SACRAMENTO — As California on Tuesday imposed its first-ever statewide rules to punish water wasters, a new survey showed why state officials say the drastic measures are needed: Californians actually increased their water use amid the worst drought in decades.

The new rules, approved by the State Water Resources Control Board on a 4-0 vote, impose new restrictions on outdoor water use starting Aug. 1 that could result in fines of up to $500 per violation.

Gov. Jerry Brown in January asked Californians to slash their water use by 20 percent. But a new state survey released Tuesday showed that water use in May rose by 1 percent this year, compared with a 2011-2013 May average.

The survey of 267 water providers by the water board found that water consumption in the Bay Area dropped 5 percent. But in coastal California, south of Santa Barbara, consumption rose 8 percent.

“California is in the worst drought we’ve seen in our grandparents’ generation or beyond,” said Felicia Marcus, the water board’s chairwoman. “Fields are going fallow. Thousands of people are going to be out of work. There are communities that are out of water — they’re bathing out of buckets and water trucks are coming in to help them.

“But many parts of California don’t seem to realize how bad it is,” she said, “because they are so far away from their source of water. We are all in this together, and this is not a time to waste water.”

The new rules ban washing cars without a nozzle on a hose; watering driveways or sidewalks; using potable water in ornamental fountains; and over-watering landscaping so that water runs off into roads and adjacent properties. Recycled water is exempt.

Under the new statewide rules, any agency that does not impose mandatory conservation measures could be subject to state fines of up to $10,000 a day. But it remained unclear Tuesday whether local agencies will be able to keep in place rules that don’t include enforcement or penalties.

Exactly how the new mandates will be enforced in the Bay Area, however, will vary widely, since enforcement is up to each city and local water district.

On Tuesday, the San Francisco Public Utilities Commission announced it will drop its voluntary conservation rules and set up a phone number for people in San Francisco to report water wasters. It also plans to send out staff members to write tickets — with a warning for a first violation — and impose fines, although the amounts have yet to be determined.

“We’re supportive of the state’s action,” said spokesman Tyrone Jue. “They are doing what they need to do to conserve water.”

The Contra Costa Water District, however, said it has no plans to change its rules.

In the spring, the district put in place such measures as a ban on watering lawns from 9 a.m. to 5 p.m. and a ban on hosing off driveways and sidewalks. But the rules are essentially voluntary, like they are at most other Bay Area agencies. The district has not been issuing fines to violators and is only telephoning or putting out door-hangers asking for compliance if somebody complains about a water waster.

“The enforcement is the outreach that we do for our customers,” said Jennifer Allen, a district spokeswoman.

The district asked for 15 percent voluntary water savings this spring, and from January to May its 550,000 customers cut back use by 8.6 percent, compared with the same period last year. But they have hit the 15 percent target in recent months, Allen said.

Many water agencies are reluctant to put in place fines and other penalties because it costs them millions of dollars in lost water sales, which could lead them to raise rates to make up the difference. Also, it is a political headache, experts say, and many Bay Area agencies in recent years already have broadened conservation and increased water supplies by expanding dams, developing underground storage or importing more water.

“For East Bay MUD or the Hetch Hetchy system or Santa Clara, they aren’t in terrible shape,” said Jerry Meral, former deputy secretary of California’s Natural Resources Agency.

“They feel like, ‘Why should we go through this?’ They don’t want to really hit people hard unless they really need to. On the other hand, they don’t want to look bad in front of the governor and the state water board. They are definitely schizophrenic.”

Reversing its original interpretation of state law, the water board said that the new rules also apply to private companies, such as San Jose Water Co., which provides water to 1 million residents of the San Jose area.

John Tang, a spokesman for the company, said officials there will decide in the next few weeks how to comply. He noted the company already has asked its customers to do most of the things the new state rules are requiring, along with only watering their landscaping every other day. But it has not issued fines or enforced the rules.

From Jan. 1 to April 30, usage by the company’s customers was down 2 percent from the prior year.

To put fines in place, as the company last did during the 1987-92 drought, San Jose Water will have to get approval from the state Public Utilities Commission, along with approval to raise rates to cover lost profits, which could take a month or so.

“The imposition of fines and penalties is not something any company takes lightly when it talks about wanting to provide exceptional customer service,” Tang said.

Why hasn’t the company already set up tough enforcement, like Sacramento, Santa Cruz, Pleasanton and other areas have?

“I don’t think our situation is nearly as dire as other parts of the state,” he said.

Water officials at the Oakland-based East Bay Municipal Utility District said their board will consider Tuesday how to comply with the rules. There may be higher “drought rates,” as in the 2008-09 drought, where residents pay more if they use more, said district spokeswoman Abby Figueroa.

The agency, which already has voluntary rules in place similar to the new state regulations, is encouraging people to water lawns no more than twice a week.

A 10 percent reduction in water use over the next year will cost the district $25 million in lost water sales, she said. The agency has asked for 10 percent savings but from January to May saw its customers in Alameda and Contra Costa counties cut use by 5 percent.

The meeting of the state water board Tuesday lasted nine hours. More than 200 people attended. Numerous water agencies asked for more lenient rules, including those in Humboldt and Placer counties who said their supplies are not dire. Some businesses also pleaded for exemptions.

“They’re saying you can’t pressure wash your house before you paint. You can’t remove graffiti from walls,” said professional pressure washer Dan Cosgrove of Welcome Building Maintenance in Concord. “I’m not sure they understand that.”

Paul Rogers covers resources and environmental issues. Contact him at 408-920-5045. Follow him at Twitter.com/PaulRogersSJMN.