Underwater Logging: Submarine Rediscovers Lost Wood

As the world's thirst for wood grows and the resulting deforestation contributes to a wide range of environmental problems, one enterprising group has gone to a surprising location to search for more sustainable wood supplies--under the water.

A great amount of timber sank during log drives or was flooded during the construction of hydroelectric dams around the world. Although under water, the trees may be as good as new. One obvious--but dangerous and expensive--way to retrieve this "rediscovered wood" is to hire divers to run underwater saws. A second solution, uprooting the trees with a chain, mucks up the water and disrupts aquatic ecosystems.

Now Triton Logging, a firm in British Columbia, has come up with a third alternative: the Sawfish. This remotely piloted submarine--named for a relative of the shark that has a beak like a giant hedge trimmer--sports a long, electric-powered chain saw. Triton president Chris Godsall, who has a master's degree in business and sustainability, had worked salvaging individual sunken logs when he realized there was more to gain by salvaging whole drowned forests. The Sawfish, he says, represents "an arranged marriage of marine and logging technologies" that may offer a sustainable way to reduce the environmental impacts of logging and the attendant road building…

Underwater logging is possible because many submerged trees and logs are barely affected by their decades of submersion. Lake and river water is often too cold and too deficient in oxygen for decay organisms to survive. (Ironically, the above-water portion of trees often must be discarded due to degradation by sunlight and microorganisms.)
Studies of logs raised from Lake Superior show slight color changes, but "the properties are virtually the same as modern timber," says Terry Mace, who has studied underwater log retrieval for the Wisconsin Department of Natural Resources. And although sugars have leached from the Lake Superior logs, this effectively seasons the wood, making it highly desirable for use in musical instruments.

It's hard to pinpoint how many trees are available for underwater logging. Some underwater logs were sunk or otherwise lost during log drives on rivers, but the majority came from forests submerged during the building of dams. The number of large dams — those more than 15 meters high — has increased nearly sevenfold since 1950, reported the World Resources Institute in World Resources 2000-2001. And while dam building has decreased sharply in developed countries due to environmental considerations and a lack of good sites, it does continue elsewhere. Godsall estimates that about 35,000 square kilometers of forest worldwide have already been submerged by dams. In British Columbia alone, he says, about 20 million trees lay underwater…

With underwater logging, every acre of drowned trees that is chain sawed in a hydroelectric reservoir should translate into an acre of forest that's left standing. And that, in turn, could translate into significant environmental benefits for the world.

David J. Tenenbaum