A complicated web of regulations governs mountaintop removal mining. One of those is the Clean Water Act. Under it, mining companies must obtain a permit from the US Army Corps of Engineers to dump the waste from blowing off the top of mountains in adjacent streams and hollows. Environmental groups challenged the Corps, saying they were issuing permits without ensuring protections for streams. The court disagreed. Army Corps spokeswoman Carol Labashowsky:“Business hasn’t changed much, because we are thorough, and we do follow the Clean Water Act," says Labashowsky.In a December regulatory action, the US Office of Surface Mining ruled that mining companies could do away with a 100-foot buffer zone around streams. Now, they must take reasonable steps to avoid harming streams but they’re not prohibited from mining through them.