Hogan plans test dredging of sediment at Conowingo Dam

Gov. Larry Hogan announced plans Tuesday to dredge a small amount of the sediment trapped behind the Conowingo Dam, a test project to determine whether doing so on a larger scale would help improve the health of the Chesapeake Bay.

Hogan said the state will ask companies this month to submit bids to dredge and reuse the sediment. The test project would be completed this winter, and then scientists would determine whether more dredging is worthwhile.

The Republican governor could not say how much the test project would cost but said the state would pay for it.

Hogan has pointed to the dam, which is an active hydroelectric generating station owned by Exelon, as a source of bay pollution. The dam controls water flow from the Susquehanna River at the top of the bay and also traps sediment — the tiny bits of dirt that wash into the river from upstream.

The area behind the dam has filled up with sediment and is unable to trap more. Hogan said he worries that one big storm could wipe out recent improvements in the Chesapeake Bay’s health.

"It is absolutely vital that we find real solutions for the problem," Hogan said at a news conference on the banks of the Susquehanna, in front of the dam.

The administration solicited a "request for information" a year ago, asking companies to propose ideas for addressing the issue. A dozen companies responded, offering ideas such as dredging sediment and spreading it on low-quality farmland that needs nutrients, or using the dredged material to make pavers and countertops.

Sediment can cloud water, preventing light from reaching underwater grasses, and it also can smother oysters and other bottom-dwelling creatures. Sediment also often has phosphorus bound to it, one of the nutrients that spurs the growth of oxygen-sucking algae blooms in the water.

But an environmental group cautioned that dredging won’t be a cure-all for the bay’s woes — the Susquehanna River and Conowingo Dam are only part of a problem that includes pollution from farm runoff, sewage treatment plants, septic systems and stormwater runoff.

Alison Prost, executive director of the nonprofit Chesapeake Bay Foundation, noted that while dredging can be a part of the solution, it's more cost-effective to prevent pollution in the first place. She noted that dredging only addresses sediment — not the nitrogen pollution that flows freely in the water.

"Long-term, is this where cleanup money should go?" she asked.

Ann Swanson, executive director of the Chesapeake Bay Commission — which advises state legislatures on bay issues — struck a more optimistic note. Swanson said the test dredging project could provide valuable information for how to treat Susquehanna pollution as part of the bay-wide restoration strategies.

"Innovation is always good and if we can provide a beneficial use of a pollutant, that's good," Swanson said.

Exelon also could be part of the solution. The company is seeking to renew its electricity generation license for the dam, and Prost suggested Hogan should require the company to contribute money toward upstream pollution prevention projects as part of the renewal.

Maryland Environment Secretary Ben Grumbles has said the state would consider using regulatory leverage to force others to help cut pollution. Under federal laws, the governor has the authority to halt re-licensing of the dam if he does not believe it meets the state’s clean water standards.

Exelon spokeswoman Deena O'Brien said in a statement that the company is working with government officials on how to address environmental issues.

The winning bidder for the test project will be tasked with dredging a tiny fraction of the sediment that's trapped behind the dam.

The state’s request for proposals will ask companies to dredge 25,000 cubic yards, said Roy McGrath, CEO of the Maryland Environmental Service, the independent agency that will oversee the project.

Officials estimate there’s about 31 million cubic yards of sediment lodged behind the dam, and the U.S. Army Corps of Engineers has estimated dredging that amount would cost $3 billion.

Maryland and surrounding states with bodies of water that drain into the bay should not lose sight of the variety of pollution sources in the watershed, said Bruce Michael, director of the Resource Assessment Service at the state Department of Natural Resources.

"There's no one silver bullet," Michael said. "This is one of many strategies we need to look at."

pwood@baltsun.com

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