A dam breach in North Carolina is threatening to pollute a large river with toxic coal ash from a power station.

A week after hitting North Carolina, Hurricane Florence's floodwaters are lapping over an earthen dike in Sutton Lake, a 1,110 acre reservoir at a power station near Wilmington where the storm first made landfall.

That water has caused several breaches in the dam on the south end of the lake which is flowing back into the Cape Fear River that is already high from the hurricane.

Paige Sheehan, a spokeswoman for Duke Energy which runs the LV Sutton Power Station, said floodwaters had breached a steel-retaining wall containing a large coal ash dump along the shoreline.

She said the company cannot rule out that ash may be escaping and flowing into the river.

Gray material, which the company said is a lightweight coal combustion by-product, could be seen floating on top of the lake.