Saturday marks four years since a massive spill at the TVA's Kingston Fossil Plant unleashed more than a billion gallons of coal ash into the Emory and Clinch Rivers.
After a year and a half of dredging the ash out of the water, crews stopped in the summer of 2010 and intentionally left a layer of ash at the river bottom.
In November, the EPA announced it had reviewed all three options in conjunction with state environmental officials at TDEC and approved the plan to let sediment naturally cover the ash.
Also last month, a federal judge ordered mediation between TVA and Roane County residents who sued over the spill. Judge Tom Varlan gave the two sides 120 days to reach a settlement.