Abandoned mine in Utah. Photo by Jason Corbett. © Bat Conservation International

Many abandoned mines, although often hazardous for humans, are worth protecting and managing to preserve important habitat for wildlife, especially bats, to safeguard cultural artifacts, and to maintains access to geological information.  Yet, by 2000, an estimated 48,000 abandoned mines in the United States had been closed through formal reclamation programs, and may others had been lost to renewed mining or closure by private landowners to avoid liability issues. This dramatic loss of mine resources led to a change in management perspective to emphasize protection of key mines whenever possible.

Mine closures are classified as either destructive — in which the mine feature is obliterated or concealed by backfilling, blasting, total site restoration, or other means —

or nondestructive, when protective measures such as bat gates, cupolas, and grates are installed while preserving the intact mine.  Today, most federal and state agencies have integrated nondestructive closures into their programs as essential options to preserve significant wildlife and other resources.

The Federal Cave Protection Act of 1988 declares that protection is the default management option for caves, but abandoned mines do not enjoy this statutory protection.  It is the responsibility of land management agencies and affected communities to consider resource protection in making mine closure decisions.  The choice of which abandoned mines should be preserved by protective closures can have profound conservation impacts.  Identifying abandoned mines used as critical roosting habitat is a vital step in ensuring the long-term health of regional bat populations.  Ultimately, though, these colonies will only be protected through installation of appropriate, bat-compatible closures.

We assume that adequate information has been gathered to make informed mine-closure decisions.  Where there is a paucity of data, closure decisions must err toward preservation. Typically, a variety of assessments must be carried out before the closures are initiated.  The most useful biological data comes from internal assessments over multiple seasons.  Cultural surveys are required at mines on federal and state properties that are more than 50 years old or are associated with materials that are at least 50 years old (even if the mines are younger).  While some mines are not old enough to warrant concern from archaeologists, most are old enough for protections mandated under the National Historic Preservation Act.  Destructive closures that seal all entrances to a mine do not ensure the long-term preservation of artifacts.

Access to geological and mineralogical information is another reason to protect some abandoned mines. Many geologists view abandoned mines as “windows into the world” that provide detailed looks at the geological history of an area. They are often the first resource investigated when prospecting for new mining ventures.