I get that, & I don't mean L.A. would remain the village it was in 1850 or so, just not the megalopolis it is OTL.
L.A. has always had the best 'salesmen' in the business
That last bit is the hardest part to overcome, if we're going to press for less-destructive practice. (I just refuse to call it "sustainable", since nobody ever defines it: how much, for how many, & for how long?) You're absolutely right.
Technically "sustainable" is self explanatory in that it assumes the most for the longest period of time as a basis but I get the point The main problem is that's not how capitalism works on just about any level so getting anyone to 'moderate' runs into the main issue that even if YOU do the other guys won't so in the end it doesn't matter. It literally took things like the fishing collapse and the Dust Bowl to get a larger and deeper 'buy-in' to at least trying to moderate things. The 'area' can make a come-back no problem, (the area we're talking about is pretty well back in terms of viable habitat) but if the population has voted "with its feet/fins" as is the case then there's very little environmental pressure to re-populate the area despite conditions. I seem to recall there was an attempt to re-introduce some of the fish populations but they got fished out by the locals before they could establish
That might do it, but it smacks of ASB. Hitting the area with a typhoon that didn't OTL, I'm fine with, because that might reasonably arise from it being an ATL; tampering with the geology...you're getting into dinosaurs & Mayans in the same film territory.
Ohhh, Mayan Dinosaurs....
Fun fact, one of my grade-schools I attended in California had a "playground" (we use the word loosely because gravel does not make the best surface to "play" on and for some reason they could never get grass to grow there ) that had a sharp (7 foot rise in less than 10 feet) between the equipment and the ball diamond. Photo's show that rise was not there prior to 1910
Randy