One thing we all have to admit is this mild winter has made driving and walking easier. Along with mild weather we have less compacted snow and ice on our sidewalks and roadways, and less need for road salt and de-icer. The reduced use of road salt or de-icer is a good thing. Most of us do not give much thought to road salt unless we are having trouble stopping, starting, or just steering. We give little thought to the costs associated with road salt.
- Of buying and storing.
- Of dispersing on the roads and highways
- Of cleaning up the residues in the spring
- Of damage to our vehicles and landscape.
- Of the damage to our streams, rivers and lakes.
Today, let us just consider the damage to our streams, rivers and waterways, and long term, to our water supply. The primary ingredients in our de-icers are sodium chloride, magnesium chloride, or calcium chloride. Unfortunately, chlorides are dangerous to aquatic life and even non-aquatic life. The Minnesota Pollution Control Agency (MPCA) recommends chloride levels below 230mg/liter or about one teaspoon of salt to five gallons of water.
You may wonder how the salt on our roadways and sidewalks make it into our waterways. I think we realize that it is washed down from the melting snows and spring rains. In our cities the storm sewer system that protects us from local flooding carries these contaminants into the waterways. Roughly 70% of the road salt makes it into our waterways.
Most of us realize the damage that road salt causes. We have all seen dead grass along our roads and driveways, or the rust on our vehicles. At the same time, most of have had experiences of sliding on the ice when stopping, of spinning wheels as we try to start from a stop, or just trying to walk. At this time there is no comparable replacement for road salt, so the best we can do is work to reduce the usage. Between 1999 to 2009 winter road salt usage increased in Minnesota from 200,000 tons to about 900,000 tons. That is enough to contaminate 657 billion gallons of water.
We should all be aware of the impact. At home we should remove snow as soon as possible after it falls to prevent compaction and ice from melting and freezing. Limit salt usage to no more than one pound per 1000 square feet. After the ice is gone, sweep up the remaining salt and deposit it into the garbage. At temperatures below 15 degrees, salt becomes less effective. Below zero degrees, it is useless. Instead, when it is very cold use sand on those icy spots.
We have less control over road salt usage on highways, but if we drive carefully when roads are slippery there will be less pressure to overuse road salt. Contact local governments and MnDOT and encourage salt conservation techniques such as dispersing in liquid solution. If we all make an effort, we can reduce the chloride contamination of our waterways.