New York State’s Adirondack Road Salt Reduction Task Force, established by the Randy Preston Road Salt Reduction Act in 2020, has been released. The Task Force was charged with conducting a comprehensive review of road salt contamination and roadway, parking lot, driveway, and sidewalk management best practices within the Adirondack Park, and making recommendations for enhancements.
“More recent scientific literature may indicate existing water quality standards are not protective enough to prevent impacts to the Adirondack Park’s sensitive natural resources and ecosystem,” the report says. “Therefore, more protective limitations specific to the Adirondack Park may be required to prevent further deterioration to the region’s water quality, wildlife, and the environment.”
New York State has a long history of producing mineral salt for use in various applications, dating back to the late 1800s. Historically, Central New York has been the hub for the state’s salt production due to natural geologic formations of halite, extracted as both underground rock salt (used mostly for melting ice and snow) and brine (used mostly for medicinal and chemical purposes).
New York ranks third in rock salt production nationally, providing approximately 16% (about 7.7 million tons) of the total national output. Rock salt is the State’s third leading valued mineral product, behind crushed stone and cement respectively.
One of the most significant forms of impervious surface within the Adirondack Park is the estimated 8,830 total lane-miles of paved roads, which require some form of management for safe winter road travel. Approximately 29% of paved roads in the Adirondack Park are maintained by DOT.
These include, State and US highways and Interstate 87, with the remaining 71% maintained by local municipalities (i.e. county, town, and local roads). According to the NYS Roadway Inventory System, State highways account for 71% of all vehicle-miles traveled in the Adirondack Park, compared to 29% for all other paved roadways.
An estimated 193,000 tons of road salt are applied annually to the road network of the Adirondack Park during the colder months of the year. Of this road salt, 44% is applied to the local road network and the remaining 56% is applied to the state road network. These application estimates equate to an average of 34 tons of road salt per lane-mile applied to state roads and 13 tons per lane-mile applied to local roads.
An estimated 820 lakes and ponds, 3,687 miles of rivers and streams, and 43,273 private residential wells are on properties adjacent to paved roads. As a result, data analyzed by the Task Force suggests water quality in surface and groundwaters associated with the state road network, is being impacted by road salt use.
The Adirondack Park includes 16 major watersheds that collectively contain more than 11,000 lakes and ponds, and more than 30,000 (12,998 greater than one mile in length) miles of rivers and streams. The combination of shallow bedrock, thin soils, and mountainous terrain makes the Adirondack Park an area where the effects of road have been observed before other areas of the state.
Once dissolved, about half the road salt applied to roads in winter runs off into surface waters through snow melt and stormwater. The remainder finds its way onto surfaces where, even during warmer months of the year when road salt is not applied, it continues to leach farther into surface and groundwaters.
At least an estimated 3,687 miles (28%) of rivers and streams and 820 (7%) lakes and ponds within the Adirondack Park have the potential to receive road salt-laden runoff from the paved road network.
Road Salt Impacts
Once in surface waters such as rivers, streams, and lakes, road salt can cause changes in the natural structure and function of aquatic ecosystems and the communities of aquatic organisms that inhabit them. For example, species composition tends to shift toward more “salt-tolerant” species, altering the makeup of communities that form the basis of the aquatic food web, including phytoplankton, zooplankton, and benthic macroinvertebrates.
In turn, chloride from road salt can lead to an overall decrease in the productivity of freshwater ecosystems, reducing the overall species abundance, or in cases where there are particularly high chloride concentrations, direct mortality of
In some lakes, sodium and chloride concentrations can increase with depth and cause oxygen depletion in the hypolimnion (lower level of the water column), triggering the release of phosphorus from sediments, possibly exacerbating cyanobacteria blooms due to the loss of large-bodied zooplankton.
Additionally, the presence of road salt in runoff is suggested to increase mobilization of trace metals (cadmium, lead, copper, iron, zinc, and others), which have been demonstrated to accumulate in fish
Once road salt is washed onto roadside soils, it not only leaches into surface and groundwater, but becomes available for uptake by plants, similar to other soil contaminants. As a result, road salt has been shown to impact the terrestrial
environment by depleting soils of essential plant nutrients.
Road salt also influences the mobilization of heavy metals, resulting in reduced plant vigor or even the death of plants along salted roads. These effects can be observed along roadsides where application of road salt is heaviest, with premature loss of leaves (defoliation), discoloration (yellowing), suppression of flowering, premature mortality, and poor regeneration.
As a result, road salt encourages the establishment and expansion of non-native vegetation that possess higher salt tolerances than native vegetation, disrupting natural terrestrial ecosystems. These changes in plant communities can have cascading impacts, which in turn, increase stormwater runoff and erosion.
In addition to its impacts on aquatic and terrestrial ecosystems, once road salt enters groundwater, it can contaminate sources of drinking water supplies. People with certain medical conditions (e.g., high blood pressure, heart diseases, kidney or liver diseases) that cause them to be on a sodium-restricted diet are especially susceptible to road salt pollution.
The negative impacts of road salt on property and infrastructure stem primarily from its well-known corrosive properties.
Within the Adirondack Park, none of the surface waters sampled by DEC exceeded EPA’s recommended chronic and acute toxicity criteria protective of aquatic life. However, more recent scientific studies indicate an array of impacts to aquatic life at lower concentrations than existing EPA guidance. Among others, the Report recommends the following with regards to road salt levels:
1) Adopt, in regulation, both the Aquatic (Chronic) and Aquatic (Acute) chloride water quality criteria set forth currently by EPA at 230 mg/L and 860 mg/L, respectively. These criteria will help establish a minimum level for protection from salt
contamination from various regulated sources.
2) Establish, for the purposes of water quality assessment, clean water planning, and a targeted road salt reduction level for pilots, a surface water chloride goal within the Adirondack Park of 40 mg/L for stress to aquatic life, and 10 mg/L as
protective of any change to aquatic life.
3) Set road salt application reduction goals, to be verified by pilot programs, in an effort to reduce the chloride level to fall at or below the 40 mg/L goal in most lakes, noting the need for reliable current application data for local and state roads, parking lots, driveways, and sidewalks. This will allow the development of actual load/rate reduction targets (as well as parking lot, driveway, and sidewalk coverage by watershed).
4) Establish sentinel, long-term water quality monitoring stations that are integrated with existing DEC and DOH networks, to monitor road salt impacts over time in both surface and groundwater in the Adirondack Park and implement
road salt reduction pilot programs and associated surface and groundwater monitoring.
In addition to setting road salt reduction targets and monitoring road salt pollution, other recommendation of the report include establishing best management practices; providing training for road salt applicators; providing State funding; providing public access to road salt data; creating a public outreach and education campaigns; and reviewing the State’s rapid response processes for road salt contamination.
The full report can be found online here.
Illustrations, from above: Snowplows apply road salt on the 1-87 Northway in the Adirondack Park; and a map of paved roads in the Adirondack Park.