RALEIGH, N.C. - Federal officials say toxic coal ash has coated the bottom of a North Carolina river up to 70 miles downstream of a Duke Energy dump where a massive spill occurred two weeks ago.
The U.S. Fish and Wildlife Service advised Tuesday that a massive bar of coal ash about 75 feet long and as much as 5 feet deep has been detected on the bottom of the Dan River near the site of the Feb. 2 spill. Deposits varying from 5 inches deep to less than 1 inch coated the river bottom across the state line into Virginia and to Kerr Lake, a major reservoir.
Federal authorities are concerned the toxic contaminates will negatively affect mussels and fish. Public health officials have advised people to avoid contact with the water.
"Biologists and environmental contaminants specialists from our North Carolina and Virginia field offices have initially found layers of coal ash of varying thickness spread out over 70 miles of the Dan River," said Tom Augspurger, Contaminants Specialist for the U.S. Fish and Wildlife Service. "At the spill site, we identified a coal ash bar about 75 feet long and 15 feet wide which had as much as five feet of ash or ash/sand mix over the natural stream bottom. Our biologists are working with the U.S. Environmental Protection Agency and Duke Energy biologists on a downstream reconnaissance; we've found ash covering natural sediment over five inches thick atop sand bars within two miles of the spill site, and two inches thick to the North Carolina /Virginia line about nine miles downstream. Further downstream as far as South Boston, Virginia, we've observed one-eighth to one-half inch of ash on sandbars and other depositional areas, and traces of ash all the way to Kerr Lake."
"The deposits vary with the river characteristics, but the short and long term physical and chemical impacts from the ash will need to be investigated more thoroughly, especially with regard to mussels and fish associated with the stream bottom and wildlife that feed on benthic invertebrates," said Augspurger. Benthic invertebrates are organisms that live in or on the bottom sediments of rivers, streams, and lakes.
Teams will need to assess conditions at the stream substrate where some of the sensitive resources reside, especially in areas where the ash accumulates.
The Fish and Wildlife Service has had field crews on the water. Just after the spill, the water was extremely cloudy, so observations were restricted to the water's surface and river banks. Service personnel have not directly observed any sick or dead fish or wildlife. A few citizens reported seeing dead turtles at two Virginia parks, and biologists visited both of those sites but didn't find any carcasses.
Looking at the surface water quality data collected by others, biologists noted exceedences of the North Carolina state water quality standard for turbidity (a measure of light scattering which indicates how clear or cloudy the water is) in most samples downstream of the spill during the first four days after the release. There were a few exceedences of arsenic and selenium standards for protection of aquatic life and frequent exceedences of the state action level for copper in water, but their connection to the spill is not certain. The Fish and Wildlife Service teams were able to assess shoreline and sandbars between the site of the release and Kerr Lake although some sections in that stretch remain to be surveyed this week. It is not yet known if the ash deposits stay in place after higher river flows, such as the recent increased flows from snow melt. More detailed assessments will follow when the emergency response phase is over.
The Fish and Wildlife Service has coordinated with state and federal biologists in North Carolina and Virginia to synthesize information on the locations of rare species and other resources at risk. They have coordinated with biologists and toxicologists familiar with coal ash to focus response and assessment efforts. Some of that includes suggestions for sample collection methods to examine potential habitat impacts (e.g., sediment sampling, sampling throughout the water column in addition to the surface) -- sampling now in progress. In addition to the field reconnaissance, Fish and Wildlife Service specialists have worked with the incident command on emergency endangered species consultations -- expediting any response actions proposed by Duke Energy and USEPA, and they have begun impact assessment discussions with Duke Energy and others.
The Fish and Wildlife Service's initial concern is the physical burying of habitat that is important for fish, mussels, and other aquatic life. The ash can coat the bottom in depositional areas, burying animals and their food. The Service is also concerned about physical effects on gill tissues in fish and mussels from exposure to coal ash. There may also be longer-term toxicological impacts to aquatic animals from metals of elevated concentrations in ash.