Wetlands in particular are pretty rare and environmentally valuable places though. The fact that you would fill them in and "set aside" some probably less valuable land somewhere else is not very reassuring.
Wetlands are mostly found around bays and estuaries.
Now, where are major cities found? That's right, around bays and estuaries! Because that's where you can build ports and lowest bridging points, and those are fundamental drivers of the development of cities.
There's something about this failure to consider basic geography and ecology that complicates an otherwise shockingly bold and simple plan that is characteristically LessWrong.
And frankly, the behavior of stopping reading of a proposal when you get to a point of disagreement is the root cause for why people have to do such weaseling: otherwise, people who do that would just stop listening or leave the room. So what we get are leaders who are forced to come up with ornate, wishy-washy language to lead people to the end of the argument so they can, maybe, digest the whole thing at the end.
That's why.
Calculate how much that particular wetland is worth ecologically and find a low-price equivalent somewhere, buy that.
The Bay gets more space to sprawl their ugly single family madness and the wetlands (or more precisely the wetland equivalents) are safe too.
Furthermore, it's possible to simply incrementally move the wetlands toward north by filling in a southern patch and wetland-ifying some of the southern parts of the Bay's open water.
And ... this modest proposal is very much the mirror that the Valley needs. Not that it will help much, but still. It would eradicate the wetlands and the Bay itself before allowing proper high-density development and mass transit.
The entire central valley was a marsh. The delta is the small part that still slightly resembles its natural state.
Look at this picture of Sacramento from 1857 surrounded by ponds and wetlands:
https://en.wikipedia.org/wiki/History_of_Sacramento,_Califor...
Rehabilitation of wetlands is a very important goal in itself. Now that 99% is already gone and fucked up (virtually beyond repair) ... well, it means it's almost irrelevant what happens to the remaining 1% if the other 99% will be "restored" somewhere else, then that 1% can be "moved" too.
Not to mention that it the fugly plain of endless mansions sitting where the wetlands were would be replaced with a few high rises, there would be ample space to recultivate a big chunk of it.