A team of scientists at University of Maryland Center for Environmental Science (UMCES) is beginning a two-year study to quantify the amount of sediment and associated nutrients present in major entry points to the Lower Susquehanna River Reservoir System and the upper Chesapeake Bay. UMCES scientists are building on a recent assessment led by the U.S. Army Corps of Engineers that analyzed the movement of sediment and associated nutrient loads through the lower Susquehanna River watershed to the upper Chesapeake Bay. Although the entire Lower Reservoir System will be investigated, special emphasis will be given to sediment and nutrient loads into and out of Conowingo Pond during high flow events. This study will help policymakers determine the best management options to reduce this effect.
“This new study builds on the considerable work that has been done and presents a rare opportunity to conduct cutting-edge research on a modern-day challenge for which big decisions are awaiting the results,” said President Don Boesch of the University of Maryland Center for Environmental Science.
Under normal river flow, sediment collects behind all the dams on the Lower Susquehanna. Major storms, however, will scour out some of this sediment and send it downstream along with sediment-laden runoff from Pennsylvania and New York that has been carried along by high water. Research will measure how much phosphorus and nitrogen is attached to sediment particles that go over the dams and determine the fate of these sediments and associated nutrients in the Chesapeake Bay.
Knowledge of the movement of these scoured sediments and nutrients is critical to determining the effects on water quality and the degree to which the additional nutrients may impact the water quality in the Chesapeake Bay. How far do the nutrient-laden particles travel down the bay? To what degree are the nutrients released into the water where they may stimulate excessive production of algae that reduces water clarity and contributes to dead zones? What is the net effect on nutrient loading? The study is designed to answer these questions.
Determining the history of sediment accumulation behind the dam using long cores will contribute information about the composition and age of sediments accumulated over time. Scientists Jeff Cornwell and Cindy Palinkas of UMCES’ Horn Point Laboratory will lead the effort to gather data from sediments behind the dam.
Horn Point Professor Larry Sanford and his team of coastal physical oceanographers expect to be on the Bay when storm events occur. In addition, physical oceanographer Ming Li will use new data from the transport research to improve predictive modeling of sediment transport during high flow events. Model results will be compared to direct observations provided by Palinkas’s team. Jeremy Testa of UMCES’ Chesapeake Biological Laboratory will develop a computer model of the cycling of the nutrients and the biological responses.
Among the over-arching issues that the research will address is the degree to which sediments and attached nutrients scoured during high flow events may reduce Maryland’s ability to meet the Total Maximum Daily Load (TMDL) goals for 2025 established by the Environmental Protection Agency (EPA) and the states. The existing Bay “pollution diet” factored in high inputs of nutrients and sediments flowing down the Susquehanna River during river floods, but it did not include additional loads due to scour from river segments of the Lower Susquehanna watershed. Research on scouring of additional nutrients during storm events will help determine what additional nutrient load reductions are required to balance the diet during the Chesapeake Bay Program’s mid-point assessment in 2017.
This research study is being funded by multiple sources, including Exelon Generation Company, LLC, which owns the Conowingo Hydroelectric Project, the Maryland Sea Grant College, and the Grayce B. Kerr Fund, Inc. Exelon has agreed to provide up to $3.5 million to UMCES, the State of Maryland and the U.S. Geologic Survey for independent study and monitoring of Conowingo Dam over the next two years. The study plans were developed by the Maryland Department of the Environment, Exelon, the Maryland Department of Natural Resources, the U.S. Geological Survey, the University of Maryland Center for Environmental Science, and the U.S. Environmental Protection Agency.
UMCES Investigators include Jeff Cornwell, Larry Sanford, Cindy Palinkas, Michael Kemp, and Ming Li of the Horn Point Laboratory in Cambridge and Jeremy Testa of the Chesapeake Biological Laboratory in Solomons.
