Oh yeah they can get as large here as SouCal..maybe even Hawaii. 100'+ are seen around the bay area. Just not nearly as many of them get the chance. It must eat up most of a century for them to get way up there. And only if they are watered the whole time. 7/11 planted a few Dean about 50 years ago. I remember seeing them when the store was built. Not watered for years I bet they topped out at under 40'. Puny-ha.
But Alameda has an avenue of giants. Hayward has historical homes with the waaaay up there W.robusta's.
I have no idea on the history of this Oasis. I'm guessing it began in the 80's. They bulldozed dozens of young palms in the forefront. Mainly to keep grasses down for fire suppression. I notice the Washys are actually winning the battle over the Sycamores.
btw- Looking at them on Palmpedia is the best. On full screen and enlarged I'm seeing them much better then on other boards.