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Dead in the Water
They're a hazard to boaters and swimmers. But drowned forests may also be a great untapped resource

Photo of Sawfish submerging

A three-ton robot armed with a chain saw is loose beneath the placid surface of Lois Lake, a reservoir 10 miles southeast of Powell River on the Sunshine Coast of British Columbia. No, it's not a runaway from a low-budget movie set. It's Sawfish, a 12-foot-long submersible, powered by a 40-horsepower electric motor, which promises a novel way to spare old-growth trees by harvesting underwater timber.

Submerged trees like those in Lois Lake are the remnants of forests that disappeared from view when valley floors were flooded deliberately behind hydroelectric dams. Although the flooded timber dies, cool water temperatures and the lack of oxygen preserve it from decay. Still in perfect condition, the drowned trees present an environmentally attractive alternative to conventional logging. The contrast is starkly visible on Lois Lake, where the surrounding mountain slopes are disfigured by logging operations.

An estimated 200 billion board-feet of high-quality timber are thought to be standing on reservoir floors behind the world's 45,000 major dams. That's more than six times the amount of timber harvested each year in the United States. Ultimately, Triton Logging of Vancouver Island, the company that designed Sawfish, believes its submersible could save about 20 million live trees in British Columbia alone. Triton's president, Chris Goodsall, estimates the province holds more than $800 million worth of flooded timber, all of it unreachable by current harvesting methods.

Although some logging companies have used commercial divers to harvest submerged trees, diving is expensive, slow, and dangerous. So Triton came up with the idea of a remote-controlled submersible to do the job, launching the patented Sawfish on Lois Lake in August 2003. Capable of operating in up to 1,000 feet of water, Sawfish can cut up to 10 trees an hour. That's somewhat slower than conventional harvesting techniques, but each dead tree harvested by Sawfish can be another live tree saved.

On-board cameras and sonar readings allow operators on the surface to snuggle Sawfish up to a tree. Then, using its pincerlike grappling arms to grasp the base of the tree, the robot attaches an inflatable flotation bag to the trunk and cuts it down with a 55-inch chain saw. The robot currently carries 36 bags, so that many trees can be brought to the surface during a single dive. Once Triton's robotic team harvests and raises its load of Douglas fir, cedar, and hemlock from the bottom of Lois Lake, the wet logs are floated to a lakeshore landing where they are milled into high-quality lumber. While freshly cut submerged wood obviously has a higher moisture content than regular timber, it soon dries in the open air or in conventional wood kilns.

The wood that Sawfish harvests from Lois Lake will go toward the creation of a branded, eco-friendly line of certified forest products. Craftsmen especially crave this vintage wood, most of which is between 100 and 500 years old, because it is essentially the same age and color and has the same grain as that used by artisans in earlier centuries to create pieces we consider fine antiques today.

Sawfish's inventors don't claim their robot will bring about a paradigm shift in logging practices. Rather, the technology is "an ingenious way of salvaging valuable timber that would otherwise be lost," says Adrian Newton, a technical adviser to the Global Trees Campaign, which focuses on trees as flagship species for conservation of ecosystems and landscapes.

For now there is only a single Sawfish in operation. But Triton plans to deploy at least 10 more Sawfish units within the next five years. The company has already received additional licenses from the British Columbia provincial government to operate Sawfish at two other locations -- Ootsa Lake, about 100 miles west of Prince George, and Kinbasket Lake, near Glacier National Park. Harvesting is due to begin at Ootsa Lake next summer.

Company president Goodsall is confident that the underwater robot/lumberjack idea will catch on more widely. So far Triton has fielded sales inquiries from Argentina, Malaysia, Ghana, Panama, and Laos, among others, and is prepared to sell the equipment and provide training once prospective buyers complete an evaluation of the harvesting potential. The company's business plan calls for the sale of 300 to 500 Sawfish units over the next 25 years. If Triton's projections are correct, Sawfishes could eventually save as many as 40,000 surface trees every month, giving consumers an environmentally friendly wood choice -- together with a touch of history and distinction. -- Douglas Page

Photo of a sawfish

Using its powerful pincerlike arms, Sawfish (shown submerging, left) can harvest trees with a diameter of up to 50 inches.

Photo of a sawfish

Lois Lake is the first of three in British Columbia where Sawfish has harvesting permits.

Photo of a sawfish

After it dries out, this vintage timber will be sought after by craftsmen.

Photos: Courtesy of Triton Logging

OnEarth. Fall 2004
Copyright 2004 by the Natural Resources Defense Council