Friday, November 25, 2016

Interim Report on Chloride Levels

Chloride Levels Have Risen in Urban Streams and Rivers in the Northern States
            A 2014 article in the Great Lakes Echo newsletter notes that rivers in wintry cities remain salty year-round.  About 35 billion pounds of salt are applied to wintry roads in the United States every year.  Much of it winds up in rivers and lakes.

            The Community Science Institute, located in Ithaca, has collected volunteer stream data for several decades, and published an article on ‘Road Salt in Local Streams’ in spring of 2015.  The article indicates that the majority of road salt (mostly consisting of sodium, calcium, and magnesium chlorides) enters streams by infiltration to groundwater.  Chloride from road salt is absorbed into groundwater over time, eventually leading to increased chloride levels in streams. 

             An interesting observation in the same article is that the chloride levels stay relatively stable in most streams throughout the year, rather than increasing in the winter and decreasing in summer.  The salt does not simply wash off the road and directly into the stream; it is apparently a slower, longer process.   We have found similar results for chloride measurements taken in various urban/suburban streams in Onondaga County during various late winter through mid-fall surveys.

read more in the  Link to Chloride Report

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