HIGH COUNTRY — When temperatures drop and snowstorms loom over the North Carolina High Country, department of transportation and municipal maintenance crews reach for the salt, sprinkling a heaping helping on local sidewalks, roads and highways to keep society moving as the snow falls.
“When you have a big snow event in the High Country, tons of salt gets laid down. Everybody knows the roads are going to be passable immediately after a storm, because you’ve got to go skiing,” said Appalachian State University biology professor Shea Tuberty. “It’s part of the economy — it comes with a cost, but it also comes with a cost if you don’t do it.”
If roads are not salted before a snow event, the costs to a High Country mountain town such as Boone can be significant, Tuberty said. In snowbelt states such as Ohio, impassably snowy roads can cost as much as $300-$700 million per day in direct and indirect costs, according to data from the American Highway Users Alliance.
“Within 30 minutes of applying salt — whatever the cost was — you’ve already made that cost up, and saved on hospital bills and damage to infrastructure from people wrecking,” Tuberty said. “Almost immediately, the salt pays for itself, which is why we do it.”
Salted roads can reduce accidents by 51 to 88 percent once the treatment is applied, according to The Salt Institute. Despite road salt’s seemingly essential role in keeping society mobile during harsh High Country winters, Tuberty, along with other students and teachers at Appalachian State University, wondered— where does all the salt go once the snow is gone?
“As soon as that snow begins to melt, or if it rains on it, that salt immediately dissolves and is carried into the streams,” Tuberty said. “We’ve been monitoring the salinity of the water and the soil by measuring it for conductivity, as an easier way of measuring salinity.”
Saltier water conducts more electricity, and the conductivity can be measured as a way to determine how much salt is in a given body of water, which is one way Tuberty and other Appalachian State scientists have monitored the health of eight local streams that flow into the Upper South Fork New River for the past decade, he said.
“Some of these streams are so healthy — so perfectly pure and pristine — that they won’t even conduct electricity,” Tuberty said. “What’s happening here in the High Country is we’re getting conductivity peaks during snow events, and when all the melting occurs immediately after the snow events.”
The more human development exists near a stream like Boone Creek, the saltier that body of water tends to be, largely thanks to salty snowmelt runoff, according to Tuberty.
“The streams get so salty this time of year, especially after snow events, that it’s equivalent to estuarine water at the coast — places where the rivers meet the oceans,” Tuberty said. “Nothing up here is evolved to live in that kind of salty water, so it’s starting to select against sensitive species like trout, mayflies, stoneflies and caddisflies.”
Mayflies, stoneflies and caddisflies are insect species that indicate high water quality, according to a thesis detailing the effects of winter road salt application by Matthew Fleetwood, one of Tuberty’s graduate students.
“Our research suggests that specific conductivity levels measured in Boone are having a negative impact on overall macroinvertebrate health in the headwater streams of the Upper South Fork of the New River,” Fleetwood’s thesis said.
According to Tuberty, sensitive bugs such as mayflies, stoneflies and caddisflies are the first to disappear when water quality drops due to something like an increase in salt. Other species susceptible to changes in water quality include trout — which draw anglers to the High Country from across the United States — and salamanders, such as the New River’s mascot, the Eastern Hellbender, Tuberty said.
“So far we haven’t degraded the water to the point where we’ve gotten rid of them,” Tuberty said. “But the scary thing about the salt levels is they’re ratcheting up every year.”
Thousands of pounds of road salt are used each winter to keep Boone’s roads clear of snow and ice, according to Boone Deputy Public Works Director Todd Moody. Boone has experimented with — and sometimes uses — a mixture of 80 percent salt brine and 20 percent beet juice as an alternative to treating the roads before a winter storm, Moody said.
“We try to limit our rock salt usage because it’s corrosive to vehicles, streetlights, the storm-water system and it gets in the river,” Moody said in a phone call. “If the temperature is cold enough and the weather comes in as snow, you can pre-treat roads with a salt brine beet juice mixture.”
According to Moody, Boone is a Southern outlier among beet juice road treatment users — generally municipalities in the Midwest and further north are known to use the concoction.
“The effectiveness is hard to determine, but I do feel it lowers the salt brine’s effective temperature, which is good,” Moody said. “The big thought behind it is environmental — if we can keep salt out of the water system. It’s a small step to help with storm water runoff and the environment.”
With a finite budget to work with in keeping the roads functional during winter weather, Moody said the biggest challenge is the significantly higher cost of beet juice — about $3 per gallon — compared to road salt — about $100 per ton.
“We only have so many funds to work with, and we’ve got to get the job done with the money we have,” Moody said.
Tuberty said he was unsure bringing beet juice into the road salt mix is a sure fix for the increasing salinity in places like Boone Creek.
“As far as beet juice’s impact on conductivity, we don’t know that,” Tuberty said. “I don’t look at it as something we should be doing for sure.”
Elsewhere in Watauga County, salt brine or regular rock salt is used to pre-treat roads before snow, according to Moody. In Ashe County, small stones mixed with salt have occasionally been used in treating secondary roads, but the tried-and-true salting methods are preferable, according to an email from NCDOT Highway Maintenance Engineer Ethan Osborne.
“I have heard of other departments of transportation experimenting with beet juice and other liquids for road treatment, but NCDOT has always just utilized salt or salt brine,” Osborne said in an email. “Salt has always been a reliable road treatment, so I foresee us staying with it in the future.”