The Salt of the Earth: Winter Roads in Your Watershed

Annual road salt use has gradually increased over the last two decades and currently fluctuates between 8 and 20 million tons per year nationwide, depending on the severity of the winter.  About a third of all road salt used in the U. S. is applied to states in the Mid-Atlantic region.  (Envirocast, January 2003).  One of the main components of road salt is chloride, which dissolves easily in water.  Road salting is thought to be the primary source of chlorides in our waterways.  In addition, road salt contains many impurities.  As much of 2 - 5% of road salt consists of other elements, such as phosphorus, nitrogen, copper and even cyanide.  In many areas, sand is combined with the salt for road application.  Add to all this the trash, gas and oil, dirt, and nutrients from the road surfaces and you have one big mess flowing into streams and lakes once the snow melts in the spring.  As expected, this can have a very negative impact on surrounding watersheds.  Chloride can be harmful to many forms of aquatic life at concentrations of about 1,000 ppm, which is easily accomplished during the winter and spring months in many areas of the country.  Salt can damage vegetation, including protective riparian buffers.   In addition, melting roads create an artificial "salt lick" that attracts both birds and mammals, where they often become road kill.  Sand and sediment can be an even larger problem than salt when it washes into streams and lakes.  Sediments contain nutrients that can accelerate the natural aging process in a lake or river.  Sand and sediment can also smother aquatic vegetation and damage habitat for fish and other aquatic life. 

What can be done to reduce the impacts of salt and sediment? Road commissioners and highway superintendents have their work cut out for them at this time of year.  With budgets stretched thin in many towns by several years of harsh winters, most municipalities feel they can’t afford to make any extra concessions to reduce the environmental impacts of sand and salt.  Alternatives to road salt do exist, but they tend to be more costly and many are still in the experimental phase.  Fortunately, several other methods exist to reduce the amount of sand and salt applied to roads and therefore reduce costs.  Examples include the use of calibrated spreaders to apply the right doses of salt and sand, more sophisticated forecasting methods to time road treatments more accurately, improved applicator driver training, the practice of wetting the salt before spreading so that it sticks to the road, the designation of low salt application zones near environmentally sensitive areas, and the construction of snow fences and rows of trees along roads to lessen snow blowing onto the road.  In Minnesota, farmers are paid to leave their corn standing through the winter in fields along the highway, because it can hold blowing snow.  Visit http://www.tac-atc.ca/english/pdf/saltplan.PDF for more information on best management practices for road salt use. 

Another important issue is the prevention of sand/salt stockpile runoff from contaminating ground or surface water.  This can be accomplished by storing the stockpile on a covered asphalt base such as a salt dome so rain and melt runoff can't seep in.  Although the construction of salt storage facilities can be costly, most states provide some financial assistance under nonpoint source pollution control or watershed initiative funding programs. 

If salt reduction is not an option in your area, riparian buffers can be planted along lakes, wetlands, and streams to reduce the pollutants in runoff from entering waterbodies.  However, if buffers are to be located along roadsides, it is important to choose hardy, salt-tolerant vegetation for planting.  These include serviceberry (Amelanchier spp. ), chokeberry (Aronia spp. ), tamarack (larch), and several species of ash (Fraxinus sp. ).  A list of appropriate riparian buffer plants, including a section on salt-tolerant buffer species, can be found at http://www.cblad.state.va.us/docs/Riparian_Buffer_Project_Docs/
Appendices/Appendix%20A%20-%20Plant%20Lists%20Rev%202%20pdf. pdf.  Please note that some other websites have listed several species as salt-tolerant buffer plants, including Russian olive and Tree-of-Heaven, that are considered highly invasive.  These are not recommended for use in any riparian buffer. 

http://www.stormcenter.com/envirocast/2003-01-01/envirocast.php. 

Next Month’s Feature Article: Maintaining Your Riparian Buffer