Despite its remote location, the Colorado River at the bottom of the Grand Canyon is dealing with pollution. A new study from the United States Geological Survey (USGS) found high levels of mercury and selenium in wildlife living there.
David Walters, who is an ecologist with USGS, was the lead author of the study and discussed its impact.
People have known about mercury in the Colorado River system for about two decades, but environmentalists are still concerned with what the report found.
We spoke with Roger Clark, program director for the Grand Canyon Trust, who is concerned with the findings.
