American Scientist

To the Editors:

Doug Larson’s excellent Macroscope column “The Battle of Bull Run” (May–June 2009) points out the challenge of effective management of watershed forests. The best approach uses selective cutting, not clear-cutting, even in relatively large patches. Research at the U.S. Coweeta Hydrologic Laboratory in North Carolina more than 50 years ago showed that selective logging had the advantages of providing income to the forest while preserving quality in water runoff. This was accomplished as well on the Stamp Creek watershed in Chattahoochee National Forest in Georgia.

It’s vital that harvesting is conducted in ways that don’t impair watershed runoff. That demands that logger or landowner profit motives alone not drive forest management. Also, revenues from forest-product sales should be used for water-supply protection, including stream maintenance and other water supply system investments. Such arrangements put responsibility on the harvester to comply with water protection practices. Put another way, preserving a quality water supply should be the first priority.

The locations and species involved in the research noted above differ from those in Seattle. And it may be that some forest types will not fit these conceptual models. Still, some forests can be managed simultaneously to benefit both timber and water resources.

Peter E. Black
Emeritus, State University of New York Syracuse, NY

Dr. Larson responds:

Despite Dr. Black’s examples of compatibility between logging and water quality in carefully managed watersheds, Dr. Richard Fredriksen’s 1975 basic premise about watersheds in the Pacific Northwest still holds true: “Water quality is optimum from forestland when the forest on that land remains undisturbed and human entry is restricted.” Unfortunately, the U.S. Forest Service managed Portland’s Bull Run Watershed—the city’s principal drinking water source—as an ordinary tree farm.

Proving that logging and water quality are compatible requires scientifically valid water-quality monitoring. Bull Run logging proceeded for nearly a decade before minimal monitoring even began. By then, about 15 percent of the watershed had been clear-cut. More clear-cutting followed with no reliable means of assessing its effects on Portland’s drinking water.

In 1977, after the U.S. Congress wisely mandated a credible monitoring program, the Forest Service vowed that protecting water quality would be its “principal management objective.” But reviews by independent scientific commissions in 1979 and 1988 concluded that monitoring was still inadequate because it did not define critical cause-effect relationships between logging and water quality. Logging opponents scoffed at the notion that piecemeal deforestation of the watershed’s ecologically fragile system of streams, lakes and runoff surfaces would protect water quality. They urged the Forest Service to halt the logging, at least until sufficient data were collected. These data were never collected, however, and the logging continued.