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Chemical De-Icers a Mixed Blessing
Steve Tonn, Extension Educator-Omaha Metro Area Lakes

Snow-melt products can be a good-bad thing. They can make walking safer on our sidewalks and driveways, but they can also damage concrete surfaces, plants, grass and can be a potential pollutant for creeks and lakes.

The problem comes when we over-apply them around our home, just to make sure the ice and snow melts. Excessive use leads to an accumulation of the active ingredients. This can damage concrete surfaces, harm plants and grass and be carried away to stormwater drains when the ice and snow melts. Pollutants entering the stormwater drains are deposited in Omaha metro creeks and lakes. De-icers can cause raised levels of chloride in creeks and lakes which is harmful to aquatic life. That is why it’s still best to remove the ice and snow by hand when you can and use only moderate amounts of a snow melt.

The five major ingredients offered in the different brands of chemical de-icer each bring advantages and disadvantages:

Calcium chloride – the traditional ice-melting product that continues melting ice in temperatures down to about -25 degrees F. It rarely harms plants unless used in excess, but it can create a slippery, slimy surface on concrete and other hard surfaces.

Rock salt – the original ice melter and the least expensive. Because it’s sodium chloride, it’s effective down to about 12 degrees F. It can, however damage not only concrete and plants but also soils and metals.

Potassium chloride – another chloride formulation that can damage plant roots. Plus, it can cause serious plant injury when washed or splashed on foliage.

Urea (carbonyl diamide) – a fertilizer sometimes used to melt ice. It’s only about one-tenth as corrosive as calcium chloride, but it still can contaminate ground and surface water with nitrates. Urea is only effective to about 21 degrees F. Urea is not recommended for use as a de-icer where runoff can enter stormwater drains or waterbodies.

Calcium magnesium acetate (CMA) – is made from dolomitic limestone and acetic acid (the principal compound in vinegar). CMA does not form a brine as the salts do, but rather helps prevent snow particles from sticking to each other or the road surface. It has little effect on plant growth or concrete surfaces; however its performance decreases below 20 degrees F.

Never over apply de-icing agents and use them only when necessary and be sure to remove the slush before it has a chance to refreeze. Also consider mixing de-icing agents with sand so the mixture is not so concentrated. These tips will help to protect your property, plants and our creeks and lakes.