Has it occurred to you that we already built ones where they're geographically and economically feasible, and that's why we've slowed down their construction?
Reservoirs require land with natural geographic boundaries (such as valleys), will displace any human populations in them, and will completely destroy whatever existing flora and fauna exists in there. Perhaps Californians are trying to wrangle with the idea that destroying ecosystems at great financial expense to deal with the problems caused by destroying other ecosystems isn't the right way to approach problem-solving.
Reservoirs require land with natural geographic boundaries (such as valleys), will displace any human populations in them, and will completely destroy whatever existing flora and fauna exists in there. Perhaps Californians are trying to wrangle with the idea that destroying ecosystems at great financial expense to deal with the problems caused by destroying other ecosystems isn't the right way to approach problem-solving.