SPRINGFIELD, Mo. - The following article appeared recently in the News-Leader.
The wintertime scenario is all too familiar.
Snow and ice storms blow in suddenly, blanketing the Springfield area streets with a mantle of white.
But after the ice and snow melts, many streets remain white - covered by a dusty layer of leftover road salt.
If not washed away, that salt can cause cars and bridges to rust.
Melting ice and snow also sends dissolved salt flowing into area creeks and streams.
But in the Springfield area, the environmental impact of road salt isn't as bad as one might think, according to those who monitor water quality.
"We've never had a fish kill event associated with deicing salts," said Wally Miller, environmental specialist with the Missouri Department of Natural Resources. "The reason? There's such a small amount that actually reaches waterways, and when it does, it's already diluted heavily."
While that may be true, the use of road salt bears watching, according to Steve Jones, Drury University biology professor and director of environmental studies.
"We don't want to tear up our cars or kill ourselves on slippery roads," Jones said. "But I think we have to recognize this is a contaminant that we're introducing, and our aquatic plants and animals are not adapted to that kind of environment."
Costly alternatives
There are alternatives to using rock salt that aren't as harsh on the environment or vehicles.
One of those is calcium magnesium acetate. However, it's up to 20 times as expensive as rock salt.
Jones said people might be willing to pay a higher cost for deicing material if they understood the potential environmental costs of using harsher products.
"Road salt may be the lesser of two evils, but we have to realize there may be a cost to using it," he said.
Steve Meyer, superintendent of Springfield street operations, said the city typically spreads 3,500-4,000 tons of crushed rock salt on city streets each winter.
That jumped to 6,144 tons last year when the city had 39 inches of snow - the third worst winter on record, he said.
Greene County Highway Administrator Kevin Lowe said county crews salt bridges and intersections, using about 3,000 tons on average.
They spread 4,400 tons of salt during the unusually severe 2002-2003 winter season.
And the Missouri Department of Transportation's 12-county District 8 - which includes most of southwest Missouri - spreads 17,000 tons of road salt in a typical winter.
That jumped to a whopping 40,000 tons in 2002-2003, according to Missouri Department of Transportation spokeswoman Angela Edela.
That sounds like a lot of salt, but Miller said it really isn't, especially compared to snowbelt areas farther north.
"When you get into areas like Canada, some of those cities use 150,000 tons of salt a year and they do have environmental problems from the runoff," Miller said. "We just don't get the kind of snow events they do."
In northern climates, it's not unusual to see dead trees and shrubs along the edges of urban roads, victims of road salt poisoning.
That frequently happens when snowplows throw salt-laden slush onto traffic rights of way.
George Marino, regional supervisor of the Green Lawn Fertilizer company, said salt draws moisture out of a plant, causing it to turn brown and possibly die.
"But honestly, I have never had an applicator in your area come back and say grass along the roadway was burned," he said.
Sodium well within limits
Meyer, Springfield's street operations manager, said road crews use rock salt that's mixed with calcium chloride, which helps activate the salt and makes it an effective de-icer at colder temperatures, he said.
Calcium chloride also makes salt stick to the road surface more efficiently.
He said road salt does flow into street drainage systems, which in turn empty into urban creeks and eventually the James River.
"It's very much a concern to us, and we try to use salt sparingly on our roads," he said. "But salt is the best and least costly product we have to treat the roads. You've got to balance your concern for pollution with the public's desire to have safe streets."
Dave Ballou, laboratory director for City Utilities, said sodium and chloride levels in Springfield drinking water sources are far below the minimum standards set by the federal Environmental Protection Agency.
Ballou said the EPA's drinking water limit for sodium is 500 parts per million, and 250 ppm for chloride.
Springfield drinking water comes from several surface lakes, deep aquifer wells and from the James River.
Ballou said sodium levels from those sources typically are only 9.4 ppm and 18.3 ppm for chloride.
Both show slight spikes during winter months, but remain far below the EPA standards, he said.
"We do feel those spikes are from road salting," he said.
Greene County Commissioner Dave Coonrod said he's concerned about road salt's potential impact on rivers and streams.
"But like a lot of things, it's a trade-off," he said. "Citizens demand a road surface that's safe for them to drive on. Our society is tied to motorized traffic that we have to accommodate.
"But we're certainly not helping our water quality by having this salt runoff escape into our waterways and underground systems," he added. "We do have a very aggressive soil and erosion control program in place that helps mitigate that kind of runoff."
Bridges vulnerable
While road salt may help keep streets passable in winter, it also can cause cars, bridges and other metal structures to rust.
Mike Wright, spokesman for the American Automobile Association, said carwashes during winter are a motorist's best defense against corrosion damage.
"Road salt certainly isn't good for cars, but it has less impact today than on cars built years ago because of modern undercoatings and metal preparations the car makers use," he said. "Cars built within the last five or 10 years are much less likely to rust out than earlier models."
Still, he encouraged motorists to hit the carwash as soon as possible after a snow event.
It's not good enough to simply wash the vehicle's exterior.
"You really have to wash the vehicle's underbody as well, to get the salt off," he said.
Bridges can be damaged by salt corrosion as well.
Paul Long, Greene County bridge inspector, said small cracks in a bridge's deck can let salt reach steel reinforcing rods embedded in the concrete.
"The salt makes the rebar rust and expand in diameter, and pretty soon it can pop loose," he said. "We flush our bridges twice a year and seal them to try to avoid that."
Bridge decks are sealed with a protective spray-on coating that impregnates the concrete and makes it water proof, Long said.
Modern bridges also are being built with epoxy-coated rebar, which blocks salt from reaching the steel.
"We've never had a bridge fail due to rust that I can recall," Long said. "If you keep up with the maintenance, seal those cracks, you can really extend the life of a bridge."