Duke Energy finished its cleanup in the Dan River for now, but environmentalists point out there are still thousands of tons of coal ash settled in the river bed.
"What's happening is that coal ash is getting layered underneath sediment, thinning out, and settling in," explained Jenny Edwards, with the Dan River Basin Association.
She and other river experts FOX8 talked to Thursday believe about 10 percent of the coal ash spilled in February has now been removed.
"We would like to see one hundred percent. But the reality is, it may be difficult to impossible for anyone, including Duke Energy, to recover one hundred percent of that coal ash from the river."
She said there are still concerns about the remaining ash as it works its way into the delicate ecosystem of the river bed.
DRBA will continue monitoring the river for any thick spots of coal ash deposit for years to come. They will alert the EPA and Duke Energy if more areas can be cleaned out. They also plan to monitor wildlife in the river.
Duke Energy Spokesperson Jeff Brooks said the company will continue its commitment to the Dan River and surrounding community.
Brooks said workers removed as much material as safely possible for now.
"What we see in most areas is if there is a deposit [of coal ash] at all, it's a very small deposit on top of the sediment layer or in many cases now circulated beneath the sediment layer. So it would actually be more harmful to remove it potentially than to leave it in place."
Brooks added, Duke Energy completed at least 2,000 surface and drinking water test samples since the coal ash spill first happened at its steam station in Eden back in February.
The tests have been encouraging, and he agreed with environmentalists that the water quality is safe for recreation and fishing on the river.
Amy Adams is the North Carolina Campaign Coordinator with Appalachian Voices.
She is satisfied the coal ash removed from the Dan River was taken to a double-lined landfill in Person County.
"That's where it should be. That's where it should have been in the first place! In a lined landfill that protected this toxic ash, keeping it from groundwater, keeping it from surface water. That's all we're asking our legislators and Duke Energy to do."
She hopes a coal ash plan for the state is hammered out in the legislature before we face any more spills.