Upstream pollution reductions could ease effects of Conowingo Reservoir infill, report maintains

Reducing pollution in the Susquehanna River watershed could ease the environmental effects of an essentially full reservoir behind Conowingo Dam, according to a final report from the Lower Susquehanna River Watershed Assessment (LSRWA) team released today.

For decades, the reservoir behind Conowingo Dam—as well as those behind the Holtwood and Safe Harbor dams—has trapped particles of sediment flowing down the Susquehanna River, along with the nutrients that are often attached. But a draft report from the LSRWA team released in November 2014 indicated this reservoir is full—and the final report upholds these findings: no substantial changes were made to the findings or recommendations of the report between the draft and final phases.

According to the report, the reservoir is trapping smaller amounts of sediment and nutrients and, during large storms, sending more of these pollutants into the Susquehanna River more often. The report indicates that reducing pollution loads, particularly nutrients, upstream of the dam would provide a more effective solution than various strategies for managing sediment at the dam itself, such as dredging or bypassing.

In 2010, the Chesapeake Bay Total Maximum Daily Load (Bay TMDL) was established to reduce nutrient and sediment loads across the watershed. Bay jurisdictions—Delaware, Maryland, New York, Pennsylvania, Virginia, West Virginia and the District of Columbia—and federal agencies are currently in the process of submitting draft two-year water quality goals, or milestones, to achieve the nitrogen, phosphorus and sediment reduction goals of the TMDL.

Read the final report.