"In the Central Valley, for instance, regulations designed to save certain fish species have required 450,000 acres to go fallow."

Who could support "impoverishing whole regions" this way? Those who understand ecology. If the Delta Smelt goes extinct, a whole chain of species, fish and otherwise, will likely go with it, with unknown consequences. This is to human Californians' detriment, to say nothing of those species. Extinction is forever.