A Multi-Scale Program to Assess Change in the Acid-Base Chemistry of Streams in the Mountains of Virginia

Research during the last two decades has shown that the regions of the United States most at risk from continued acidic deposition are located along the Appalachian Mountain chain. Surface waters associated with upland forested watersheds in the mid-Appalachian region are especially vulnerable to future acidification due to the coincidence of elevated deposition and sensitive ecosystems with delayed-response characteristics. Thus, for the purpose of evaluating surface water response to changing levels of atmospheric deposition, the mid-Appalachian region warrants a high prioritization of research and monitoring resources.

The proposed program will maintain an existing framework of integrated hydrochemical data collection for comparatively undisturbed, forested upland watersheds in the Ridge and Valley and Blue Ridge Physiographic Provinces of western Virginia, including watersheds in Shenandoah National Park. The broad objective of the program is to support assessment of change in the acid-base chemistry of surface waters following enactment of the Clean Air Act Amendments of 1990. The specific objective is to determine temporal trends and status changes in the acid-base chemistry of streams in the region that support reproducing populations of the indigenous brook trout. This will be accomplished by:

1. Re-sampling (in the spring of 2000) the 344 streams included in the 1987 Virginia Trout Stream Sensitivity Study (VTSSS), a near-census survey of the identified brook trout streams in the western Virginia region.
2. Continuing the 11-year quarterly chemistry record for 64 streams representing six geologically defined subpopulations of the larger biologically defined population of streams included in the 1987 VTSSS survey.
3. Maintenance of intensive data collection in Shenandoah National Park, including long-term weekly and episodic sampling of streams representing geologically defined stream populations.</li.