Concern on the environmental impact

(Taylor McKinnon/Center for Biological Diversity via Los Angeles Times)

Steve Martin, superintendent of Grand Canyon National Park and an Interior Department employee, says uranium is "a special concern" because it is a toxic heavy metal and a source of radiation. He worries about uranium escaping into the local water and about its effect on fish in the Colorado River (above) at the bottom of the gorge, and on the bald eagles, California condors, and bighorn sheep that depend on the canyon's seeps and springs.