For the sake of our lakes, keep your pavement on a low-salt diet

Contact: Taylor Holland, 651-757-2385

St. Paul, Minn. — As Minnesota prepares for a return to wintery weather this week, most of us will rely on a crucial tool to clear the roads and sidewalks: salt. It is estimated that we toss more than 350,000 tons of salt on the metro area roads, parking lots and sidewalks annually.

According to the Minnesota Pollution Control Agency (MPCA), our waters should follow the advice our doctors have been giving for years — stick to a low-salt diet. Road salt, which contains chloride, is the most commonly used de-icer. But, much like table salt, road salt’s benefits are peppered with danger. Salt keeps us safe on icy roads but can have the opposite effect on the nearby environment. Its public safety benefits come with environmental drawbacks like polluted waters and poisoned aquatic wildlife.

In the Twin Cities metro area, 78 percent of the salt applied to roads stays within the region’s watershed. Chloride from road salt is washed away into our lakes, streams and wetlands and eventually finds its way into the groundwater. Once in the water, it becomes a permanent pollutant and continues to accumulate in the environment over time.

As our winters become harsher, the piles of salt we spread are becoming a bigger problem. The MPCA recently analyzed Minnesota's uppermost groundwater, typically not tapped for drinking, for any changes in chloride concentrations. One-third of the assessed wells showed increasing trends, which suggests salty water is gradually seeping down into our drinking water aquifers.

This year the number of chloride-impaired water bodies more than doubled. Currently, that includes are 21 lakes, 22 streams and 4 wetlands. Of the impaired waterways, 40 are in the seven-county metro area.

De-icing material was singled out as a major culprit and the salt we use is becoming a bigger problem. High chloride levels are toxic to aquatic life. De-icing salt can also kill plants and trees along the roadways and those that soak up salty water through their roots. Salt in the groundwater can affect the taste of drinking water and can be a health issue for those restricted to low-sodium diets.

“Too much chloride has serious water quality consequences.” said Brooke Asleson, chloride project manager at the MPCA. “We are trying to spread the word that less is more when it comes to applying road salt. It only takes one teaspoon of road salt to pollute five gallons of water. The MPCA is collaborating with MnDOT, cities, counties and local partners to tackle this dilemma.”

Asleson’s study on the real cost of salt use shows that chloride comes with economic consequences, too. Cities throughout the state have been able to reduce salt use through smart salt use and by taking advantage of additional trainings. The city of Waconia has been able to reduce their use by 70 percent with an estimated total cost savings of $8,600 annually. Last year’s nasty winter depleted salt stockpiles and caused salt prices to rise. This year, some places will experience cost increases of 23-30 percent.

The MPCA remains concerned about the need to provide safe roads and paved areas, while also protecting surface and groundwater resources from contamination. The agency recommends the following tips for reduced salt use while maintaining safety:

Shovel first. The more snow and ice you remove, the less salt you will have to use and the more effective it can be. After the ice has been broken up, you can decide if deicer is even necessary to maintain traction.

Apply salt before the storm. Salting before can prevent snow and ice from building up on roads, therefore reducing overall salt use.

Slow down. Drive for winter conditions, and be courteous to slow-moving plows. The slower they drive, the more salt will stay on the road where it’s needed.

More salt does not mean more melting. Use less than four pounds of salt per 1,000 square feet (an average parking space is about 150 square feet). One pound of salt is approximately a heaping 12-ounce coffee mug. And be patient: salt takes time to work. Applying more will lead to unnecessary contamination.

15 degrees is too cold for most salt to work. Most salts stop working at this temperature. In frigid conditions, use sand for traction.

Sweep up extra salt. If salt or sand is visible on dry pavement, it is no longer doing any work and will be washed away. The excess can be swept up and reused for the next snow or disposed of in the trash.

For more on what you can do to reduce chloride in our waters, or to read more about MPCA’s role on this issue, visit the agency’s {article k2:2372}{link}Road salt and water quality webpage{/link}{/article}.