Sonoma County supervisors unanimously endorsed a new financial policy Tuesday that will allow broader use of county open space funds to speed the opening of new local parks.

The move is meant enable cash-strapped park agencies to take ownership of thousands of acres of recreational land protected by the county's Agricultural Preservation and Open Space District and make the improvements needed to open those properties to visitors.

More than $42 million over then next 18 years now could be made available specifically for those efforts, including the costliest projects — parking lots, restrooms and trails — that in many cases have to come before public access.

The first test cases will be four properties, totaling over 1,100 acres and ranging from the coast to the Mayacmas Mountains overlooking Sonoma Valley, that the county's Regional Parks department aims to take on as projects over the next two years.

Supervisors said it was a timely decision, coming after a decade of significant land conservation success for the taxpayer-supported Open Space District but marked also by long delays finding partners to own and manage park properties.

Having access to many of those properties was a clear public priority when voters reauthorized the district's quarter-cent sales tax in 2006, supervisors said.

"It's about how to meet the intent of the (reauthorization) measure and the will of the voters," said Supervisor Efren Carrillo.

Though basically an accounting overhaul, the policy change represents what could be a pivotal shift for the 23-year-old Open Space District, pushing it into closer collaboration on park planning and development efforts.

That move could increase tension with some camps, including farming representatives who've questioned the district's greater focus on recreational land and also with rural landowners concerned about how open space is developed for visitors.

The policy change came especially at the urging of Supervisor Shirlee Zane, a district supporter who has turned critic of late, hammering on the backlog in unopened parkland and stopgap measures, including guided outings and special permitted access, the district has used in the interim.

On Tuesday, immediately after a staff presentation that kicked off the well-attended three-hour hearing, Zane launched into a five-minute speech about her concerns. She suggested that many of the district's projects, without public access, could amount simply to windfalls for wealthy landowners.

"The social justice issue for me, which is at the heart of this discussion today, is do we tax a low-income family for pair of children's shoes so we can pay a millionaire for the development rights on a remote property that isn't going to be developed anyway?" Zane asked.

District supporters later defended the agency's range of conservation projects, including easements protecting private farmland, watershed acreage and wildlife habitat not necessarily intended for recreation. Overall, district-protected lands now cover more than 106,000 acres.

Supporters said care will be needed in assessing which of the 6,400 acres the agency owns outright should be opened as parkland.

"We just want to urge everyone to work on these transfers happening in such a way that recreational uses don't degrade the other benefits that these properties bring," said Caitlin Cornwall, a biologist with the Sonoma Ecology Center.

Others echoed the call for accelerating park openings.

"Our residents deserve the chance to be outside sooner, not later, more often and closer to their front door mats," said Craig Anderson, executive director of LandPaths, a Santa Rosa group that has partnered with the district in land management and guided outings.

The district for years has engaged in efforts to jumpstart parks. The difference now is that it has a clear go-ahead to support capital projects for parks out of an operations and maintenance fund.

Voters in 2006 authorized expenditures from that fund to support initial public access, capped at 10 percent of district revenue. County projections show that amount at more than $42 million through the end of the current tax measure in 2031.

A side question — whether to count the district's $5.2 million that has been spent on capital projects on parks since 2006 toward the cap — was resolved without much opposition from Zane. She wanted to start the count at zero and go forward with $7 million allocated for park transfers by supervisors in June from the district's main pot of money. Instead, under a district proposal, the previous spending will be counted toward the cap, essentially reversing the $7 million allocation and making new projects dependent on current and future tax revenue from the operations fund. It currently has a surplus of $1.25 million.

"This has provided an opportunity for all of us to really have the conversation, to go over very carefully the details of what we've been doing, where we're going and trying to come up with some estimate of the cost of opening parks and how to get there," said Supervisor Susan Gorin.

District and county parks officials seemed to agree there was enough money to get started. Regional Parks Manager Caryl Hart ticked off a list of nine properties she wants to take on over the next six years, at a tentative development and startup cost of $16 million.

The four properties on the front burner include the 247-acre Lawson Ranch addition to Hood Mountain Regional Park east of Oakmont; 537 acres adjacent to Jack London State Park on the north slope of Sonoma Mountain; the 355-acre Carrington Ranch north of Bodega Bay; and a 16-acre wetland parcel on the Laguna de Santa Rosa off Occidental Road.

As with the recent opening of Taylor Mountain Regional Park, the process for each property is likely to take several years.

But Bill Keene, general manager of the Open Space District, called it a "great and important day" in the agency's history.

"What we're talking about today is getting land open to the public and that's a great thing," he said.