Final report released analyzing sediment and pollution flow impacts to Chesapeake Bay from Conowingo Dam

Published March 10, 2016

The final Lower Susquehanna River Watershed Assessment (LSRWA) report was published online, March 10, 2016. The draft report released for public comment Nov. 13, 2014, indicated that the reservoir behind Conowingo Dam is trapping smaller amounts of sediment and has essentially reached its limit to trap in the long term, and that a large majority of the pollution to the Chesapeake Bay from the Susquehanna River is a result of runoff from pollution sources upstream, as opposed to sediment and nutrients collected behind the dam.

This report was developed by the U.S. Army Corps of Engineers (Corps) and non-federal sponsor the Maryland Department of the Environment (MDE). The interagency team addressed the approximately 350 comments received during the public comment period. Some additions and clarifications were made to the report; however, no substantial changes were made to the findings or recommendations as a result of these comments. The comments, along with the agency responses to the comments, can be viewed in the final report’s appendices. 

The report concluded that following through on the blueprint to clean up the Chesapeake Bay and its tributaries will have a much greater and longer-lasting effect on water quality than addressing the Conowingo Dam problem, alone. However, if the additional nutrient and sediment load impacts from the Conowingo Dam reaching full capacity are not addressed, Bay water-quality standards will not be met by 2025 in three mid-Bay segments even with full watershed implementation plan (WIP) achievement.

Major recommendations in the report include quantifying the full impact on Chesapeake Bay water quality and living resources based on new understandings; integrating findings from the report into ongoing analyses and development of WIPs as part of the Chesapeake Bay Total Maximum Daily Loads (TMDL) assessments; developing and implementing management options that offset impacts to the upper Chesapeake Bay ecosystem from increased sediment-associated nutrient loads; and committing to enhanced long-term monitoring and analysis of sediment and nutrient processes in the watersheds to promote adaptive management into the future.

The Bay jurisdictions and participating federal agencies are in the process of submitting their draft 2016-2017 milestones to the Environmental Protection Agency for goals and program activities to achieve nitrogen, phosphorus, and sediment pollution reductions as part of the TMDL. EPA will provide final evaluations of the milestones in June 2016. 

The two-year milestones represent key check-in points to having all pollution-reduction measures in place by 2025 to restore the Bay and its tidal rivers. By 2017, controls should be in place that would achieve 60 percent of the necessary pollutant reductions.

The LSRWA interagency team is comprised of the Corps, the Corps’ Engineering Research and Development Center, MDE, U.S. Geological Survey, Susquehanna River Basin Commission, Nature Conservancy, U.S. Environmental Protection Agency, Maryland Department of Natural Resources, and Maryland Geological Survey.

The total cost of LSRWA was approximately $1.38 million. Funding was received in 2009, and the assessment began in 2011, after scoping and partnership agreements laid the groundwork. The LSRWA report directly contributes to Executive Order 13508 goals to restore clean water, recover habitat, and sustain fish and wildlife; and was authorized by Section 729 of the Water Resources Development Act of 1986, as amended.


Additional media contacts for LSRWA team partners:

Jay Apperson, MDE, 410-537-3003,

Karis King, Maryland DNR, 410-260-8001,

Stephanie Smith, Chesapeake Bay Program partnership, (410) 267-9881,

Tom Wenz, EPA Chesapeake Bay Program Office, 410-295-1360,

Sarah Gross
443-301-2580 (cell)

Release no. 16-010