Looking over a wobbly guardrail, Dale Landmann uncoiled a few feet of rope, cautiously lowering a white plastic pipe into the opaque waters of the Calumet River on a recent hot weekday morning. Attached to one end of the pipe was a buoy to keep the apparatus afloat; on the other end, a metal grate weighed it down so river water could flow into a small glass jar. After collecting the first ...