Changes

Between 5 and 7 million tonnes of salt is applied every year in Canada for winter maintenance of roads and other paved surfaces, making it one of the most ubiquitous contaminants in urban environments.  NaCl- is the most common de-icer applied for winter maintenance, comprised of 40% sodium and 60% chloride.  Sodium chloride rock salt is often treated with liquid MgCl2 and CaCl2 to reduce the effective temperature range of salts.  Liquid brines comprised of NaCl-, MgCl2 and CaCl2 or a combination of these products are increasingly being used on roads for anti-icing.

Between 5 and 7 million tonnes of salt is applied every year in Canada for winter maintenance of roads and other paved surfaces, making it one of the most ubiquitous contaminants in urban environments.  NaCl- is the most common de-icer applied for winter maintenance, comprised of 40% sodium and 60% chloride.  Sodium chloride rock salt is often treated with liquid MgCl2 and CaCl2 to reduce the effective temperature range of salts.  Liquid brines comprised of NaCl-, MgCl2 and CaCl2 or a combination of these products are increasingly being used on roads for anti-icing.

[[File:(LSRCA Logo) Atherley Narrows annual chloride concentrations (1971 - 2020).png|thumb|700px|A graph showing increasing average levels of chloride found in Atherley Narrows, (located between Lake Couchiching and Lake Simcoe), over the past few decades, due in part to increased use of rock salt in parking lots, roadways and commercial and residential properties. From 2005 - 2020 the amount of chloride increase per year has doubled when compared to 1971 - 1986 (1.26 mg/L per yr. vs. 0.63 mg/L per yr.) (LSRCA, 2021). It is estimated that by 2120 the average level of chloride within the the Lake Simcoe watershed will exceed the 120mg/L guideline set by CWQG. (LSRCA, 2018)<ref>LSRCA. 2018. Parking Lot Design Guidelines: Municipal Policy Templates to Promote Salt Reduction in Parking Lots. https://www.lsrca.on.ca/Shared%20Documents/Parking-Lot-Design-Guidelines/Parking%20Lot%20Design%20Guidelines.pdf.</ref>]]

[[File:(LSRCA Logo) Atherley Narrows annual chloride concentrations (1971 - 2020).png|thumb|500px|A graph showing increasing average levels of chloride found in Atherley Narrows, (a rural sampling location, between Lake Couchiching and Lake Simcoe), over the past few decades, due in part to increased use of rock salt in parking lots, roadways and commercial and residential properties. From 2005 - 2020 the amount of chloride increase per year has doubled when compared to 1971 - 1986 (1.26 mg/L per yr. vs. 0.63 mg/L per yr.) (LSRCA, 2021). It is estimated that by 2120 the average level of chloride within the the Lake Simcoe watershed will exceed the 120mg/L guideline set by CWQG. (LSRCA, 2018)<ref>LSRCA. 2018. Parking Lot Design Guidelines: Municipal Policy Templates to Promote Salt Reduction in Parking Lots. https://www.lsrca.on.ca/Shared%20Documents/Parking-Lot-Design-Guidelines/Parking%20Lot%20Design%20Guidelines.pdf.</ref>]]

==Impacts on the Environment, Human Health and Built Infrastructure==

==Impacts on the Environment, Human Health and Built Infrastructure==