When Will Macdonald goes before a Boy Scouts’ review panel and is asked to name the biggest challenge he faced in completing his Eagle Scout project, he has no doubt how he’ll answer.

It’ll be the time the materials for his project disappeared.

“It’s definitely a major setback,” he said Saturday.

Macdonald, a junior at Vashon High School, was poised to begin the final push in his ambitious project, the capstone in his effort to secure an Eagle Scout badge. Under the guidance of Scout leader Steve Kicinski, Macdonald planned to build an open-sided yurt that would serve as the school district’s outdoor environmental classroom, situated next to a retention pond in the expansive woods between Chautauqua Elementary School and McMurray Middle School.

But when he went to his building site next to the pond a few weeks ago, he found his 20 9-foot-long Douglas fir logs — the framework to the structure — had vanished.

He had already skinned a few of them. They were cut to length and carefully stacked. To those familiar with the situation, it seems clear the logs were stolen, likely for firewood.

“I feel disappointed and pretty let down,” Macdonald said of the heist. “I have another source for logs, so it’s not the end of the world. But it’s going to be a hassle to get them.”

The logs will now likely come from a forest near Enumclaw, rather than the Chautauqua woods, which were recently thinned. Kicinski said that, too, is a disappointment. The idea of the project was to have a light carbon footprint and use logs from the site to build the small yurt.

“We were trying to use (the logs) as an ecological lesson,” Kicinski said.

Even so, he and Macdonald are moving forward, determined, both said, to see the project to fruition.

Kicinski came up with the design for the yurt, an artful-looking, tapered structure that will have a Plexiglas roof and be big enough for one classroom to gather in. “It’s a really beautiful structure and will blend in with the woods,” Kicinski said.

Macdonald’s role is to use the logs to create the tapered sides, placing the logs on concrete footings. Kicinski and others plan to help him in the complex project; Kicinski will install the dome over the top.

The project is part of a bigger effort to transform what was at one point just a utilitarian retention pond into a place of beauty and ecological interest, said Dave Wilke, the school district’s facilities director. With the help of a King County ecologist, the school district designed what Wilke called a “living pond.” Work crews have removed invasive plants and installed native ones. Students have tested the water quality. A bio-swale was installed to help filter the run-off that goes into the pond.

Today, the pond is already bursting with life. Buffleheads and other ducks gather there; frogs and salamanders are abundant. And once Macdonald’s project is completed, the pond — already a destination for science teachers and their students — will become an even greater academic asset, Wilke said.

“It’ll definitely bring the area to where we want it to be,” he said.

As for Macdonald, he’s taking it all in stride. “It’s going to be a hard project. But with the help of others, it shouldn’t be too bad. I’ll get it done,” he said.