Can we narrow down which dam these young people might have died at?
List of dams in LA county:
Category:Dams in Los Angeles County, California - Wikipedia
Of the ones listed, these were built between 1921 and 1951:
Mulholland Dam (1923-1924)
Rindge Dam (1924-1926)
St Francis Dam (1924-1926) (Failed in 1928, Demolished in 1929)
Santa Anita Dam (1924-1927)
Bouquet Canyon Dam (1934)
Hansen Dam (1939-1940) (US Army Corps of Engineers)
Santa Fe Dam (1941-1949) (US Army Corps of Engineers)
Sepulveda Dam (1941-1949) (US Army Corps of Engineers)
Of those 8, I think we should be looking at the 5 pre-war ones. Those are the ones that would have used civilian labour and are most likely to account for 2 kids or teenagers, ie family members of employed labour, mucking about. I'm guessing that site security would have been much tighter at the 3 built by the army just before and during wartime. Also, it seems likely that inventory of explosives would be much more closely controlled during wartime than during peacetime so it seems less likely that dynamite would just have been left lying around during and after construction.
I'm not sure this really gets us any further forward but the speculation is interesting in itself.
The failure of the St Francis Dam is also interesting. I imagine it's well known in the US but for the rest of us it's an interesting read.
St. Francis Dam - Wikipedia
What's particularly interesting is that local farmers and landowners in the Owens Valley carried out a number of what today we would call terrorist acts, dynamiting parts of the nearby aqueduct which carried water from the mountains to Los Angeles so it's clear that at least some local people had access to substantial amounts of explosives.
Does anyone know what would have happened to the remains of the victims in LA county during this time period? Would they have been buried and if so where? Without having access to the bodies (and thus DNA) there's probably no way to push this case forward.