While Winter weather has become much more problematic as to severity and duration of time across the Northern and Mountain sections of the USA, its appearance on the nations roadways in the form of snow and ice continues to be tackled by road crews with Road Salt(sodium chloride)................10-20 million tons of this toxic compound is applied to USA roads annually with horrific effects on lake and pond water quality............... Iconic fish species such as Brook Trout are particularly sensitive to die off as Road Salt reaches 250mg/L........Frogs often end up with birth defects from ingesting the salt.......Deer and Moose are attracted to the salt with horrific death and destruction to both them and human drivers......Trees and plants brown out and die off along roadway with some evidence that the salt hastens invasions of non-native plant species,,,,,,,,,,,,,How to slow down the use of salt?................"Over the past few years, beet juice, sugarcane molasses and cheese brine, among other substances, have been mixed in with salt to reduce the overall chloride load on the environment"............... "These don't eliminate the need for conventional salt, but they appear to be playing a small role cutting down just how much salt we dump on the roads"

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THURSDAY, JANUARY 19, 2017

Road Salt Impacts Waterways, Soils and Infrastructure

by Corrina Parnapy

Living in the Northeast we depend on clear roads during winter to maintain our way of life. Organizations, agencies and municipalities throughout upstate NY and VT understand that there is an impact to the environment from road salt application practices. We must find the balance that protects the environment and still allows for safe roads.

Road salt (sodium chloride) was first utilized within the U.S. on roads in NH in 1938. By 1941 a total of 5,000 tons of salt were applied to highways nationwide. Today, between 10-20 million tons of salt are applied annually. This increase in road salt application is having a negative impact on our waterways, soils, cars, and infrastructure. Lake Champlain alone has seen a 30% increase within the past 10 years in chloride levels and many bodies of water within the Adirondack Park have levels high enough to impact native aquatic organisms including fish populations.

Road salt lowers the freezing point of ice and prevents icy roads to a certain temperature. 15 degrees is regarded as the magic number, below that sodium chloride does not work. On pavement sand is occasionally used as a deterrent to slippery roads and provides some traction.  While sand costs less then salt, it has negative environmental impacts and is ineffective. Not only is sand easily blown away, it can cause sedimentation to local waterways and add phosphorus, which in turn can cause excessive algal growth and potential toxic algal blooms.


salt damaged highway foilage in Spring and Summer

Road salt application within our waterways is generally measured in levels of chloride. Every body of water will differ as to what the background levels were historically and at what level the addition of chloride will have an impact. A low nutrient (phosphorus and nitrogen) body of water can experience impacts to algae (the base of the aquatic foodweb) at as little as between 2-10 mg/L of chloride, while other bodies of water with higher nutrient levels  may not have an impact until chloride levels reach 70+ mg/L. An increase in chloride levels will shift algae dominance from chlorophyte (green algae) to cyanobacteria (blue-green algae), which can lead to toxic algal blooms. Native brook trout populations are impacted at 250 mg/L, and there is a shift in sensitive macroinvertebrate (aquatic bugs) populations at 220 mg/L. Many streams and lakes within the Adirondacks have already been identified as impacted by chloride through water quality monitoring efforts and exceed EPA standards and levels that would impact brook trout populations.
B
Salt collects and drys on the road post snow storm attracting deer and other wildlife to their
early demise via car collision

Soil bacteria nearby roadways are impacted at 90 mg/L. The sodium chloride will also strip the soils of calcium, magnesium and other import components needed for healthy soils. This can allow for invasive species to take hold. It is not hard to find damage to trees along roadways. Sodium chloride burns the needles and leaves of species within 15 feet of roads and can impact sensitive plant species as far away as 650 feet.

The addition of sodium chloride to waterways impacts the movement of metals, causing toxic accumulation and can release sediment bound heavy metals back into the water column. The density of the water can be altered by sodium chloride, impacting how a lake turns over in the spring and fall, this impacts oxygen levels.

In 2015 the U.S. National Highway Traffic Safety Administration noted salt corrosion as the cause of thousands of vehicles brake damage and failure. Sodium chloride can damage vehicles so bad they can have issues with steering, rust, and damage to any exposed metal; while technology is improving cars, the impacts from road salt can still be found. Estimates on vehicle depreciation due to de-icing salts is staggering, approximately $854 per car, per year in cold climates according to Transport Canada.

Our regions bridges, highways and infrastructure are heavily damaged by sodium chloride. It causes concrete to break and spread apart meaning costly fixes. In some areas this had led to the decreased lifespan of bridges and buildings. Sodium chloride contaminates drinking water, damaging wells and pipes. In Flint, Mich. Road salt was a contributing factor to the lead poisoning as it corroded pipes allowing toxins to enter the drinking water. Within our homes and businesses, sodium chloride damages floors, baseboards and can be harmful to our pets and yards.

Wildlife, like humans enjoy something salty to snack on and road salt will attract them to roads causing accidents with local drivers. There have been many reported bird kills from eating the road salt within the U.S. and Canada. Sodium Chloride that enters wetlands and vernal pools can alter sex ratios of species of frogs and decrease the development of eggs thereby pushing already threatened species to the brink.

With all the known impacts, and still a need for safe driving conditions, what can we do?


Deer attracted to salted roadway

A key strategy for addressing impacts from road salt to our soil and water health is the monitoring of sodium chloride levels within waterways and groundwater in addition to the implementation of best management practices (BMP’s) to reduce the application rates while maintaining a level of service expected. BMP’s include equipment calibration, current technology, real-time road condition and weather monitoring, applying the product at the right time and speed, and pre-wetting the product. BMP’s should be followed not just by our municipal and state applicators, but also by private contractors. To that end, in the fall of 2017 the Winooski Natural Resources Conservation District along with partners including the Lake Champlain Sea Grant and UVM Extension will be offering a salt applicator training for any private contractor who applies product within the Lake Champlain Watershed and beyond.

We, the users of the road have a role to play as well. It’s as simple as driving slower, putting studded winter tires on our vehicle and understanding the level of service that is provided by our road crews. The reduction in application of road salt can be achieved without impacting the level of service provided, if Best Management Practices are followed. We all would like to see a reduction in costs to our towns and the state, thus a reduction in costs to the public and the protection of our natural resources.  Together we can achieve the lasting protection of our natural resources.

Photo: Winter road treatment using salt brine, courtesy Wikimedia User Z22.

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What Happens to All the Salt We Dump On the Roads?

In the U.S., road crews scatter about 137 pounds of salt per person annually to melt ice. Where does it go after that?

. A group of scientists that tracked salt levels from 1952 to 1998 in the Mohawk River in Upstate New York. They found that concentrations of sodium and chloride increased by 130 and 243 percent, respectively, with road salting.   More recently, a study of a stream in southeastern New York State that was monitored from 1986 to 2005 found a similar pattern, with significant annual increases and road salting to blame for an estimated 91 percent of sodium chloride in the watershed.

Because it's transported more easily than sodium, chloride is the greater concern, and in total, an estimated 40 percent of the country's urban streams have chloride levels that exceed safe guidelines for aquatic life, largely because of road salt.

Road salt pollution is generally a bigger issue for the surrounding environment and the organisms that live in it. It's estimated that chloride concentrations above 800 ppm are harmful to most freshwater aquatic organisms—because these high levels interfere with how animals regulate the uptake of salt into their bodies—and for short periods after a snow melt, wetlands nearby highways can surpass these levels. A range of studies has found that chloride from road salt can negatively impact the survival rates of crustaceans, amphibians such as salamanders and frogs, fish, plants and other organisms. There's even some evidence that it could hasten invasions of non-native plant species—in one marsh by the Massachusetts Turnpike, a study found that it aided the spread of salt-tolerant invasives.

Moose attracted to salt on highway

On a broader scale, elevated salt concentrations can reduce water circulation in lakes and ponds (because salt affects water's density), preventing oxygen from reaching bottom layers of water. It can also interfere with a body of water's natural chemistry, reducing the overall nutrient load. On a smaller scale, highly concentrated road salt can dehydrate and kill trees and plants growing next to roadways, creating desert conditions because the plants have so much more difficulty absorbing water. In some cases, dried salt crystals can attract deer and moose to busy roads, increasing their chance of becoming roadkill.

How can we avoid killing trees and making roadkill of deer while de-icing the roads? Recently, in some areas, transportation departments have begun pursuing strategies to reduce salt use. Salting before a storm, instead of after, can prevent snow and ice from binding to the asphalt, making the post-storm cleanup a little bit easier and allowing road crews to use less salt overall. Mixing the salt with slight amounts of water allows it to spread more, and blending in sand or gravel lets it to stick more easily and improve traction for cars.

Elsewhere, municipalities are trying out alternate de-icing compounds. Over the past few years, beet juice, sugarcane molasses and cheese brine, among other substances, have been mixed in with salt to reduce the overall chloride load on the environment. These don't eliminate the need for conventional salt, but they could play a role in cutting down just how much we dump on the roads.