Salt mini-course program

This mini-course provides information and best practices on salt and its excess use on winter roads and sidewalks.

Introduction

The concern

Salt is a major concern for all bodies of water. Every winter, we are kept safe by applications of salt melting icy roads and sidewalks. However, the excess salt is carried away as snow melts into our storm drains, which empty directly into our waterways. Chloride, a compound found in salt, permanently pollutes our lakes, rivers, groundwater, and more. Salt also causes costly damage to our buildings, vehicles, and plants. 

Quick facts

  • De-icing salt is the #1 source of chloride use in Minnesota.
  • At high concentrations, chloride can harm the fish and plant life in our waters.
  • According to the Minnesota Pollution Control Agency (MPCA), 50 water bodies exceed the water quality standard for chloride (230 mg/L) in the Twin Cities metro area.
  • Data show that salt concentrations continue to increase in both surface waters and groundwater across the state.1

The course

Read through the following sections and watch the videos. At the end, you can pledge to practice salt stewardship in your community and request a salt decal to show your commitment.

Topic

Time

Read:

10 minutes

 Watch:

24 minutes

 Read:

 2 minutes

 Pledge:

 

Chloride is a permanent pollutant

Once in the water, there is no easy way to remove chloride .Imagine pouring a packet of salt into your glass of water, how would you remove the salt after it dissolves? On a large scale, the process of chloride removal is reverse osmosis, an extremely costly and labor-intensive process(1) This is not a solution, therefore we must pledge to use salt more effectively and responsibly. 

Major impacts

Drinking water

Most natural water contain traces of chloride, but too much can affect the taste of drinking water. Thirty percent of the wells in the Twin Cities have chloride concentration that exceed the water quality standard.2

Aquatic and wildlife

Excess road salt in the environment affect the health of wildlife, such as birds and mammals. Birds are sensitive to salt because they often mistake salt crystals for seeds and consuming even small amounts of the salt can result in death. Mammals like deer may drink snow melt and ingest chloride resulting in salt toxicity. Overall, road salt can cause declines in salt sensitive species ultimately reducing natural diversity.3

Chloride in surface water can be toxic to aquatic species including fish, macroinvertebrates, insects, and amphibians. Elevated levels of chloride threaten the health of food sources and pose a risk to species survival, growth, and reproduction.

Pets

Pets may consume deicing materials by eating them directly, licking their paws, or by drinking snow melt, all of which can harm their health. Exposure to deicing salt can cause irritation, inflammation, and cracking of their feet pads. Be mindful of how much salt you are putting down to protect the pets in your neighborhood.

Infrastructure

Chloride corrodes concrete on bridges, parking structures, and other buildings, leading to compromised structural integrity, and increased maintenance and repair costs. Deicing salt also accelerates rusting, causing damage to vehicle parts, another costly undertaking. 

What de-icer should I use?

When applying salt, know at what temperatures your product works. Not all salts work at all temperatures. Using the correct de-icer ensures that you apply salt in the most effective way possible. Look at the label on your product to determine what melting agent is most prevalent in your de-icer.

You can determine the temperature of your pavement by using a surface temperature insturment/infrared thermometer. These can be found at your local hardware store and are critical to the proper application of salt. Follow the application guidelines below ehn using and choosing de-icers. 

Melting agent

Lowest pavement temperature at which product works

Urea

20° F

Sodium chloride (NaCl)

15° F

Magnesium chloride (MgCl2)

-10° F

Potassium acetate (KAc)

-15° F

Calcium chloride (CaCl2)

-20° F

Blends

Check with manufacturer

Sand

Never melts, provides traction only

Modified from Mississippi Watershed Management Organization

What can you do to help protect our water?

Unfortunately, there are no environmentally “safe” alternatives to salt that can melt snow and ice. However, we can reduce excess salt by using smart salt application strategies identified in the videos below. Smarter application of salt reduces chloride damage to our water, wildlife and infrastructure, and is more cost effectiveSand by itself does not melt snow or ice, but can provide traction on shoveled walkways. Sand can be swept up and reused. The City of Minneapolis offers free sand for sidewalks to Minneapolis residents. Thsand provided is a mixture of 75% sand and 25% saltAfter clearing your sidewalks, spreading sand can help provide traction. 

Ways you can reduce salt use:

  • Shovel and scrape often. The more snow and ice you remove manually, the less salt is needed and more effective it becomes
  • Select the correct de-icer (different de-icers work at different temperatures)
  • Sweep up and reuse leftover salt in airtight containers.
  • Scatter salt only where critical (aim for 3 inches of space between salt granules)

 

Man in construction vest shoveling snow
A member of Minneapolis Public Works staff shovels snow to reduce the need to use salt.
Man in a blue uniform sweeping a city sidewalk
A Minneapolis Downtown Improvement District ambassador sweeps salt from the sidewalk for reuse.
White bucket of blue salt and a hand holding up a spoonful of salt
One teaspoon of salt pollutes five gallons of water.

Videos

Conclusion

Takeaways

  • More salt does not mean more melting
  • Chloride is a permanent pollutant, it stays in our water bodies forever
  • 1 teaspoon of salt pollutes 5 gallons of water  
  • Chloride is toxic to fish and plants 

Sources

  1. Minnesota Pollution Control Agency. Twin Cities Chloride Management Plan

  2. Minnesota Pollution Control Agency. Chloride 101

  3. New Hampshire Department of Environmental Services. Road Salt Reduction

Notes

This is not a smart salting certification. This is a pledge to commit to salt stewardship.
If you’re interesting in becoming smart salt certified, the MPCA offers Smart Salting training.

Videos provided with permission from: Mark Pedelty and the Econsong.Net Collective,
Mississippi Watershed Management Organization (MWMO), and Minnesota Pollution Control Agency (MPCA).

Learn more with the MN Pollution Control Agency

 

Take the pledge

Request accessible format

If you need help with this information, please email 311, or call 311 or 612-673-3000.

Please tell us what format you need. It will help us if you say what assistive technology you use.

Contact us

Shahram Missaghi

Water Resources Coordinator
Surface Water & Sewer Division
Public Works

Phone

612-673-3260