The Shenandoah Watershed Study (SWAS)

The Virginia Trout Stream Sensitivity Study (VTSSS)

Objectives of the SWAS and VTSSS programs  

(1)  to improve understanding of hydrologic and biogeochemical processes that govern ecosystem conditions in the forested watersheds of the Shenandoah National Park and the surrounding mountain region, and

(2)  to document and assess change that is occurring in these highly valued natural systems.

Text Box: The SWAS program is in its 25th year. It is the longest continuously conducted watershed research and monitoring program in the national park system.

Current SWAS data collection in Shenandoah National Park includes a combination of quarterly, weekly, and higher-frequency water quality sampling on 14 streams, continuous discharge measurement on 5 streams, and determination of precipitation amount and composition at 2 locations. Current VTSSS data collection includes quarterly water quality sampling on an additional 51 streams located mostly in the George Washington and Jefferson National Forests. The streams studied by the SWAS/VTSSS programs provide habitat for native brook trout.

Logistical and financial support for the SWAS/VTSSS programs is provided by the National Park Service, the Environmental Protection Agency, the Forest Service, the Virginia Department of Game and Inland Fisheries, and Trout Unlimited.

Major program findings

Due to the magnitude of ecosystem change that confronts our regionís forested mountain watersheds, an understanding of the processes and factors that determine biogeochemical conditions is critical for informed resource management. SWAS/VTSSS findings for Shenandoah National Park and western Virginia include:

…      Stream acidification is a continuing problem in the regionís forested mountain watersheds.  Despite recent reductions in acidic deposition and evidence for recovery in other regions, chronic stream acidification in continuing on a regional basis in western Virginia.

…      Stream acidification may have stabilized in Shenandoah National Park.   Recent analysis provides some evidence for recovery from acidification in Park streams, although the degree of recovery is small in relation to historic acidification and in relation to surface water recovery observed in other regions.

…      Regional model forecasts indicate that current and prospective air pollution control programs may be insufficient to achieve biologically significant recovery and prevent further stream acidification.  Due to depletion of basic materials in watershed soils, stream acidification will continue to be a problem even if reductions in acidic deposition are much greater than will be achieved by implementation of the Clean Air Act Amendments of 1990.

…      Geology accounts for much of the variation in regional response to acidic deposition.  The acid neutralizing capacity of Virginia mountain streams is closely related to watershed bedrock type. Acidification effects are most pronounced for the subset of watersheds associated with sandstone and quartzite, which includes one-third to one-half of the watersheds that support native brook trout.

…      The integrity of fish communities in regional mountain streams is related to stream acidification.  Research in Shenandoah National Park has shown that as streams acidify they lose fish. Less-acidic streams have higher fish species diversity, more-successful fish reproduction, and healthier fish.

Contribution to regional assessments

The SWAS and VTSSS programs have proven essential for environmental analysis in the central and southern Appalachian mountain region. Information obtained through the SWAS and VTSSS programs has provided a strong scientific foundation for interpretation of the generally less-intensive information available for the larger region. Examples of regional environmental assessments that have relied on SWAS/VTSSS findings include:

…      The National Acid Precipitation Assessment Program ñ 1990

…      The Southern Appalachian Assessment ñ 1996

…      Current and Projected Status of Coldwater Fish Communities in the Southeastern US in the Context of Continued Acid Deposition ñ 1998

…      The Southern Appalachian Mountain Initiative ñ 2002

…      Assessment of Air Quality and Related Values in Shenandoah National Park ñ 2003

…      Response of Surface Water Chemistry to the Clean Air Act Amendments of 1990 ñ 2003

 

 


More information concerning the SWAS and VTSSS programs is available at:   

swas.evsc.virginia.edu