We are actually making some progress in capturing more of the water, but as Patty mentioned, putting new land underwater is a challenge just about everywhere. Between the cost of the land and the decade plus of regulatory approvals, things move awfully slowly here. One LA story from back in January:
Here in Orange County, we've made quite a bit of progress as well. We are more famous for our wastewater treatment program (toilet to tap for those opposing such things), but we're making baby steps of progress on capturing storm water as well.
I'm trying to figure out if I'm allowed to do curb cuts to capture more gutter water flowing down our street, but we're in an unincorporated part of OC and figuring it out with the county has been a challenge.
Which is all a long way of saying this problem isn't going away anytime soon -- at least until someone can figure out how to economically turn salt water drinking water.