This might not be surprising from CNN, which earlier this month cut its entire science, environment, and technology news team. Not surprisingly, the Society of Environmental Journalists and several other journalism organizations have formally protested the CNN cuts.
Of course, CNN Center in Atlanta is only about 200 miles from Harriman, TN -- just a three-hour drive... They could have thrown a regional news team on the story, but... On the bright side, the Knight Science Journalism Tracker notes today that the NY Times is forming a new reporting unit for environment and climate change coverage. So hopefully they won't keep overlooking stories like this.
The lack of national mainstream news coverage of this disaster isn't stopping the story from spreading. Tenn.-area news orgs and individuals from all over the US have been tweeting about this story, and many people have been blogging it. There are also videos on YouTube. Twitter is an easy way to find this coverage. Just search there for the hashtag #coalash, as well as for the terms coal ash and TVA.