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A dump truck and an excavator work on a hill near Johnston Road and Camino Tassajara. The land is part of San Ramon's plan to bring Tassajara Valley into that city's sphere of influence.
San Ramon's attempt to take control of one of the largest remaining undeveloped parcels in Contra Costa County has been delayed, after county officials said the city has not adequately addressed the impact of bringing more growth to the region.

The staff of Contra Costa County's Local Agency Formation Commission -- the body that ultimately will decide whether San Ramon gains control of the 4,900-acre Tassajara Valley -- says the city is going about it the wrong way.

A letter sent this week by the commission's executive officer called San Ramon's environmental plan for bringing the area under the city's sphere of influence "insufficient." The letter urges city leaders not to submit a completed application to the commission until a more detailed environmental study is done.

San Ramon's plan has alarmed its neighboring town of Danville, which fears Tassajara Valley development will bring more traffic through Danville.

Danville, the Sierra Club, Save Mount Diablo and the Greenbelt Alliance all have sent letters to San Ramon challenging the environmental report.

Danville opposes it on the grounds that it "completely ignores any mention of possible impacts on Danville," said Mayor Candace Andersen.

A worker in San Ramon Mayor H. Abram Wilson's office said Thursday that the city's planned March 11 public hearing on the environmental report has been delayed until May or June.

Wilson was out of town and could not immediately be reached for comment. City Manager Herb Moniz and planning chief Phil Wong did not return calls for comment Wednesday or Thursday.

Though San Ramon's environmental report says "no new development is being contemplated" in Tassajara Valley right now, both that document and the San Ramon General Plan make reference to possible "future development of the area," the Local Agency Formation Commission's executive director, Lou Ann Texeira, wrote in her letter to the city.

Development in Tassajara Valley would have "potentially significant" environmental effects, none of which are addressed in San Ramon's environmental report, she wrote. They include the possible "conversion of agricultural land, loss of open space, effects on utilities and service systems and impacts on public services," Texeira wrote.

San Ramon officials acknowledge the city's general plan leaves open the possibility of Tassajara development if the city gets control of the land. But council members have repeatedly said they have no intention of trying to develop the valley in the near future.

They point to the general plan, which first would require a citywide vote in 2010 to extend the city's urban growth boundary into the Tassajara Valley. If San Ramon voters agreed to broaden the city's sphere of influence, city officials then would have to craft, in cooperation with the county and Tassajara Valley landowners, the Eastside Specific Plan -- a theoretical development strategy for the area -- before any development could occur.

That plan would have to go through a public hearing process and could not be adopted without buy-in from nearby cities, San Ramon Councilman Dave Hudson said in response to Danville officials' claims that they are being left out of the planning.

"A sphere of influence change does not mean development. It does not allow any development whatsoever," Hudson said at Tuesday's City Council meeting. "Everyone knew we were doing this in the year 2010. This should not be a surprise. It has been in the public for about six years."

Crafting the Eastside Plan will be expensive and time-consuming, and it doesn't make sense to do it unless San Ramon leaders are certain the city will one day control Tassajara Valley, Moniz said in an e-mail to Danville officials this week. "Thus the time to plan is now."

But Texeira says San Ramon officials are "putting the chicken before the egg" in wanting assurances before crafting plans.

Even minus a Local Agency Formation Commission staff recommendation, San Ramon officials could submit their sphere of influence application to the commission as-is, Texeira said. Commissioners include county Supervisor Mary Piepho, who represents the San Ramon Valley, and her husband, David.

For many, the mere possibility of the county's voter-approved urban limit line -- which bars Tassajara Valley development until at least 2026 -- being trumped by a new San Ramon growth boundary in 2010 is frightening. It could happen if San Ramon voters change the city's urban limit line and the Local Agency Formation Commission agrees to let San Ramon annex Tassajara Valley, said county planner Patrick Roche.

"The county's and city's urban growth boundaries (carry equal weight) -- one is not greater than the other," Roche said. "Ultimately, the decision on the legal boundary of the city is a decision (the commission) will have to make."