Coal ash ponds at Duke Energy's coal-fired Riverbend Steam Station in Gaston County, NC on the Catawba River. The plant, put into service in 1953, was shuttered on April 1, 2013. but environmental groups say that the coal ash ponds are seeping pollutants into the Catawba River, the drinking water source for the city of Charlotte. The foreground water is part of a series of coal ash settling ponds, the River is in the background. Duke Energy monitors the stream of water that flows to the river as well as several deep wells drilled around the ponds, to ascertain levels of seepage.