Conowingo Dam's Effectiveness in Question

As the dam undergoes a relicensing process, lawmakers and environmentalists debate how to proceed.


Exelon Power is negotiating a new 46-year license to operate the Conowingo hydroelectric generating dam on the Susquehanna River in northern Maryland, which provides power to more than 700,000 homes. The current license expires in September 2014.

But state officials and legislators from the Eastern Shore said Friday that sediment and fish passage issues need to be worked out first in order to better protect the Chesapeake Bay.

Sediment levels are one of three major contributors to pollution in the Chesapeake Bay, along with nitrogen and phosphorus, and more and more sediment has been passing through the Conowingo Dam in recent years, particularly during storms.

Legislators are frustrated by the amount of state money spent on sediment studies at the dam, when much of the sediment is flowing in from Pennsylvania.

Sen. E. J. Pipkin, R-Queen Anne’s, asked for an action plan to take the place of studies and meetings that have been going on for too long. “Can we ask for a summit with Pennsylvania?” he said.

The Eastern Shore Delegation will be sending a letter to Gov. Martin O’Malley to make sure Pennsylvania is appropriately involved in the discussion.

Scientists have been aware of sediment issues at the dam since the 1970s, Maryland Department of the Environment Secretary Robert Summers said Friday, and efforts to decrease its flow with erosion and land conservation strategies have been working.

“We have seen a decrease of sediment flowing into the reservoirs,” Summers said. “There is progress.”

The Conowingo Dam is on the Susquehanna River about five miles from the Pennsylvania border and 10 miles from the Chesapeake Bay. Sediment that passes through the dam from Pennsylvania eventually reaches the bay.

The dam has historically been a great controller of sediment, Ann Swanson, executive director of the Chesapeake Bay Commission, told legislators. Three million pounds of sediment reach the dam every year, and the dam only lets 1 million of that through, storing the other 2 million in reservoirs.

At equilibrium, when water levels on both sides of the dam are equal, all 3 million pounds of sediment pass through, Swanson said.

Equilibrium currently occurs only during storms. But studies show that as the dam’s storage capacity is used up, permanent equilibrium could be reached in the next several decades.

“So whether you believe that equilibrium is going to be reached in the next 10 years, next 20 years, or the next 40 years, it’s going to happen during the next license cycle,” she said. “So what that means is we better get the license right now, and we better negotiate whatever we can associated with sediment, associated with fish passage, associated with flow and land conservation.”

The dam, which has been producing power since 1928, is licensed by the Federal Energy Regulatory Commission, and both Maryland and Pennsylvania are responsible for issuing water quality certifications.

Federal and state agencies are working with environmental groups to study the inflow and outflow of sediment, and fish passage. The $1.38 million study uses computer modeling to determine whether and where to dredge, and whether it would be beneficial to let sediment through at times that would be less damaging to the bay.

Exelon is also participating in the study, which will be ready by 2014. But those parts of it that will be necessary for licensing negotiation will be available this year, said Frank Dawson, assistant secretary of aquatic resources for the Maryland Department of Natural Resources.

The dam cannot be the only stopper of sediment, Summers said. Maryland and Pennsylvania need to prevent sediment from entering the dam to begin with.

“The sediment issues require participation from multiple parties,” said Mary Helen Marsh, director of environmental operations for Exelon Power.

For all of the state resources going into resolving the sediment issue at the dam, sediment only seems to be increasing, legislators said.

“It’s time for some action,” said Delegate Jay Jacobs, R-Kent. “It’s time for some resolution. You can’t keep taking and not giving.”

Mike Tarbert January 22, 2013 at 01:21 AM
SO....Even "If" the dam were to be in equilibrium year round there would be 700,000 homes getting electric power from a source producing no pollution .
JB January 22, 2013 at 01:58 AM
Some people can find something wrong with any solution to a problem, no matter how good it is.
Tom Fitzpatrick January 22, 2013 at 01:30 PM
On the surface, this doesn't make much sense. The Conowingo Dam was never meant to be a sediment trap. Were it not there, 100% of the sediment load from that part of the River would flow into the Bay at ALL times. Oddly, Mr Pipkin does not mention the pesence of Cold Harbor or Holtwood, which have also trapped a lot of sediment. But they aren't in Maryland! The EPA TMDL mandate requires drastic reductions in the amount of phosphorus, sediment and nitrogen flowing into the Chesapeake Bay watershed. Since the entire length of the Susquehanna River is part of the Chesapeake Bay drainage area, the river is governed by the same Federal mandate that the poultry farmers which make up Mr Pipkin's poltical base are so upset about. Pennsylvania has lagged behind Maryland in adopting updated regulations and enforcement to meet this Federal requirement. But Eastern Shore farmers are upset because, until very recently, they weren't regulated at all.
Curtis Coon January 22, 2013 at 02:48 PM
Without being polarized on the politics of it, surely everyone must agree that with a 46 year renewal coming up. long-term planning and proactive protections must occur now. A program may be in place, but renewal of licensure is the right time to reassess the whole plan for conservation. The leverage exists now. It should be wisely used and fairly applied, irrespective of whether Pipkin is "this" or "that".
Sharon Duncan January 22, 2013 at 05:25 PM
Amen to Curtis... but it does seem that government agencies from local to federal get polarized on the politics of everything leaving wisdom and fairness in the wake of political self gratification.
Brian January 23, 2013 at 02:51 PM
I don't see the connection between sediment, a natural product of moving water, and pollution. Regardless, if Exelon does not renew, than who?, and at what cost thereafter?
John May 13, 2013 at 09:29 PM
Rainwater runoff comes from more than soil. Hard surface runoff is the most obvious source of pollution, but so is pollution from organic and nOn organic fertilizers from lawns and farmland. There is also pollution from legal and illegal dumping as well as unregulated sewer systems. You also hav to account for all of the potential accumulated pollution currently stored in all of the sediment trapped behind Conowingo,holtwood and safe haven dams. If the damn reaches equilibrium, that means Conowingo Lake has reached a minimum acceptable depth for water storage. Meani g the dam may be in capable of storing enough water for effective hydroelectric generation.
John May 14, 2013 at 12:31 PM
IMHO , what Pipkin is saying is enough already. We know where all the sediment is coming from, just like we know where the nutrient pollution inks coming from. His constituents have to pay and take action. When I'd Pennsylvania going to do the same. Maryland is shouldering the burden and the cost of Penbaylvanias inadequate actions. It's like me having to pay to remove all of the leaves my neighbor blows on my yard


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