Environmental Impacts of Road Salt

Article by Doug Britt, FMN and member, Reston Association’s Environmental Advisory Committee

Salt-based de-icing and anti-icing agents are routinely applied to roadways during and prior to winter storm events in Northern Virginia for the important purpose of maintaining public safety.  The primary agent used is sodium chloride (NaCl). The sodium, chloride, and other impurities in the salt eventually make their way into our environment through runoff from meltwater, as well as through splash and spray from vehicular traffic and wind. These processes can elevate sodium and chloride concentrations in the environment to harmful levels; although, sodium is not as prevalent a concern as chloride, owing to the greater solubility of the latter.

Road salt can contaminate drinking water resources, impair the ecology of lakes and streams, and harm local plants and animals. Salts also have negative impacts on infrastructure, vehicles, and other property. Corrosion from salts can increase the costs of maintenance, repair, and replacement of such infrastructure. Although there are a number of alternative de-icing agents available, sodium chloride as a brine solution appears to have the least negative environmental impact when considering the full life cycle of its production and application. Sodium chloride, nevertheless, can generate a host of environmental problems.

Water Quality Impacts

Contaminants from road salt enter water resources through storm drains, surface runoff, and infiltration into groundwater. In most parts of North America, chloride concentrations in freshwater surface waters are less than 120 mg/L. Chloride concentrations in Fairfax County surface waters have steadily increased for the past 25 years, consistent with the use of de-icing agents. Concentrations of chloride in surface waters are also correlated with the proportion of impervious surfaces in a watershed. Chloride also is seeping into groundwater throughout Northern Virginia where concentrations are steadily increasing with time. De-icing salts that seep into groundwater can be discharged as baseflow to local streams following a lag time of tens to hundreds of years.

Elevated chloride concentrations can lead to chemical stratification in lakes and ponds which impedes turnover and mixing of bottom and top waters – leading to oxygen deficiencies in deeper layers. High chloride levels are toxic to aquatic organisms such as fish and macroinvertebrates, and some aquatic plants. The presence of salt can also release toxic metals from the sediment. Various federal and Virginia state water quality standards and guidelines have been established to protect public health and the environment from the negative effects of sodium and chloride:

Soil Impacts

Through the process of cation exchange, the sodium ion replaces other soil cations such as calcium (Ca+), magnesium (Mg+), and potassium (K+) and changes soil permeability making soil more impervious, less stable, more acidic, and less fertile.

Pet Impacts

Ingestion of road salt directly (or from licking paws or drinking meltwater) can harm pet health in many ways, and in severe cases cause death. Salt exposure to a pet’s paws can also cause inflammation and sores that are slow to heal.

Wildlife Impacts

Birds may mistake salt crystals for seeds or grit. Consumption of even small quantities of salt can lead to death due to the extreme sensitivity of birds to salt. Some mammals (e.g., deer) are attracted to salt resulting in a higher risk for collisions with vehicles. Loss of salt sensitive vegetation can also impact wildlife habitat and create conditions favorable to non-native invasive species. Amphibians such as frogs, toads, and salamanders also are known to be sensitive to elevated salt levels given their very permeable skin, their physiological dependence on osmotic processes, and their early life stage in wetland habitats.

Roadside Vegetation Impacts

Impairment of roadside vegetation is often the most visible sign of salt damage to the environment. Salt impacts vegetation foliage via dehydration and can affect root health through osmotic stress. Salt also can disrupt nutrient uptake, seed germination, and plant development. Impacts to roadside vegetation can impair wildlife habitat, destroy buffer zones that capture and retain pollutants, and lower species diversity.

Infrastructure Impacts

Salt exposure impacts infrastructure, which can greatly increase required maintenance and replacement costs. Corrosion of roads, bridges, and sidewalks is a documented consequence of winter road activities, as is corrosion of vehicles. De-icing salts also can damage vehicle parking garages, which suffer the same corrosion damage as bridge decks. In addition to corrosion damage, de-icing agents can increase the frequency of freeze and thaw cycles that are deleterious to asphalt.

What is Being Done to Address this Issue Locally?

Recently The Izaack Walton League of America has initiated a Winter Salt Watch program, encouraging citizen scientists to monitor local streams before and after road salting activities. Several Reston residents, including myself, are now participating by monitoring Reston tributaries of Difficult Run (DR) and Sugarland Run (SR). As a baseline, I recorded chloride concentrations prior to the first 2019 winter storm at two of these sites. The results were 91 mg/L (SR) and 101 mg/L (DR), both being above average but within the normal range for North American streams. Chloride concentrations measured at these same locations subsequent to road salting associated with the first two snow/ice storms of 2019 exhibited more than a fourfold chloride increase (412 mg/L and 479 mg/L, respectively). Data from other Reston sampling sites are not yet available. If you would like to participate in the Winter Salt Watch program, you may do so directly through the Izaack Walton League of America (https://www.iwla.org/conservation/water/join-the-winter-salt-watch), or you may contact Will Peterson, Reston Association Watershed Manager (wpeterson@reston.org). Reston Association and has been monitoring the water quality in Reston’s four lakes since 1997. Although chloride concentrations are not directly measured, conductivity values are recorded multiple times each year. Conductivity is a measure of the electrical conductance of water and is positively correlated with salinity. The conductivity of all four Reston lakes is much greater since 2015 than their historic values.

The Virginia Department of Environmental Quality (VA DEQ) is currently developing a Salt Management Strategy (SaMS) planning process. The goal of the SaMS is to develop a comprehensive suite of management measures capable of achieving the chloride loads called for in the Accotink Creek chloride Total Maximum Daily Loads (TMDLs). TMDLs are developed to determine the total amount of a pollutant that a waterbody can handle without resulting in the impaired status of that waterbody. Although the TMDL was specific to the Accotink Creek watershed, the SaMS is intended to be applicable to the Northern Virginia region, including Reston, since winter application of salt products occurs similarly across all of our region. The final SaMS product will be a report outlining a comprehensive strategy to successfully reduce the impacts of salt products applied to manage snow and ice while maintaining high standards of public safety.

In 2018, the VA DEQ completed a report entitled “Salt Management Strategy: Environmental Impacts and Potential Economic Costs and Benefits of Improved Management Practices in Northern Virginia.” A literature review conducted as part of that report suggested that by using Best Management Practices (BMPs) to optimize de-icing agents and their application methods, it is possible to reduce both the costs and the negative impacts of de-icing operations without jeopardizing public safety. Next steps in the development of the SaMS include identifying traditional and non-traditional BMPs to achieve the SaMS goal, developing a water quality monitoring program to evaluate implementation effectiveness over time, developing a comprehensive education and outreach campaign, and developing a mechanism to track BMPs and salt use through a stakeholder-driven participatory process. The final report is expected in early 2020.

Meanwhile as individuals and business owners we should be cognizant of the potential environmental impacts associated with the application of de-icing agents. This understanding may help us better balance the twin goals of protecting public safety while minimizing environmental damage.


• Fay, L., D. Veneziano, A. Muthumani, X. Shi, A. Kroon, C. Falero, M. Janson, and S. Petersen. 2015. Benefit-cost of various winter maintenance strategies. Minnesota Department of Transportation No. CR 13-03.
• Laite, K., 2017, Annual Environmental Monitoring Program Lakes Anne, Thoreau, Audubon and Newport, Bright Pond and Butler Pond, Aquatic Environment Consultants, Inc.

Native Plant Gardener Needed

Meadowlark Botanical Gardens in Vienna, VA is seeking a part time Native Plant Gardener. This position oversees gardening work in two main native collections with mulching, weeding and plant care. Ability to assist with signage and identification is helpful. Most time is spent in the Potomac Valley Collection (PVC). The PVC was initiated nearly twenty years ago to support the Global Strategy for Plant Conservation (GSPC). Since that time it has developed into a key educational resource.

The PVC was recently documented in consultation with the Ted Bradley Herbarium at George Mason University. Currently, 82 families, 164 genera and 221 species are cultivated in a natural forest setting with many more in situ taxa present.  Unlike most public garden native plant collections, no selections are used and it features plants found only in the Potomac River basin as a biogeographic province. Full details of cultivated taxa in the collection can be seen at: http://sernecportal.org/portal/checklists/checklist.php?clid=5139&emode=0

The second collection is the Native Virginia Wetland; here they are creating an example of the Great Dismal Swamp around a two acre lake and adjacent woodland. Thirty-five year old bald cypress trees anchor this beautiful space. Many species native to Southeastern Virginia are flourishing in cultivation.

Up to 25 hours a week. Flexible schedule. $12.18 per hour. Deer free environment.
Call Keith Tomlinson for further information 703-255-3631 X 102

NVCT Conservation Luncheon, 21 March 2019

Key Bridge Marriott, 1401 Lee Highway, Arlington, VA  22209

Thursday, 21 March 2019

11:30 am Registration/Networking

12-2 pm Lunch and Program

Save the date for the Northern Virginia Conservation Trust (NVCT) 2019 Conservation Luncheon! On March 21, 2019 NVCT will host their 25th Anniversary Luncheon at the Key Bridge Marriott in Arlington, VA.  The speakers for the luncheon are going to include top business and political leaders from Northern Virginia, including Chairman of the Arlington County Board Christian Dorsey, about the impact of Amazon’s arrival in our region. The featured speakers will share their expertise and views on the balance we must find between open space and land conservation and the new development and infrastructure necessary to attract growing, innovative businesses.

Secure your seat now. Click here to purchase your ticket. If you’re interested in learning about sponsorship opportunities, click here.

Fairfax Master Naturalist CaterpillarsCount! Project

Fairfax Master Naturalist CaterpillarsCount! Project

Don Coram

CaterpillarsCount! (Citizen Science Service Code C254) is part of a multi-year, multi-site National Science Foundation-funded study to determine whether seasonal activity of plants, insects, and birds are all responding synchronously to climate change. The lead universities for the study are University of North Carolina, Georgetown University, and University of Connecticut.  Figure 1 maps the 73 sites around the Eastern U.S. that collected data in 2018. 

The paper that was the impetus for the project is Increasing phenological asynchrony between spring green-up and arrival of migratory birds”, which appeared in Nature’s Scientific Reports, Vol. 7, in 2017. Phenology is a branch of science dealing with the relations between climate and periodic biological phenomena (such as bird migration or plant flowering). At each site, volunteer citizen scientists count caterpillars and other arthropods on a specific collection of 50 leaves on each of 10 trees during the growing season (May-August). (50 is an arbitrary number intended to be a balance between getting enough data and not creating an overwhelming data collection chore.) These counts will be repeated over several years to look for trends. With 73 sites, there is no way this data could be collected without citizen scientists, hence the participation of naturalists like us.  Researchers at the universities analyze the data.  

For the Fairfax County site, the selected trees are in the Walker Nature Center (WNC) in Reston. WNC Director, Katie Shaw, is the site manager. I am the lead data collector, assisted by two other FMN members, Kim Schauer and Claudia Thompson-Deahl. Elise Larsen of Georgetown University has been our point of contact with the national CaterpillarsCount! project.  

In 2018, we conducted 140 surveys on 14 different dates, observing a total of 500 arthropods, including 13 caterpillars, which were present on 9.29% of surveys. (A “survey” observes the 50 leaves of one tree.) Nationally, the top 10 sites had caterpillars present in average of 5.32% of surveys, so our site looks good from this perspective.  

One of the prettiest caterpillars we found was the American dagger moth caterpillar, Acronicta americana, shown in Figure 2. We also observed fall webworm moth caterpillars, geometer moth caterpillars, and others that we could not identify.  . Among the other arthropods we observed were debris-carrying lacewing larvae, daddy longlegs, beetle larvae, and sylvan jumping spiders.  

Because caterpillars are a major source of food for nestlings of migratory birds, we are especially interested in the timing of caterpillar availability. Caterpillar phenology  (e.g., lifecycle events) at the WNC site is shown in the Figure 3. Caterpillar occurrence peaked at 36.36% of surveys on August 19. Note that August 19 is late to provide a food source for nestlings. My conjecture for this lateness is that the insects usually responsible for caterpillars in the spring are becoming rarer (along with most flying insects; see More than 75 Percent Decline over 27 Years in Total Flying Insect Biomass in Protected Areas) and fall insects do not suffer as much predation by birds. No conclusions can be suggested yet about the effect of climate  change, since the sturdy will need to go on for several years to obtain comparative data.  

It is interesting that the “caterpillar” we observed most often is not a caterpillar at all. By definition, caterpillars are in the Order Lepidoptera (butterflies and moths), whereas the most observed larvae were dogwood sawfly larvae, Macremphytus testaceus, in the Order  Hymenoptera (bees, wasps and ants). Two of these larvae are shown in Figure 4. The larvae were so numerous that they defoliated the tree, a Red Osier dogwood.  

One benefit in participating in CaterpillarsCount! is learning to identify all sorts of arthropods. There is an online training course and field guide for this purpose. As a novice entomologist, I found both the opportunity and guidance valuable. 

One unexpected benefit is the opportunity to observe nature surrounding the survey sites in a leisurely way, closely, and repeatedly. I noticed animals that I missed on other visits to WNC, such as tadpoles growing legs, a Northern water snake sunning on the rocks, a grey catbird taking a bath, an American rubyspot damselfly, and a violet dancer damselfly.  

The project could use additional volunteers this year and in the future. New volunteers could establish a new survey site or help with the WNC site. Training and support are provided.  

Please join me at the Walker Nature Center on April 23 for a discussion of the project. Elise Larsen will present with me. The talk counts for continuing education credits.

Researcher bios

Elise Larsen, PhD, Biology, University of Maryland 2013. Post Doc, Georgetown University, 2013 – present. Co-investigator on CaterpillarsCount!

Don Coram, PhD, Mathematics, University of Wisconsin, 1985. Graduate, Fairfax Master Naturalist 2016, certified 2017.  

Friends of Wolf Trap’s First Time Campers Program

First Time Campers Program: Spring 2019 (April 5 – 6)

April 5 @ 8:00 am – April 6 @ 5:00 pm

Wolf Trap National Park for the Performing Arts, in conjunction with the Friends of Wolf Trap (FOWT) and Scouts BSA Troop 55 (Great Falls, VA) sponsors a camp out for Fairfax County 5th & 6th graders in the spring and fall each year. The campout helps campers learn new skills, demonstrate that outdoor activities can be fun, teaches them about different aspects of nature and fosters a meaningful connection to the natural world.

This is an opportunity for Fairfax Master Naturalists to help youth learn to become comfortable with the outdoors, have fun and build confidence, while not venturing too far from home. This is also a great way for parents to learn to become more comfortable that their child can thrive independently.

Fairfax Master Naturalists should refer to Project E248 in the Service Catalog for additional information on the program and participation requirements.

Canada Goose Management Strategies Workshop

Wednesday, March 6th, 2019 10:00- 11:30 am
Fairfax County Animal Shelter 4500 West Ox Rd., Fairfax, VA 22030

A free workshop for parks, private citizens, homeowner associations, schools, golf courses, corporate parks, etc.

Learn about Canada goose behavior, effective goose management techniques (egg oiling, border collies, exclusion techniques), community case studies and regulations. This event is limited to 40 participants. Please register by March 4th.

Sponsored by the:

  • Fairfax County Wildlife Biologist
  • Fairfax County Park Authority 

For more information and to register please contact Kristen Sinclair by phone at (703) 324-8559 or email kristen.sinclair@fairfaxcounty.gov.

Want to become a Riverbend Park volunteer? 

Attend the next monthly Volunteer Orientation: Saturday, March 2, 9:30 am – 12:00 pm

Learn about our upcoming opportunities, projects, and events and get started on your training with a hands-on project!

Upcoming Opportunities 

  • Wildflower Survey (Feb-May) NEW – Identify & document native and non-native wildflowers 
  • Spring Salamander Survey (Feb-May) – ID, measure, and document salamanders 
  • Turtle Survey (Feb-May) NEW – ID native turtles and help us track & document their presence at Riverbend
  • Wildlife Camera Monitor NEW – Help us set up & track wildlife cams throughout the park and review footage for     some action! 
  • Exhibit Animal Care – Help provide care for our exhibit animals (min 4hrs/month for 6 months) 
  • Survey Data Entry (winter-spring) NEW – Enter data on our salamander survey onto a spreadsheet     
  • Spring/Summer Programs – Join our interpretive team and provide assistance at our camps & programs 
  • Dragonfly Survey (March-Oct) *training in March 
  • Bluebell Festival on April 6th! 
  • Ongoing Opportunities Watershed Clean ups, Habitat restoration, Trail maintenance and restoration, Gardening/plants Park Support 


Valeria Espinoza, Volunteer Coordinator valeria.espinoza@fairfaxcounty.gov

Rita Peralta, Natural Resources Manager rita.peralta@fairfaxcounty.gov

New spring projects at Hidden Oaks

Each of these projects is on the FMN Service Project Calendar and count toward your FMN hours.  

Friday, March 1, 9am-11:15 pm or Saturday, March 2,  Dr. Seuss Celebrations  

Assist a naturalist with a salute to native animals that have real adaptations that rival the author’s fanciful creations.  Contact Fiona Davies, fiona.davies@fairfaxcounty.gov or 703-941-1065.

Saturday, March 9, 8am – 1pm, Office for Children, Reptiles and Amphibians

Assist a naturalist at Hidden Oaks with the professional child caretaker three hour workshop on reptiles and amphibians to include leading crafts, walks, games and, if desired, part of of the presentation to 50 adults who care from 5-25 preschool children. Class is half outdoors or more depending on the weather. Please contact with interest and questions to suzanne.holland@fairfaxcounty.gov

Monday, March 11, 3:00pm – 4:15 pm, Centreville Library Outreach (Spring Changes)

Lead or assist a spring changes program for families at Centreville Library based on Hidden Oaks’ proram. Materials, animals, craft etc. provided. Can carpool from Hidden Oaks or meet there if assisting. If leaving from Hidden Oaks, start time is 1:45. Contact Fiona Davies at fiona.davies@fairfaxcounty.gov or call 703-941-1065 


Join Potomac River Watershed Cleanup, Saturday, April 13

The Alice Ferguson Foundation is sponsoring the Potomac Watershed Cleanup on Saturday, April 13.

Join the 31st Annual Potomac River Watershed Cleanup. The official date is Saturday, April 13, however, there will be cleanups throughout the entire month of April.

The Annual Potomac River Watershed Cleanup is the largest regional event of its kind, and the Cleanup aims to engage citizens and community leaders and to generates momentum for change.

The Friends of Accotink Creek website has information about Accotink Creek watershed cleanups on weekends, April 5 through May 11.

This project is eligible for FMN service credit.

Hear bird calls at FMN Quarterly Meeting, Mar. 18

Photo by Barbara J. Saffir (c)

Hidden Oaks Nature Center
7701 Royce St., Annandale VA
Monday, 18 March 2019
7:30 – 9 pm

Public welcome!  The Fairfax Chapter of the Virginia Master Naturalists will have a brief chapter meeting, enjoy some food and drink, give out door prizes, and enjoy a presentation on Beginning Birding by Ear by Colt Gregory. Colt Gregory has been pursuing birds since the 1970’s when he first saw an Oystercatcher through a scope at Assateague.
He started closely listening for birds when small children limited his outings to neighborhood walks.  He expanded his knowledge by listening to the Allen Kellogg LPs – (founder of Cornell Laboratory of Ornithology) and moved on to CDs and MP3s! (Got to keep up with the technology.) Colt is an active member of Arlington Regional Master Naturalist, Northern Virginia Audubon Society, Northern Virginia Bird Club and volunteer for the National Park Service.  He participated in the two year birding census for National Park Service at Wolf Trap, leads a section on the Christmas Bird Count and co-leads the weekly Sunday bird walk at Great Falls National Park with Fairfax Master Naturalist Kristine Lansing.

Master naturalists can earn one hour of continuing education credit.