New study finds Exelon able to make significant contributions to mitigate environmental impacts of Conowingo Dam while remaining profitable

ANNAPOLIS, MD | December 05, 2017

A new study commissioned by the Chesapeake Bay Foundation (CBF) and The Nature Conservancy (TNC) shows Exelon Generation Company can mitigate a substantial portion of environmental impacts caused by its Conowingo Dam operation, while continuing to make a healthy profit.

“The good news that comes with this report is that Conowingo’s environmental performance can be brought into the 21st century with effective mitigation measures while the dam continues to provide low carbon energy and Exelon receives a reasonable return on its investment,” said Mark Bryer, TNC’s Chesapeake Program Director.

The report, “An Economic Analysis of the Conowingo Hydroelectric Generating Station,” examined the dam’s revenues and expenses, various flow scenarios, market prices and rates of return. It concluded Conowingo generates sufficient revenue to provide $27 million to $44 million annually in “headroom for remediation” depending on flow regimes and energy prices.

The report was conducted by Energy+ Environmental Economics of San Francisco, California, for the Water Power Law Group, CBF and TNC. It was released prior to a public hearing today by the Maryland Department of the Environment on the Conowingo pollution issue.

“More pollution will come through the Conowingo Dam and into the Bay than scientists previously calculated,” said CBF President Will Baker. “Exelon has the responsibility and revenue to pay for its share of the solution.”
Conowingo Dam is the largest dam on the Susquehanna River, which is the largest river on the East Coast of the US.  The Dam and its reservoir contribute excess pollution to the Chesapeake Bay. The dam’s operation dramatically impacts habitats in the river and Bay, and populations of migratory fish, freshwater mussels, and underwater grasses, all of which have vital economic and ecological value.

For decades, the Conowingo Dam acted as a drain stop to trap significant amounts of sediment and nutrient pollution flowing from farms, sewage plants and other sources upstream in the Susquehanna River watershed. But the reservoir behind the dam nearly has filled up, and earlier than was expected. Big storms push some of that pollution through the dam and into the Chesapeake.

Recent studies affirmed that while most of the sediment and phosphorus in the dam reservoir originates upstream, the dam itself also worsens downstream water quality because it alters the form of the sediments and phosphorus and the timing of their discharge. Other studies have shown that Conowingo discharges water in a way that is more harmful to downstream water quality and fish than average dams elsewhere.
Exelon has filed an application with the Federal Energy Regulatory Commission (FERC) for a new operating license for the Conowingo Dam. Under federal law and FERC’s relicensing process, Exelon is required to obtain a Clean Water Act Water Quality Certification from MDE. Exelon must demonstrate that the dam’s operation meets Maryland’s water quality standards. MDE will hold a public hearing on the certification today. The public has until Jan. 15 to submit written comments.

CBF and TNC both testified at the public hearing that, based on the information from the economic report, MDE should require Exelon to 1.) mitigate the incremental harm the dam causes to downstream water quality, including a financial contribution to mitigate sediment and nutrient pollution; and 2.) make operational changes to restore safe and effective habitat for migratory fish like American shad and striped bass – and for keystone species like freshwater mussels and aquatic vegetation; and 3.) make structural investments to restore fish passage connectivity to upstream spawning habitats. 

Download the report: An Economic Analysis of the Conowingo Hydroelectric Generating Stations (pdf)

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Contact information

Matt Kane
The Nature Conservancy
(240) 630-7052

Tom Zolper
Chesapeake Bay Foundation
(443) 482-2066