"POOLESVILLE, Md. — When environmentalist Brent Walls saw a milky-white substance in a stream flowing through a rural stretch of central Pennsylvania, he suspected the nearby rock mine was violating the law.

Recent rains had filled the ponds at the mine that allow sediment to settle out of the water, but Walls couldn’t easily take a look because they were surrounded by private property. To quickly investigate and avoid trespassing, Walls captured images of the area with his drone.

“That’s when I found the illicit discharge,” he said. The photo of cloudy liquid flowing into the creek provided evidence Walls used to accuse Specialty Granules LLC of violating the Clean Water Act.

Fifty years after that landmark legislation was signed into law, drones are giving environmentalists a new tool to capture wrongdoing where it is hard to see or expensive to find, though their use to investigate polluters is still pretty rare, Walls said."

Michael Phillis and Julio Cortez report for the Associated Press June 29, 2022. [2]