They told Vince Calcagno to cut his water use by more than a third last year as the desert summer loomed with its 112-degree highs. He stood near the swimming pool in his pretty back yard off a Palm Springs golf course and wondered, “How am I going to make this work?”

It worked as badly as he envisioned. After months of almost no watering, “the back yard looks pretty awful now,” Calcagno, a retired restaurant owner, said recently. “It’s brown and full of crab grass.”