Starting high up on the western slope of the Mayacmas Mountains, Stuart Creek drains a swath of Wine Country that remains mostly wild.
Mountain lions, bobcats, foxes and deer, along with other creatures, use the creek as a pathway across Sonoma Valley, moving from the rugged mountains in the east or from the wooded flanks of Sonoma Mountain to the west.
Now plans are under way to protect and restore much of the creek's length as a corridor for those migrating species, including the once-numerous steelhead trout.
It's an idea that began years ago and has picked up steam as housing and vineyard development have expanded in the valley along Highway 12.
Stuart Creek bisects the highway just south of the Arnold Drive intersection. The wide, natural-bottomed culvert makes it one of the few good places where wildlife can safely cross the busy roadway by passing under it.
A series of recent land acquisitions in the area by the nonprofit Sonoma Land Trust and pending projects to remove barriers in the creek and along its banks are geared toward preserving what conservationists say is a critical link in the regional ecosystem.
Such links are seen as increasingly important for wildlife that will have to move and adapt with climate change, scientists say.
"It provides us with the opportunity to do something that is really lasting," said Tony Nelson, project manager with the land trust.
The private organization in August purchased an undeveloped 14-acre property on the west side of Highway 12, across from its 234-acre Glen Oaks Ranch. It has protected two smaller creekside parcels downstream, totaling just over 3.5 acres, and is also working to purchase 40 acres of chaparral and woodlands at the creek's headwaters, just west of the Napa County line.
Together with other protected acreage, including the neighboring 535-acre Bouverie Preserve owned by Audubon Canyon Ranch, the deals have sewn up 50 percent of the watershed and provided direct access to 2.5 miles of Stuart Creek.
The area has been on conservationists' radar for decades and is one of only two wildlife corridors recognized in the county's general plan.
"It's a long-term effort," said Caitlin Cornwall, a biologist with the nonprofit Sonoma Ecology Center, which has been lobbying for protection of the area for nearly 15 years.
"The community can see the opportunity there to make that connection between Sonoma Mountain and the Mayacmas Mountains," she said.
Much of the habitat is in great shape, requiring little of the costly work to remove weeds and treat other problems, Nelson said.
Some old fences will be taken out to ease movement for land animals. Improvements for public access, including parking, benches and interpretive panels, are envisioned on one of the downstream parcels off Arnold Drive. The land trust already offers guided walks of its Glen Oaks Ranch.
The biggest challenge is how to deal with three manmade barriers that have for decades blocked upstream access for steelhead, which swim up Sonoma Creek from San Francisco Bay to spawn.
The obstacles include a culvert under a deteriorated wooden bridge alongside Arnold Drive that has scoured out a downstream pool, creating an impassable seven-foot jump for fish. Another is an old flash dam on the Glen Oaks Ranch.
With a $132,000 grant from the California Coastal Conservancy, the Sonoma Land Trust is drawing up plans for how to remove the barriers and modify the streambed to bring steelhead back.
Heavy machinery will be used in at least one spot, near the deteriorated bridge, to place big boulders in the creek and create a series of stairstep pools that fish can use to migrate upstream.
Construction, which could begin in mid-2014, is slated to cost up to $750,000, Nelson said.
Already the project is drawing notice. State and federal fish biologists have visited and shared their hopes on its success. And the Bay Area Open Space Council, composed of public agencies and private groups, this year named the Sonoma Valley Wildlife Corridor, including Stuart Creek, a key part of the larger link between the coast and interior mountains around Lake Berryessa.
Last month, another visitor to the creek provided what could be a good omen for its future. As Nelson looked on at a torrent rushing under the wooden bridge tagged for removal, a tiny rainbow trout flung itself into the falls and disappeared back into the pool.
"Did you see that?" he said. "Very cool!"
Such moments are remarkable even for a biologist with 20 years in land conservation. That makes the opportunity on Stuart Creek all the more rare, Nelson said.
"It's one of the more exciting projects I've been a part of," he said.
You can reach Staff Writer Brett Wilkison at 521-5295 or email@example.com.