The U.S. Senate Committee on Environment and Public Works; Subcommittee on Water and Wildlife held a hearing today at Conowingo Dam to gather information pertinent to relicensing the hydro-electric dam, which spans the Susquehanna River ten miles upstream from Chesapeake Bay,  near the town of Darlington.

Sen. Benjamin Cardin presided over the hearing, which elicited testimony from the U.S. Army Corps of Engineers, the U.S. Fish and Wildlife Service, Exelon -- the dam’s operator and the applicant for the license -- and Maryland environmental officials.

The questions at the hearing addressed how to make the dam a better partner in protecting natural resources, using the considerable funds a power company like Exelon has at its disposal and new technologies to help fish and reduce sediment.

The Conowingo Dam is a marvel of engineering standing 50 feet above the wide, rocky expanse of the Susquehanna River. It provides low-carbon power to thousands of residents and is directly responsible for hundreds of jobs. Its 53 floodgates determine whether many of the towns below it have a future, and what kind.

In deciding whether to issue a new license, the Federal Energy Regulatory Commission is also seeking the opinions of the many agencies that manage wildlife, recreation, natural resources and pollution, as well as the opinions of other interested parties.

The dam is an impediment to important fish, eels and mussels. It blocks the migration of anadromous fish downstream to the ocean and upstream to spawn. Millions of American shad, river herring and American eels have met their end at Conowingo.

The dam also contributes to a sediment problem in the Chesapeake Bay in two ways. One, the dam has long trapped sediment carried down the Susquehanna in its reservoir. Now the reservoir has nearly reached its storage capacity and the sediment is washed out during major storms, sending a plume of grit all at once down the Chesapeake. Secondly, scientists have found the dam traps too much of sandy sediment, a type of sediment that many creatures, including the eastern elliptical mussels, require for habitat.

"All of our policies should be based on the best science," Cardin said before the hearing began. "I've seen the fish passage facility here. It's impressive. But are we doing the best we can for fish habitat? What about sediment? How does the relicensing provide us with an opportunity to deal with these issues?"

The first issue on the agenda was the sediment trap. On average, the dam traps about 3.5 million pounds of phosphorus and 2 million tons of sediment every year - about a third of the phosphorus and more than half the sediment that's heading downstream, as reported previously in the Bay Journal

Studies showed that the dam would be full by 2025, but scientists now believe that will happen much sooner.

Since Tropical Storm Agnes came through and massive amounts of sediments rushed into the Bay and destroyed many grass beds, the Conowingo Dam has experienced 11 "scouring events," according to the Army Corps of Engineers. In these instances - storms but not necessarily huge ones - the increased river flow picks up trapped sediment and sends it down the Chesapeake.

The U.S. Army Corps of Engineers undertook a study in 2011 to model scenarios and determine how much these plumes hurt the Chesapeake. They determined that only 20 percent of the sediment entering the Bay was coming from scouring events; the rest of it was coming from activities in the watershed.

Even as the reservoirs fill up, Conowingo still traps about half the sediment coming downstream, said Col. J. Richard Jordan III, Commander and District Engineer of the Corps' Baltimore District.

Jordan characterized the problem as "not a major threat to aquatic life." The Watershed Implementation Plans, which each state is required to complete and implement and which will address stormwater and sewage-treatment plants, will, he said, "have a far larger influence than scouring."

Maryland's top environmental leaders agreed with that statement.

"It is important to recognize that the Conowingo Dam is not the Bay's only or even its main problem," said Maryland Department of Environment Secretary Bob Summers and Department of Natural Resources Secretary Joe Gill in a joint statement following the hearing. "In addition to all of the studies and the work that needs to be done as part of the relicensing process, it cannot be said enough that the Watershed Implementation Plans are proven, science-based blueprints already in place that outline pollution reduction strategies needed to improve water quality in our local tributaries and the Chesapeake Bay. Their full implementation is critical to a successful Bay restoration.”

Left unsaid at the hearing was the challenge the Bay restoration faces from the Conowingo-focused Clean Chesapeake Coalition, a group of Maryland counties that have joined to oppose plans to increase pollution controls.

The Clean Chesapeake Coalition has argued that poorer, rural counties should not be forced to spend limited resources on expensive stormwater upgrades when the Conowingo Dam sends plumes of sediment down the Chesapeake.

But as Donald F. Boesch of the University of Maryland Center for Environmental Science pointed out at the hearing, what happens at Conowingo has no bearing on an Eastern Shore river like the Choptank or a Southern Maryland one like the Patuxent. Both rivers struggle because of local land-use decisions - and those have nothing to do with sediment at the dam.

In terms of fish passage, Conowingo can and should do much more, said Genevieve LaRouche, supervisor of the U.S. Fish and Wildlife Service’s Chesapeake Bay Field Office.
The fish elevators work well for gizzard shad, a species that are important food for eagles but not necessarily prized as a catch, but they fail at protecting American Shad, in part because the gizzards fill up all the spaces. And they don't work at all to help eels migrate upstream. The eels are important to the survival of filter-feeding mussels.

After the hearing, Cardin said he wasn't ready to give the sediment issue a pass, even though the Army Corps said it wasn't cost-effective to dredge it.

"I'm not ready to say that we can be passive as it relates to the issue of sediment," he said.