PIERRE | A South Dakota group is helping to lead a national effort to clean up old uranium mines.
The Defenders of the Black Hills is participating in a national "Clean Up The Mines" project launching Tuesday on Earth Day.
The event's coordinator says some rivers including the Cheyenne River contain runoff from abandoned uranium mines. South Dakota is home to more than 250 such mines.
The environmental group is working with a member of Congress on legislation mandating mine reclamation.
Officials with the state Environment and Natural Resources Department say the old mines are on their radar but are too expensive to reclaim. They say uranium occurs naturally in South Dakota's western rivers.
The event will take place at 10 a.m. on the Highway 40 Cheyenne River Bridge.