Driving through Beverly Hills one afternoon this spring, I pulled over at a corner lot with a tennis court, a pool, a guest house, twenty towering sycamore and redwood trees, and an acre of emerald grass. I had arrived at the mansion of Lisa and Joshua Greer, their five children, and an American Staffordshire Terrier rescue. Although California is now in the fifth year of a historic and devastating drought, the Greers have kept their lawn looking as lush as if it were in Ireland. “I just didn’t want brown,” Lisa told me. Lisa runs a management-consulting firm; Joshua cofounded RealD, a company that makes 3-D glasses and sold last year for $551 million. Lisa was standing on her front walk sporting a Fitbit, designer sweats, and a perfectly coiffed auburn bob. “Some people are like, ‘We just let our grass go brown,’ and I’m like, ‘Really?’ I don’t know if that’s the right thing to do.” A stretch safari jeep packed with tourists was slowly rolling along the street. Lisa gave me the rundown: Jimmy Stewart’s old house was on the corner, Lucille Ball’s (“Lucy’s house”) was the Mediterranean villa across the street, the Gershwins were a few doors down, and Ella Fitzgerald lived a half block away. “Especially with these star tours all day long, I didn’t want our house looking like a dump,” she said.