Just an FYI, the flood plain mapping will set minimum FINISH FLOOR heights in the Natomas area. The support structure below has to be 'breakaway' to allow for free flow of water.
It's pretty flat out there, but there is some variation in elevation IIRC and thus this 20' above grade is just the worst case scenario (but of course the number the media latches onto).
In the case of the airport, they may just have to raise the ground floor slightly and rework the grading of the aircraft aprons (at least SMF has lots of room for such things). Anything already existing would be grandfathered.
Interestingly enough, you could still build taller above grade parking structures with a building on top and meet the FEMA requirements. Density anyone?
But new single family homes? Awful expensive to raise the grade between 5'-20' to meet FEMA requirements.
It'll be interesting to see the results of these new regulations.