California regulators approved sweeping, unprecedented restrictions Tuesday on how people, governments and businesses can use water amid the state’s ongoing drought in the hope of enticing residents to conserve more water.

The State Water Resources Control Board approved rules forcing cities to limit watering on public property, encouraging homeowners to let their lawns die and imposing mandatory water-savings targets for hundreds of local agencies and cities that supply water to California customers.

Gov. Jerry Brown sought to tighten the already strict regulations, arguing that voluntary conservation efforts have not yielded the water savings needed amid a four-year drought. Brown ordered water agencies to cut urban water use by 25 percent from levels in 2013, the year before the drought emergency was declared.

"It is better to prepare now than face much more painful cuts should it not rain in the fall," board Chairwoman Felicia Marcus said Tuesday as the panel voted 5-0 to approve the new rules

Although the rules are called mandatory, it’s still unclear what punishment the state water board and local agencies will impose for those who do not meet the targets. Board officials expect dramatic water savings as soon as June and are willing to add even more penalties for those who do not meet the targets.

However, the board lacks the staff to oversee each of the hundreds of water agencies, which range dramatically in size and scope. Some local agencies tasked with achieving savings do not have the resources to issue tickets to waste water.

It is also unclear whether Californians have grasped the seriousness of the state’s drought situation and the need for conservation. Data released by the board Tuesday showed that Californians conserved little water in March, and local officials were not aggressive in cracking down on waste.

Under the new rules, each city must cut water use by as much as 36 percent compared with 2013. Some local water departments have called the proposal unrealistic and unfair, arguing that achieving steep cuts could cause higher water bills and declining property values. Critics also say it could dissuade projects to develop drought-proof water technology.

Representatives of San Diego-area water agencies have been especially critical of the water targets, noting that the region has slashed consumption and agencies have spent $3.5 billion to prepare for dry periods after facing severe cuts in earlier droughts.

"San Diego has lived the horror of what the state is going through right now," Mark Weston, the board chairman of the San Diego County Water Authority, told state regulators Tuesday.

After a 10-hour hearing that included more than 5 hours of public testimony, the water board again on Tuesday rejected calls to create easier targets for communities in drier areas or for cities that have been conserving since before the drought.

Private water utilities and local water departments would lose a total of about $1 billion in revenue through lost water sales if they failed to meet the set goals, an economic analysis of the water board’s proposal estimated.

Residents and businesses use less than a fifth of the water withdrawn from the state's surface and groundwater supplies. Farms in the state's agricultural heartland have had deliveries from government reservoir systems slashed and some have been ordered to stop diverting water that is normally available to them from streams and rivers.

Brown said last week he would push for legislation boosting authorizing fines of up to $10,000 for extreme wasters of water, but he needs legislative approval to do so, and no bill has been introduced. Another tool -- tiered pricing, in which the price rises as water use goes up -- is in question after a court struck down water rates designed to encourage conservation in San Juan Capistrano in Orange County.

The Associated Press contributed to this report.