These data depict the locations (only) of all Aquatic Macroinvertebrates Monitoring Locations study sites in the park. Great Smoky Mountains National Park (GRSM) contains over 3400 km (2000 mi) of pristine waterways. As streams drain the forested ecosystems of the Park, they integrate and reflect conditions in those ecosystems. Aquatic macroinvertebrates are subjected directly to changes in the physical and chemical conditions of the water, and because of this dependent relationship with the water they live in, aquatic macroinvertebrates are good indicators of ecosystem health. They are found in all aquatic environments, are less mobile than many other groups of organisms, and are of a size that makes them easily collectable. Moreover, benthic macroinvertebrates have been shown to be a cost-effective monitoring tool (Lenat 1988). Aquatic biota exhibit responses to a wide array of stressors, including those having synergistic or antagonistic effects. In the Smokies, these stressors include primarily acid deposition and forest changes due to exotic pest infestations. The overall goal of this program is to maintain a Park-wide system of benthic macroinvertebrate monitoring sites to track the environmental health of Park streams, and to detect and quantify changes in conditions. The specific objectives are: to develop long-term aquatic biota data for large streams; to determine correlations among macroinvertebrates, fish, habitat, and water quality monitoring data; and to develop baseline data on aquatic macroinvertebrates. When conducting a monitoring program, the main goal is to analyze long-term data to evaluate changes in condition, and progress toward meeting a management objective. The aquatic macroinvertebrate monitoring program in GRSM is designed to provide this data through repeated sampling over time to answer the question of whether or not a particular benthic macroinvertebrate population displays trends indicative of ecosystem stress. This data relates directly to many other Inventory and Monitoring components in the Park, particularly the fisheries and water quality programs. Additionally, this data provides a baseline dataset for many areas outside of the Park which may be experiencing greater impacts to their aquatic resources. Benthic macroinvertebrates represent an integral part of lotic systems by processing organic matter and providing energy to higher trophic levels; therefore, an understanding of the effects of anthropogenic, as well as natural stressors, on their distribution and abundance is critical for comprehensive impact assessment of streams and rivers (Carter et al. 2006). Changes in macroinvertebrate population relative abundances, life-history traits, and growth rates are sensitive indicators of perturbations and are routinely used when evaluating the impacts of pollution (Carter et al. 2006). The deleterious effects of acidic stream water, for example, are well established, primarily in terms of reduced numbers of species and individuals (Allan 1995). Direct physiological effects and mortality due to acidification and to the subsequent mobilization of toxic metals, have been observed among various groups of aquatic invertebrates (Burton et al. 1985). Indirect effects of acidification also occur, through behavioral responses and alterations of food availability (Allan 1995).