The Conowingo Dam, at the mouth of the Susquehanna River near Havre de Grace, is owned and operated by Exelon Corporation. Exelon uses the dam to generate electricity from the river at a profit. The dam was completed in 1928 and has been trapping sediment and nutrient pollution from the Susquehanna and its 27,000-square-mile drainage area ever since.
The reservoir behind the dam is now basically at capacity — it cannot trap any more sediment. This is a problem because when it rains, runoff pollution from the largely agricultural area upstream from the dam makes its way into the river and ultimately the Chesapeake Bay. Even more problematic is the potential for “scour,” where powerful floodwaters can actually scoop out the stored sediment behind the dam and send that downstream to the bay. If not for the Conowingo Dam, this load would have been delivered to the Lower Susquehanna River and Chesapeake Bay at normal rates.
When planning for an emergency, you generally plan for the worst-case scenario. Ships need to carry enough life boats for every passenger, not just a few. Fire regulations call for smoke detectors in every bedroom, not just one per floor. Vehicle safety ratings are tested for full-speed collisions, not just fender-benders. We should expect the same for environmental regulations. Unfortunately, a recent decision by the Maryland Department of the Environment concerning the Conowingo Dam does not follow the same rationale.
Exelon has requested a new 50-year federal license to operate the dam. In order to receive it, the State of Maryland must certify that the dam’s operations will not adversely impact water quality under the Clean Water Act (CWA). Last month, the Maryland Department of the Environment (MDE) announced that it had issued its CWA water quality certification for the Conowingo Dam. The certification acknowledges the impact of the dam on water quality, including the threat posed by the accumulated sediment. And while there are admirable goals, the certification only requires Exelon to adopt a “nutrient corrective action plan” rather than put specific measures in place.
We cannot afford to give Exelon a new, 50-year license without specific, measurable conditions that ensure its operations do no more harm to the Chesapeake Bay. MDE, under Governor Hogan's leadership, should include a requirement to dredge some portion of the accumulated sediment and nutrient pollution stored behind the dam as a condition of its water quality certification for the new license. We also call upon MDE to properly account for the damaging effects of large storm events during the new license period.
To achieve the best results, we must plan for the worst. The Chesapeake Bay deserves a good emergency plan.