Quantifying impacts of upstream reservoirs on the Potomac River due to Consumptive Use Beverly Lanza1, Cherie Schultz2, Celso M. Ferreira3 1Undergraduate Student, Department of Civil, Infrastructure and Environmental Engineering, George Mason University 2Director, CO-OP Operations, Interstate Commission on the Potomac River Basin 3Assistant Professor, Department of Civil, Infrastructure and Environmental Engineering, George Mason University Introduction Potomac River Basin Facts Results The Potomac River basin is home to more than six million residents and has experienced moderate and severe droughts in the past (e.g., 1930, 1966, 1999, and 2002). With population growth and consequential increasing water demands, net water withdrawals by upstream users can impact the water supplies for downstream populations (Washington Metropolitan Area, WMA) This study focuses on investigating if upstream reservoirs which are not part of the WMA system partially mitigate the impacts of Upstream Consumptive Use (CU) on the Potomac River. Using various parameter a safe yield is calculated for each reservoir. This information is useful and must be considered in order to properly determine the impacts of upstream reservoirs. SAFE YIELD Calculations Step 1: Collect reservoir inflows for historical data record 1960, 1966, 1999, 2002 (worst droughts) Reservoir inflows were unknown Streamflow estimation was conducted QR = Qg(AR/Ag) Step 2: Water Balance equation for each reservoir Step 3: Plot each reservoir Step 4: Add up all Safe Yield quantities 6.11 Million  Total Potomac River Basin Population 5.1 Million  WMA Population 600 MGD  Total Potomac River Water Withdrawals 500 MGD  WMA Water Withdrawals Study Upstream Reservoirs Used Army Corps of Engineer’s Dam Inventory to located all water supply reservoir within the Potomac River Basin and above Little Falls Dam Chose largest reservoirs with Storage Capacity > 500 ac-ft https://frederickcountymd.gov/6563/Lake-Linganore-Dredging Consumptive Use Water withdrawn that is not filtered back into the basin for future use Examples: Natural: Evaporation and transpiration Manmade: industry, agriculture, water supply, and livestock This study focused on WATER SUPPLY ONLY. Objective This study focused on: Reservoirs, one of the main water supply sources. Determining how upstream reservoirs not included in WMA water supply system mitigates consumptive use. Reason for investigating upstream reservoirs: Upstream population and withdrawal  Water Flow Downstream 1) Monie Bay National Estuarine Research Reserve References Ahmed, S. N., Bencala, K. R., and Schultz, C. L. (2015) Washington Metropolitan Area Water Supply Study:Demand and Resource Availability Forecast for the Year 2040. 15-4. “CorpsMap: The National Inventory of Dams (NID),” (n.d.). CorpsMap: The National Inventory of Dams (NID), <http://nid.usace.army.mil/cm_apex/?p=838%3A 1%3A0%3A%3ANO> “2010 Comprehensive Plan | The City of Frederick, MD - Official Website.” (n.d.). 2010 Comprehensive Plan | The City of Frederick, MD – Official Website, “2013 Comprehensive Plan City-Wide Element – Cumberland” (n.d.). <http://www.cumberlandmd.gov/documentcenter/view/1278> “Comprehensive Plan Update.” (2017). City of Harrisonburg, VA, <https://www.harrisonburgva.gov/comprehensive-plan#plan_update> Community Services and Infrastructure. (n.d.). administrator, <http://www.staunton.va.us/directory/departments-h- z/planning- inspections/images%20and%20files/> “Borough of Chambersburg 2016 Water Quality Report.” (n.d.).<http://www.borough.chambersburg.pa.us/pdf/2016waterqualityreport.pdf> Borough of Waynesboro, PA » Joint Comprehensive Plan. (n.d.). Borough of Waynesboro PA,<https://www.waynesboropa.org/joint-comprehensive- plan/> “Borough of Waynesboro, PA » Water Plant.” (n.d.). Borough of Waynesboro PA,<https://www.waynesboropa.org/water-plant/>