On Thursday, US President Trump signed legislation blocking the Stream Protection Rule, a key Obama regulation that limited mining companies from dumping excess spoil into waterways. Waste from mining operations can contain sulphur-bearing minerals which, mixed with water, create what the EPA calls "acid mine drainage". It's a fair trade-off, in Trump's mind, for stimulating coal industry job growth. Trump is set to kill even more regulations. The problem: Deregulation won't bring back coal jobs.