![Illustration by Jack Rooney](https://appvoices.org/images/uploads/2014/08/SeleniumArticleInfoG_sky2_RGB-150x150.jpg)
Most people have probably never heard of selenium, but for coal operators and fish it’s a big deal. Appalachian Voices’ water quality expert takes a moment to explain the issues surrounding this mineral — necessary in small amounts but toxic to aquatic life even at very low levels — and the EPA’s controversial attempts to regulate it.