The Trump administration is acquiescing to the requests of industry and rolling back safeguards against coal ash pollution. Coal ash, the residue left over from burning coal, is regularly stored in giant, unconfined piles or used by construction companies as a cheaper alternative to soil. This gross and often sludgy stuff can leach harmful substances, such as arsenic and lead, into soils and water supplies. It also wreaks havoc when it is spilled—like in North Carolina in 2014 and Tennessee in 2008. To control leaching pollution, the Obama administration capped the amount of coal ash that could be on a single site at 12,400 tons in 2015. But not anymore. The U.S. Environmental Protection Agency just reversed course, removing all volume restrictions for the waste. The agency is making a bad problem that much worse: A recent study showed that 241 of the nation's coal-fired power plants are already polluting the groundwater with toxic metals.