From 50 feet above the hoof-pounded Colorado plain, I can hear police sirens stir the coyotes. One after another they serenade Denver’s first responders with their canine howl. This may be the nuttiest thing I have ever done for a picture: chase semi-wild bison around with a 50-foot aerial boom lift hitched to a pickup truck.

Of course the proud herd of 87 below me want none of my games, but this is the vantage point I’ve chosen from which to collect landscape views for a National Geographic story on America’s toxic wastelands—EPA Superfund sites. The Rocky Mountain Arsenal Wildlife Refuge in Commerce City, Colorado, is one of them.

From the 1940s to 1982 the area was used for chemical weapons and