CHARLOTTE, N.C. (AP) — Duke Energy told shareholders Thursday that cleanup costs resulting from its massive coal ash spill into the Dan River won’t have a material effect on the $50 billion company’s bottom line.

The nation’s largest electric company said in a regulatory filing with the U.S. Securities and Exchange Commission that it had spent $15 million so far on plugging the collapsed pipe at its Eden power plant that triggered a Feb. 2 spill and polluted 70 miles of the Dan River with toxic sludge. The company has also begun the process of trying to dredge some of the spilled ash from the river.