Q: How many of these abandoned mines are actually dangerous to the public?

Given the right circumstances, any mine, no matter how shallow, can be perilous. The hazardous rating of an inventoried mine is based on summation of sixteen ranking parameters. If the resulting score of a mine is over a certain level, then the mine is deemed a "Significant Public Hazard." Roughly 13% of the mines inventoried in the last eight years have received this designation. This means approximately 1,200 of the mines assessed pose an extreme risk to public safety.