A decade ago, Annie Roberts bought what her tax preparer jokingly called “a swamp” — the mucky tidelands beneath Raab’s Lagoon off the northwestern edge of Maury Island.

Fearful that it could be developed or destroyed, she snatched up the tidelands when a development company that owned it went bankrupt and the land went into foreclosure. But it was a stretch for her, and when a balloon payment came due a few years ago, she had to borrow money from her father to hang on to it.

Now, Raab’s Lagoon stands as one of the crown jewels of a multimillion dollar conservation effort by King County, the Vashon-Maury Island Land Trust and the Cascade Land Conservancy. For the last three years, King County and the land trust have used $7.5 million in federal and county conservation funds to purchase tidelands and marine habitat along Quartermaster Harbor, one of the biggest efforts at marine conservation on the Island in decades.

All told, the county purchased 57 properties totaling 143 acres and conserved 1.75 miles of beach. At Raab’s Lagoon, the county now owns about 15 acres, including Roberts’ bottomland and a grassy expanse at the mouth of the inlet that serves as a picture-perfect picnic spot. Roberts, who lives with her twin daughters in a home perched above it, said she’s amazed by the turn of events.

For years, she’s been one of the lagoon’s biggest advocates, reminding her neighbors of the importance of the fragile wetlands that fringed it. She was called — not always fondly — “the queen of the lagoon.”

“It’s turned out beautifully,” she said of the county’s purchase of her land earlier this year. “I couldn’t have dreamed of a better ending.”

The public money was initially pulled together from various conservation funding pots several years ago as a down payment to buy out Glacier Northwest’s 240 acres on the eastern flank of Maury. Glacier’s corporate parent, however, asked for nearly 10 times what the county and others were able to secure and ultimately declined to negotiate, forcing the county — close to reaching a deadline for the money’s use — to direct the money elsewhere.

With the support of the Vashon land trust and the Cascade Land Conservancy, county officials decided to purchase the best shoreline and marine habitat they could find on other parts of the Island, focusing largely on Quartermaster Harbor.

It’s been hard going, said Tom Dean, the land trust’s executive director. Conservation groups like to work on large land deals — one big site that reflects a significant conservation win. Instead, the land trust — which has helped to locate and facilitate each of the deals — has had to piece the effort together, one small parcel at a time, Dean said.

“This is the hard way to do it, the risky way to do it,” he said. “You end up trying to knit together a landscape that has been pixelated by severe platting. It just means it becomes a very, very long view. It’s not an instant success. It’s a process.”

It was also disappointing to conservationists not to see the money go towards purchasing Glacier’s site — the controversial sand and gravel pit that the corporation wants to expand dramatically. Erik Steffens, formerly a project manager for the Cascade Land Conservancy and now with The Nature Conservancy, said the Glacier property contains a remarkable stretch of beach that he and others would love to see protected and preserved.

“In total, the county was able to protect more shoreline that is probably as, if not more, ecologically important,” he said. “However, they’re segmented, they’re smaller pieces, fragments of a larger landscape, while Glacier has a lengthy piece of shoreline that’s in decent shape.”

“It’s the way to connect the dots,” he added. “You start small and work up. Unfortunately, there are very few large pieces left.”

The county has purchased shoreline and uplands habitat at several sites: Inspiration Point, Manzanita, Northilla, Piner Point, Neall Point, Dockton Park and Raab’s Lagoon. In each case, conservation officials have sought to find parcels that provide habitat for the animals that form the basis of the marine food chain: surf smelt, sand lance and herring, the so-called forage fish that support a range of other species, from salmon to killer whales.

Quartermaster is a particularly important part of the central Puget Sound region; its eelgrass beds support the best herring stock in the region.

“There’s a reason orcas come down past Vashon and to the narrows in the winter; it’s because there’s still food to eat down here,” Dean said.

Quartermaster is not pristine, he noted. Failing septics along the bay have fouled many of its beaches. But the land trust is also working to protect Judd Creek, the Island’s largest stream and the biggest source of freshwater into Quartermaster. The creek’s protection, Dean said, helps to ensure that it continues to flush clean water into Quartermaster.

“It’s a small Island. It all ties together,” he said.

County officials said they’re pleased by what they’ve accomplished with

the Maury Island Conser-vation Initiative, as they dubbed the effort. With so much attention focused on Puget Sound and its health, they opted to direct their money towards protecting and restoring the natural processes that are considered vital to shoreline and near-shore health, said Lori Larkin, the Vashon Basin Steward for the county’s Department of Natural Resources and Parks.

That meant buying what she calls “feeder bluffs,” the eroding banks that provide sediment for beach replenishment, and protecting those stretches of shoreline with “drift cells,” long currents of water that create habitat by depositing sediment at key points along the shore. Such processes, in turn, help to ensure that fish such as the sand lance and surf smelt have the sandy beaches they need to lay their eggs.

“You have to have the processes in place to create a beach. In my mind, that’s the big success of this project,” Larkin said.

“Beaches over time can go away,” she continued. “And you need the beach. You need the sediment. … You need that whole nearshore process to remain intact. And when it doesn’t, species … begin to decline, and that’s one of the reasons we’re facing a declining Puget Sound.”

Dean, standing at the mouth of Raab’s Lagoon last week, said he’s particularly pleased by its addition to the constellation of preserves and parks on Vashon. A county sign welcoming pedestrians to the preserve at the end of Kingsbury Road S.W. is already in place, and a new gate keeps vehicles from driving onto a grassy swath near the lagoon’s mouth; once a known party site, it’s become a place for birdwatchers and picnickers, he said.

The site is rich in Island history, Dean noted. An old weir at the mouth of the lagoon once supported a wooden bridge — part of the original boardwalk road that went from north Maury Island to Dockton. The weir’s remains are still in place, keeping the lagoon from turning into a mudflat, and a remnant of the old road that once led to Dockton can be seen on the other side of the lagoon’s mouth.

Here, too, is excellent tidepool habitat, he noted; colorful purple and orange sea stars clung to the wooden braces that formed the weir.

It’s also popular with people. Despite rain on this particular day last week, Matthew Poffenbarger and Brenda Stewart, visitors with ties to Vashon, played with their dog at the mouth of the lagoon, watching it dive for sticks. They paused to ask Dean about the new sign and the area’s designation as a park, then smiled happily at the news.

“We’re not trespassing anymore,” Poffenbarger said before throwing the stick for his dog again.