Science

How road salt affects our drinking water

The salt-crusted letters spelling "U.W. Primary" on a forged-metal manhole utility cover are pictured near the Extension Building at the University of Wisconsin-Madison during a winter day. Photo courtesy of Jeff Miller/UW-Madison.

Image By: Jeff Miller

In an effort to combat extreme weather, the city of Madison has taken an aggressive approach to rid the streets of hazardous ice. The Madison Streets Division salted every single road in the city, a solution which has been unprecedented since the ‘70s. 

While keeping the people of Madison safe through yet another winter storm is the first priority, the effects of our salt usage will not go unnoticed. 

The road salt can make its way to our bodies of water, including our 22 drinking water wells. In fact, five out of those 22 wells have already been contaminated. 

Road salt is made up of sodium and chloride, neither of which are a concern when presented in low levels. These chemicals are actually expected to be found in our drinking water. However, the taste threshold, 250 mg/L, indicates when our water will begin to taste salty due to over-saturation of chloride, and is becoming less and less distant from our current measurements. 

Located on University Ave, well 14 has had the steepest increase in chloride levels, now measured at 45 mg/L according to Madison Water Utility, and is expected to surpass the taste threshold in the next 17 years.

The other wells are predicted to follow suit in the decades thereafter. 

Aside from the salty taste, the chloride does not pose a serious threat to human health. However, people on low sodium diets for medical reasons should definitely heed warning.

We aren’t the only ones who will be experiencing the effects of substantial salt usage, as small aquatic life is put at risk as well. Several bodies of water in Madison’s area have exceeded toxic levels of chloride for small aquatic life. 

Spokesperson for the Madison Streets Division, Bryan Johnson, explained the decision: 

"The rationale behind it is one, public safety, so other people on the roads can try to get around and use those roads a little easier. And also for our trucks. If we're going to be out there pushing the snow from the snowstorm, we wouldn't be able to get traction on these roads if there was a hard pack layer of ice underneath all this heavy, wet snow."

In the end, the safety of both pedestrians and drivers on the streets of Madison takes priority. 

The issue of water contamination due to road salt is not new to Madison or to the country as a whole. This is a problem that has been building up for years, and soon we will be forced to deal with the consequences. 

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