California officials have approved a first-of-its-kind regulation that will set long-term limits on the amounts of water the state’s urban utilities can use on an annual basis. The State Water Resources Control Board granted unanimous support Wednesday to sweeping conservation measures that are expected to generate about 500,000 acre-feet in water savings each year by 2040. The quantity conserved is enough to quench the thirst of more than 1.4 million households on an annual basis, according to the Water Board. The regulation requires the state’s largest suppliers to calculate individual water budgets based on residential indoor and outdoor water use,...