The Davidson River Project

The Davidson River, situated in Pisgah National Forest, NC, is historically a fairly healthy and relatively undeveloped river. While the North Carolina Department of Environmental Quality (NCDEQ) biological monitoring program assesses the health of this river for statewide management purposes, members of Pisgah Chapter Trout Unlimited (PCTU) and the United States Forest Service (USFS) have been interested in a much more in-depth survey of the macroinvertebrates of this river.

Volunteer monitoring was first conducted in 2002, followed by a study by Marchal in 2003.  The 2018 study is the next follow up assessment. Nine sites along the Davidson River within the National Forest were surveyed, 8 of which were the same as for the study by the volunteer monitoring team in 2002 and Marchal in 2003; one site that essentially replicates another was replaced with a site immediately downstream of the fish hatchery to determine the effects of the hatchery effluent on the aquatic insects.

The 2003 “Marchal Study” was conducted with an abbreviated version of the much more extensive North Carolina macroinvertebrate assessment protocols and identification to genus level for most macroinvertebrates (Marchal unpublished). Water chemistry and basic habitat parameter data were also collected.

In 2016, PCTU decided to conduct a survey as a follow-up of the work by Marchal. Of special concern were the effects of the fish hatchery effluent, as previous surveys did not include any monitoring immediately downstream of this nutrient source.

The results show that the Davidson River within Pisgah National Forest continues to support a diverse community of macroinvertebrates, with some evidence that the fish hatchery effluent is negatively impacting the biota immediately downstream but recovering quickly as it flows. Some rare taxa were collected, indicating the river is a refuge for these insects. Future conservation efforts should be focused on maintaining the ecological integrity of the river and improving it by reducing or minimizing the impact of the hatchery effluent and other stressors.