SACRAMENTO — Few Californians listened earlier this year when Gov. Jerry Brown begged them to conserve water. So now, with no end to the extreme dry weather in sight, state officials are poised to slap water wasters with unprecedented fines of up to $500 a day.

Drenching your lawn or washing your car without a nozzle on the hose would be among the violations that trigger penalties under emergency conservation rules the state Water Resources Control Board is set to consider next week. If approved, the new regulations — which would represent the first time the state has imposed mandatory statewide restrictions and fines on residential outdoor water use — would take effect Aug. 1.

“Having a dirty car and a brown lawn should be a badge of honor because it shows you care about your community,” Felicia Marcus, the board’s chairwoman, told reporters in a teleconference Wednesday. “We don’t know when it will rain again. It’s prudent to act as if it won’t.”

Marcus warned Californians to prepare for further restrictions. “What we’re proposing here as an opening salvo is the bare minimum,” she said. “If it doesn’t rain later this fall, we certainly will consider more stringent measures.”

Mandatory and voluntary restrictions at a local level has so far resulted in a statewide water use reduction of 5 percent through May — short of the 20 percent sought by Brown.

Water regulators are hopeful the state’s residents will respond as well as they did in the last severe drought in 1976 and 1977, when Brown — who was also governor then — called for statewide conservation measures and Californians responded by reducing water consumption about 20 percent.

Although the overwhelming majority of California’s water is used to irrigate Central Valley farms, the new regulations would target urban water users. In some cities and towns, Marcus said, more than half of the water is used on landscaping.

In addition to prohibiting excessive lawn-watering and irresponsible car-washing, the new rules would block water users from power-washing hard surfaces and using potable water in decorative fountains if the water isn’t recycled. Indoor water usage for laundry, dishwashing and showering, however, will remain unrestricted.

The proposed rules also apply to urban water suppliers, who must implement plans to restrict customers’ outdoor water use if they haven’t done so already.

Agencies that fail to comply could face fines of up to $10,000 a day, but while public water utilities will be bound by the new rules if they’re adopted, private water providers like the San Jose Water Co. will be encouraged but not required to participate in the conservation plan. The reason is the water board has no authority to regulate private water usage.

“We’re not saying ‘They shall.’ We’re saying ‘They should,'” Marcus said.

Officials of San Jose Water, which has about a million customers, did not return repeated phone calls Wednesday for comment.

Public water suppliers in the Bay Area on Wednesday generally characterized the state’s plan as a modest way to get Californians to conserve water amid a seemingly endless drought. But some questioned how the rules will be enforced, especially in areas like San Jose that are largely served by private water companies.

State water officials said communities will have broad discretion to decide how aggressively to enforce the proposed rules, should they be adopted, and decide whether local water department employees or police should be writing tickets for violators.

The five members of the water board are appointed by the governor. They are acting under Brown’s emergency drought proclamation in January and a related executive order in April, in addition to drought legislation he signed in March.

“I think what they’re calling for are common sense measures that people should be doing anyway — perhaps in all years,” said Bert Michalczyk, general manger of the Dublin San Ramon Services District. “I generally have reservations about mandatory measures from the state because of the wide diversity of water situations in California, but this seems like a reasonable minimum.”

Marty Grimes, a spokesman for the Santa Clara Valley Water District, a water wholesaler, said the district is encouraged by the state’s interest in greater water conservation. Having state mandates will “make it easier in many ways” for the water district’s customers to restrict water usage, he said.

The reaction of water customers, too, seemed generally positive.

“Brilliant,” said San Jose resident Amanda Stoner. “I believe that only a proper fine will get people to make them understand that we are in a drought.”

Eighty percent of California is currently experiencing extreme drought. More than 400,000 acres of farmland are expected to be fallowed, thousands of people may be out of work, fish and wildlife species are threatened, and some small communities are at risk of running out of water.

Earlier this year, meteorologists predicted a drenching El Niño might break the stubborn drought, but those predictions have since been downgraded, leaving Californians wondering if and when the dry weather will ever let up.

The Dublin San Ramon agency has already imposed more stringent water use restrictions on its customers than what the state has proposed. So far, the district has fined 45 violators and sent out warning letters to roughly 500 first-time offenders.

The Contra Costa Water District has no plans to ask police for help enforcing its mandatory water use restrictions this year because water wasters typically shape up when contacted by the district, spokeswoman Jennifer Allen said.

So far this year, the district scolded 200 customers, mostly for watering lawns during the day, and only four of them needed a second call from a water district official before stopping, Allen said.

In Berkeley, peer pressure has become a powerful tool to stop people from wasting water, said Andy Katz, the East Bay Municipal Utility District’s board president. “It’s pretty obvious when people aren’t doing their part,” he said.

Despite not facing mandatory water use restrictions, the 1.3 million people in the public East Bay water district have reduced their water use this year by more than 10 percent compared with last year.

Elsewhere in California, however, Brown’s calls to reduce water use voluntarily haven’t gone over smoothly. Some Bay Area water districts have seen reductions of as little as a single percentage point.

Contact Jessica Calefati at 916-441-2101. Follow her at Twitter.com/calefati. Read the Political Blotter at IBAbuzz.com/politics.