All across Georgia, on the banks of the Coosa, Chattahoochee, and Ocmulgee and other rivers, sit large lagoons filled with coal ash, the toxic residue left behind after coal is burned. These massive impoundments hold millions of tons of toxic stew , and most are unlined. As a result, heavy metals in the coal ash — such as arsenic and mercury — quietly leach into the ground and nearby water bodies.  In 2015, the Obama administration passed rules requiring utilities to clean up the ponds and implement monitoring requirements, transforming the Environmental Protection Agency into the chief regulator overseeing these sites. States were also given the opportunity to assume this regulatory role — as long as they met minimum federal requirements.  Georgia was among the first to do so . In 2019, the EPA approved the state’s authority to oversee coal ash management.…