USGS: Susquehanna Dams Near Breakthrough

Conowingo Dam on Susquehanna River

Sediment reservoirs in lower Susquehanna reach capacity, deliver more pollutants into Bay

Sediment reservoirs near the mouth of the Susquehanna River are filling up faster than researchers expected, posing a new obstacle for improving water quality in the Chesapeake Bay.

As the holding areas behind the lower Susquehanna's three dams reach capacity, their ability to trap upriver sediment and the phosphorous that is often attached wanes, and the sediment that is held grows more and more likely to flow out of the reservoirs and into the river.

According to a report released by the U.S. Geological Survey (USGS), strong storms, severe flooding and faster-moving water have turned the one-time pollutant blockers into less effective gates.

The Susquehanna delivered more phosphorous and sediment into the Bay last year than it has in more than three decades of monitoring. The past 15 years have seen a 55 percent increase in phosphorous entering the Bay from the river and a 97 percent increase in sediment. And while nitrogen flow has dropped, it shows a jump during large storms--like Tropical Storm Lee in 2011 or Hurricane Ivan in 2004--and the flooding that follows.

Breakthrough, in a chromatographic column, occurs when all the sites in the column are fully loaded, and will not retain any more of the substance of interest.

Since I arrived in Maryland in 1983, managers and scientists have been warning that the dams that hold back the sediment and pollutants coming down the Susquehanna River were filling up, and that some means of dealing with the problem needed to be found.  It reaffirms my faith in humanity that we have succeeded in putting off that solution until it is nearly too late...

The Lower Susquehanna River Watershed Assessment team, composed of federal, state and regional partners and administered by the U.S. Army Corps of Engineers, is exploring ways to expand the reservoirs' capacity.

My idea is to take that sediment out of the reservoirs, and used it as to make new soil, to replace that which has eroded to make the sediment.