Our sources of freshwater are being invaded by salt; we are paying the price


Salt and brine is applied to roads, parking lots, and sidewalks in winter to help melt ice and snow … and then washes off into streams, rivers, and lakes.  Burning coal and other fossil fuels in power plants creates emissions which makes rain acidic–and then slowly dissolves rocks, soils, buildings, and roads releasing yet more salt into the environment.  The amount of concrete and asphalt used globally continues to expand … and slowly break down.  More and more salts get into freshwater streams and rivers.

The result?  “At least a third of the rivers and streams [in the United States] have gotten saltier in the past 25 years.”  “By 2100, more than half of them may contain at least 50% more salt than they used to.”  

The impact?  Think Flint, Michigan; a decision to take drinking water from a “saltier local river” resulted in the salt leaching lead from old pipes and putting it into the water supply causing a very dangerous and expensive tragedy.  “Nationwide, salts are crusting the insides of home boilers and the cooling tanks of power plants.  They are also coating the land where crops grow.  And they are stressing plants and animals in freshwater ecosystems, in some cases until they disappear.”

Too much salt flowing into our sources of freshwater reduces the amount of available drinking water and increases the amount of water too salty for irrigation use.  The saltiest freshwater areas in the U.S. are the northern Great Plains (due to mining and oil and gas extraction), the urban Northeast, and the Midwest (due to agriculture).

But, the arid Southwestern U.S. may see the largest increases in salt in the future due to expanding agricultural irrigation and less rainfall.  The economic cost of too much salt in the Southwest is already huge–$300 million annually in the Colorado River basin; $3.7 billion (as of 2014) in lost agricultural production in California alone.

All this, of course, is just the immediate impact on people.  The price being paid by plants, animals, and our ecosystems is and will be high.  “The natural streams that collect water across the landscape and carry it along to the rivers and lakes we get our drinking water from are like a neural network connecting us to nature.”  “If they are unhealthy, sooner or later we’ll pay the price.”

Read the article (Tim Vernimmen, Scientific American, December 6, 2018).

For more information about the impacts of salinity, search the Science Primary Literature Database and the Headline Science Database.

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