Mountain streams are not as clean as previously thought

Although mountain spring water is often claimed to be the cleanest water to drink, a new study led by the University of Georgia has revealed that this is often not the case. By using data from the Southern Appalachian Mountains that has been collected over 40 years, the scientists found that water quality in high-elevation streams has been negatively affected by sediment caused by deforestation, constructions, and agricultural runoff.

“We had access to studies from 1976 to last year that encompassed both stream and terrestrial studies,” said study lead author Rhett Jackson, a professor at University of Georgia’s Warnell School of Forestry and Natural Resources. “Some streams in Macon County have very high sediment concentrations, four times greater than found in forested streams.” 

When streams carry such a large amount of sediment, it is more difficult for animals to find food in the water, and it also affects fish growth and disease resistance. Moreover, if sediment flows downstream and reaches public water supplies, cities and towns will need to invest more money in order to filter the water.

According to Professor Jackson, Appalachian water quality issues began over a century ago, with the arrival of European settlers. “The landscape you see now isn’t what it was like in 1900 – the early settlers logged everything,” he explained. While for generations, native Cherokee Indians left the hillside forests untouched, the settlers cut the forests and tried to farm the hills, causing soil erosion and sediment movement into the streams.

More recently, building houses on mountain ridges and unpaved roads to reach them created even more land disturbance. “Roadside ditches and unpaved roads produce a lot of sediment, and their sediment production increases as roads get steeper and as gravel roads get more use,” Jackson said.

Finally, farming practices are also negatively impacting the water quality of streams. Since farmers use increasingly larger amounts of fertilizers, much of the stream water contains high concentration of nutrients, such as nitrate.

“Because the water in streams comes from the whole landscape, everything we see on the land has some effect on streams. But streams are resilient, and as long as we intelligently modify our actions a little bit, we can farm and live near streams while protecting their water quality. Maintaining the quality of our landscape requires a little thought and work on our parts,” Jackson concluded.

The study is published in the journal BioScience.

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By Andrei Ionescu, Earth.com Staff Writer