ANNAPOLIS – The health of the Chesapeake Bay soon may face a new threat – sediment from the Susquehanna River – and authorities in three states are unsure what to do about it.
The Conowingo Dam, a hydroelectric dam on the Susquehanna located between Harford and Cecil Counties, might soon be unable to stop much of the massive amounts of nutrients and silt flowing down the river from entering the Chesapeake Bay.
And the Conowingo is the last line of defense: The other dams on the Susquehanna River in Pennsylvania already have reached capacity.
The Conowingo reservoir is expected to reach capacity in 17 to 20 years, according to the U.S. Geological Survey. However, hurricanes, floods or other natural disasters that increase the river’s silt level could shorten that timetable.
The Susquehanna River Basin Commission’s Sediment Task Force is expected to ask for funding to study the feasibility of dredging the sediment – the first step toward a solution.
“Work is being done right now to characterize the sediment to see if the dredge could be used beneficially,” said Tom Beauduy, task force chairman.
When the Conowingo reaches capacity the USGS estimates that 250 percent more sediment and 70 percent more phosphorus will pour into the bay.
Those increases would be bad news for the bay. Sediment blocks sunlight from reaching the bottom of the Chesapeake Bay, preventing growth of underwater grasses that harbor aquatic life, while phosphorus was one of the nutrients blamed in the pfiesteria crisis that struck the bay in 1997, causing fish kills and human illnesses. “Sediment and nutrients are two of the biggest problems in the bay,” said Jenn Aiosa, a scientist for the Chesapeake Bay Foundation. Whatever the solution turns out to be it will likely be expensive according to Beauduy. “The feasibility study alone is likely to cost $6 (million) to 8 million,” he said. Delegate David D. Rudolph, D-Cecil, vowed to press the Maryland government to fund any efforts in the future. “If there’s a cost to (reducing silt), the state must step to the plate,” Rudolph said.
The SRBC said there might be some coal in the sediment, which could be sold to offset some dredging expenses.
Besides expenses, there are other concerns with dredging such as stirring pollutants settled on the river bed and the issue of where to put the dredge spoil once removed.
In 1999, the Maryland Port Administration sparked controversy by proposing to dump dredge spoil from the Port of Baltimore near the northern edge of Kent Island known as Site 104.
Dredging behind the dam could result in a similar problem.
Maryland has little control over the sediment in the Susquehanna because only 1 percent of the river basin lies in state. However, the river contributes almost 50 percent of the Chesapeake Bay’s freshwater.
Pennsylvania, which comprises the largest portion of the Susquehanna River Basin, has created several programs to deal with sediment, including stream restoration plans and Growing Smarter, an initiative similar to Maryland’s anti- sprawl, Smart Growth program.
However, little data exists on how successful these programs have been in treating the problem.
The task force, which is funded by the Maryland, Pennsylvania, New York and the federal government will submit its recommendations this summer.