There are patches of brown scattered between the manicured lawns, fountains and lion statues behind the gates at Blackhawk, the exclusive vicinage of 2,400 homes outside Danville where curb appeal is both a right and an obligation.

Four years of drought have transformed this biosphere of wealth into something a little less than immaculate, with some homeowners actually letting their lawns turn brown in an effort to conserve precious water.

But enough is enough, declared the Blackhawk Homeowners Association, which issued a letter to residents saying that, as of June 1, “beautiful landscaping” will again be required. Residents should keep a healthy lawn, it said, or hire a contractor to rip the grass out in favor of drought-tolerant landscaping.

The letter, which expresses concern about property values, is an example of how some exclusive enclaves have grown weary of the drought’s assault on aesthetics, especially after some decent El Niño rains.

The edict, though, may be illegal or at least unenforceable under the drought emergency declared by Gov. Jerry Brown and a 2014 law written by Assemblywoman Nora Campos, D-San Jose, who said homeowners’ associations “shouldn’t punish people who are doing the right thing.”

“The Board is initiating aggressive enforcement of the landscaping standards,” stated Mark Goldberg, Blackhawk’s community manager, in a March letter to the gated community’s 9,354 residents.

In case folks doubted his seriousness, he threatened fines and even litigation if people do not comply with the order.

“It is no accident that Blackhawk is widely viewed as the premier community in the East Bay, and it is the responsibility of all residents to maintain that reputation,” wrote Goldberg, who declined to be interviewed. “We believe there is no longer any reason that all landscaping in the community cannot flourish as it once did.”

Drought not over

It was, to some residents, a surprising declaration given that state water resources officials have not declared the drought over.

Under Campos’ legislation, homeowners’ associations cannot fine residents for cutting back on watering or require them to replace their lawns or overhaul their landscaping during a state or local drought emergency. Gov. Brown also signed an executive order in 2014 that prohibits homeowners’ groups from fining members for brown lawns.

David Rose, an attorney for the State Water Resources Control Board, said his agency or the local water supplier can issue fines of up to $500 a day to homeowners’ associations that violate the prohibition.

But there are caveats, according to James McCormick, an attorney in Encinitas (San Diego County) who specializes in homeowners’ association regulations. He said the groups can still fine residents for breaking rules on unsightly vegetation as long as the problem doesn’t have anything to do with water.

“The nuance (in the law) has to do with homeowners who are using the statute simply not to maintain their lawns,” he said.

Below-average snowfall

California officials have been urging continued water conservation. Rainfall in Northern California was average this winter, but snowfall in the Sierra was below average, leaving some reservoirs full and others still hurting for water. Pardee Reservoir, which serves some 1.3 million East Bay Municipal Utility District customers in Alameda and Contra Costa counties — including Blackhawk — is 97 percent full.

The district’s customers have cut water use 16 percent since January compared to the same time frame in 2013, state records show. And now is no time to start slopping water around again, especially since the state is seeking a 25 percent overall reduction in water use, said Tracie Morales-Noisy, a district spokeswoman.

It is still illegal for any Californian to hose down a sidewalk or soak landscaping to the point that water runs into the street. Homeowners in the East Bay Municipal Utility District can water vegetation only two days a week.

Asked about Blackhawk’s mandate, Morales-Noisy said, “I think it would be ideal if communities waited until we have a better picture of what our drought condition is.”

Abundant water violators

The country club’s landscaping rules struck some nearby residents as curious considering the development’s multimillion-dollar mansions have featured prominently on the utility district’s water-violator lists, which call out homeowners who use more than 1,000 gallons a day in a two-month billing period.

“If you live in Blackhawk, you don’t worry about the water bill,” quipped Gene Gonzalez, 62, of Danville. “It’s like when you own a Mercedes, you don’t worry about the maintenance bill.”

The stereotype doesn’t totally hold true. In fact, Morales-Noisy said, Blackhawk’s operators have cut water use roughly in half since 2014 for their golf courses and common areas, thanks in part to installing drip irrigation and replacing especially thirsty landscaping.

“They have actually become one of our irrigation success stories,” Morales-Noisy said.

In its letter, the Blackhawk Homeowners Association urged residents to consult landscape architects and nurseries on drought-tolerant alternatives to lawns and, for those with dead or diseased grass, to submit an application by May 15 “showing what changes you propose to remedy this.”

A quick tour of Blackhawk this week found many lush green lawns, tropical plants and exotic trees, though some grass had turned brown. Other properties appeared to be in the midst of renovation, bringing in drought-resistant shrubbery.

Lisa Anderson, 55, who lives on Deer Ridge Place in Blackhawk, said she is happy to comply with greenery rules, but is having a hard time getting ahold of her gardener because so many of her neighbors are replacing their lawns, including one who covered what used to be grass with a circular driveway.

“I think it’s a great plan,” said Anderson. “They’re saying you can’t just leave a dead lawn.”

Not just lawns

Anderson said swimming pool leaks were a bigger problem in Blackhawk.

“Just about everybody I know has a pool, and the pools are older,” said Anderson, whose own recent leak caused her water bill to soar to about $450 a month before she had it repaired. “That’s a huge issue.”

Howard Klein, another Blackhawk resident, said he just finished planting drought-resistant plants in his yard.

“We haven’t been watering our lawn for a year,” Klein said. “Not everybody in Blackhawk uses 5 million gallons a day.”

San Francisco Chronicle

staff writer Kurtis Alexander contributed to this story.

Peter Fimrite is a San Francisco Chronicle staff writer. Email: pfimrite@sfchronicle.com Twitter: @pfimrite