Road salt applicators in the public and private sectors apply an estimated 20-30 million tons of salt to pavement in the U.S. to treat ice each year. This salt persists in soils, streams, and inevitably ends up in our drinking water.
Groups like Friends of Sligo Creek who are monitoring local waterways with the help of the Izaak Walton League of America’s Salt Watch program help identify “hot spots” for road salt pollution in local waterways and encourage smarter road salting practices. Simple actions like reducing road salt use at home can reduce ice risks and reduce environmental damage from road salt pollution.
The problem
Road salt has been used on roadways, sidewalks, and parking lots to melt ice in the winter as early as 1938 in the U.S. but too much salt can have major impacts on infrastructure, drinking water and wildlife.
After salt is applied, it persists in the environment for years to come. As snow and ice melt and as rain falls, salt is washed into soils, groundwater, and into storm drains leading directly to local waterways, which over 117 million Americans rely on for their drinking water. Once salt enters the environment, there is no feasible way to remove it. One teaspoon of salt permanently pollutes five gallons of water. When buying road salt at the store, a fifty-pound bag of salt has the potential to permanently pollute 10,000 gallons of water.
Many homeowners also do not know how much salt to apply or when to apply it. Unfortunately, the same is true for many commercial road salt applicators. Often, salt applicators (especially in the private sector) have very little information on the amount of salt needed, proper salt application, salt storage, and salt clean-up. And even worse, many are contracted by the amount of salt they apply each year, causing contractors to oversalt just to meet a quota.
The cost to the environment and taxpayers
Road salt deicers typically contain sodium chloride, potassium chloride, magnesium chloride, and calcium chloride or a mixture of salts. Chloride, a common component of road salt, is used as an indicator to detect salt pollution in waterways. According to the United States Environmental Protection Agency (US EPA), chloride has a long-term (chronically) toxicity at 230mg/L and a short-term (acute) toxicity at 860mg/L.
In Maryland’s waterways, chloride at or exceeding 50mg/L (ppm) is a biological stressor on freshwater aquatic life and is considered chronically toxic.
Although the immediate purchase cost road salt is low, about $73/ton (for sodium chloride), there are indirect and long-term associated costs. Chloride is incredibly corrosive. Pipe corrosion from chloride contamination can cause water main breaks and water quality issues with drinking water.
As chloride accumulates in our waterways, it can increase the amount of corrosion in pipes, increasing the risk of toxic chemicals and heavy metals making their way into tap water. This is something that has already been documented with lead (Pb) in the US, now known as the Flint Water Crisis. Corrosion of vehicles and infrastructure (bridges, roadways, pipes, etc.) and mitigation and remediation of removing salt from the environment in our surface water, groundwater, and soils are major factors when considering the “true” cost of salt. Bolton and Menk, Inc. have estimated (based on 2023 inflation) that for each ton of road salt applied, damage to infrastructure can cost up to $17,000.
An additional problem is that most water utilities do not have the infrastructure or funding to remove* salt from the water. This leads to salt persisting in our drinking water. Because the most used road salt is sodium chloride, this creates a public health risk for individuals on low-sodium diets, as their drinking water becomes a source of daily unexpected sodium. Anthropogenic sources of salt such as road salt, water softener discharge, fertilizers and sewage contamination only add to the problem, often creating higher salt concentrations in wastewater discharge, compounding the problem and further impacting those downstream.
* The US EPA has a secondary standard of drinking water of 250mg/L (ppm) for chloride. At this level, water utilities are required to remove salt from the water, which will greatly increase the cost of water, putting a huge strain on taxpayers. Simultaneously, the US EPA recommends that individuals on low-sodium diets do not drink water that contains more than 20mg/L of sodium.
Impact on drinking water in the DC region
Because salt persists in the environment once it is applied, salt concentrations will continue increasing unless we make changes now to our road salting practices. The more salt we use each year, the more impacts we will see. And these impacts are already being documented. WSSC Water, our local water utility in Montgomery County and Prince Georges County, Maryland has noticed a substantial increase in chloride in both the Potomac and Patuxent Rivers, which are drinking water sources for millions of Americans in Maryland, Virginia, and Washington, D.C. In the past thirty years, there has been a 41 percent increase in chloride in the Potomac River and a 102 percent increase in chloride in the Patuxent River, measured by WSSC Water.
Monitoring salt in Sligo Creek
Local volunteer groups monitoring water have noticed chloride increases as well. Volunteers from Friends of Sligo Creek (FOSC) near the DC border in Maryland have been monitoring with the Izaak Walton League of America’s Salt Watch program along this creek since 2022. Viewing data for the past few years (see below) shows that the problem is only getting worse (view data at www.cleanwaterhub.org).
The salt influx into Sligo Creek has gotten so bad that FOSC has had to purchase test strips that extend to higher ranges than the test strips volunteers have been using in their Salt Watch kits (which range from 30-600mg/L). FOSC volunteers have been reporting readings that have even been “off-the-charts” for the high range test strips, which range from 300-6,000mg/L chloride.
As a result of this, they have been using their data to make change and have sent letters to numerous agencies, including: Montgomery Parks, Montgomery County Department of Environmental Protection, Montgomery County Department of Transportation, WSSC Water, State Highway Administration, Maryland Department of the Environment, City of Takoma Park Public Works Department, and more. The letters and responses can be found on the FOSC website: https://www.friendsofsligocreek.org/home/who-we-are/advocacy-committee/letters-and-testimony/.
How to reduce salt pollution
Reducing the amount of road salt used is key. Following these three key steps can help to provide safety, reduce the amount of salt used (thereby reducing pollution) and save money.
- Shovel early and often reduces the amount of snow that turns to ice. Sweeping after shoveling can also help to get sidewalks and driveways down to bare pavement where salt might not even need to be applied.
- Scatter salt. A 12 ounce mug (a typical coffee cup) holds enough salt to salt a 20 footlong driveway, 10 sidewalk squares, or 2 parking spaces. Each salt granule should be spaced out about three inches apart (salt needs space in order to melt most effectively).
- Sweep up any excess salt and store that salt in a closed container to use during the next storm event.
These tips and additional resources at www.saltwatch.org can be shared with neighbors, building managers, property managers, condo and homeowners associations and others who apply salt or who hire those who do.
Many state legislators are introducing bills to reduce road salt or incentive programs for road salt applicators to adopt best practices. Currently in the Maryland Legislature, HB 1360 has been introduced which aims to reduce road salt pollution by requiring proper storage of outdoor salt piles.
Contacts
Abby Hileman, Salt Watch Coordinator, Izaak Walton League of America, ahileman@iwla.org
Dean Tousley, Water Quality Committee Co-Chair, Friends of Sligo Creek, drtousley@gmail.com
During the week of January 27-31, organizations across the U.S. held events to raise awareness about the dangers of and solutions to road salt pollution. The week was a collaboration of government and NGOs across the U.S. and Canada (www.wintersaltweek.org). A series of webinars and events were held during the week. Among them, Dr. Jess Hua discussed the fact that “sublethal” concentrations of salt can still be harmful to wildlife. Ted Diers of the New Hampshire Department of Environmental Services, Cara Hardesty of the Ohio Environmental Protection Agency and Bryan Gruidl from Bloomington, Minnesota, spoke about policy solutions that have been enacted to address various facets of the salt pollution problem. Friday was a “Local Salt Monitoring” day with at least 16 events in seven states (Maryland, Michigan, Minnesota, Missouri, New Jersey, Pennsylvania, and Wisconsin).
Michael Reinemer, Communications Director, Izaak Walton League, mreinemer@iwla.org; 301-548-0150 ext 220.
Founded in 1922, the Izaak Walton League fights for clean air and water, healthy fish and wildlife habitat and conservation of our natural resources for future generations. The League plays a unique role in supporting community-based science and local conservation and has a long legacy of shaping sound national policy. See www.iwla.org.