Minnesota’s lakes and rivers are among the state’s most beloved features, but the excessive use of salt to treat winter sidewalks and soften water threatens the health of these waterways. Chloride (salt) in lakes and rivers is an issue of growing concern. Two sources of salt pollution — sidewalk deicing and water softeners — offer homeowners a chance to make a difference. 


Hard water, caused by minerals such as calcium and magnesium, can cause scaling and mineral deposits in residential appliances. Water softeners counteract this build-up, but the resulting salty brine in wastewater has become a major contributor to chloride pollution. In Minnesota, an estimated 136,000 tons of chloride passes through wastewater facilities each year as a result of residential and commercial softening efforts. 

One teaspoon of salt, such as the salt used for sidewalk deicing, can permanently pollute five gallons of water. An estimated 730 million pounds of salt are spread across roadways and parking lots throughout a typical Minnesota winter. With that much salt coating the pavement for months, some inevitably washes down storm drains, where it enters local waterways untreated.



Smiling people in the snow
Take a proactive approach to snow removal, and remember that one teaspoon of salt can pollute five gallons of water.

What happens to lakes and rivers polluted with excess salt? It’s not a pretty picture. Normally deep lakes “turn over” during the changing temperatures of spring and fall, mixing a top layer of warm, oxygen-rich water with a bottom layer of water that’s rich in nutrients but low in oxygen. Saltwater is heavier than freshwater, and it disrupts this seasonal cycle of lake water mixing. It sinks to the bottom of lakes, starving fish and other organisms of the oxygen they need to survive. 

Today 54 lakes and streams are labeled as impaired (hazardously polluted) by the MN Pollution Control Agency because chloride levels are too high to sustain fish and aquatic life. Chloride pollution also threatens drinking water sources. The MPCA monitors a network of wells for potential contamination, and 27% of shallow aquifer monitoring wells in the Twin Cities metro have chloride levels higher than EPA drinking water guidelines. These shallow wells are a kind of “early warning system” that detects contamination in groundwater.


Graphic re: chlorides
Excessive use of salt in water softeners and sidewalk deicing takes a toll on our waterways. Graphic by MPCA. CC BY-NC 2.0


How to Decrease Your Salt Use

Many homeowners assume their water needs to be softened, but in certain cities throughout the metro, water is centrally treated before it reaches homes and businesses. Here are concrete steps you can take to reduce your salt use at home.

  1. Test Your Water’s Hardness & Streamline Softening: Take a water sample from a source that isn’t softened, such as a garden hose. If you do find that your water is hard, check the calibration on your water softener to make sure you don’t overdo it. One method to reduce the amount of salt used by your water softener is to extend the time between regeneration cycles. You should also set your system to only soften hot water taps, further minimizing salt use with an existing system.
  2. Upgrade Your Water Softener: Newer water softeners are more efficient and use less salt. One sign that you may be due for an upgrade is if you’re using more than one 40 lb. bag of salt in a month. Check with your local watershed management organization to see whether you might qualify for a grant to upgrade to a more efficient water softener.
  3. Shovel First, Salt Sparingly When the snow flies, take a proactive approach to shoveling to reduce the need to salt. Removal, using a variety of tools such as a broom and steel-tipped shovel will help prevent ice from forming. If you must use it, sidewalk deicing salt is only effective when the temperature is above 15 degrees Fahrenheit. Scatter individual grains of salt broadly, leaving an inch or two between each particle. 


We’re at a critical juncture with more rivers, lakes, and streams threatened by chloride pollution every year. Now is the time to take a more salt-aware approach to water softening and winter sidewalk maintenance. Conscientious choices today can help make sure the lakes and rivers are safe and healthy for future generations. 


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