The vision to create a 550-mile trail around the San Francisco Bay is threatened by state park closures scheduled for this summer, trail advocates say.

The Bay Area Ridge Trail may not be the target of California state budget cuts, but because it runs through four state parks that are on the chopping block, advocates are worried about its future. As the July 1 deadline approaches on state park closures, the trail advocates say it’s still unclear how trail access, maintenance, and public safety will be handled, as well as what happens to long term prospects for connecting new trails to the loop.

“The goal is to connect the parks and leverage what we do have to make those connections,”said Dee Swanhuyser, the director of the Bay Area Ridge Trail’s North Bay section. “Our future ability to complete the trail is at stake.”

State parks spokesman Roy Stearns said he foresees no change in trail access in parks that remain open through partnerships with local volunteers and non-profits, as is the case with Samuel P. Taylor State Park. That Marin park, with its campground and 8.5 miles of Ridge Trail, was on the state closure list until the National Park Service stepped in with funding support for operations of the park, which borders part of the Golden Gate National Recreation Area.

The situation is murkier for segments of the Bay Area Ridge Trail that pass through parks the state still plans to close down, Stearns said. Those parks are: Jack London State Historic Park in Glen Ellen, Annadel State Park near Santa Rosa, Sugarloaf Ridge State Park north of Sonoma, and Benicia State Recreation Area.

“We have never, ever done this before and so there is no foundation to turn to that outlines how to do this, how it will work and what the outcomes may be,” Stearns said in an email.

In some cases it may be impractical to physically bar public access, while laws concerning federal funding and public trust doctrine on shoreline access may come into play to prevent full closures in others, as in the case of the Benicia State Recreation Area.

The Bay Area Ridge Trail was the vision of former National Park Service director William Penn Mott Jr., who imagined a continuous loop of trails connecting the ridgelines of the Bay Area. The first segments were dedicated in 1989, and it has since grown to 335 miles that pass through state parks, national park lands, open space district properties, and many private properties. If completed, the trail would connect over 75 public parks and open spaces.

Every year, hundreds of volunteers donate their time and energy to the trail’s completion. This kind of outpouring of support may come through for the state parks on the closure list as well. There are potential partners for all four of the parks containing segments of the ridge trail.

“I think our goal is to find ways to grant access, not curtail it,” said Stearns. “All of our supporters and partners will need to play some role in helping us do that.”