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Efforts to implement Maryland’s science-based blueprint to restore the Chesapeake Bay should move forward in parallel with work to address concerns about the impact of the Susquehanna River as it flows over the Conowingo Dam, a review of Maryland’s contribution to Bay pollution shows.
A delay in reducing Maryland’s nutrient and sediment loads to the Bay could significantly undermine Bay restoration work that has already been accomplished – and would likely cause the State to fail to meet the requirements of the multi-state “pollution diet” for the Bay.
At the same time, Maryland, in partnership with the U.S. Army Corps of Engineers, is seeking to identify strategies to address the declining ability of the Conowingo Dam to hold back sediment that can eventually reach the Bay. And Pennsylvania and New York are working to reduce the pollution that enters the Susquehanna River in the first place, as required under the federal Bay TMDL.
A study of pollution releases over the dam suggests that the Chesapeake Bay is already seeing the effects from loss of reservoir sediment storage capacity behind the Conowingo Dam. Some local jurisdictions, represented by the law firm of Funk and Bolton, are arguing that addressing sediment storage capacity behind the reservoir is more important to Chesapeake Bay restoration than reducing Maryland-derived loads as called for under Maryland’s Watershed Implementation Plan, the federally-approved Bay restoration blueprint.
The Susquehanna River contributes 46 percent of the nitrogen, 26 percent of the phosphorous and 33 percent of the sediment to the Bay, according to studies that take into account major storm events and the resulting “scouring” of sediments behind the Conowingo Dam. These contributions are large but, still, more than half of the nitrogen and other pollutants entering the Bay and its tributaries originate in local streams and rivers other than the Susquehanna. This includes the streams running through Maryland’s urban and industrial developments, farms and backyards. Reducing pollution from the Susquehanna River will help to restore the Bay, but it will not be possible to meet water quality standards in Maryland's portion of the Bay -- and improve water quality in its local tributaries -- without similar pollution reductions in all our State's streams and rivers.
The U.S. Environmental Protection Agency’s Chesapeake Bay TMDL(total maximum daily load) accounts for the sediments behind the dam. The federal Bay watershed model was calibrated using monitoring data from the Conowingo Dam (station 01578310). This TMDL analysis also includes high-flow events likely to produce scour of sediments behind the dam. Appendix T of the Bay TMDL document is devoted to this issue, and Maryland continues to work with its sister states to help EPA ensure that the model is based on the best available information.
In addition to meeting its federal Clean Water Act responsibility to help implement the Chesapeake Bay TMDL, Maryland has long recognized the importance of sediment storage capacity behind the Conowingo Dam. This led MDE and the Department of Natural Resources to sign a cost-share agreement with the U.S. Army Corps and the Nature Conservancy in 2011 to fund the Lower Susquehanna River Watershed Assessment (LSRWA). The study’s goal is to identify watershed and reservoir sediment management strategies for maintaining reservoir storage capacity. Options under consideration include the possibility of dredging sediment behind the Conowingo Dam or releasing sediment at times of the year when environmental impacts are relatively limited.
Meanwhile, the Conowingo Dam is going through a relicensing process through the Federal Energy Regulatory Commission (FERC). The dam’s current license expires in 2014. FERC requires that any potential environmental impacts associated with project relicensing be minimized. Conowingo’s owner, Exelon Corporation, has filed an application with FERC for a new license, resulting in environmental studies to address related fisheries, hydrology, sediment introduction and transport and Chesapeake Bay issues. Under the federal Clean Water Act, MDE has legal authority to issue a state water quality certification for the Conowingo Dam only if projected water quality and quantity impacts to Chesapeake Bay fall within acceptable and verifiable limits.
The Maryland-Army Corps study and the FERC re-licensing process are being closely coordinated to minimize redundancy, identify data gaps and ensure that any cross-cutting issues are addressed prior to final approvals. The FERC re-licensing process and LSRWA study also require public participation and afford an opportunity to address local concerns regarding sediment storage capacity in the Conowingo reservoir. However, neither LSRWA nor the FERC re-licensing process guarantees funding to implement strategies to address sediments behind the Conowingo Dam.
Addressing sediment storage capacity issues in the Conowingo reservoir is part of the complex solution needed to restore the Bay, but sediment from the Susquehanna is not the only water quality problem facing the Bay. Maryland will fail to meet its Bay restoration goals without the cooperation of local jurisdictions in controllling their pollution to address local water quality impairments as well. Living on the shores of a national treasure, Maryland citizens have a great stake in the outcome of Bay restoration. If Maryland fails to implement the WIP in a timely manner, the consequences – environmental and economic – will be borne by future generations of Marylanders.
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