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"Salt Lick" -- The Discovery Files

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A salt assault that could lead to big problems for drinking water, urban infrastructure and natural ecosystems. Across North America, streams and rivers are becoming saltier and more alkaline.

Credit: NSF/Karson Productions

Audio Transcript:

Passing the salt.

I'm Bob Karson with the Discovery Files, from the National Science Foundation.

(Sound effect: river or stream sounds) A "salt" assault that could lead to big problems for drinking water, urban infrastructure and natural ecosystems. A new study led by National Science Foundation-funded researchers is first to assess long term changes in freshwater salinity and pH on a continental scale. The team analyzed data gathered from 232 monitoring sites across the country over the past 50 years.

Their findings? America's rivers, streams and ponds are becoming saltier. Main culprits? Road salt de-icers, fertilizer runoff, mining waste and other salty compounds that ultimately end up in our waterways.

They found that over a third of U.S. drainage area significantly increased in salinity and that alkalinization -- influenced by salinity and other factors -- increased by 90 percent.

The team says until now we didn't fully appreciate the role different salts play in altering the pH of streams and rivers and the potential impacts. Think Flint, Michigan, where the Flint River's high salt load combined with chemical treatments made the water corrosive and caused lead to leach from water pipes. But the scientists say problems with de-icing, fertilizers and infrastructure can be successfully addressed.

As long as we don't take this with a grain of salt.

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