Sodium Chloride (Road Salt) Monitoring
Curious about the impacts of road salt on your local rivers and streams? Join our Road Salt Sampling Team this winter!
Road salt, most commonly in the form of rock salt (sodium chloride), is used extensively during winter months to keep people safe by melting ice on roads and sidewalks. However, excess salt doesn’t disappear after it is applied. It can end up in streams and rivers, and even in your drinking water. Excess salt concentrations in streams and rivers can harm freshwater fish and insects that can’t survive in salty water. While sediments and nutrients can be filtered and treated in the municipal water supply easily, it is more difficult to remove salt. Most water treatment plants are unable to filter out high levels of salt, so it can end up in your tap water. The same holds for those that draw from wells. While sodium is not harmful to most in low levels, it could impact those who have dietary sodium restrictions in concentrations over 100 mg/L. Additionally, chlorides, while not posing a direct health risk, can, in levels exceeding 250mg/L, corrode the inside of your pipes leading to plumbing damage and the leaching of harmful metals, such as lead and copper, into your drinking water.
The Izaak Walton League of America (IWLA) Salt Watch program aims to measure the impact of road salt pollution on aquatic ecosystems nationwide and advocates for more responsible salt application. As a Salt Watch partner organization, Pomperaug River Watershed Coalition began its sodium chloride monitoring program in the winter of 2023-2024 to monitor the level of road salt pollution in the Pomperaug River Watershed. Monitoring sites were selected to test for road-salt contamination from November to March based on their proximity to impervious (paved) areas such as roads and parking lots.
Click link above for full screen map.
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This map shows locations tested for sodium chloride. Users can click on the site to view more information about the monitoring location, including stream name, description of the site, town, as well as the conductivity level at the time the water sample was collected. Chloride concentration is reported as milligrams per liter (mg/L). Click the icon in the top left corner of the map to view the map legend and explore chloride results by month.
The different colored icons and chloride ranges represent risk thresholds for aquatic life.
Chloride concentrations over >230 mg/L in freshwater streams are toxic to aquatic life.
Here's how to interpret the data presented:
RED DIAMOND
(Chloride >230 mg/L)
Toxic Conditions for Aquatic Life
ORANGE DIAMOND
(Chloride >100 to 230 mg/L)
Poor Conditions for Aquatic Life
NOTE: Chloride levels can change from day to day. This information is a snapshot of river conditions at the moment the sample was taken.
YELLOW DIAMOND
(Chloride >30 - 100 mg/L)
Fair Conditions for Aquatic Life
GREEN DIAMOND
(Chloride <30 mg/L)
Excellent Conditions for Aquatic Life
What Can I Do?
The amount of salt being applied to roads is increasing each year. The best way to mitigate road salt pollution in your community is to simply use less salt while still maintaining public safety.
For Residents:
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Be informed about the impacts of salt on your watershed and drinking water. The Pomperaug River Watershed Coalition is monitoring the presence of road salt pollution by testing for chloride in the watershed’s streams and rivers. Residents who own wells should test their water regularly and make informed decisions about treatment options.
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Start at home by reducing the amount of salt applied to your driveway - Remember, all you need is 12 oz of salt for every 20 feet of pavement!
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Educate those you know in your family and community about the impacts of road salt.
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Take action by visiting Salt Watch (iwla.org) and taking the Salt Watch Pledge. Those who take the pledge will be sent a free kit with everything you need to test your local streams for road salt.
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For Municipalities:
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Employ best practices by only salting where needed and installing application regulators on spreading vehicles to control how much salt is being applied.
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Consider brines over rock salt. Pre-treating roads before a storm with a brine solution can prevent snow and ice from bonding to the pavement. This makes plowing easier and reduces the amount of salt that needs to be applied.
How Road Salt Impacts the Environment and Wildlife
PRWC speaks on WPKN 89.5 FM Community Radio about the impacts of excessive road salt on freshwater streams and what residents can do to protect the health of their water resources.
Listen to learn how you can help reduce road salt pollution in your community this winter!