Yesterday, I rounded the corner of the block in my neighborhood and immediately pulled my dog off the sidewalk. Spread out before us was a carpet of chalky white salt crystals stretching across nearly a dozen square panels of concrete.
Why was it there? I’m not sure. We’ve had alarmingly little precipitation this year and the immediate forecast is for weather in the 40s. Sure, there’d been some daytime thaw and nighttime freezes going on, but the sidewalk in front of my house on the same block had stayed clear and any little ice that did form was nothing a little sand wouldn’t have fixed.
The problem is, the idea of using salt to clear icy surfaces is basically page one of “How to Survive a Midwestern Winter.” Salt is so cheap. You just buy a giant bag, spread it and forget it.
But we use too much – far too much – salt. So much that it stops serving any purpose.
The salt spread out before me was doing exactly zilch for snow control. It was only posing a hazard to my dog’s paws. Well, and posing a future hazard of eventually running off into the nearby storm drain and polluting Lake Monona.
How much pollution, I wondered? Well, there was an easy way to find out. I grabbed my broom and dustpan.
A few minutes later, I had a dustpan full of rock salt. I took it inside and got out the kitchen scale. It turned out I had swept up 480 grams of salt. I then weighed out a teaspoon of the salt. It came in at 5 grams. So I had 96 teaspoons of salt.
Considering that one teaspoon of salt is enough to turn 5 gallons of freshwater toxic, that meant my dustpan contained enough salt to pollute 480 gallons of Lake Monona – where it was inevitably bound before I swept it up.
Now, I’m not saying that we don’t need salt at all in winter. There are some cases where it is crucial for public safety. But we need to use salt much, much smarter if we want to protect our freshwater. Here’s how in three easy steps.
Use the Right Amount of Salt
This is a picture of what a properly salted piece of asphalt looks like:
Now compare it to a sidewalk section in my neighborhood.
See that melted oval around the pile of salt? That’s there because a few dozen crystals of salt have dissolved and mixed with the thin layer of snow on the sidewalk. The result is a solution of salt and water called brine that has a lower freezing temperature than freshwater. The brine can then either runoff of the sidewalk or the water in it can slowly evaporate, leaving behind a non-slip surface.
But the rest of those salt crystals literally have no purpose. They are left over from far too much salt application. There’s nothing for them to melt, so they’ll just sit there on the sidewalk until people walking by kick them to the curb or another snow event buries them and they can melt a little bit of that new precipitation and head downhill for the closest water body.
Use Salt at the Right Time
Another way we can salt smarter is by making sure we’re timing it right. The picture below is not one of those times!
Yep, that’s a big ol’ pile of salt dumped at an intersection that is in no danger of getting slippery. Not because of the salt, but because it is a sunny day well above freezing with no snow in the forecast. This particular pile showed up one spring after a snow that left behind maybe a tenth of an inch of accumulation that had all melted by sunrise the following day.
Check the forecast before putting down salt. Even if there might be snow or ice, how long will it last? If a warm, sunny day is on the way, consider skipping the salt. If you still watch to reduce the risk of slips and falls, here’s a good alternative:
Opt for Sand Whenever Possible
Did you know you can get sand free at locations all around Madison? And that sand works wonders for traction on ice? It’s true! Unfortunately. many communities in Wisconsin mix salt into the sand that they provide residents – but it’s still roughly half as bad as using nothing but rock salt on your sidewalk!
Remember, when it comes to winter, we need to salt smarter, not harder. It really is possible to have safe streets and sidewalks and safe lakes for the freshwater organisms that call them home.