Wait, the migrating birds need the wetlands that the rice pairs imitate. It's not as bad as you think. The whole central valley was wetlands, this is better than draining all of it for alfalfa or almonds.
California right now has an endorheic basin which is rapidly subsiding due to groundwater draws, and that doesn't really work for agriculture in the long term. We need to re-establish a gradient to the ocean, and a limited wetland system, to flush out the salts if nothing else.
