The Photo

A picture is worth a thousand words…

The NASA satellite image below appeared in the August 2012 U.S. Geological Survey report that confirmed the loss of trapping capacity in the Conowingo Dam reservoir, and has since served as a calling card for the Coalition. We added the Maryland county jurisdictional boundaries.

ASA MODIS photograph from the Terra satellite, September 13, 2011, showing sediment plume extending  to near the mouth of the Potomac River, a distance of about 100 miles. (County lines added by Clean Chesapeake Coalition.)

There are some staggering numbers behind the photograph of the 100-mile long sediment plume emanating from the Conowingo Dam a few days after Tropical Storm Lee in September 2011.

Estimated amounts transported into the Bay during this single storm event are shown below:


*According to the U.S. Geological Survey

  •  42,000 tons nitrogen 
  • 10,600 tons phosphorus
  • 19 million tons sediment (of which 4 million tons was scoured from the reservoir)

 *According to the UMCES- Horn Point (Cambridge, MD) Survey

  • 115,910 tons nitrogen
  • 14,070 tons phosphorus

For comparison, below are the yearly pollutant loading averages from 1978-2011 

  • 71,000 tons nitrogen
  • 3,300 tons phosphorus 
  • 2.5 million tons sediment

What will the next significant watershed storm event do to the Bay and to the restoration efforts below the Conowingo Dam?