Road salt and water quality
MPCA recommends a low-salt diet for Minnesota waters. Doctors tell us to stick to a low-salt diet. Our lakes and streams should follow the same advice. When winter comes and snow and ice build up on Minnesota roads, parking lots, and sidewalks, one of the most common reactions is to apply salt, which contains chloride, a water pollutant.
Salt pollutes. When snow and ice melts, the salt goes with it, washing into our lakes, streams, wetlands, and groundwater. It takes only one teaspoon of road salt to permanently pollute 5 gallons of water. Once in the water, there is no way to remove the chloride, and at high concentrations, chloride can harm fish and plant life. Less is more when it comes to applying road salt.
Learn more about training opportunities for winter maintenance professionals under the Training tab below.
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In the news
- 4 ways to use less polluting salt in cold weather — MPR News, Jan. 9, 2014
- A call for less salt in our roadways diet — Star Tribune, Feb. 7, 2013
- KUMD Morning Show interview with Brooke Asleson, MPCA Dec. 19, 2012
- Check out the article in this month's national stormwater magazine: Ice School: Melding the science and craft of winter road maintenance.
- Check out this WCCO radio interview/article dated March 25, 2011: Road Salt: Essential For Winter Roads, Toxic For Lakes
- StarTribune article, March 23, 2011: Road salt turning Twin Cities lakes into dead seas
- Twin Cities DAILY PLANET article dated December 26, 2010: Hold the Salt
- Ice management article: Ahead of the pack
- StarTribune article, January 2, 2010: State's roads aim for low-salt diet
- Environmental Science and Technology journal. A Fresh Look at Road Salt: Aquatic Toxicity and Water-Quality Impacts on Local, Regional, and National Scales: free download.
Chloride and our water — monitoring the mix
Follow these simple tips to protect our water!
There are many ways to reduce salt use while maintaining high safety standards.
- Shovel. The more snow and ice you remove manually, the less salt you will have to use and the more effective it can be. Whether you use a shovel, snow blower, snow plow, or ice scraper, get out there as early as you can and keep up with the storm. You may even decide that salt isn't needed.
- 15°F is too cold for salt. Most salts stop working at this temperature. Use sand instead for traction, but remember that sand does not melt ice. Use the reference table below to apply the correct product for the conditions.
- Slow down. Drive for the conditions and make sure to give plow drivers plenty of space to do their work.
- Be patient. Just because you don't see salt on the road doesn't mean it hasn't been applied. These products take time to work.
- More salt does not mean more melting. Use less than 4 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. Consider purchasing a hand-held spreader to help you apply a consistent amount.
- Sweep up extra. If salt or sand is visible on dry pavement it is no longer doing any work and will be washed away. Use this salt or sand somewhere else or throw it away.
- Watch a video. This video, produced by the Mississippi River Watershed Management Organization, provides tips to homeowners about more environmentally friendly snow and ice removal: Improved Winter Maintenance: Good Choices for Clean Water
- Share a brochure. Read and pass along Nine Mile Creek Watershed District's brochure about residential snow and ice care: Residential snow and ice care (Nine Mile Creek Watershed District)
- Check out other resources. If you are responsible for snow and ice removal somewhere other than your home, please check out our training and resources tab.
Know about the salt product
Salts can range from simple table salt to calcium chloride. Salts are used because they are able to decrease the freezing point of water. Whatever product you chose, make sure you know at what temperature it stops working. We recommend using the table below as labels may be misleading. Note that pavement temperatures are usually warmer than air temperatures. To find out the pavement temperature near you, search the Road Weather Information Service.
Lowest pavement temperature
Calcium chloride (CaCl2)
Potassium acetate (KAc)
Magnesium chloride (MgCl2)
Sodium chloride (NaCl)
Calcium magnesium acetate (CMA)
Check with manufacturer.
Never melts, provides traction only.
Environmental concerns about road salt
Road salt harms our environment
Road salt, a commonly used deicer, helps keeps our roads free from ice and safe for drivers. An estimated 365,000 tons of road salt is applied in the Twin Cities Metropolitan Area (TCMA) each year. The chloride in road salt flows into our lakes, streams, and groundwater and harms our environment. Water softening, industrial dischargers, and fertilizer also contribute chloride to surface waters. We have made a lot of progress in Minnesota, but there is still a lot of work to be done in order to keep our waters clean, while keeping our roads safe. This year the number of waterbodies that are impaired for chloride more than doubled. Currently, there are 21 lakes, 22 streams, and 4 wetlands that are impaired for chloride.
Once chloride is in water, the only known technology for its removal is reverse osmosis through massive filtration plants, which is not economically feasible. This means that chloride will continue to accumulate in the environment over time. A study by the University of Minnesota found that about 78% of salt applied in the TCMA for winter maintenance is either transported to groundwater or remains in the local lakes, and wetlands (Stefan et al. 2008).
Research identifies the negative impacts that chloride has on the environment, but there are still many unknowns. Continued research will help us understand how chloride interacts with the environment and therefore, how to protect our water resources.
What’s the problem with salt?
- 75% of Minnesotans rely on groundwater for drinking water. High amounts of salt in groundwater cause drinking water to taste salty, which could restrict its use for drinking. The cost to remove salt from drinking water using reverse osmosis would be expensive.
- Salt in drinking water is a health concern for people with high blood pressure, or hypertension.
- Chloride can be naturally present in Minnesota's groundwater in varying amounts due to the weathering of rocks and varies greatly across the state. However, additional (non-natural) chloride also enters groundwater from deicing salt, fertilizer, water-softening salt, and septic systems.
- Groundwater flows into streams, lakes and wetlands. If the groundwater contains high amounts of chloride, the organisms that live in surface waters can be negatively affected.
The MPCA groundwater report found that:
- 27% of monitoring wells in the TCMA in the sand and gravel aquifers had chloride concentrations that were greater than drinking water guidelines set by the EPA (250 mg/L), likely from winter de-icing chemicals.
- 30% of wells in the TCMA had chloride concentrations greater than the chronic water quality standard (230 mg/L).
- The source of high chloride concentrations in the TCMA and other urbanized areas is likely from salt applied for winter maintenance.
- For more information check out the full report: The Condition of Minnesota’s Groundwater, 2007-2011 or the summary of key findings: Summary .
Fish and aquatic bugs
- High amounts of chloride are toxic to fish, aquatic bugs, and amphibians.
- Chloride can negatively affect the fish and insect community structure, diversity and productivity, even at lower levels.>
- Chloride changes the density of water, which can negatively affect the seasonal mixing of lake waters. Mixing increases oxygen levels required by aquatic life.
- Direct deicing salt splash can kill plants and trees along the roadside.
- Plants can also be harmed by taking up salty water directly through their roots.
- When chloride flows into streams, lakes, and wetlands, it harms aquatic vegetation and can change the plant community structure.
- Salt may cause soil to lose its ability to retain water, which could lead soil erosion. Increasing sediments going into surface waters can negatively impact aquatic organisms.
- Excess salt can make soil more alkaline and compact, and less permeable, making it more difficult to store nutrients that plants need to grow.
- Pets may consume de-icing materials by eating them directly, licking their paws, or by drinking snow melt and runoff, which can be harmful to pets.
- Exposure to road salt can cause pets to experience painful irritation, inflammation and cracking of their feet pads.
- Some birds, like finches and house sparrows, have an increased risk of death due to ingesting deicing salt.
- Salt attracts wildlife to roadsides, where they can be hit by cars.
- Deicing salt can cause a decline among populations of salt sensitive species, reducing natural diversity.
- Chloride corrodes road surfaces and bridges and damages reinforcing rods, increasing maintenance and repair costs.
- Deicing salt accelerates rusting, causing damage to vehicle parts such as brake linings, frames, bumpers.
Did you ever think about what happens to tons of salt that goes on our roads, parking lots, and sidewalks each winter? Most of it ends up in our lakes, streams, and wetlands. As a result, clean water in the Twin Cities is in jeopardy.
No salt, or very little salt, is needed if you've done a good job of snow removal. To learn a few easy things about tools, techniques, and products that you can use to keep your driveways and sidewalks safe while protecting our waters, watch this new video.
Improved Winter Maintenance: Good Choices for Clean Water (15 Minutes)
The MPCA gives special thanks to the Mississippi Watershed Management Organization for producing this video.
Salt pollutes postcard (tips on ways to reduce salt use). Print this postcard and distribute to residents and local businesses.
Changing our waters with salt February 1, 6:15-7:30 pm, Edina Public Library, Grandview Square. The event is sponsored by the Minnehaha Creek Watershed District, Minnesota Waters, 9 Mile Creek, and Citizens for Minnehaha Creek Corridor. For more information on the workshop, visit Nine Mile Watershed District's calendar page.
For building entrances and sidewalks
This 20-minute video will introduce you to best practices for maintaining small spaces (sidewalks, entryways, steps, etc) in the winter, including deicer material selection and application rates.
Training Video - Winter Maintenance Training for Small Sites
Part 1 (10 minutes)
Part 2 (10 minutes)
The MPCA give special thanks to the Mississippi Watershed Management Organization, the University of Minnesota, and Fortin Consulting for producing this video.
For property managers
How do I find a certified contractor?
If you hire out snow removal on your property, choose a contractor who is certified by the state in Snow and Ice Control Best Practices or encourage them to become certified.
Certified practitioners may found in the file below.
- Road Salt Applicators Training Certificate Holders (November 2012)
Why should I hire a certified contractor?
Many local lakes and streams have elevated levels of chloride, a common ingredient in road salt. In some cases, the chloride contamination is high enough to impact or even kill fish and other aquatic life. Winter snow and ice practices have been identified as the primary source of this chloride. Certified contractors have taken a training on how to mitigate the effects of de-icing materials on the environment, without compromising safety or effectiveness.
Voluntary certification in Snow and Ice Control Best Practices from the MPCA is given to individuals who:
- Attended voluntary training
- Complete and pass the associated test
- Agree to voluntarily apply best management practices to reduce chloride impacts
14th Annual Road Salt Symposium!
Coming February 2015
For information on the 13th Annual Road Salt Symposium, visit the Freshwater Society's Road Salt Symposium Web page.
In February 2005 a $25,000 Pollution Prevention (P2) grant was awarded to Fortin Consulting of Minneapolis. The purpose of this grant was to develop and test an education outreach program to local government and private applicators of road salt. The key objectives of the outreach were to:
- develop best management practices (BMPs) for application of road salt;
- develop a training program and conduct three pilot training sessions;
- follow-up those trained to learn what changes occurred as a result of using best management practices, as summarized in the following report:
The target of this training is private applicators. However, other interested parties and local government officials are also being trained. In this way local officials will be knowledgeable about the training that is going on in their city, can learn the newest techniques, and be in a position to continue training in their city. Also, cities have the opportunity at these training sessions to address the audience and cover any other environmental concerns affecting lakes and streams.
For road maintenance staff
MPCA Level 1 Certification: Snow and Ice Control Best Practices
Through education and outreach, applicators of road salt can learn best practices and significantly reduce their use while maintaining road safety.
Who should participate? Contractors and staff maintaining private/public walkways and/or parking lots, Property managers writing contracts, distributors of anti-icing/de-icing products, snowplow drivers— those who make it happen.
Why Is it important? This class will help:
- Save you money.
- Keep our parking lots and sidewalks safe.
- Protect our water.
- Get you certified.
A voluntary certification was given to individuals who:
- Attended Voluntary Training;
- Completed and Passed the Associated Test; and
- Agreed to Voluntarily Apply Best Management Practices to Reduce Chloride Impacts
The list of individuals given this voluntary certification to date is contained in the following document:
- Road Salt Applicators Training Certificate Holders (March 2014)
Please note: Individuals Certified in Minnesota will have to re-certify once every five years.
Because of the initial success of the pilot project, Fortin Consulting has received a 319 grant to conduct additional training sessions in Minnesota. The following training schedule is changed periodically as training events are completed/added.
- Road Salt Training Schedule (2014/2015 Season)
In the Spring of 2006, additional P2 funds were provided to develop written materials to be used by applicators. Under this approach, a technical advisory group was formed to provide input into a winter maintenance manual. It was originally thought the manual would be compact in an effort to encourage applicators to have it available in their vehicle. After a number of meetings with the technical advisory group it was decided to split off key charts and information critical to have in a vehicle before, during and after winter storm events. This created a stand alone manual and two pages of charts/critical information (clip board pages).
- Winter Parking Lot and Sidewalk Maintenance Manual (October 2010) - this manual will be used and handed out as a reference document during the training sessions. A copy of the manual will be given to each training participant as a take home reference document.
- Clip Board Pages (p-tr1-20) (October 2010) - for applicators attending training will be given a clip board containing critical information. The hope is that this clip board will be a useful tool for applicators to keep in there vehicles during storm events.
Additional Winter Maintenance Resources
Sample Snow Policies
- Scott County Snow Policy
- Goodhue County Snow Policy
- Olmsted County Snow Policy
- City of Eagan Road and Trail Snow Policy
De-icing chemicals applied to roadways can impair water quality and habitat, and are costly for local governments to purchase and to apply. Fortin Consulting and the Minnesota Local Technical Assistance Program provided a Minnesota Pollution Control Agency-sponsored winter maintenance training course for snowplow drivers in Dakota County Minnesota in November 2008. The goal was to improve operator effectiveness, and to reduce the amount of chemicals entering nearby water bodies. The Minnesota Pollution Control Agency (MPCA) and the University of Minnesota's Water Resources Center (WRC) partnered to evaluate the training through a KAP (knowledge, attitudes and practices) study. Beforehand a baseline was established. The study was repeated after two winter maintenance seasons and the results were compared. Fourteen months post-training, KAP results documented measureable improvements in driver knowledge, attitudes and practices related to specific application activities.
The study confirmed that the winter maintenance training fostered many changes. After Dakota County employees attended winter maintenance (road salt) training reductions in the use of chlorides were documented. For the 2008/2009 season the county used 14,175 tons of salt for thirty-five snow events, averaging 405 tons per event. For the 2009/2010 season the county used 9,585 tons of salt for twenty-seven events, averaging 355 tons per event. The correlates to about 40 million gallons of freshwater protected from chloride contamination per snow event. County staff attributed the decrease in salt from 405 to 355 tons to the use of computerized spreaders, the use of magnesium chloride, and to the winter maintenance training provided by Fortin Consulting in partnership with the MPCA. For detailed information concerning the P2 results of this study please refer to the following report:
TCMA Chloride Project
Metro Area Chloride Project
Chloride is a unique pollutant in that once it is in our waters there is no available technology to remove it and the primary source of chloride (road salt) is currently necessary for public safety; therefore preventing chloride from entering the environment and protecting waters from degradation while still providing public safety is critical to achieving the desired water quality.
The final outcomes of this project will be a chloride management plan which will lay out a strategy for addressing chloride impacts to our surface waters for the 7-county metropolitan area. This chloride management plan will satisfy EPA requirements for impaired waters, address waters not yet listed, and develop a strategy to protect waters that are currently meeting the water quality standards. This management plan will also include implementation activities for reducing chloride to TCMA waters as well as identify high priority areas to target implementation activities. The MPCA and the hired consultants will work with the inter-agency team, a technical advisory committee, a monitoring advisory team, and implementation plan committee and local stakeholders to develop this management plan to ensure that it is supported by our local partners and will result in ownership of the final plan.
TCMA chloride monitoring results
View Larger Map
Note: This map shows only waters that have been assessed for chloride by the MPCA in the 7-county metro area. Waterbodies without a colored label do not have chloride data available.
The MPCA project team will develop and execute a stakeholder process that facilitates positive interactions and ownership of the final restoration and protection plan recommendations and implementation efforts. The meetings will include identification of risks and opportunities, education on modeling and scientific data, and decision-making on preferred strategies and allocations. The diagram below shows the various teams that have been created (or will be created) to engage and participate in the project at various stages. A list of the members participating on each committee can be found below.
Interactions of the seven stakeholder groups
- Stakeholder Team Membership List (updated November 2014)
There are 10 tasks that have been created as part of a work plan for this effort. For a detailed description of each task, please refer to the complete project work plan available on the project website.
- Task 1 Targeted chloride monitoring
- Task 2 Update existing data compilation with recent data
- Task 3 Categorize and define waterbodies for protection and restoration
- Task 4 Develop target concentrations for non-impaired waters
- Task 5 Source identification
- Task 6 Modeling and analysis
- Task 7 Develop Education/Outreach materials
- Task 8 Write draft and final TCMA chloride management plan:
- Task 9 Write draft and final implementation plan and long term monitoring plan
- Task 10 Stakeholder process
The 10 tasks are on schedule to be completed within approximately 4 years. At the conclusion of the project, the state agencies and all local partners will have the information necessary to begin implementing practices to reduce the amount of chloride entering our waters.
Project work products
- Work Plan Summary
- TCMA Chloride Monitoring Plan and QAPP- lakes
- TCMA Chloride Monitoring Plan and QAPP - Streams and Stormsewers
- Economic Analysis of Salt Use Report
For details on the project history including the Metro Chloride Feasibility study results, the partners involved, the process, and the detailed technical information, visit the project history page.
All meeting information, including agendas, minutes, presentations, and electronic handouts can be found in PDF documents below. This document is bookmarked for ease in searching for specific meeting details.
Technical Advisory Committee meetings
- July 1, 2014, 1:00-3:30 pm
- April 23, 2014, 1:00-3:30 pm
- December 12, 2013, 1:00-3:30pm
- March 27, 2013, 9:30-12:00 pm
- January 15, 2013, 9:30-11:30 am
- October 12, 2011, 12-2:30 pm
- September 8, 2010, 1-3 pm
- TAC meeting information
Inter-Agency Advisory Team meetings
- January 16, 2014
- November 16, 2010
- March 17, 2010
- IAT meeting information
Monitoring Sub-Committee meetings
- February 26, 2013, 1-3 pm
- October 6, 2011, 9-11 am
- March 3, 2011, 9-10:30 am
- October 14, 2010, 1-2:30 pm
Education and Outreach Committee meetings
- March 11, 2014, 10-12 pm
- April 12, 2012, 9-12 pm
- December 7, 2011, 1:30-4 pm
- October 6, 2011, 1-3 pm
- EOC meeting information
Implementation Plan Committee meetings
- May 9, 2013, 8:45-12:30 pm
- July 10, 2012, 8:30-1:00 pm
- IPC meeting information
Outreach Group meetings
- Sand Creek Community Meeting: July 30, 2014, 1:00-3:00 pm
- Sand Creek Meeting Information
MPCA project team presenting at the following events/conferences:
- Minnesota Association of Watershed Districts (MAWD) Meeting (October 21, 2014, Capitol Region WD)
- Water Resources Conference (October 14-15, 2014, RiverCentre-St. Paul) - Water Resources Conference Presentation
- Metro City Engineers Meeting (April 17, 2014) — Twin Cities Metro Area (TCMA) Chloride Project Presentation
- Metro WaterShed Partners Meeting (March 12, 2014, Mississippi WMO)
- Water and Watersheds Conference (February 27, 2014, MPCA)
- AMLAC Annual Meeting (February 19, 2014, Medicine Lake City Hall)
- 13th Annual Road Salt Symposium (February 6, 2014, Minnesota Landscape Arboretum) – pdf of presentation available at freshwater society website
- 12th Annual Road Salt Symposium (February 7, 2013, Minnesota Landscape Arboretum)
- Webinar - Road salt pollution prevention strategies (U.S. EPA)
- CONDAC Meeting (January 18, 2013, Lakeville Heritage Center)
- 11th Annual Road Salt Symposium (February 2, 2012, Minnesota Landscape Arboretum)
- Water Resources Conference - poster presentation (October 18-19, 2011, RiverCentre-St Paul)
- Twin Cities Metropolitan Area Chloride Monitoring
- Water and Watersheds Conference (February 28, 2011). Day 1. Chloride track starts at 1:25:20. Metro Chloride Project, February 2011 Update Presentation
- 10th Annual Road Salt Symposium (February 3, 2011, Minnesota Landscape Arboretum) (wq-iw11-06t)
- MnDOT Hydraulics Workshop (October 5-6, 2010, Arden Hills Training Center)
- Twin Cities Metro Area Chloride Feasibility Study Presentation
- Water Resources Conference - poster presentation (October 19-20, 2010, RiverCentre-St Paul)
- WRC Poster Presentation
Watershed Project Manager
Minnesota Pollution Control Agency
520 Lafayette Road
St. Paul, MN 55155
Follow me on Twitter @brookeMPCA
Road Salt Education Program
Minnesota Pollution Control Agency
520 Lafayette Road
St. Paul, MN 55155