region and adjacent upland areas, including Shenandoah National Park.

The key components of this work, the Shenandoah Watershed Study and Virginia Trout Stream Sensitivity Study (SWAS/VTSSS), constitute a combined watershed studies program that serves to improve understanding of and identify change in the hydrologic and biogeochemical change in this geographic region, which is recognized as a transition zone with respect to forest and stream health, as well as other watershed conditions subject to alteration by both natural and anthropogenic stressors.

A continuing emphasis of the program is evaluation of regional surface water and landscape response to air pollution reductions achieved due to Clean Air Act and other regulatory requirements.

The emphasis of SWAS/VTSSS data collection has been surface water composition, which serves as both an indicator and integrator of watershed responses to stressors.

The program accounts for both spatial and temporal variation among regional watersheds through a study-site selection strategy based on differences in landscape properties and through data collection at different frequencies.

This year’s (2009) efforts will contribute to the objectives of the SWAS/VTSSS watershed studies program by providing funding for the VTSSS component of the program to the UVA’s Department of Environmental Sciences to continue the framework of integrated hydro chemical data collection and analysis maintained through the project 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 (SNP).

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 work will be accomplished by:• Continuing the 20-year chemistry record for 66 western Virginia streams representing six geologically defined subpopulations of the larger biologically defined population of streams included in the 1987 VTSSS survey.• Maintenance of intensive data collection in Shenandoah National park, including long-term weekly and episodic sampling of streams representing geologically defined stream populations.• Conducting analysis of monotonic trends and status changes in the acid-base chemistry of individual sampled streams and the defined populations of streams.