MYRTLE BEACH, S.C. (AP) — Federal authorities have approved a plan to allow S.C. Electric and Gas to leave a slick of polluted coal tar in the Congaree River rather than cleaning it up.

The Sun News of Myrtle Beach reports the U.S. Army Corps of Engineers approved a permit Wednesday allowing the power company to cover the toxin-tainted coal tar with stones or other material to hold it in place.

The company backed away from a plan to dig up the coal tar and haul it away because of expense.

Congaree Riverkeeper Bill Stangler says his group is group is considering legal challenges to the Corps' decision. State regulators say the coal tar hasn't hurt water quality, although testing has been limited.

The Corps approved the plan Wednesday and made it public Friday. .