Conowingo: One Dam, Two Views

A Baltimore Sun editorial (2017-07-19) and a Clean Chesapeake Coalition letter to the Washington Post (2017-07-07) offer contrasting views on addressing the sediment and nutrient pollution caused by the Susquehanna River and the Conowingo Dam. The Sun editorial argued that addressing the Conowingo issue should not necessarily be a top State priority based nor should it be done in lieu of addressing other locally impaired waterways or be based on political rhetoric similar to that used in the stormwater remediation fee/”rain tax” debate.  The Clean Chesapeake letter argued that the Chesapeake Bay Total Maximum Daily Load (TMDL) and Watershed Implementation Plans (WIPs) already address local water pollution and that addressing the Conowingo should be a top State priority.

From the Sun editorial:

Maryland and the other states in the Chesapeake watershed need to take an “all of the above” approach to protecting the bay from pollution, whether it comes from chicken manure, parking lot runoff, failing septic tanks, sewage spills or anything else.

The problem with pointing a finger at the Conowingo is that first, it’s a difficult problem to “fix.” The most obvious remedy would be to dredge all the sediment behind the dam and truck it to some upland location. But Governor Hogan’s call for suggestions has so far produced some novel approaches such as using the silt to create pavers or countertops, dumping it into the ocean or turning it into concrete. That’s welcome, but the proposals all appear to be costly and no more than “nibble” at the huge inventory of sediment, which the U.S. Army Corps of Engineers has already estimated would cost billions of dollars to remove. The second is that this isn’t necessarily the pollution source that should be the top priority for Chesapeake Bay cleanup efforts.

Why? Because while that silt and sediment flowing over the Conowingo can certainly be described as pollution, it primary has an impact on the Chesapeake Bay’s central stem, the deep water that already has problems with low dissolved oxygen. However, the sediment overflow doesn’t really affect valued tributaries like the Potomac, Choptank, Chester or Pocomoke rivers, which contain some of the most critical and environmentally sensitive habitats in the watershed. Nor is it clear that dredging silt from behind the Conowingo (no matter what you do with the dredge material) is the most cost-effective way to reduce the muck coming from the Susquehanna or, in particular, the excess nitrogen and phosphorus those sediments contain. …

In the Conowingo, the governor has correctly identified a problem for Chesapeake Bay water quality, but he speaks of it in a misleading fashion, much as he did with the “rain tax.” Mr. Hogan eventually came around on storm water pollution by making the fees optional while actually better enforcing anti-storm water rules. There’s similar hope for the Conowingo, where any new approach to sediment control is welcome as long as it doesn’t compromise the ongoing federal and state partnership and “pollution diet,” the comprehensive plan to reduce all forms of pollution leading to the bay.

From the Clean Chesapeake Coalition letter:


We have “pollution diets”, mandates, bureaucrats and [Non-governmental organizations] galore waving the Bay restoration banner, but no commitment or plan to specifically address the devastating amounts of nutrients, sediment and other contaminants that are scoured into the Bay during storm events and in equally harmful proportions now on a regular basis because the reservoir above Conowingo Dam is full. …

My fellow Clean Chesapeake Coalition county officials and I refuse to accept as the new normal for the Maryland portion of the Bay that all of the reservoirs in the lower Susquehanna River are full, that enormous amounts of Susquehanna River pollution are no longer being trapped, that more storms and harmful scour are inevitable and that dredging Conowingo reservoir is off the table.

The owner of Conowingo Dam (Exelon Corp.) is seeking a 46-year relicense from the federal government. How many storm events can we expect during that period, and how much scoured pollution from Conowingo reservoir, unless we have a plan?

Fortunately, Governor Hogan and his Administration are committed to developing a plan to manage the accumulated sediments in the lower Susquehanna River, regain trapping capacity behind Conowingo and give the Bay some breathing room until Pennsylvania gets its act together.

Useful Links

Prior Conduit Street Coverage of Conowingo Dam

Washington Post Article on Conowingo Dam (2017-07-04)

Clean Chesapeake Coalition Website

There will be a facilitated discussion on the Chesapeake Bay Total Maximum Daily Load and the Phase III Watershed Implementation Plans at the 2017 MACo Summer Conference. Check out the “What Will We See in Phase III? A Bay TMDL Update” on Friday, August 18.

Learn more about MACo’s Summer Conference: