After a billion-gallon spill of coal ash in Tennessee, the agency sought to regulate the often-toxic byproduct of burning coal. It largely failed.

Coal ash contains known carcinogens such as arsenic, lead and mercury. This is why the EPA is now regulating coal ash. As power companies shut down or upgrade their facilities, the need to permanently dispose of this hazardous byproduct is growing. So far, these companies have dumped millions of tons of coal ash into unlined landfills across America -- putting our water supply at risk.