CHLORIDE

What is chloride and where does it come from? 

Chloride is a compound that comes primarily from the salt used on roads and sidewalks during the wintertime. Chloride levels in the Upper Mississippi River basin have increased by over 30% since 1989, with a current 360,000 tons of salt being applied to the Twin Cities Metro Area every year. 78% of this salt makes its way into groundwater, local lakes and rivers, and wetlands, with damaging effects to freshwater aquatic ecosystems.

How does chloride impact the Mississippi River and other waterways?

When chloride reaches toxic levels in a body of water, it can kill freshwater aquatic plants and animals and lead to harmful algal blooms. Overall, increased salinity leads to decreased abundance, growth and reproduction outputs of freshwater organisms. Chloride also poses health risks to humans when it gets into groundwater or when it corrodes lead and copper drinking pipes. Because chloride doesn't break down in water, it will pollute a lake, river, or wetland permanently once it is introduced. In fact, 1 teaspoon of chloride has the ability to pollute 5 gallons of water forever.

What can you do to combat chloride pollution?

Friends of the Mississippi River is working toward chloride reduction on a large legislative scale, but you can take small-scale action too:

• Use as little salt as possible

Effective salting calls for only 4 pounds of salt per 1,000 square feet of pavement. This will look like a 3-inch spread between granules of salt.

• Don't use salt when the temperature is below 15°F, it won't work!

• Use alternatives to salt when possible

Traction grit and sand both work when it's too cold for salt to be effective. Afterward, sweep up the grit or sand to reuse next time, and to prevent either from becoming another pollutant.

• Shovel often to slow the formation of ice

SOURCES

FMR, Reduce salt pollution. https://fmr.org/legislative-updates/reduce-salt-pollution 

InsideClimate News, Road Salts Wash Into Mississippi River, Damaging Ecosystems and Pipes. https://insideclimatenews.org/news/16012023/mississippi-river-road-salt/#:~:text=Just%20a%20teaspoon%20of%20salt,into%20the%20Gulf%20of%20Mexico. 

Mississippi Watershed Management Organization, Snow and Ice Removal. https://www.mwmo.org/learn/preventing-water-pollution/snow-ice-removal/ 

New York Times, Road Salt Works. But It’s Also Bad for the Environment. https://www.nytimes.com/2022/01/07/climate/road-salt-water-supply.html