We had the season’s first real snowstorm this weekend, and we weren’t really prepared for it. I didn’t even know where our shovel was! We also didn’t have any salt for the front steps, so I took this opportunity to find out if we could get something that had less of an impact on the environment.

From what I can tell, there’s no truly environmentally friendly way to melt snow and ice. The two main materials people use—rock salt and calcium chloride—are both bad; it’s really just a choice of which is better. Along with many others, the City of Cambridge recommends using calcium chloride rather than rock salt or sand. (Ironically, the city also provides rock salt free of charge.) Many de-icers are a combination of multiple ingredients, so check the label. Here’s what I could find in local stores:

Rock Salt – NaCl (Sodium Chloride)

• toxic to plants and animals in high concentrations
• increases salinity of waterways
• corrosive to metal
• works best at temperatures above 20 degrees Fahrenheit

Magnesium Chloride – MgCl

• similar to calcium chloride below, but generally a liquid or additive to other de-icers (often rock salt)
• increases salinity of waterways
• less corrosive than rock salt

Calcium Chloride – CaCl₂

• only half as much is needed (a handful per three square yards)
• works better than rock salt at temperatures below 20 degrees Fahrenheit
• increases salinity of waterways

Urea – (NH₂)2CO

• adds ammonia to waterways
• increases algae blooms (much like fertilizer)
• works best at temperatures above 20 degrees Fahrenheit

Sand (Or Kitty Litter, Ashes, etc.)

• clogs sewers
• increases sedimentation in streams
• increases turbidity, reducing water quality and potentially killing fish and aquatic plants
• makes hard ice more slippery
• doesn’t melt ice

Calcium magnesium acetate and potassium acetate are two promising de-icers, but they’re generally only available for large-scale use or as additives to rock salt.

Since all ice melters have adverse effects on the environment, the best thing we can do is use less of them. To me, this means that calcium chloride is the way to go. It’s more effective in smaller amounts, and, if I could find the colored kind (I couldn’t around here), I’d be able to see the coverage and use less of it.

Keep in mind that these compounds are not supposed to take the place of shoveling, but break up the ice so we can shovel it away and prevent more skin from forming. That crunch under your feet is an indication that someone used waaay too much.