The rules, years in the making, were mandated by a package of laws that tasked state agencies with making "water conservation a California way of life." They force 405 cities and other urban water suppliers serving about 95 percent of Californians to meet individualized water budgets that decline over time.
The regulations, adopted unanimously by the State Water Resources Control Board today, usher in a new phase of mandatory conservation for California. They set long-term targets for water use that aim to account for myriad regional differences, from climate to ownership of llamas and other livestock.
The water board's initial proposal -- unveiled last year and estimated to cost $13.5 billion at the time -- faced an onslaught of criticism from water suppliers and state analysts, who called the rules too costly and difficult to achieve.
In March, the state water agency revised its proposal to delay enforcement of the conservation targets and extend the timeline for tightening the water budgets based on outdoor residential use.
Individual residents won't be regulated -- only suppliers, who must meet their conservation targets or face fines or other penalties.
The costs of complying through 2050 are now estimated at more than four-and-a-half billion dollars -- which is largely expected to be passed onto ratepayers -- but water agencies and their customers will also save more than six billion dollars, in large part from buying less water, according to the agency's analysis.