Seems like an area so dependent on water from elsewhere would try to retain that water instead of letting it flow out to sea.
Years ago I was looking at some county maps of New Mexico. Every stream, every runoff had several small dirt dams on it to prevent runoff of the sparse water they get there. Just something to stop the flow and allow the water to soak into the soil.
Gavin and Nancy and the Sierra Club and the Chinese approve of the Delta letting trillions of gallons to flow to the ocean.