Standing next to a small, unnamed stream near where it empties into Mountain Pond on a cool September day, scientist Dan Kelting reads a sensor he just dipped in the water to measure electrical conductivity, which is used to gauge road-salt concentrations.
Pure water is a poor conductor of electricity, but road salt, or sodium chloride, increases conductivity. Based on the conductivity reading (285 microsiemens per centimeter), Kelting calculates that the water contains 80 milligrams of chloride per liter. This means the stream contains roughly 160 times more chloride than a similar size stream a few miles away.
Why the difference? The stream near Mountain Pond, north of Paul Smith’s College, is downstream from Route 30, a state highway that is heavily salted in the winter. The other stream, which Kelting refers to as Smitty Brook, runs through the Forest Preserve and is upstream of roads. » Continue Reading.