by Alicia Pimental
December 01, 2009
A new report issued by the U.S. Geological Survey points to contaminated riverbank and floodplain soils as the main source of mercury found in fish in several Shenandoah Valley rivers.
The study found that 96 percent of the mercury loads to the South River – a tributary of the Shenandoah River’s South Fork – are from soil that was contaminated more than 50 years ago by a textile manufacturing plant in Waynesboro, Va.
Between 1929 and 1950, the textile plant discharged mercury waste that washed into the South River, eventually contaminating the South Fork of the Shenandoah River, the Shenandoah River and the floodplains along all three rivers.
“Currently, about 416 pounds of mercury get into the South River per year,” said Jack Eggleston, a USGS hydrologist and author of the report. “To meet safety standards in fish for human consumption, mercury loads to the South River cannot exceed 4 pounds per year. That’s a reduction of 99 percent.”
A health advisory on the consumption of fish from 128 miles of river downstream of the plant has been in place since 1977. The U.S. EPA sets mercury limits for fish at 0.3 parts per million, but fish and other wildlife can exceed this amount because they accumulate mercury in their bodies throughout their lifetime.
USGS scientists worked with partners from the Virginia Department of Environmental Quality (DEQ) and the U.S. EPA to collect and analyze hundreds of water and sediment samples. Computer models were used to simulate the movement of water, sediment and mercury in the South River watershed.
Based on the results of this study, Virginia DEQ will develop a plan for cleaning up the contaminated rivers.
Visit the USGS website for more information about the report.