A fence? George Hancock owned the property and donated it to LA County in 1916. Suppose the County did not deem the natural state of the area worth protecting or an area from which visitors needed protection - until the '50s and '60s. Even then, the fence did not seem to be much of a barrier.
Is there a history of people who have gone missing there?
1910
1937, very impressive flagstone walls in second pic, but no apparent fence around the large body of water.
1941
unk date, but seems to span '41 though '60
1962
All from
lapl