Keeping Groundwater Supplies Clean During the Winter Season

By Heather Voorman, The Groundwater Foundation

We all breathe a sigh of relief when we see the road maintenance crew salt, sand and shovel out the roads after a winter storm.  The truth is however, too much road salt can contaminate groundwater supplies.   So what can be done to make roads safe without harming the environment?

How do road salts contaminate groundwater?

First, it’s important to understand how road salts contaminate groundwater. When the snow melts and spring rains come, all the salt that accumulated over the winter ends up in storm water catch basins and streams.  The salt that is carried to surface water can harm fish and plants.  The salt can also damage vegetation and soil along the shoulders of roads, causing erosion issues. 

The salt can get into underground drinking water supplies by infiltrating the groundwater and contaminating wells.  Salt can remain in groundwater for decades.  If the salt does get into groundwater supplies used for drinking water it can affect the taste of the water, affect individuals with hypertension, and corrode plumbing infrastructure.  

Lowering salt applications make roadways safer.

Although salt is used because many municipalities believe it is one of the only ways to ensure roadways are safe, there are techniques, equipment and chemicals that require less salt to be used and actually make roads safer.  In Kamloops, BC, Canada following the change to a low-salt application technique, the city saw an 8% decrease in accidents.  Similarly, in Idaho transportation officials switched from heavy salt and sand applications to liquid magnesium chloride on one stretch of road and saw an 83% reduction in accidents in that area.  This sort of success story probably won’t happen in every case, but by utilizing lower salt application techniques, roadways become safer and the environment becomes healthier.

What can you do?

Here are some ideas you can recommend to your local municipality to protect groundwater supplies from salt contamination:

1.     Use the right amount: The most important factor to remember when applying salt is the surface temperature.  When roads are warmer, less salt is needed.  Municipalities might consider purchasing inexpensive infrared thermometers for spreading trucks.

2.     Only use it where it’s needed: Make sure salt is being used in areas where it is most needed.  Hills, curves, bridges, etc. need more salt than other areas of the road.  There are also times when salt won’t help melt ice on roads.  If the surface temperature is below ~10º F, a road won’t benefit from salt.  Instead, use another chemical suited for lower temperatures. 

3.     Apply early!: Don’t wait until the snow starts falling to apply salt.  It takes more salt to melt snow that has accumulated than it does to prevent the accumulation.  Brine can be applied days before a weather event in the right conditions. 

You can also use these techniques when you apply salt on your own driveway and sidewalks so you can stay safe while keeping groundwater supplies clean!

[source: www.epa.gov]