Issue 5

Reducing the Impacts of Forest Roads

For the single greatest threat to water quality in the forest, look no further than the road that brought you in.

As long as there have been roads into the forest, those roads have dumped sediment runoff into forest streams, damaging water quality. Many forest roads are old; some date back more than 100 years. They’re often poorly planned and located, lying right along streambeds. According to environmental regulations and current best management practices (BMPs), they couldn’t be built today. Many are still unpaved. A recent study by scientists at the Coweeta Hydrologic Laboratory found that no less than 80 percent of the sediment found in forested watersheds was directly attributable to unpaved roads.

“Roads are the arteries that support most activities on the nation’s public lands,” says Johnny Grace III, research engineer with SRS Forest Operations Research unit in Auburn, AL. “Previous research in various regions has shown the impact of poorly planned and located roads on water quality. Future research needs to focus on methods and alternatives to reduce the impacts associated with the current road system.”

Coweeta scientists have spent a lot of time delineating the impact of forest roads. A 2002 study by researchers Barry Clinton and Jim Vose examined four different types of forest road surfaces, ranging from an unimproved gravel road to a 2-year-old paved road, to determine which type contributed the most sediment to the watershed. Studying more than 20 miles of roadway, Clinton and Vose measured the amount of total suspended solids deposited in nearby watersheds, using the results to rank road surfaces from least to most responsible for reductions in water quality.

The results were no surprise to scientists who’ve advocated for more environmentally sound forest roads for more than a decade. The paved, reconstructed road was the best, generating the least amount of contaminants. The unimproved gravel road was the worst, dumping the most contaminants into the water. Not surprisingly, they also found that the more traffic on those roads, the more sediment found its way into the watersheds.

Paving alone doesn’t do the trick, though. If you’re going to upgrade a roadbed to lessen its effects on the watershed, you should be armed with the best that we know about building environmentally sensitive roads. That’s where Johnny Grace’s work comes in. (...continued...)