Sediment buildup behind Conowingo Dam poses a relatively small threat to the Chesapeake Bay's health, a federal official said at a Senate hearing Monday. He predicted it could cost billions of dollars to address the risk by dredging the river bottom, and suggested it was not worth the expense.
Col. J. Richard Jordan III, commander of the Baltimore District of the Army Corps of Engineers, testified at the hearing — held at the dam, rather than in Washington — that only 20 percent of the muck that turned the upper bay brown after Tropical Storm Lee in 2011 came from the buildup behind the hydroelectric facility, according to a joint federal-state study.
Exelon Corp., the dam's owner, is seeking to renew its federal license for the dam, which expires Sept. 1. The company has been negotiating with state and federal officials over what it might be willing to do about the sediment buildup, and to help restore migratory fish populations in the river that have been cut off by the dam.
The study's findings, which the Army official said are still being evaluated, appear to discount concerns raised by rural Maryland lawmakers. They contend the buildup of 86 years' worth of sediment behind the 94-foot-high dam is a greater threat to the bay than farm and suburban runoff, and should be made a priority in the cleanup effort.
Jordan said the study found that roughly 80 percent of the mud fouling the bay after the 2011 storm had been washed over the dam from farther up the Susquehanna, which begins in New York and drains much of Pennsylvania. The study suggests that efforts to reduce sediment and nutrient pollution upriver are more critical to the bay's health than buildup behind the dam, he said.
Sen. Benjamin L. Cardin, D-Md., who presided over the hearing, said the study's findings were "not expected." As chairman of the Senate water and wildlife subcommittee, Cardin said he wanted to know how best to deal with the sediment buildup, and to ensure that the burden of cleaning up the bay is fairly shared.
Dredging out just 15 percent of the accumulated sediment would cost from $500 million to $3 billion, Jordan estimated, adding that he believed the effort would yield "very little bang for the buck downstream."
Others at the hearing said even if not the major source of the bay's woes, Exelon still needs to help deal with the pollution periodically flushed from behind the dam by big storms. They also said the company needs to expand and upgrade a fish lift at Conowingo to help restore American shad and eel populations cut off from their historic spawning areas. Just 13,000 shad used the lift last year.
Vicky Will, an Exelon vice president, told Cardin the company has agreed to provide $2 million for more study of the dam's impact on bay water quality. She said the company believes the existing pair of fish lifts at the dam is sufficient to help millions of shad get upriver.
But Genevieve P. LaRouche, supervisor of the U.S. Fish and Wildlife Service's bay field office, said officials believe bigger lifts and other adjustments are needed to reach a goal of restoring 2 million American shad to the river.
Noting that issues like fish passage only get addressed when dam licenses are up for renewal every 30 or 40 years, LaRouche called this a "once-in-a-generation opportunity" to improve the river's fish and eel populations.