The Contra Costa County Board of Supervisors voted 4-1 on Tuesday to approve the Tassajara Parks development, bringing 125 homes to 30 acres east of Blackhawk and moving the urban limit line, and securing acres of open space in the Tassajara Valley.

Supervisor Candace Andersen, whose District 2 includes Danville -- which officially opposes the project -- was the only board member to dissent.

Local officials were out in force speaking on either side of the issue during two hours of public comment. Representatives from the city of San Ramon, East Bay Regional Park District -- the beneficiary of 727 acres of the project site -- Save Mount Diablo and others, supported the project. The San Ramon Valley Fire Protection District, which will receive seven acres of land in the deal for a training facility, also voiced support.

Lining up against the development were representatives of East Bay Municipal Utility District -- whose board formally said on June 8 it does not have adequate water for project -- the Sierra Club, the town of Danville, former county Supervisor Donna Gerber, and others. The county's own planning commission also recommended the supervisors deny the project.

Supervisor John Gioia, a former EBMUD board member, said he understood the water issues, but approval means what is likely the largest land donation, at least as far as ratio of preserved to developed acreage, in county history: 24 acres to 1.

"To me, what this really comes down to is can we put a stop to the decades-long battle to develop the Tassajara Valley in a significant way," Gioia said.

"It seems like it is in the public's interest to approve development on 5% of the property, with nearly 95% dedicated to the park district," said Gioia, whose district includes West Contra Costa County. "If we did not approve this, there would be continued development pressures in the valley."

Danville officials said the environmental impact report isn't adequate and the town wasn't included in the process. Andersen, a former member of the Danville Town Council, said she would prefer that voters decide whether to move the urban limit line.

"I also have very, very strong reservations about certifying an EIR when we do not have water," Andersen said.

Instead of offering 15% of the units for lower-income housing, as mandated by state law, developer FT Land LLC will pay the county $484,000 so affordable housing can be built elsewhere in the county.

Gioia asked the board to impose a few more conditions on the project, including the county refusing to issue building permits for the project if EBMUD has declared a water emergency requiring 20% conservation from customers. As of the date of the meeting, EBMUD was asking customers to conserve at least 10%. Gioia also asked the developer to build homes that run only on electricity rather than natural gas.

Last month, EBMUD's board officially declared "the district has not planned to serve the project and does not have adequate water supplies to support the proposed annexation of the project into the district's service area."

Instead, the developer would fund off-site, accelerated conservation measures to mitigate the water demand of the 375 people anticipated to live in the development. A county staff report says development can't proceed without water agreements in place. Homeowners will face water limits as enforceable provisions of the project's covenants, conditions and restrictions.

The residential area, which is limited to parcels north of Camino Tassajara, will also include a community park. Lot sizes will range between 5,000 and 12,744 square feet.

The project was bigger when first proposed in 2007, under the name New Farm. The scope has since shrunk from a planned 185 homes on both sides of Camino Tassajara, surrounded by working orchards and vineyards. That plan drew considerable opposition from environmentalists before being changed.