The blowout of acid drainage water from the long-abandoned Gold King Mine in August 2015 was huge news — if only because it gave critics a chance to blame and blast the U.S. Environmental Protection Agency (EPA). Little of the media coverage noted that acid drainage from abandoned mines is a common problem across much of the country, and that Congress has never enacted laws to really deal with it.
Wherever you may be practicing environmental journalism, there's a fair chance abandoned mine drainage is a problem near you. Now there is some help from databases to help you find and evaluate such problems.
The nonprofit SkyTruth, an innovator in applying map technology to environmental problems, offers an interactive version of an obscure federal database on abandoned coal mines (the Gold King Mine was a "hard-rock" mine). It includes 48,529 mines. You can find the SkyTruth site here.
That data comes from a system maintained by the federal Office of Surface Mining, called the enhanced Abandoned Mine Lands Inventory System, which is not easily available to the general public.
There is also some data on abandoned hard-rock mines, maintained by the Bureau of Land Management (BLM). It contains some 48,126 sites, but only sites on public lands. The Abandoned Mine Lands Site Inventory, as it is called, is not searchable or downloadable online.