Dam No Big Deal After All

The Dam is Not So Threatening After All, Geologists Say

Federal geologists once warned that the silt trapped behind Conowingo dam was “a time bomb,” threatening to choke the life out of Chesapeake Bay. The mass of muck piled up behind the dam over the years is enough to fill M&T Bank Stadium 80 times over. And a major storm could hurl tons of it through the flood gates down river and into the bay, destroying grass beds and suffocating oyster bars.

But those fears may have been overwrought. According to a new state-federal study, only 20 percent of the mud that turned the Upper Bay into a brown mess after Tropical Storm Lee in 2011 came from behind the dam. The rest came from upstream.

What that means, says Colonel Trey Jordan, commander of the Baltimore District of the Corps of Engineers, is that those worried about sediment in Chesapeake Bay would have “a better target of opportunity” if they concentrated on the 80 percent of the sediment that’s “coming from upstream of the dam.”

That doesn’t mean there’s nothing to fear, adds Don Boesch, president of the University of Maryland Center for Environmental Science. But this study suggests the sediment issue is “not a game changer in terms of what we’re trying to achieve in bay water quality.”

When I first arrived in the Chesapeake Bay region, back in 1983, one of the first environmental issues I heard about was the threat that the pool behind Conowingo Dam was filling with sediment and one day soon (I vaguely recall 20 years being cited), it would not be able to hold all the sediments and nutrients coming down the Susquehanna, and it would be the end of the Bay as we know it, unless something is done.

I tend to discount the threats when scientists get their paychecks from the people who really want to address the threats, just as you should discount the dismissal of threats by scientists who say the threats are insignificant.  They could be right either way, but there's an excellent chance their judgement has been skewed by the self-interest, and that the truth lies somewhere off the worst or best case scenarios.

Now, in the fight over sediments and nutrients and the costs of the Bay Diet, the ag industry has settled on the filling of Conowingo damn as the real culprit, rather than their own contributions.  And curiously, now the Bay environmentalist community, which has been after the farmers to clean up their act, have suddenly discovered that maybe the Dam was not all the threat it was cracked up to be after all.

It's dam suspicious to me.