Stream Monitoring Program
The Shenandoah Watershed Study (SWAS) was founded by Dr. James Galloway, Dr. George Hornberger and Dr. Roger Pielke, as a joint program between the University of Virginia Environmental Sciences Department and Shenandoah National Park (SHEN), to assess watershed response to elevated acid deposition in the central Appalachian region. In 1979, SWAS established its first site in SHEN for weekly stream water sample collection and analysis of acid-base chemistry and stream discharge monitoring. The water chemistry monitoring program was spatially expanded in 1987 with the initiation of the Virginia Trout Stream Sensitivity Study (VTSSS) which, in collaboration with the Virginia Department of Game and Inland Fisheries (VDGIF) (recently renamed Virginia Department of Wildlife Resources, VDWR) and Trout Unlimited (TU) citizen volunteers, sampled the majority of native brook trout streams (Salvelinus fontinalis ) in Virginia. Results from the state-wide trout stream survey determined that the chemical response to acid deposition is primarily mediated by underlying bedrock (Sullivan, Webb, Snyder, Herlihy, & Cosby, 2007; Webb, Cosby, Galloway, & Hornberger, 1989). This point-in-time assessment informed a quarterly stream water sampling scheme for a geographically and geologically/chemically stratified subset of 72 sites (Webb et al., 2004). Further spatial and temporal expansion of the SWAS program occurred in the early 1990’s in conjunction with the Fish in Sensitive Habitats (FISH) program (Bulger et al ., 1995), with 6 sites throughout SHEN sampled weekly by 1992. A subset of 3 weekly sites (hereafter ‘intensive sites’), representing the range of sensitivity to acid deposition, were selected for streamflow monitoring and event-based sampling necessary to assess high-flow chemistry/episodic acidification (Eshleman, Miller Marshall, & Webb, 1995; Hyer, Webb, & Eshleman, 1995). In addition to maintaining the episodic, weekly and quarterly sampling until present, the SWAS program further advanced temporal monitoring in 2014/2015 with the incorporation of in-situ high-frequency air and water temperature and conductivity sensors at the 3 intensive sites. The state-wide VTSSS water quality survey (hereafter ‘decadal survey’) has been repeated in 2000, 2010, and is planned for 2021. A timeline of the SWAS-VTSSS program is presented in Figure 1.