Road salt pollution affects public health
The Great Flats Aquifer and the Mohawk River in NY have rising levels of sodium and chloride
Road salt pollution continues to receive attention in New York State because of the harm being caused to aquatic ecosystems and municipal water supplies. Several recent high-profile reports warn of the effects of salt on sensitive ecosystems and drinking water in the State. Salt pollution is problematic in the Capital District of NY, which is in the lower part of the Mohawk watershed. My commentary on salt pollution and public health was published on 6 April 2025 in the Sunday Gazette [here - 1], and it is annotated here with sources and notes:
“Road salt is damaging our drinking water and endangering our health. Recent assessments by the Adirondack Road Salt Reduction task force [2], and the Salinity Management assessment by the NYC Department of Environmental Protection [3] highlight problems to the north and south. However, municipal water quality reports show that salt pollution here in the Capital District is among the most problematic in the State [4].
The Salt Reduction task force report concluded that road salt is harming lakes, streams, and drinking water sources in the Adirondacks [2]. Streams and rivers, groundwater, and ponds have mean chloride levels generally at 10 parts per million (ppm), but higher elsewhere in the state. The report also suggested salt pollution is harming fish and other organisms that rely on freshwater, not saltwater, for their life cycle, and we need to re-evaluate current water quality standards [2].
Drinking water in NYC comes largely from reservoirs in the Catskills, but a recent report by the NYC DEP highlights rising salt pollution in the more urban Croton reservoir [3,5,6]. The City has worked hard to protect its water supply from road salt, with impressive results. The annual water quality report for NYC shows chloride levels averaged 15 ppm in 2024 [7]. However, the assessment warns that some water may become undrinkable in 83 years [3]. Using this same criteria, some of the water in the Capital District will be undrinkable in the next 15 to 30 years [8].
Drinking water in the Capital District comes from reservoirs, aquifers, rivers, and private wells [i.e. 9,10]. The Mohawk and Hudson corridors are heavily urbanized with significant transportation infrastructure. Noteworthy are salt increases in the Mohawk River and Great Flats Aquifer (GFA), which together serve about a quarter of a million people [11,12,13,14, 15]. Salt contains sodium and chloride, and most municipalities in the Capital District now report levels exceeding the limit for individuals on severely restricted sodium diets [14].
Since road salting began, chloride levels in the Mohawk have risen over 300% and they are elevated year-round [12, 14]. We have spread so much salt across the landscape that we’ve altered the chemistry of the river. Long-term water quality data from Cohoes and Colonie, which use the Mohawk as a water source, show a sharp rise in sodium and chloride over the last decade [14]. In Cohoes, chloride levels have increased ~125% in that time [14]. The river actually gains sodium and chloride as it passes through the Capital District due to accumulated salt in surrounding sand and gravel deposits [14].
Chloride levels are particularly high in the GFA [12,13,14], one of our most precious resources [9,10]. Chloride in the GFA is typically 200% to 500% higher than the Mohawk [14]. In 2024, Scotia, Rotterdam, and Niskayuna reported levels between 120 and 219 ppm, upper values close to the regulatory limit [14]. Oversalting our roads is part of the problem, and so are large piles of salt stored on top of the aquifer [11].
The trend in salt pollution has been upward for decades [15]. Chloride in Scotia water has risen by nearly 800% since the 1970s, but it has increased 4000% since the pre-salt days [12]. Chloride promotes pipe corrosion, increasing the risk of lead poisoning [16]. Scotia exceeded the lead action level in 2020, and in 2021, state-mandated tests found lead above the action level in multiple Scotia-Glenville schools [17]. A corrosion-control study was subsequently initiated [18]. The high school had the most problems, with data showing that 45% of samples had high lead [17]. There is no safe level for lead, especially for children, which is why the EPA has set a goal of zero [19].
New York leads the nation in road salt use and salt pollution is a problem across the state [11,12]. We need stricter regulations on salt storage, especially in sensitive areas like the GFA. We also need a strategy to address road salt pollution and part of this will be adopting best management practices [20]. Recent legislation introduced by Senator Harckham would establish a road salt reduction council that may put us on the right path [21]”
Too much salt on a road in Schenectady County (JI Garver).
Further reading and notes
[01] Garver, JI. 2025. “Road Salt pollution affects public health” in Sunday Daily Gazette (Schenectady NY), 6 April 2025 (here).
[02] Adirondack Road Salt Reduction Task Force Assessment and Recommendations. 2023 (here).
[03] NYC Department of Environmental Protection, Bureau of Water Supply, “Salinity Management Assessment” 21 March 2025 (here).
[04] Annual water quality reports are available from municipalities across the Capital District, and elsewhere in the state. For an analysis of these trends in the Capital District, see 11,12,13,14 below.
[05] Gilson, Roger Hannigan, 22 March 2025. “Some New York City water could be undrinkable in 80 years due to upstate road salt: Levels of chloride in water bodies in Westchester and Putnam counties have risen dramatically since the 1990s. Albany Times Union (here).
[06] Howard, Hillary. 25 March 2025. “Salty Suburban Roads Are Clouding the Future of N.Y.C. Drinking Water: A new environmental report finds that rising salt levels in New York City’s water supply could make some of it undrinkable by the turn of the century.” New York Times (here).
[07] New York City Drinking Water Supply and Quality report 2024 (here)
[08] Several municipal water sources have salt levels that are increasing dramatically. This is a calculation based on the increase in chloride in the last decade as reported by Annual Water Quality reports for the Village of Scotia. Using both a linear and an exponential fit to the last decade of data (this results in the range given), these are the number of years before chloride equals or surpasses 250 mg/l at the current rate of increase, assuming no other changes.
[09] Winslow, J.D., Stewart, H. G., Jr., Johnston, R. H., and Crain, L. J., 1965, Ground-water resources of eastern Schenectady County, New York, with emphasis on infiltration from the Mohawk River: New York State Conservation Department, Bulletin 57, 148 p.
[10] Brown, AG, 1982 “The Schenectady Area - Chapter 2” in Walker, RM, and Finch, AJ, 1982. Atlas of eleven selected aquifers in New York. UG Geological Survey, Water resources investigations, Open File report 82-553. (Prepared in cooperation with the NY State Department of Health). 255 p. (Brown chapter is p. 15-40).
[11] Garver, JI. 2020, Road Salt: Heavy salt application on roads is damaging the Watershed, In Notes from a Watershed, at Substack.com (here).
[12] Garver, JI. 2023. Salinization in the Mohawk Watershed: Road Salt contamination in the Great Flats Aquifer threatens public health. In Notes from a Watershed, at Substack.com (here)
[13] Garver, JI, Ragland, CJ, Wright, J, Manon, MR, Mundell, H, Smith, JA, 2023. Regional salinization in the lower Mohawk River: effects on urban streams, the Great Flats Aquifer, and raw water for municipal use. In Garver, J.I., Smith, J.A., and Rodak, C. (eds) Proc. 2023 Mohawk Watershed Symposium, Schenectady, NY, v. 13, p 11-16 (here).
[14] Garver, JI, and Smith, JA, 2023. Salinization of the Mohawk River and the Great Flats Aquifer in Upstate New York. Geological Society of America Abstracts with programs, v. 55, n. 6. (here).
[14] Garver, JI, Manon, MR, Rodak, C, and Pillitteri, S., 2025. Sodium and Chloride in the Lower Mohawk River: Implications of imperviousness and urbanization on drinking water sources. In Rodak et al. (eds), 2025 Mohawk Watershed Symposium, Program and abstracts, v. 15, p. 27-32. (here).
[15] The increase in road salt pollution has been recognized here in the Mohawk Watershed (see 11-14 bove), and elsewhere in the Northeast. For examples see: Kaushal, S.S., and other 2022. Freshwater salinization syndrome alters retention and release of chemical cocktails along flowpaths: From stormwater management to urban streams. Freshwater Science, 41(3), pp.420-441. AND Dugan, H. A., and Arnott, S. E. (2022). The ecosystem implications of road salt as a pollutant of freshwaters. WIREs Water, e1629.
[16] Many studies have shown the link between high chloride, pipe corrosion, and elevated household lead. Hintz and colleagues note that: “Using Cl−-contaminated water for drinking water can be dangerous because Cl− results in the dezincification of water plumbing and galvanic corrosion, which increases the thinning of pipe walls and metal leaching” see Hintz, W.D., Fay, L. and Relyea, R.A., 2022. Road salts, human safety, and the rising salinity of our fresh waters. Frontiers in Ecology and the Environment, 20(1), pp.22-30 (here). ALSO see Stets, E.G., Lee, C.J., Lytle, D.A. and Schock, M.R., 2018. Increasing chloride in rivers of the conterminous US and linkages to potential corrosivity and lead action level exceedances in drinking water. Science of the Total Environment, 613, pp.1498-1509.
[17] See Annual water Quality reports for the Village of Scotia. Lead values in Scotia Schools are presented in a letter from Susan Swartz, superintendent of the Scotia-Glenville school district, dated 11 April 2021. The winter 2021 testing for lead (Pb) in the Scotia-Glenville school district can be seen in spreadsheet form. See also: Supardi, Briana. 12 December 2022. “Scotia residents voice concerns over water lead testing” WRGB. (here).
[18] See: Prime AE proposal to the Village of Scotia for a Water System Corrosion Control Study (Proposal for Engineering Services) Proposal is dated 3 Nov 2022. Also: Supardi, Briana, 15 Dec 2022. Water quality improvement plan discussed during Scotia Board meeting, at WRGB. Also: see Vaughn-Holdridge, N., 2022. Scotia finds elevated levels of lead in some drinking water samples. The Daily Gazette. 1 December 2022. All the communities evaluated here except Scotia report using corrosion control in their finished water (for most systems this is the addition of orthophosphate to the finished water). Active links for these are at the end of this post, here.
[19] US EPA. For a summary of “Basic Information about Lead in Drinking Water” by the US Environmental Protection Agency see this website. Since the initial round of testing, the action level for lead has been lowered by the NY State.
[20] Since the ADK Salt reduction task force released its report in the Fall of 2023, there has been concern that action on this issue has lagged. See Matson, Zachary, “Advocates plan push for accountability legislation when lawmakers return to Albany” in Adirondack Explorer. 16 September 2024. (here) and Craig, Gwendolyn, “Settling the Salt Score: ADKAction holds State accountable for lack of progress. In Adirondack Explorer. 10 February 2025. (here).
[21] See NY Senate Bill S6976. Establishes the New York road Salt reduction council and the New York Road Salt reduction advisory committee. Status of bill and the bill itself are here. There are a number of other states that have already taken on the issue of road salt and public health. See: “Working together to keep freshwater fresh” Wisconsin Salt Wise (here) has become a leader in salt solutions, including best management and legal strategies.