We introduce salt to the environment in a variety of ways. De-icing salts are used by state, local, and private contractors, as well as residents, on roads, driveways, and walkways. A certain level of salt application in the winter is necessary to ensure public safety. Road salt storage areas, wastewater from water treatments systems, stormwater and urban runoff (deterioration of concrete structures such as bridges, sidewalks, etc.), fertilizers, sewage, and food waste are other sources of salt to our environment.

Contrary to popular belief, salt doesn’t melt snow or ice. Rather, salt is used to prevent the formation of ice/snow crystals. When salt dissolves in water, it breaks up into two ions (charged atoms) that mix with the water molecules and prevents the water molecules from bonding to form ice and snow. This is also known as “lowering the melting point” of water. When we walk on salt on sidewalks, or drive on salt applied to roadways, the rock salt is crushed so that it can start reacting with the water to prevent future ice/snow crystals from forming.

Sodium chloride (NaCl) in the form of rock salt is the most common salt used in Connecticut for the removal of snow and ice. Sodium chloride is effective for the removal of snow and ice down to 15-20°F. To make sodium chloride more effective, sometimes other salts such as magnesium chloride (MgCl₂) or calcium chloride (CaCl₂) are used in place of, or added to, the sodium chloride. Magnesium chloride is effective down to 5°F and calcium chloride is effective to -10°F.

Salts used for winter maintenance can be applied as either a solid (rock salt) or as a brine (a solution of dissolved rock salt in water). Brine can be applied to surfaces up to 48 hours before a storm or mixed with rock salt that is spread on roadways, parking lots, or sidewalks to enhance how well the rock salt melts snow and ice. When applied before a winter storm, brines help to prevent the snow and ice from bonding to the pavement surface, make plowing more effective, and reduces the amount of salt required throughout and after a storm. When brine is applied to the rock salt (known as pre-wetted salts), the water “activates” the rock salt so that it reacts faster with the snow and ice which reduces the amount of the rock salt required.

Today’s commercial market offers a variety of products labeled as “alternative” or “eco-friendly” salts. It is important to note these are all still salt-based products. The “eco-friendly" de-icers use organic materials such as a beet juice, molasses, beer yeast, or cheese brine mixed with salt. These organic materials allow the salt to stick to the road surface more effectively to minimize the bounce and scatter of the rock salt off of hard surfaces. Although well meaning, these “eco-friendly” products can have unintended consequences to the environment. You can read more on our wildlife page.

In July 2015, a report titled “Winter Highway Maintenance Operations: Connecticut” was prepared for the Connecticut Department of Transportation (CT DOT) by the Connecticut Academy of Science and Engineering (commonly referred to as the CASE study). The CASE study concluded the use of abrasives, such as sand, only provide temporary traction until they are removed from surfaces during plowing or when the sand is kicked out of the road by traffic. It does not take very many vehicles to kick the sand out of the road and render the sand worthless. Tires grinding on the sand also tends to round off the particles, which greatly reduces its effectiveness. Unlike salt, the properties of sand do not melt snow and require the addition of salt to prevent the sand from freezing so it can be spread. Research has demonstrated that sand binds heavy metals (such as chrome, zinc, or nickel) and other petroleum-based contaminants, which causes it to become polluted throughout the winter season. Once the sand is polluted, special care must be taken to make sure it is disposed of properly for the safety of human health and environment.

The CASE study estimated more than 50% of abrasives (like sand) applied to the road are not recovered following the winter season. The excess abrasives remaining in the environment negatively impacts air quality (in the form of dust) and adds costs for sweeping, removal, and disposal of polluted sand to both municipalities and the CT DOT. The CT DOT shifted from using sand/salt mixes to only salt in 2006 for winter maintenance operations to minimize these impacts. It was noted in the CASE study that other northern region states across the United States were also transitioning away from sand/salt mixtures at the same time the CT DOT transitioned.

While it may seem like there is a direct connection between the switch to salt-only applications and damages to cars, the connection is not as clear as many think.

It is likely that the increase in rusting cars over time may be more directly linked to changes in the metals used to plate car frames and the average age of cars driven in America. Specifically, the chromium that was used on cars in the past (hexavalent chromium) was found to be highly toxic to people and the environment. The chrome used today does not have the same resistance to corrosion as chrome did before. However, changing the chrome formula has been significantly beneficial to human health and the environment. Also, researchers have suggested that the average American keeps their car longer and drives more miles than in the recent past. This means that today’s cars are exposed to more road salt over longer periods of time. The age of today’s cars combined with the different materials used to build cars may be the connection to the extent of damage we see in cars today.

While salt can corrode the metal of motor vehicles, it can also corrode materials like concrete. Concrete is a mixture of calcium and magnesium-based materials. Salt, such as sodium chloride, can pull the calcium and magnesium out of the concrete making the concrete brittle and crack. As the concrete cracks, water can seep into the cracks where it will freeze and expand in the winter leaving larger gaps in the concrete. This cycle can occur each winter season, slowly deteriorating concrete infrastructure. This type of damage to infrastructure, like bridges, can create a serious public safety concern. Meanwhile, commercial property owners have also expressed frustrations about the damage salt causes to the metal on buildings, such as door plates and metal staircases. Both forms of damages to infrastructure can be expensive, challenging to repair, and may result in future public safety hazards.

Both sodium and chloride have the potential to cause direct and indirect impacts to people and to pets.

Potential Human Health Impacts

Some individuals may notice a salty taste to their water, or they may notice aesthetic changes in their water such as odor, color, turbidity (particles or cloudiness), and hardness as the salt concentrations in their water increase.

If sodium levels in drinking water exceed 100 milligrams/Liter (mg/L) it can lead to a substantial addition to dietary sodium. This can be dangerous to those on a sodium-restricted diet. Anyone in the household on a medically ordered sodium-restricted diet should speak with their physician about the sodium concentration in their well water if it exceeds 100 mg/L.

Chlorides do not present a direct health risk to humans. However, elevated chlorides (>250 mg/L) increase the corrosivity of water, which can pull harmful metals such as lead, copper, and manganese out of household plumbing, bedrock, and soils into the water. Exposure to these metals can present significant health risks. The increased corrosivity of the water can also cause damage to household plumbing and appliances, placing a financial burden on residents.

Further information on sodium, chloride, lead, copper, iron, and manganese in private drinking water wells can be found on the DPH Private Well Program Webpage.

Potential Pet Health Impacts

Salt (even “pet-safe” salts) applied to roadways, walkways, and driveways can get stuck to pets’ paws and skin which can cause irritation or chemical burns. When pets eat or lick the salt, it can lead to various health issues including electrolyte imbalance, vomiting, diarrhea, increased thirst, increased urination, hypertension, cardiac arrhythmias, muscle tremors, seizures, or in extreme cases, death. Check with your veterinarian about what de-icing salts are safest for pets if you need to use de-icing salts at your home.

Although not as widely known, magnesium chloride brine solutions or flakes, have become a popular method for controlling dust and freezing riding ring conditions at equestrian facilities. Exposure to magnesium chloride can dry out horses’ hooves which can increase the risk of cracks and brittleness. Damage to the horse’s hooves can lead to discomfort and increased need for using extra care products to protect and heal the horses’ hooves. There could also be unintended consequences of polluting the groundwater that is used for providing drinking water to horses on the property.

The main way to minimize salt impacts is to use less salt in all applications. Reducing the amount of salt used on roadways, parking lots, sidewalks, and driveways while still maintaining public safety, and decreasing frequency of ion exchange backwash discharges can dramatically reduce the salt load to the environment and diminish the risk of impact to groundwater and surface waters.

If you are a homeowner, there a number of ways you can reduce your salt footprint on your property. Find more information on our What Can I Do? page.

If you’re a municipality, or private applicator, there are a number of resources detailed on our What Can I Do? Page.

Sometimes it can be hard to see how salt applications could impact wildlife, but there are many unintended side effects from salt on wildlife.

Salt applied to roadways attracts wildlife as they search for sources of salt in the winter months, which can increase the chances of car accidents with large animals like deer and moose. Salty water that flows into wetlands and waterbodies from roads can impact the health of frogs, dragonflies, fish, and other freshwater animals. Increasing concentrations of salt in freshwater bodies has even been demonstrated to increase the number of mosquitoes!

Learn more about the potential impacts to wildlife here.

Elevated sodium concentrations can strip essential nutrients from the soil that are necessary for the health of plants. This can lead to poor growth or even die back. You may have seen this along roadways where vegetation appears “burned” or stressed.

Read more about the potential impacts to plants here.

Salt can change the chemistry and structure of soil. Specifically, sodium can “kick” important nutrients like potassium, magnesium, and calcium off the soil. As sodium builds up in the soil, the structure can become denser and more uniform which can limit proper water flow into the soil. These changes can have effects on all types of soil including those by roadways, in inland wetlands, and in garden beds.

Salt can also pull certain metals out of bedrock and soils, such as iron and manganese, into groundwater. Groundwater high in iron and manganese can impact nearby water supply wells and can lead to staining of surfaces.

Read more about the potential impacts to soil here.

It takes very little salt to contaminant water. One teaspoon of salt can pollute 5 gallons of freshwater. And once that salt is added to the water, it can’t be easily removed. Think of it as adding salt to a pot of cooking water. If you add too much salt while cooking the only way to make the food less salty is to dilute the salt, which isn’t always possible depending on what you’re cooking.

Increased concentrations of salt in freshwater systems are changing the water quality from freshwater to saltwater on a global level. Scientists refer to this change as freshwater salinization. One of the primary concerns surrounding freshwater salinization is that there is no easy solution to remove salt from freshwater. Once salt is added to water, the primary method to “fixing” the problem is allowing freshwater to replace the saltwater to flush out the salt. This process can take decades!

Therefore, prevention is key! The best way to avoid making our freshwater systems salty is to reduce the amount of salt we add to the environment.

Read more about the potential impacts to water here.

Based on the private well cases reported to DEEP, DEEP has documented groundwater chloride concentrations ranging from 30 mg/L (significantly below the Connecticut Maximum Contaminant Level) to >4000 mg/L (>10x higher than the MCL) and sodium concentrations ranging from 5 mg/L (significantly below the Department of Public Health’s guidance level) to >1500 mg/L (>10x higher than the DPH guidance level).

Typically, seawater has a salinity (salt concentration) of 35 parts per thousand, or 35,000 mg/L. When compared to seawater, even the worst of the impacted groundwater in Connecticut has much lower salt concentrations.

The first step is to have your well water tested for basic indicators. You can find information on what to test for and how to test on the DPH Private Well Program webpage https://testyourwell.ct.gov/.

After you test your well water, review the results. Check to see if sodium is >100 mg/L and/or if chloride is >250 mg/L. If either sodium or chloride are greater than those concentrations, review the information on the Remediation Salt Investigation page.

DEEP is charged with protecting the groundwaters of the state used for drinking water under Connecticut Law (Connecticut General Statute 22a-471). When drinking water is found to contain concentrations of materials greater than what is considered “natural” DEEP’s Remediation staff may investigate to determine if the high concentrations are a result of human activities. If they are, then DEEP staff will conduct an initial investigation to identify potential responsible parties. Once identified, DEEP staff will engage with these parties to identify possible solutions to reach a resolution and provide a long-term source of clean well water to the impacted property.

If the impacted private well is on a property that abuts a Town road, then DEEP will coordinate with the respective municipality and Local Health Department to discuss the complaint and potential sources of salt. DEEP Remediation staff may send a questionnaire to the local Department of Public Works to collect information regarding snow and ice management Best Management Practices. It will be very helpful to DEEP for municipalities to share their Winter Maintenance plans. This information can help determine the amount of salt used by a municipality and identify if there are any practices they could consider updating to Green Snow Pro methods.

DEEP does not have legal jurisdiction over damages to household infrastructure. DEEP’s authority under CT law is limited to protecting the groundwaters of the State and identifying Responsible Parties whose activities caused pollution to the groundwater that could reasonably create a risk to human health and the environment.

If you have experienced damages to the plumbing and/or appliances in your home because of salt which has been confirmed with a lab test, then you may reach out to your local health department to file a complaint that will be submitted to the CT Office of Policy and Management (OPM) (pursuant to Public Act 23-31). Otherwise, if you are seeking reparations for damages to your home, you will need to file a claim against the identified Responsible Party(ies) for polluting the groundwaters of the State that resulted in excessively corrosive water that damaged your property.

Improving the efficiency of your treatment system through regular maintenance and/or upgrading to efficient technology is the best way to minimize salt discharges from a water treatment system in your home. More ways to reduce the salt footprint from your water treatment system can be found on our What Can I Do? page.

There are many challenges with resolving salt impacts to private wells, so there are also many options for how to resolve the impact and/or provide a long-term permanent source of clean drinking water to the impacted property. Below are just a few ways that responsible parties have resolved salt-impacted wells across Connecticut.

Improved Stormwater Drainage

When a well is close to a roadway, road runoff can be a significant source of salt into the well water. Some cases have been resolved by simply improving stormwater drainage, including regrading of the road, improving curbing, replacing drywell catch basins with concrete-cast basins, and/or repairing cracked catch basins. These improvements divert salty road runoff away from affected properties, resultingin improved well water quality.

Well Repairs/Alterations

Because some of Connecticut’s infrastructure is older, well construction throughout the state can vary based on when the well was constructed. CT well construction laws apply at the time of the well’s construction. Sometimes salt impacts to a well can be resolved or improved by conducting repairs or alterations to the existing well which may include extending the well’s casing or adding well seals and liners. Responsible parties may want to investigate the existing well to determine if improvements can be made to reduce salt water from entering the well.

Installation of a New Well

CT DOT has experienced success with replacing approximately two dozen impacted private wells with deeper wells (at least 350 feet deep) with at least 60 feet of steel casing into bedrock. DEEP has worked with other municipalities who have also had success installing similarly constructed wells.

While drilling deeper wells and installing deeper casings is a possible option, this option does not guarantee they will provide clean drinking water; it is impossible to know the chloride concentration in the deep groundwater aquifer until drilling has taken place.

Whole-house Reverse Osmosis (RO) Treatment System

Using a whole-house RO system can be a viable option for reduction of salt in water but is a significant financial investment that requires using large water volumes, produces and discharges significant volumes of wastewater, and requires regular maintenance.  RO wastewater contains concentrated contaminants removed from the water including salt, metals, and minerals that get discharged back to the environment, which can continue the pollution cycle. If your property uses an on-site septic system, RO wastewater cannot discharge to septic systems and requires installation of a dedicated water treatment wastewater subsurface dispersal system according to the DPH Technical Standards for Subsurface Sewage Disposal Systems.

Connection to Public Water Service

Where available, connecting to public water can provide a long-term source of drinking water. However, recent data shared by the CT Department of Public Health (DPH) has demonstrated that some public water supplies are being impacted by chloride. Additionally, in rural areas, where public water is not readily available, extension of a public water main may not be possible or can be cost prohibitive.

Other Northern Region states throughout the U.S. are also spreading the word of salt reduction. A few states have dedicated  programs that focus on salt application training and outreach and education, including the New Hampshire Road Salt Reduction Program, Wisconsin Smart Wise, Illinois Salt Smart, and Minnesota Smart Salting Training.

Other states that use deicing salts have begun to publish webpages dedicated to salt reduction including:

Maryland Winter Salts: 411 On Salt (maryland.gov)

Northern Virginia Salt Management Strategy: Northern Virginia Salt Management Strategy | Northern Virginia Regional Commission - Website (novaregion.org)

Rhode Island DOT Winter Storm Operations: Winter Storm Operations - Rhode Island Rhode Island Department of Transportation (ri.gov)

Lake George Association: Reduce Salt | Lake George Association

Unfortunately, we are experiencing more extreme weather including droughts and intense, less predictable rain and snow events.

We are seeing more extreme winter weather events that have wild temperature swings from above freezing to below freezing and precipitation shifts from snow to ice to rain within 24-48 hours. These extreme changes are making it more challenging for salt applicators to plan types of application (brine vs. rock salt) and application rates. When weather is unpredictable, it is possible that salt is applied in anticipation of an ice storm, only for a precipitation shift to rain that washes the salt into the environment.

There is no single application rate or application method that works for every weather condition. Planning application rates and methods require a good understanding of the forecast, anticipating any changes, and accounting for public use of the roadways, walkways, and parking lots.

Not only does climate play a role in the practical applications of salt, it also affects the dilution and flushing of salt out of the environment. Increasing changes of drought means less dilution of salt in fresh water and less chance of flushing salt that has built up in soils.

The best we can do as a society is to learn best practices for salt application to reduce how much salt we apply and be mindful of the changing weather. Learn more on our What Can I Do? page.