The curse of sprawl may not disappear now that bold new growth rules have been laid down in Stanislaus County. But they are likely to slow a steady outward creep of houses on the fringe of cities, a familiar sight across the San Joaquin Valley.

The recent decision by the county's growth-regulating agency -- the region's first to embrace a particular type of farmland protection -- signaled a change of heart in some elected leaders. It's time we do more, they said, to set aside some of the planet's richest soil and slow the traffic and air pollution that bring us down.

A monumental vote? Perhaps. The test will come when a city puts forth an annexation request, which could take a while in this economic slump.

It's clear, however, that people far and wide with stakes in the struggle to safeguard farmland were watching.

"You are far ahead of other LAFCo's in the valley," the American Farmland Trust's Dan O'Connell told Stanislaus Local Agency Formation Commission members before their landmark 4-1 vote. "All eyes are upon you." Similar policies have been enacted in counties such as Napa, San Luis Obispo, Santa Clara, Ventura and Yolo -- but nowhere around here.

"You're right there on the cutting edge," John Gamper, director of land use for the California Farm Bureau Federation, said.

It's not the first time.

Last year, county leaders prevailed in a California Supreme Court dispute with home builders over the county's farmland mitigation policy. It requires that acreage equal to that needed for new subdivisions be permanently preserved for agriculture.

The new LAFCo policy requires that cities do the same when they apply to annex land -- often, hundreds of acres at a time. It's costly for cities and developers, which must arrange or pay to establish conservation easements, typically monitored by third-party land trusts.

Participating farmers are paid for not turning fields and orchards into subdivisions.

"I wanted a way for my son to afford (farming) in the future," said Tom Ulm, whose almonds, walnuts and grapes west of Modesto became protected forever in a deal with his parents before his father died in March.

"It's too bad you have to force (cities) to do this," Ulm continued. "We've got to preserve farmland." An option under the new policy enables cities to get around so-called mitigation, if they can persuade their voters to adopt growth boundaries limiting expansion for a certain time period. That idea was roundly debated by commissioners, a majority of whom approved it.

The only dissenting vote was not cast in opposition to farmland, but because that commissioner felt the voter exemption weakens the new policy.

It's a new day, some say, when no voting leader defends home builders.

With the vote, "We moved one rung up the ladder to making things better for everyone," said Allen Gammon, chairman of the Farmland Working Group. "Whether it's effective will depend on the next vote and the background campaigning and arm-twisting by those who want an exception."

The change in leaders' outlook might be a natural result of decades of private advocacy. Both avant-garde policies -- county and LAFCo -- came after voters in 2008 approved Measure E, a private initiative restricting subdivisions in unincorporated areas.

Denny Jackman, a former Modesto city councilman who championed Measure E after leaving office, lauded the decision.

So did his Measure E partner, Garrad Marsh, elected as Modesto's mayor earlier this year.

Interestingly, Modesto was among a majority of the county's cities opposed to the new LAFCo policy. Marsh said he didn't like it because some language is vague, but said he continues to strongly support farmland protection.

"I'm a believer," the mayor said. "I've said all along that mitigation is important to the future of our valley. Some say it's a job-killer, but it's a fallacy to think that it has any substantial impact on (cities') ability to develop." Hughson stood alone among the county's nine cities in its support of the vote. Leaders are well aware that Ceres and even Modesto are within striking distance, if those larger neighbors someday get greedy.

"We're one or two general plans away from being swallowed up, if we don't focus on preserving ag," said Hughson Councilman Matt Beekman.

Turlock City Manager Roy Wasden said he was heartened that LAFCo members exempted commercial and industrial growth from the new rules.

"That's an important distinction," Wasden said. "We want to preserve ag land, but we have to have economic growth that lifts us out of the Central Valley doldrums."

Ed Thompson, state director for the American Farmland Trust, said Stanislaus County's various farm-saving efforts suggest a realization that uncontrolled growth comes with a heavy price.

The vote "represents progress," Thompson said. So did Fresno City Council's unanimous vote last month to revitalize older neighborhoods, sparing some farmland, and an order that cities in Kings County shrink unreasonably large growth areas, he said.

On the other hand, policies in Madera and Tulare counties essentially endorse sprawl, Thompson said.

"I expect the conversation to get deeper" in Stanislaus County, Thompson said. "I'm hoping it's reaching critical mass, where we can have robust, purposeful, meaningful discussions on what the options are."

He and Waterford Mayor Charlie Goeken, who is chairman of Stanislaus LAFCo, appeared in Monterey as panelists at an annual conference for the California Association of Local Agency Formation Commissions. Their topic: "Sustaining Agriculture and the Regional Economy."

It's telling that Karen Ross, California's food and agriculture secretary, will deliver a keynote speech on the role of local agency formation commissions in protecting farmland, said CALAFCo executive director Bill Chiat.

He senses "growing interest in balanced growth that is driving LAFCo's to think about their ag policies," with Stanislaus as the latest example.