PARENT SESSION
Poster Session #7: Resource Management and Risk Assessment.
Monday, August 5. Presentation from 5:00 PM to 6:30 PM. Exhibit Hall B & C, TCC

A watershed-level ecological risk assessment of nonpoint pollution sources in North Carolina.

Potter, Kevin^*,1, Schaberg, Rex², Cubbage, Frederick¹, ¹ North Carolina State University, Raleigh, North Carolina² Duke University, Durham, North Carolina

ABSTRACT- Change in the abundance of benthic macroinvertebrates, such as Ephemeroptera (mayflies), Plecoptera (stoneflies), and Trichoptera (caddisflies), is considered a good indicator of short-term and long-term alterations in stream habitat and water quality. We use a watershed-scale ecological risk assessment methodology to analyze and quantify the impact of nonpoint pollution sources on macrobenthic invertebrates inhabiting North Carolina streams, with an emphasis on forestry best management practices (BMPs). Forest harvesting activities contribute to water quality degradation through the runoff of sediment, nutrients, and other nonpoint pollutants; this is of particular concern in the Southeast, a region with extensive forestlands and high-quality aquatic resources. While the reported implementation of forestry BMPs is high throughout the Southeast, it is unclear whether these measures effectively protect aquatic biota. Such information is necessary to properly evaluate whether BMPs should be altered to better protect aquatic habitat in a cost-effective manner. The end result of this risk assessment is the creation of an empirical model describing the vulnerability of North Carolina stream macroinvertebrates to changes in nonpoint pollution sources, based on secondary land use change and macroinvertebrate abundance data. Our preliminary models, based on data collected at the eight-digit USGS Hydrologic Unit Code (HUC) level, use multiple regression analysis, where the dependent variable is change from the early 1980s to late 1990s in the average of two macroinvertebrate abundance metrics. The independent variables are change in forest cover, agricultural cover, urban cover, and precipitation. The preliminary models are significant, but explain only a modest amount of the variability in stream biota abundance for North Carolina's Blue Ridge Mountains, Piedmont and Coastal Plain.

KEY WORDS: stream, habitat, watershed, risk