You could additionally store more water in the soil. Dig some basic water harvesting earthworks in the mountains, maybe plant a few select species and within a

You could additionally store more water in the soil. Dig some basic water harvesting earthworks in the mountains, maybe plant a few select species and within a few years all the mountain streams will flow for much longer during a drought. As a bonus it will leave a lot more trees alive when the wildfires come through. Of course this is impossible in California, even if it didn't violate environmental laws (it does), a project like this would be sued and propositioned to oblivion.