The fact that rivers run to the sea isn't really a management problem. There is actually only one river in California without a dam at present, all of the others have controlled levels, hydroelectric generation, and take-outs of much of their water volume for various purposes.
We've already destroyed much of the fisheries and are having trouble recovering them. We might have about 5% of the birds the state once had. The Central Valley, which was swampland only a century ago, has been made a desert. Giant lakes have disappeared.
No surprise if this has changed the weather. A huge heat sink was removed from the environment and there is a perpetual windstorm as cool air is sucked into that valley.
Proper management is not to suck down the remaining 5%, interrupting the flow of rivers to the sea permanently. Proper management is to attach the real economic cost to water delivered to agriculture, rather than to vastly subsidize it.
Yes, this means that farming, and farming jobs, would change. Sorry, you asked more of the land than it could provide forever, your resources have run out, game over.