapsed like an emptied fire hose for nearly two miles of its length. In some places the top of the pipe was forced in by atmospheric pressure to within a few inches of the bottom. The pipe is ten feet in diameter, and the plates are 1/4 and 5/16 of an inch thick. Many engineers pronounced the collapsed pipe a total loss, and advised that it be taken apart, the plates re-rolled and the siphon rebuilt.
The damage was repaired, however, by the simple expedient of turning the water on after the break was mended, relying on the pressure to restore the pipe to circular form. The hydraulic pressure, under gradually increasing head, restored the pipe to its original shape without breaking any of the joints or shearing the rivets, and a month after the collapse the siphon was as good as new. The total cost of repairing the siphon was only $3,000. It would have cost about $250,000 to take it apart and rebuild it.” 
Water management and policy has always faced challenges, even unexpected ones following great technical triumphs. But sometimes challenges require only some simple creativity based on fundamental insights and a willingness to venture forth and adapt. Sometimes.
 Complete report on construction of the Los Angeles aqueduct, Los Angeles Board of Public Service Commissioners, Los Angeles, CA 1916. (pp. 20-21) https://openlibrary.org/works/OL13802476W/Complete_report_on_construction_of_the_Los_Angeles_aqueduct
 LADWP historic photo archives – https://tessa2.lapl.org/digital/collection/dwp/search