The cost to reduce the added nutrient pollution spilling over the Conowingo Dam now has a price tag: at least $53 million a year.

That’s the rough estimate contained in a draft strategy aimed at finding ways to offset the additional nutrients passing through the dam to the Chesapeake Bay, now that the dam’s 14-mile long reservoir is filled with sediment.

The dam is located on the Susquehanna River in Maryland 10 miles upstream of the Bay. Most of the cleanup work proposed in the draft plan, released for comment Oct. 14, would take place upstream in Pennsylvania, primarily on farms.

The plan envisions attracting private investors to front the money needed to jump-start the work but said that will only happen if the states and U.S. Environmental Protection Agency commit to paying them back — something that has not happened so far.

Beth McGee, director of science and agricultural policy at the Chesapeake Bay Foundation, said she liked much of the proposed strategy, but said its success depends on whether the state-federal Bay Program comes up with a way to pay for it. “It’s only a plan,” she said. “If it doesn’t get implemented, we’re no better off.”

The dam, completed in 1929, actually helped to reduce Bay pollution for decades by trapping sediments and associated nutrients. It’s long been known that the reservoir would eventually fill, allowing sediment and nutrients to flow more freely into the Chesapeake. When the latest Bay cleanup plan was drafted in 2010, though, that wasn’t expected to occur until after the 2025 deadline that states are striving to meet.

But that has already happened, and computer models estimate an additional 6 million pounds of nitrogen and 260,000 pounds of phosphorus now reach the Bay in a typical year.

The Susquehanna River flows through the Conowingo Dam, 10 miles upstream from the Bay. A draft strategy for reducing an increased load of pollution from behind the dam is open for public comment until Dec. 21. Credit: Dave Harp / Bay Journal Media

That’s enough to keep the Chesapeake’s 2025 clean water goals out of reach.

With states already struggling to meet their individual pollution reduction goals, the Bay Program in 2018 decided to have an outside group develop a separate plan to offset nutrient increases from the dam and come up with a way to finance it.

Last year, the EPA awarded nearly $600,000 to the Center for Watershed Protection, Chesapeake Conservancy and Chesapeake Bay Trust to tackle the job.

“It’s a massive lift,” said Bryan Seipp, a watershed planner with the Center for Watershed Protection, who led the team. “It took decades and decades for this material to build up behind the dam. Trying to solve a problem that took decades to create in a fraction of that time is a challenge.”

The team examined nearly a dozen options, some of which included actions outside the Susquehanna watershed that would achieve the same benefits to the Bay, before settling on the recommended strategy. Most of the other options cost more — one came in at $368 million a year.

The lowest cost strategy came in at $49.5 million dollars annually but relied solely on reductions from agricultural lands in the Susquehanna basin. Seipp said that raised concerns that an overreliance on agriculture would result in taking too much farmland out of production.

The selected plan focuses entirely on the Susquehanna watershed — primarily in Pennsylvania. It also identifies places where nutrient control actions would be most effective and suggests more than a dozen on-the-ground pollution control practices that would be the most cost-effective to implement.

The plan still relies mostly on agriculture, but also seeks a sliver of nutrient reductions from developed lands.

The strategy cautioned, though, that its estimated costs are “likely low.” They do not include, for example, the cost of providing technical support staff to work with landowners on runoff control practices.

The draft also opened the door to other alternatives, such as dredging built-up sediment from behind the dam. Maryland is planning a pilot study to determine whether that is feasible.

It also raises the possibility of extending the deadline for meeting Conowingo goals beyond 2025.

Seipp said there is no firm timeline to issue a final strategy. That, he said, would hinge on public comments that may require plan revisions, as well as more clarity about funding.

A separate financing strategy will be released in December that is intended to identify ways to attract private money to support the plan.

That would spare cash-strapped states from having to pay up front and could speed implementation. But, the draft plan cautioned, “The only way that private investors will make money, at least in the near future, is if the public sector is compelled, for whatever reason, to pay them back for their investments.”

Although states in the watershed chipped in funding to help develop the plan, there has been no commitment about who would ultimately pay for the actual work.

The team writing the financing strategy said in a Sept. 23 memo that it assumes the Bay states “will have the ultimate responsibility” for funding the plan. Without that commitment, it said, implementation “will be very limited in scale and impact.”

Some state officials have hoped that other funding mechanisms will arise, such as philanthropic support that doesn’t need to be paid back. But efforts to lure outside money have been elusive.

At the time that the Bay Program agreed to create the Conowingo plan, state and federal officials were hoping that a settlement between Maryland and Exelon — the utility that owns the dam — would generate tens of millions of dollars a year for the cleanup. The utility needs approval from the state before it can get a new federal license to operate the dam.

Earlier this year, though, the state and Exelon struck a deal that committed just $19 million over the 50-lifespan of the license for that purpose. Some environmental groups and lawmakers have sought to block that agreement from being finalized.

“We still think that they should be held accountable for their downstream impacts, and we would love to see some of their dollars go upstream as opposed to what’s currently in the settlement agreement,” McGee said.

The draft Conowingo Watershed Implementation Plan is open for comment until Dec. 21. Comments should be submitted to

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