When the Snow Melts, the Salt Remains

Salt levels in our freshwater is such a pervasive issue affecting so many lakes that it deserves attention. Canada uses five million tonnes of road salt every year. Once the snow and ice melt the chloride flows into streams, rivers and eventually into our lakes and groundwater. Unfortunately, that chloride will stick around all year, long after winter ends. Researchers have found that some freshwater bodies experience salinity levels that are 25% the concentration of seawater.

At the current rate of increasing salt use and concentration, Lake Simcoe could reach the long-term exposure threshold by 2058, which is 120 mg/L. This is approximately 11 years earlier than previously anticipated by scientists. Despite salt application training and best practices being used more widely than ever, salt levels are on  the rise. There is a relationship between the growth of the road network and increases in chloride concentrations in Lake Simcoe.

We know that highways play a part in this nightmare scene. For instance, according to the Lake Simcoe Regional Conservation Authority, prior to the 404 extension being built in 2014, 12% of samples taken from the Maskinonge River (over which the 404 travels) exceeded the chronic (or long term) chloride level. Between 2014 and 2019 that number increased to 84% of samples! 

This issue is of real interest to those concerned with the health of Lake Simcoe and the impacts of the Bradford Bypass. Ontario’s fast tracked Environmental Assessment process does not look at the operation of the highway, only its construction, and it does not look at the health of Lake Simcoe, at all. Their solution for dealing with salt contaminated soil is just to remove it. Out of sight out of mind? We should be doing more to reduce the use of salt, and we should seriously consider whether it makes sense to put this highway here, where the salt levels in the East Holland River already exceed the chronic long term exposure limit. (See the next chart!)

Chloride Concentrations in Lake Simcoe Tributaries (rivers that flow into the lake)

Note the East Holland River above has exceeded the chronic chloride threshold (120 mg/L) for more than 20 years.
Source: Increasing chloride concentrations in Lake Simcoe and its tributaries – Jennifer G. Winter, Amanda Landre, David Lembcke, Eavan M. O’Connor and Joelle D. Young

Some of the adverse effects of increased chloride concentrations in freshwater include:

  • Changes to the structure of the lake because salt water is denser than freshwater
  • Helping invasive saltwater species to survive in our lakes. 
  • Reducing the abundance and biodiversity of microscopic plants and animals. This has a cascading effect on the rest of the food web
  • With less competition from species sensitive to chloride, we will see an increase in mosquitoes. 
  • Exposure to high (acute) concentrations of salt is deadly to fish and amphibians but lower (chronic) concentrations affect how they reproduce, grow, and thrive.

How Salt Affects a Lake Ecosystem

Albecker, M. A., & McCoy, M. W. (2017)

Freshwater in Ontario, including Lake Simcoe, is not being prioritized and protected by our provincial or federal governments. The Province has refused to classify salt as a toxic substance under the Environmental Protection Act. The Federal Minister of Environment and Climate Change could use the Fisheries Act to fight the excessive use of salt because its application and movement into waterways can be toxic to fish if levels are high enough. 

There are ways to mitigate and reduce toxic chloride concentrations. According to the Lake Simcoe Conservation Authority many times there is just too much salt being applied. They have noted a drastic reduction in salt used in parking lots following training and education. A common salt alternative is sand, which is widely used in colder climates where salt is ineffective. Additionally, beet juice and brine have been implemented with success in cities like Calgary and Winnipeg. 

For more information about the Bradford Bypass or to get involved see: https://rescuelakesimcoe.org/bbp/ 

We will be posting social media about salt and its impacts during the month of February – please follow and share.

To donate to our work please visit www.rescuelakesimcoe.org/donate 


https://www.canada.ca/en/environment-climate-change/services/pollutants/road-salts/frequently-asked-questions.html https://georginapost.com/2021/07/22/the-river-has-become-an-industrial-inlet-residents-call-for-maskinonge-river-to-be-restored-and-protected/ https://www.thestar.com/news/insight/2012/05/26/blue_crabs_in_mimico_creek_an_urban_mystery.html https://www.pnas.org/doi/10.1073/pnas.2115033119 https://environmentaldefence.ca/2019/02/06/salt-ernatives-options-keep-roads-clear-freshwater-clean-winter/

Albecker, M. A., & McCoy, M. W. (2017) Adaptive responses to salinity stress across multiple life stages in anuran amphibians. Frontiers in Zoology, 14, 40. https://doi.org/10.1186/s12983-017-0222-0