MIKE CHRISMAN looks out from his SUV as he drives through seemingly endless rows of walnut trees on his property near Visalia, in central California. “I have to be optimistic, I’m so tied to this land,” he says. His great-grandfather, after trying his luck in the Gold Rush, settled in Visalia in the 1850s, and the family has been there ever since. But as California’s secretary for natural resources—a job at the intersection of the environmental and farming lobbies, perennially at loggerheads over the state’s scarcest resource, water—Mr Chrisman also knows that optimism has become a minority view.

His land is in California’s Central Valley, a region that covers... http://www.economist.com/world/united-states/displaystory.cfm?story_id=1...