“We thought we were doing the right thing to save water,” Staci Terrace Goldfarb, a Southern California homeowner, said late last winter. “I hate looking at it.” It had been a little more than a year since Goldfarb had the small, semicircular lawn in front of her 1960 Cape Cod in the San Fernando Valley replaced with drought-tolerant landscaping. Yet her front yard was a flat patch of gravel, the kind you can buy in bulk at Home Depot. It was the work, she said, of a company called Turf Terminators.