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North Shore Streamkeepers use 'spider excavator' to restore salmon habitat

The rare machine does whatever a spider can, which will help Lynn Creek’s salmon.

There’s an Amazing Spider-Man, of sorts, coming to the rescue of fish on Lynn Creek.

The North Shore Streamkeepers have brought in a rarely-seen spider excavator, which “walks” on four legs, to restore a once robust but now almost defunct piece of salmon habitat.

Paradise lost

Left to its own devices, a wild river will become scattered with logs, boulders and channels that create ideal conditions for fish to hide from predators, rest, eat and spawn. A side channel of Lynn Creek just north of Highway 1 once provided all of that. But the creek has been heavily manipulated by humans through logging, nearby development and armouring of its banks and today, the creek’s flow has changed, clogging the channel with gravel and choking it dry in the summer.

With the spider excavator, the Streamkeepers and their partners are now beavering away on an “engineered log jam” that should correct the creek’s flow.

“We're putting back some of the habitat that we’ve destroyed over the last 150 years,” said David Harper, an instructor in BCIT’s Ecological Restoration Program, a partner on the project. “We’re not going to solve the problem overnight, but this is one important step to help give a home for salmon when they come back to freshwater.”

The Amazing Spider-Man

Hiring a spider excavator costs more than double what it would to bring in a more familiar piece of heavy equipment on tracks, but Parker said there’s nothing like having the right tool for the job.

The spider excavator’s arm is much more sophisticated in how it can pick up and manoeuvre the hundreds of rocks and boulders into carefully selected positions. And because of its legs, this one can easily walk to where it’s needed while making minimal disturbance to the creek bed and banks.

“We carried 100 logs and boulders. You go walk on the paths and you wouldn’t know we were here, whereas if we would have went with 100 trips with a track excavator, we’d have a quagmire on both sides,” said Glen Parker, Streamkeepers treasurer. “They’re a very specialized piece of equipment. There’s only a handful of them in British Columbia.”

Paradise regained

When the project is complete, Parker foresees the channel as a “paradise” for salmonids once again. Every salmonid type except for sockeye salmon live and spawn in Lynn Creek and its tributaries.

“By creating an engineered log jam and re-wilding the river, we should be able to re-establish this. And this is some of the best salmon habitat on the creek. We’re looking at 'as good as it gets,' and this will be full of coho and steelhead as soon as it’s wet. They’ll be here,” he said.

The Streamkeepers volunteers have drummed up about $250,000 in grants, donations and in-kind contributions to make the Lynn Creek project possible, Parker said. The District of North Vancouver helped with the mountains of paperwork and permits. The City of North Vancouver contributed boulders dug up from the Harry Jerome Community Recreation Centre, and the Tsleil-Waututh Nation contributed some rocks of their own. North Vancouver-based engineering firm Northwest Hydraulics contributed all of the engineering work on a pro-bono basis, including building a 1/10th scale model of Lynn Creek in their lab to simulate the before and after configurations of the creek.

The work began on Aug. 1 when the federal fisheries window opened and will continue until Aug. 18.

Public spectacle

Because they have been situated between two very busy walking trails, Parker said they’ve had hundreds of passersby come inquire about the strange machinery manipulating boulders in the creek.

“The public support and the number of positive comments we’ve got is just unbelievable,” he said. “For the public to be able to see salmon in our community, it will give them a connection and perhaps it will have a positive influence across all of our salmon populations.”