The Tennessee Valley Authority may have a big problem—and one that could soon spill over into Mississippi. The federally owned corporation manages the now-defunct Allen Fossil Plant in Memphis, Tenn., where environmental experts claim ash ponds have been contaminating groundwater said to be locally connected to the Memphis Sand Aquifer since at least 2017. This aquifer is the primary source of drinking water for the city of Memphis and serves other communities across the Mid-South.