epa has been collecting dissolved contaminant concentration data in the dan river (from the va/nc state line to midway between danville and south boston) since the coal ash spill. the organization has been periodically comparing the retrieved water/sediment chemistry data to ecological risk screening levels (ersls) to assess risk to aquatic and plant life. coal ash is made up of various materials after the burning of coal takes place. these include silica, arsenic, boron, cadmium, chromium, copper, lead, mercury, selenium, and zinc. certain contaminants that were measured exceed the screening levels, necessitating that the water/sediment chemistry must continue to be monitored. coal ash can coat and degrade the habitats of aquatic animals as well as cause direct harm to certain organisms.