Thursday, January 19, 2017

Road Salt Impacts Waterways, Soils and Infrastructure

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.

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.

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?

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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Corrina Parnapy, an Adirondack native  transplanted to Vermont with her husband and son, is the District Manager for the largest Natural Resources Conservation District in the State of Vermont.  She is the lead Aquatic Biologist/ Phycologist for Avacal Biological, and writes about the natural world for the Adirondack Almanack and other Northeast publications.


21 Responses

  1. Keith Gorgas says:

    Well written, concise,and spot on. Besides the obviously harsh environmental impacts, there is a steep human cost. When salt is laid down on snow, or under snow, it forms a very slippery non-cohesive mix. Traction is impaired. Quite a few fatal accidents ( and countless non-fatal accidents) have occurred immediately following the application of road salt.. This slippery mix is far more treacherous than plain snow.
    The use of straight salt is most common on State highways, while county and village road crews generally lay down a far more suitable mix of sand and salt. The downside of salted sand is the cost of cleanup each spring and the appearance of the roadways.
    I think that straight salt should be banned, except possibly in ice storms, and even then one would think that mixing sand in would be beneficial. Thanks for publishing this article

  2. Scott says:

    I really like the start of your closing paragraph….I believe we should take individual responsibility for our own actions and don’t ask the government to control everything and dont ask the government to provide everything.

    • terry says:

      Yes we would all like people to be more responsible for themselves but we are talking about a road here, one of the more socialist endeavours undertaken by government. you cant expect people o maintain the road as they drive on it.

      • Scott says:

        I didn’t think of people maintaining the road. I meant put snow tires on your car, leave earlier when roads are snowy, drive slower when roads are snowy, and don’t expect bare roads when it snows. If you crash because you drove too fast for road conditions it is your fault, not the road’s fault or the weather’s fault and not the government’s fault.

  3. Jay says:

    spot on scott,

  4. James Marco says:

    I agree. Road salt is a real problem with no real solution. There is one road construction detail they ignore. The use of geothermal heat to warm roads. This is expensive. It is a process of digging a road 4-8′ down laying pipes across the bottom angled about 5-10 degrees up, connected in a loop to a horizontal layer of pipes under the actual pavement. Water mixed with various freeze retardants is installed.

    As water warms it becomes less dense, so as it picks up ground heat it will rise to the upper pipes warming the pavement. The cold water will get dense and simply flow back down a pipe in a circuit. This should raise pavement temps to around 35F in winter and cool road temps in summer. Cooling the road will make it stiffer and stronger, hence lasting longer by reducing rutting/creep. Of course the initial outlay would be quite expensive and does not solve the bridge/bedrock areas a road travels over, but is partially defrayed by decreased maintenance, savings on salt/sand and overall better road conditions(reduced fatalities, accidents.)

  5. Boreas says:

    Regarding lake and river monitoring of Cl levels, it would be interesting to know when and how often the data is collected. Mid-summer? Spring run-off? Mid-winter? Monthly? All of the above? Just curious.

    Another issue to be considered is the recent lack of precipitation. While one would think less precipitation would equate with less road salt usage, it isn’t necessarily the case. Much snow can be removed with a plow, whereas ice requires sand and/or salt. Along the same lines, in years of heavy snowfall, while salt usage may increase, there would be a larger dilution factor when all the snowpack finally melts. Conversely, one would think there would be less dilution in lower precip. winters.

    Sand avoids many of these variables, although it is far from a perfect solution and introduces its own problems. Sand increases stream siltation, which may be even more threatening to the health of streams. Sand is also destructive to vehicles via sandblasting undercarriages. And some localities/states use very coarse “sand” that contains pebbles that take a toll on paint, windshields and headlights. It is also unsafe on a dry road due to lack of traction, especially with 2-wheeled conveyances.

    Ultimately, the best solution for the environment is plowing only and mandatory use of snow tires, studs, chains, and staying home in bad weather. But studs and chains create their own road surface issues, and our economy wouldn’t tolerate the associated absenteeism and revenue loss. So, again, when push comes to shove, the environment loses.

    • Corrina says:

      Thank you greatly for your well thought out comments and questions.
      The monitoring for some bodies of water takes place all year, while others focuses on low flow to catch the groundwater impacts. That being said, if the results focused on just the spring the numbers would be far higher. Most sampling data is collected between every week to every other week, with limited funding, some will only sample once a month. For proper data analysis multiple years of collection need to take place with additional meta data.

      With the lack of precipitation (snow) one would think that less road salt would be applied, however that is not so. With the crazy weather and temperature fluctuations it means that more water is on the roads and freezing, thus more product has been applied this year. The road salt is finding its way into the water ways before the spring thaw.

      I fully agree on snowplowing. It is the best tool of road managers and reduce the need for product application. It all comes down to understanding road and weather conditions, apply product at the right time and amount, being proactive and not reactive and for the public to understand that there is NO stipulation for clear roads in local snow and ice policy and they drive accordingly.

      Thank you again for your comments and I encourage everyone to continue the conversation.

      • Boreas says:

        I wonder if a granular form of wood by-products (finely ground leaves, needles, mulch, sawdust, etc.) could be used near sensitive trout streams instead of sand or salt, or mixed in with either. It would probably work well in very cold weather, but could be a mess when things get warmer. But if you could cut sand or salt by 1/2 near streams, it could be worthwhile.

  6. Todd Eastman says:

    Who sells the salt to the highway departments?

    No kickbacks there, eh?

  7. John says:

    One other cost not mentioned is the high cost of Vehicle repairs caused by the salt. Replacing brake rotors, ball joints, exhaust systems, air conditioning condensors, radiators, bumpers etc can result in thousands of dollars in expenses. With the advent of many safety features on vehicles, most people(if they use common sense) should be able to drive safely on snow covered roads. Many older readers of this somehow managed to drive safely for years in vehicles without antilock brakes, traction control, stability control with rear wheel drive and bias ply tires.

    • Boreas says:

      I agree. I survived, but became well-aquainted with ditches. This was in the lake-effect snow belt – back when cinders were used. People just stayed home until the roads were safe. Now everyone feels they must be able to drive the speed limit regardless of conditions.

  8. Paul says:

    I always put on snow tires, but I don’t think this is one where we can go back to the 1940’s way of doing things. Now people expect the roads to be pretty clear in the winter. It is especially important if you are trying to make your living in a place like the Adirondacks where we get more winter precipitation. The only answer is to come up with technology that is more environmentally friendly. There are now certain types of road surface materials being developed that have much better traction in icy conditions w/o much salt needed. That is what we need to figure out and use it in sensitive areas. The idea that everyone should just stay home or chain up is a non-starter as I see it.

  9. Charlie S says:

    On December 26 I took a drive up towards northern Vermont. The morning started with blue skies and temperatures in the low 20s. By mid morning the skies were dark as thick clouds came in.Above Killington sleet and rain began to fall and the roads became slick. The trucks were out spreading coarse sand at this time on Rt. 100. Not salt. That night a thin sleet and rain fell down which immediately turned to a very slippery sheet of ice. The next morning that sheet of slippery ice was still present except for on the roads which were very clean-looking roads not the salt-laden ugly look we get here when even a hint of snow hits the ground.

    I saw the same thing near Tunbridge, Vermont a few winters ago when I was driving through there, trucks spreading a coarse sand after a snow fall. I’ve seen the same in other areas of Vermont. They don’t use sand everywhere in Vermont. In Rutland they seem to be spreading salt when it snows but it seems they don’t use heavy doses like they do here.

    What Scott says, about individual responsibility for our actions is fine and dandy but what do you say to people who are just getting by and can hardly afford toothpaste never mind snow tires or chains or whatever we need to do to reduce the spread of salt on our roads. Drive slower when roads are snowy? Vermont drivers are very cautious in slippery conditions. In New York, including the Adirondacks, drivers are too often in a mad rush no matter what the weather conditions are. It’s like night and day these two places.

    We have some of the cleanest water in the country…or so it is said. How much longer can that last with all of the salt we spread. This is a very serious issue if we value our water. They started talking about this a year or two ago and I hope clear heads get together and do something about it. It is a problem!

    • Corrina says:

      Thank you for your comments. I originally wrote this article as part of testimony provided to the VT legislation, as I now live in VT. The application rates of the salt product applied here in VT are comparable to slightly less than those that are applied in the Adirondacks. It all depends on the winter, alternative product and conditions.

      For the most part the State (VTrans) here in VT uses a brine solution that is not noticeable on the roads after it is applied and is a highly effective BMP. It is applied at the start of the storm, followed up with lots of plowing. Sand is primarily used on the vast system of class 3 (dirt) roads by towns, which is also mixed with sodium chloride.

      There is no difference in driver mind-set between the Adirondacks and VT. coming from the Adirondacks to VT, I have over the past 2 winters seen similar driving conditions, and similar cars off the road during slick conditions. To be honest, I see more studded snow tires in VT than I did in NY.

      The salting of our waterways is a serious issue that needs to be addressed not just within NY, but regionally within the Northeast. It will take partnerships, collaboration and informing the public and elected officials.

      I encourage you and the readers of the Adirondack Almanack to keep commenting. The open dialogue is important to spreading the word.

      • Charlie S says:

        “A brine solution that is not noticeable on the roads..” you say. This makes sense to me,is why Vermont roads look so good after ice or snow. Spreading salt on the roads! Just imagine what even 25 more years of this will produce! It has to have a negative effect. Indeed this is agreed upon by all parties but it seems to me nothing is being done….or not near enough.

        They start spreading salt in mall parking lots hours before even an inch of snow is predicted…heavy doses of salt as if it were a cheap commodity. Every time I see this the first thing that comes to mind are insurance companies. The big boxes are afraid of lawsuits in case someone slips and falls in their lots.Salt is cheaper than lawsuits……at the expense of the soil and water! Maybe we should stop building the endless shopping centers that we seem to keep building. This would save on salt, would save beautiful old farm fields, save many wood lots…………………………. But then this would take away from the ever abundant supply of tax havens that our puppet leaders just love so much to grab at every turn.

        I had to have my frame welded above both rear wheel wells of my truck last year as the metal was worn to about an inch or less from the top. One good pothole and my rear end would have collapsed. It’s a good thing my mechanic found these during a routine service. That set me back about $800. which was a good price. Imagine what the salt is doing to our soil and water if it can do this to metal! We’ve gotten too far ahead of ourselves and we are going to pay dearly in the near future. Thank you for your piece and your concerns Corrina.

  10. Charlie S says:

    Boreas says: “Ultimately, the best solution for the environment is plowing only and mandatory use of snow tires, studs, chains, and staying home in bad weather…….our economy wouldn’t tolerate the associated absenteeism and revenue loss. So, again, when push comes to shove, the environment loses.”

    We’re not capable of doing what is best for the environment Boreas. We’re number one, economy is foremost and this is final. It’s all about convenience for us. Think remote starters for cars where you can push a button and start warming up your car 50 feet away without having to step out of the house. Think about how much more carbon emissions into our atmosphere because of this one mere convenience! We’re not taught to be responsible stewards. There’s no hope for us…sadly I say!

  11. Cranberry Bill says:

    Two items here, the quick one first – Is calcium chloride used very much. It melts ice at lower temperatures than sodium chloride. Is it less harmful to the environment?

    Second, I need to visualize the amounts of salt you have posted. Using table salt for which I could get more numbers, I propose the following ratios using just a few numbers from Wikipedia, the source of all knowledge in the universe. The numbers are: 1 teaspoon of salt weighs 5690 milligrams and sodium chloride is 60% chlorine. Calcium chloride is close to that percentage also. I guess that road salt would have a lower concentration of chlorine since it is not as pure as table salt.

    And these are the numbers I get: One teaspoon of table salt will contaminate 3.6 gallons of water at 250 milligrams per liter; or 49 gallons at 70 mg/L; or 450 gallons at 2 mg/L. I do not think road salt numbers would be more than 10% less.

    • Boreas says:


      I am not sure if CaCl is better or worse environmentally. It just melts ice at lower temps. But I believe it is much more expensive – probably because it is manufactured instead of mined. Both have the chloride (Cl) ion which tends to be the problem because it is quite reactive and corrosive. I think as the weather gets colder some road crews increase the amount of CaCl in the mix.

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