Virginia’s estimated 51,021 miles of streams and rivers contribute nearly 10 billion gallons of freshwater per day to the Chesapeake Bay (VDEQ, 2009) and support globally significant resources including the Clinch River in southwest Virginia, a biodiversity hotspot with more species of endangered and rare freshwater mussels than anywhere else in the world; and the Roanoke drainage, known for the most distinctive freshwater fish communities on the Atlantic Slope of the United States (VDCR, 2009). In addition to supporting these well-known natural treasures, Virginia’s waters also support public health, environment and economic growth for the Commonwealth’s nearly 7.9 million residents (US Census, 2009). As demand for water and the frequency of drought events increases, defining the unique set of beneficial water uses within each watershed and assigning the requisite in-stream flows necessary to sustain them is becoming an essential part of determining water availability – and maintaining healthy waters. 

The Commonwealth of Virginia is currently developing a “systems-based approach to integrated watershed assessment, protection and conservation” (U.S. EPA, 2009) as outlined by the U.S. EPA’s Healthy Watersheds Initiative. To assist in achieving this goal, the Office of Surface and Ground Water Supply Planning (OSGWSP) at the Virginia Department of Environmental Quality (DEQ) has designed a Water Supply Decision Support System (WSDSS) to provide a holistic approach to data acquisition, analysis and modeling. The WSDSS is currently used for water supply permitting and planning, specifically, to evaluate the cumulative flow altering effects of the full range of water supply activities: withdrawals, discharges and reservoir operation. 

With technical assistance from the U.S. Geological Survey, the Virginia Department of Game and Inland Fisheries, and academic experts from Virginia and the Mid-Atlantic including Virginia Commonwealth University, we propose to use extensive existing biological and hydrologic data, including the Virginia’s Interactive Stream Assessment Resource (INSTAR) and U.S. EPA’s Chesapeake Bay Program Phase 5 Watershed Model, to identify relationships between flow alteration, water quality and loss of ecological integrity for different stream types in Virginia. These quantified relationships can then be used to support public decision-making regarding the in-stream flow necessary to sustain wildlife and wildlife habitat in Virginia’s waters. Expanding the WSDSS to evaluate the interaction between ecology, water quality, flow-alteration and land use will enable DEQ to engage stakeholders in continuous, scientifically defensible, socially acceptable and practical adaptive management of aquatic resources to identify, maintain and restore Healthy Watersheds throughout the Commonwealth.