They've been talkin for years 'bout building more reservoirs to "catch" the torrential rains for future human consumption here in So Calif. But like all things in this country/state related to $$, many people hate the words "new taxes," even if the positives outweigh the negatives. Go figure...
I'm hoping that in the near future as people cont to become much more eco-conscious that projects like these aren't an issue & they become mandated fixtures. We'll have to wait & see however.
Edited for the following:
So the answer to your 1st ques is that it's "cheaper" to turn this off again & use up the natural resources rather than spend tax $$ to build reservoirs.