Influence of Road Salting on the Nutrient and Heavy Metal Levels in Stream Water

The increased use of forested areas for winter recreation in the mountains has resulted in substantial road development and maintenance activities such as road salting. This study evaluated the influence of road salt on levels of nutrients, heavy metals, and sediment in streams as modified by topography. As a result of an extremely low snow pack, salt inputs and stream discharge were low. This reduced losses of nutrients and salt from the below road areas; however, the losses which did occur were strongly linked to the road salting practice. All study areas showed an accumulation of road salt because of the low discharge. The addition of massive quantities of sodium caused the release of other cations and significantly altered soil structure. The breakdown of soil structure appeared to be the major reason for large losses of sediment and heavy metals from the below road areas. Most streams had very low levels of dissolved heavy metal ions.

Because of the low snow pack and discharge it was difficult to evaluate a mulching and revegetation treatment. Most of the differences between watersheds seemed a result of topographic features. Steep slopes and a large road area to below road area ratio appear most influencial in altering water quality.

Project No. 3109-68, A-057-NMEX