Forest Detectives Solve Asheville Watershed Mystery


EFETAC ecologist Bill Hargrove (left) meets with Lee Hensley from the Asheville Water Resources Department. Photo by USDA Forest Service.

Scientists with the USDA Forest Service Eastern Forest Environmental Threat Assessment Center (EFETAC) headquartered at the Southern Research Station in Asheville, North Carolina, recently discovered an area of damaged trees within the watershed from which Asheville draws most of its water supply. Though monitoring forest health is an everyday role of the Forest Service, what makes this event unique is that the scientists made the discovery from their desks using a satellite-based forest monitoring and assessment tool called ForWarn.

ForWarn was developed with the Forest Service Western Wildland Environmental Threat Assessment Center, NASA Stennis Space Center and other federal and university partners, including the University of North Carolina Asheville National Environmental Modeling and Analysis Center. EFETAC scientists use ForWarn to detect and track potential forest disturbances across the lower 48 United States. On June 8, while comparing current map images of the Asheville area with those from a year ago, EFETAC scientists picked up the first signs of unusual forest activity in the Asheville watershed, which encompasses almost 18,000 acres that include nationally significant forest ecosystems and 15 miles of the Blue Ridge Parkway corridor.

EFETAC scientists couldn’t immediately determine the cause of the disturbance, but they ruled out late frost and cold air and thought damage from insects or disease also unlikely. They contacted the Asheville Water Resources Department to notify them of the findings, and on June 14 ecologists William Hargrove and Steve Norman went out to the watershed with Lee Hensley, the Departments water production maintenance supervisor, where they observed shredded leaves and damaged branches—signs of severe hail damage from a storm that likely occurred on or around May 8.

Before the visit and despite the relatively intensive management of the watershed, Water Resources Department personnel were unaware of the hail storm or its significance in the watershed. “The branch wounds were particularly impressive, and suggested that the hailstones were at least the size of a quarter,” said Hargrove. “We also saw a place across the watershed where trees had not even leafed out much at all since the storm.” 

Almost 18,000 acres of forest make up the Asheville watershed. Photo by USDA Forest Service.

According to Norman, Asheville’s high quality water is more than what comes out of the tap; it reflects success at keeping the forested watershed healthy. “Our ForWarn monitoring is designed to watch out for that, and we solved a bit of a mystery in this case by examining available evidence and working with folks on the ground.”

ForWarn’s monitoring capabilities are connecting research and advanced technology with natural resource management to sustain healthy forests and the essential services they provide to millions of Americans, including the residents of Asheville who depend on a source of clean and abundant water originating in this watershed.

Access ForWarn.

ForWarn is the result of ongoing cooperation among federal and university partners. In addition to the Forest Service, NASA and NEMAC, partners include the U.S. Geological Survey and the U.S. Department of Energy Oak Ridge National Laboratory.

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