In an effort to uncover coal impoundment locations, I filed a Freedom of Information Act request for a copy of MSHA's coal impoundment database in October 2013. The agency responded with information and locations related to all MSHA-regulated coal impoundments in the United States, as of December 2013. I filed a follow-up request for an updated dataset in the fall of 2015, but an MSHA employee told me that they no longer provide geographic coordinates of impoundment locations. Therefore, this is likely the most recent and reliable dataset available.
The map below displays the data from the request—and has a search function which allows users to type in their community. Users can also click on each impoundment to find information on ownership, creation date, and other data. The dataset can also be downloaded here.