In One Month, The Chesapeake Bay’s ‘Most Critical’ Pollution Issue Could Be Unsolvable

In this 2011 image, the Conowingo Dam overflows sediments into the Susquehanna River in the aftermath of Tropical Storm Lee. CREDIT: U.S. Geological Survey
In this 2011 image, the Conowingo Dam overflows sediments into the Susquehanna River in the aftermath of Tropical Storm Lee. CREDIT: U.S. Geological Survey

For more than 30 years, states and environmental groups have been fighting to clean up the heavily polluted Chesapeake Bay. But according to some, the tremendous effort will all be for nothing if one issue isn’t addressed soon: the Conowingo Dam.

If we do nothing to dredge that sediment, the bay is doomed.

“The Conowingo Dam is a sediment trap,” said Chip MacLeod, general counsel at the Clean Chesapeake Coalition. “It’s been in existence for 85 years, and it’s never been dredged or maintained. If we do nothing to dredge that sediment, the bay is doomed.”

Today, approximately 175 million tons of polluted sediment sits trapped behind the Conowingo hydroelectric power dam in northeastern Maryland, a product of nearly a century of build-up from clay, silt, fertilizer runoff, and sewage plant runoff from Pennsylvania and New York. The sediment — enough to fill about 80 football stadiums — contains phosphorus, nitrogen, and other harmful nutrients that can cloud waters, sprout toxic algae bacteria, harm ecosystems, kill aquatic life, and sully drinking water.

Since 1929, the Conowingo Dam has been collecting that pollution and largely preventing it from entering the Chespeake Bay. But now, that polluted sediment has nearly reached the brim of the dam, and MacLeod worries that just one big storm event could send it over the edge, blanketing and destroying the Bay.

“We think this is the most critical issue for the Chesapeake Bay right now,” he said.

The “most critical issue” MacLeod is referring to is not only the sediment, but also the fact that the Conowingo Dam’s operating permit is up for renewal. The dam’s owner, Exelon Corp., has applied for a permit from the Federal Energy Regulatory Commission. That permit could be approved as early as September 1, and if that happens, Exelon will not be legally required to remove the sediment for another 46 years.

“This is the time for everybody who cares about the Chesapeake Bay to be focused on this re-licencing,” MacLeod said. “This is a once-in-a-generation chance to make sure someone does something with the sediments that have been accumulated.”

Clash Of The Conservationists

While the potential deadline for Exelon’s renewal permit is fast-approaching, the urgency of the sediment problem is not new. Local fishermen and environmental groups have been trying to get something done about the sediment for years.

Standing in their way, however, is the Chesapeake Bay Foundation (CFB) — the largest and arguably most powerful environmental group dedicated to protecting the bay. Beth McGee, a senior water quality scientist at the CBF, says that’s because the Conowingo Dam’s sediment issue is not as big of a problem as its being made out to be.

We no longer have the protection of Conowingo trapping New York and Pennsylvania’s pollution, and we can’t keep up.

“The dam is now pretty much full. Historically, we thought that when that happened, it was going to be armageddon,” she said. “But an Army Corps of Engineers study specifically looked at the impact that scouring behind the dam has on the bay. And turns out, it’s not as big a deal as we thought.”

The study McGee refers to will be fully released on September 1 — the day Exelon’s permit expires. But preliminary results show that 80 percent of the sediment flowing into the bay is from the entire Susquehanna River watershed — not from the sediment piled up behind the Conowingo Dam.

The foundation has determined, looking at that percentage, that the Conowingo Dam is not a priority. But the Clean Chesapeake Coalition, which specifically represents local counties surrounding the dam, disagrees. McLeod cites 2011’s Tropical Storm Lee, during which 19 million tons of polluted sediment was dumped into the bay from the Susquehanna. Of that 19 million, four million tons came from behind the dam, shocking the upper bay.

“On average, 2.5 million tons of sediment from behind the dam gets released into the bay every year. But in that single storm even, four million was scoured,” McLeod said. “The fact is, we no longer have the protection of Conowingo trapping New York and Pennsylvania’s pollution, and we can’t keep up.”

According to McGee, the costs of dredging the sediment behind the Conowingo Dam are too high to justify — $60 million to $250 million per year, she says — and that groups like the Clean Chesapeake Coalition are using the issue “as an excuse not to clean up their local waters.”

“From our perspective, the question becomes, do you want to spent $60 to $250 million every year to dredge?” she said. “Or would you rather spend this money someplace else.”

The ‘Conowingo Scandal’

Safe to say, the impacts of the Conowingo Dam are contested and complicated. Still, there is presently no commitment from the state and federal government or Exelon to specifically address the sediment scoured into the bay during storm events, much less the amount of sediment scoured on a daily basis. And if Exelon’s 46-year permit is renewed on September 1, it will be much more difficult to legally require the company to dredge if indeed it is found that the dam’s sediment significantly threatens the bay.

The imminent permit deadline, combined with the uncertainty surrounding the sediment issue, has some Maryland residents unaffiliated with the dueling environmental groups fighting for an extension of the permit process. Specifically, brothers Thomas and Matthew Locastro — lifelong visitors of the Chesapeake Bay’s tributaries — have created a trailer for a documentary exploring the reasons why their state government has not addressed the issue.

“The fact that no one is addressing the elephant in the room is why we called it the ‘Conowingo Scandal,’” said Thomas.

The brothers are urging Maryland residents to call their elected officials and insist that Exelon only receive a one year re-license until a plan to address the sediment is put in place. They’re also asking for donations to make a full documentary about the Conowingo Dam, saying the issue has been hidden from the public eye (they weren’t even aware of it until one month ago).

For example, the Locastros cite the fact that a bipartisan resolution calling on the U.S. Army Corps of Engineers to dredge Conowingo unanimously passed the Maryland state senate, but was quickly killed in the House of Delegates by a desk drawer veto from Del. Maggie McIntosh, the chair of the Chesapeake Bay Commission. This happened despite McIntosh’s pledge to focus on Conowingo Dam sediment “as her number-one issue.”

“We just want to stress that this is a bipartisan issue that every single Democrat and Republican in the state senate voted to address,” Thomas said. “We are doing what this bipartisan group was not allowed to do since that resolution was given a desk drawer veto.”

Missing Pieces

The Conowingo issue is fraught with accusations on both sides. McLeod of the Clean Chesapeake Coalition says the Chesapeake Bay Foundation is taking money from Exelon, the dam’s operator, and actively trying to prevent them from forming coalitions to bring attention to the issue. The CBF, in a letter to Maryland Gov. Martin O’Malley asking him to prevent that coalition, accused McLeod of “preying on fear” of local counties and trying to “mislead” efforts away from overall bay cleanup.

“To point to the dam and say it’s the biggest problem is inaccurate, and delays other local efforts that will not only benefit the bay but that will benefit local water quality,” McGee said. “We’re not saying nothing should be done, we’re just saying it needs to be put into context.”

This is a bipartisan issue that every single Democrat and Republican in the state senate voted to address.

Still, McGee acknowledges that scientific studies on the pollutant concentration of the sediment have yet to be released. And until then, she agrees that FERC should not issue a 46-year operating permit to Exelon. In fact, she says, she doesn’t think the agency will.

“I am positive that FERC will not issue the license to Exelon in September 2014,” she said. “It just isn’t going to happen. There are too many missing pieces to legally move forward.”

Instead, McGee said she thinks FERC will issue a temporary license, though a spokesperson for the agency would not confirm whether that was true.

“We do not telegraph when we’re going to do something or what we’re going to do,” the spokesperson said. “However, if we don’t do the full re-licensing by [September 1], we would issue an annual license.”

Until then, the future of the sediment behind the dam is unknown. But the Locastros hope that, if a one year license is given, they’ll be able to create a film that would bring national attention to the dam — the upper bay’s last line of defense from Pennsylvania’s and New York’s pollution.

“Without focusing on states upriver, which is what addressing the Conowingo does, we will never have a healthy bay no matter how much we do in Maryland,” Thomas said. “It will all just be a waste if we do not address what’s behind the Conowingo Dam.”


An earlier version of this story misquoted CBF scientist Beth McGee’s position on the reason behind CCC’s support of dredging Conowingo. She believes they’re supporting the dredging as an excuse “not” to clean up their local waters, not to clean up their local waters.

In addition, an earlier version of this story mischaracterized a study on the contents of the Conowingo sediment. It is a pollutant study, not a toxicity study.