Bay 101: Conowingo Dam

Back in 2011, when we had Tropical Storm Lee, people saw this huge chocolate plume of sediment
coming all the way down to the Potomac River. It raised an alarm that this must be extremely detrimental to the
Chesapeake Bay. We certainly saw a significant impact,
especially to the submerged aquatic vegetation
right below the dam. But it wasn’t the sediment that caused the problem. It was the sheer force, the velocity of the water that ripped
up the plants. Sediment actually falls out fairly quickly, but the nutrients associated with the sediments might be more of a problem to the Bay and meeting its water quality standards. The Conowingo Dam on the Susquehanna River
traps sediments and associated nutrients behind the dam,
and keeps them from getting into the Chesapeake Bay. Even though the dam’s sediment
storage capacity has reached what we term dynamic
equilibrium during low-flow conditions and normal
flow conditions the dam continues to trap sediments
and associated nutrients. It’s only during these high-flow
conditions that cause scouring behind the dam that
delivers the sediments and nutrients to the bay in a pulse. In the long term, the Bay will be
healthier if we pursue management strategies upstream
for reducing nitrogen and phosphorus getting into the Susquehanna River. Pursuing short-term strategies like
dredging are not as beneficial as taking care of the
problem at its source.

1 thought on “Bay 101: Conowingo Dam

  1. Conowingo was damaged during tropical storm Agnes in 1972. It was repaired by drilling holes into bedrock thru the dam base and inserting steel cables anchored with epoxy. Some say another storm like Agnes will take the dam out. Couple that with 100 years of toxic sludge and you have a major environment disaster.

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