Reservoirs near the mouth of the Susquehanna River just above Chesapeake Bay are nearly at capacity in their ability to trap sediment. As a result, large storms are already delivering increasingly more suspended sediment and nutrients to the Bay, which may negatively impact restoration efforts.
Too many nutrients rob the Bay of oxygen needed for fish and, along with sediment, cloud the waters, disturbing the habitat of underwater plants crucial for aquatic life and waterfowl.
"The upstream reservoirs have served previously to help reduce nutrient pollutant loads to the Chesapeake Bay by trapping sediment and the pollutants attached to them behind dams," explained USGS Director Marcia McNutt. "Now that these reservoirs are filling to capacity with sediment, they have become much less effective at preventing nutrient-rich sediments from reaching the Bay. Further progress in meeting the goals for improving water quality in the Chesapeake will be more difficult to achieve as a result."
"It has been understood for many years that as the reservoirs on the Lower Susquehanna River fill with sediment, there will be a substantial decrease in their ability to limit the influx of sediment and nutrients, especially phosphorus, to the Chesapeake Bay," said Bob Hirsch, research hydrologist and author of the report. "Analysis of USGS water quality data from the Susquehanna River, particularly the data from Tropical Storm Lee in September 2011, provides evidence that the increases in nutrient and sediment delivery are not just a theoretical issue for future consideration, but are already underway."
According to a new USGS report, the Susquehanna River delivered more phosphorus and sediment to the Bay during 2011 than from than any other year since monitoring began in 1978. Flooding from Tropical Storm Lee made up a large fraction of the Susquehanna River's inputs to the Bay for both 2011 and over the last decade. During the flooding the Susqu
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United States Geological Survey