Gone? No, just eroded a bit, leaving a pile of rubble. Completely natural process. I can show you outcrops of similar cave collapse sediments that are hundreds of millions of years old. Yes, groundwater withdraw by humans contributes, but so does drought. Precipitation has been low up there, or so I've heard.

As fare as mining goes, nobody just dumps the water out into a field. ALL of the mines I have worked for or visited had water treatment plants that released water that was to drinking water standard, far cleaner than what came out of the ground, cleaner than the creeks recieving this discharge. Sometimes, a whole lot cleaner.

There is a case out in New Mexico, though, where a coal mining project was halted because it would have altered the groundwater to a really cool salt lake. Which is also held sacred by just about every Native American tribe within a hundred miles of the place.

It's called Zuni Salt Lake, (http://en.wikipedia.org/wiki/Zuni_Salt_Lake)and I'd like to see it someday.