Salt on the Streets: Battles Icy Roads, Threatens the Environment

As fall's crisp air rolls out, we are reminded of the harshness yet to come: North Country winters. Piles of snow, endless shoveling, and treacherous road conditions lead to highway salting to accommodate the slippery situations caused by winter snowfall. Scientists are discovering, however, that over time road salt is impacting freshwater ecosystems.

Salt seems to be a more efficient deicer than sand, according to the Department of Transportation.

According to New York State Department of Transportation (DOT) public information officer, Michael Flick, about 25 thousand tons of road salt are dumped onto Clinton County state highways each year, with total snow and ice removal costs averaging $3.8 million annually. When the roads are salted, the heavy buildup accumulates on pavement and surrounding land. The salty buildup is then transported by things like rain and slush into groundwater, rivers, lakes, and streams. About 55 percent of the sodium chloride ends up in waterways through surface runoff, while the remainder is absorbed by the ground, causing potential damage to trees and roadside plant life. Because so many of the North Country’s roads run next to rivers and rural waterways, there is fear that salty run-off could harm our prized natural environment. Heightened sodium chloride levels could also compromise area drinking water supplies, as many health conditions suggest low sodium diets.

A recent study at the Institute of Ecosystem Studies (IES) in Millbrook, New York, showed that the levels of salt in freshwater systems in the Northeast have increased tremendously over the past 30 years. In fact, some waterways studied in Hudson Valley, New York and Baltimore, Maryland, were one quarter as salty as sea water. If this pattern continues, experts believe that surface waters in those areas could become toxic to aquatic life and unfit for humans over the next century. The study, which covered areas in the White Mountains of New Hampshire, Wappinger Creek, the Mohawk River in New York, and parts of Baltimore, Maryland, was based on data collected since the 1970s, which monitored salinity changes in freshwater.

“In the Adirondacks, there’s few roads overall, so it doesn’t seem like we’re moving toward those levels.”

Similar studies on the Adirondacks have shown that the overall amount of salt building is relatively low. A sizable study is currently being conducted at Clarkson University to test sodium chloride levels in the Upper and Lower Cascade lakes on Route 73 in Essex County. The study, involving Dr. Tom Langen at Clarkson, the DOT and the New York State Department of Environmental Conservation (DEC), has shown that the salt levels are elevated, but are not yet affecting the aquatic life in the lakes. The lakes are home to an endangered species of fish, the round whitefish, and there is worry that the increased sodium chloride levels may harm them in the future, according to Rich Preall, fisheries biologist at the DEC. Freshwater fish and other aquatic life cannot survive in waters contaminated by high levels of sodium. According to DEC fisheries manager, Bill Schoch, concentrations of sodium would have to be very high to affect fish. “In the Adirondacks, there’s few roads overall, so it doesn’t seem like we’re moving toward those levels.”

Dr. Peter Groffman, microbial ecologist in charge of the IES study in Millbrook, believes that sodium chloride concentrations are also increasing in places where the amount of road salt applied has not, suggesting that sodium is accumulating in the environment. The IES study found a strong relationship between areas of newly paved roadways and levels of salt concentrations.

“There’s a general consensus that as places urbanize, salt in surface waters increase,” said Doug Burnham, of the Vermont DECs bio monitoring lab. Burnham thinks that industrial and commercial service maintenance of large parking lots and dense highway networks are one of the most significant sources of polluted runoff. “People should be aware that salt is very mobile and that if you’re dumping salt in your driveway, it could easily end up draining into a nearby river or stream.”

“People should be aware that salt is very mobile and that if you’re dumping salt in your driveway, it could easily end up draining into a nearby river or stream.”

Flick believes that there are no current alternatives to road salt in terms of cost and effectiveness. Alternatives, such as a compound of crushed glass and calcium magnesium acetate (CMA) is considered to be a suitable replacement, but comes at a cost—averaging $700 per ton, compared to $30 per ton for road salt. And although sand may seem like a reasonable solution to deicing roads, it isn’t as effective as salt. “Although less expensive at first glance, when total costs are factored in—additional wear and tear on equipment and people, additional cleanup costs, and a higher application rate—sand is no cheaper than salt,” said Flick.

Until a better deicing replacement comes along, Burnham advises to store salt in protected areas away from surface and groundwater resources, and to use it in a “reasonable manner” with awareness of the potential to contaminate and cause negative impacts on our natural resources.

What do you think about using salt as a deicer? Let us know!

The round whitefish, a native Adirondack species, is now endangered—quite possibly due to increased levels of road salt. Here is a list of other endangered fish species in the Adirondacks, according to the DEC:

-Round Whitefish: Once fairly common throughout the Adirondacks, the round whitefish could be found in about 60 different lakes including Big Tupper, Piseco, Big Wolf, Raquette, Blue Mountain, Meacham, and the Fulton Chain. Many lakes were stocked with hatchery reared fry between 1886 and about 1904, but the consequences were uncertain. However, surveys conducted from 1985 to 1987 by New York State's Division of Fish and Wildlife could only find round whitefish populations in six Adirondack water bodies. Surveys conducted before 1979 found them in only 14 waters and surveys between 1979 and 1997 found them in only nine.

Possible reasons for the decline in round whitefish populations include: predation by invading yellow perch on whitefish eggs and fry; predation by smallmouth bass; competition with lake whitefish; overfishing; loss of spawning sites; siltation; and lake acidification. Some of these factors continue to pose a threat to remaining populations. Round whitefish are now protected from harvest or possession by the Endangered Species Law.

-Shortnose Sturgeon: A combination of factors can be blamed for declines in shortnose sturgeon populations. During the 1800s and early 1900s, large tidal rivers, such as the Hudson, served as dumping grounds for pollutants that lead to major oxygen depletions and resulting high fish losses. At the same time, great demands for sturgeon eggs (caviar) and the fish's smoked flesh resulted in overexploitation of sturgeon stocks. In addition, damming of the Hudson for hydroelectric and navigation purposes cut sturgeon off from their upriver spawning grounds. Maintenance dredging of the Hudson's navigation channel and trapping of sturgeon eggs and larvae in turbines of electric generating plants are also considered problems for the Hudson River shortnose sturgeon stock. Riverwide population estimates in the 1990s showed the spawning population had increased substantially from that observed in the 1970s.

-Silver Chub: Following years of high population levels in Lake Erie, the silver chub suffered a drastic decline in its numbers in about 1953. Scientists theorize that the population decline was due to several factors, including deterioration in water quality, decreases in the number of mayfly larvae (the chub's preferred food), and habitat modification that resulted in loss of suitable environment for the silver chub. It was caught in nearby Pennsylvania in 1971, but is extirpated from New York.

-Pugnose Shiner: The pugnose shiner is one of the rarest minnows in North America. Populations of this fish have been reduced or extirpated in the United States, and in Canada its range is diminishing. The primary cause for the loss in pugnose shiner populations is thought to be increased turbidity.

-Bluebreast Darter: Since there have not been any studies to date to quantify the status of bluebreast darter populations, it is not possible to determine trends in abundance. However, the sparse bluebreast population in New York State is restricted to the Allegheny River basin.

-Gilt Darter: The gilt darter has declined in numbers throughout its range. This fish is quite intolerant of slow water and silt, and given this information, recent declines in New York's Allegheny River populations are being attributed to siltation of the river. Since the Kinzua dam in northern Pennsylvania prevents any upstream movement of that state's gilt darter populations, New York's population is now isolated from its historically broader genetic base.

-Spoonhead Sculpin: Spoonheads are believed to be locally extinct in Lakes Ontario and Erie. The causes of the decline are unknown.

-Deepwater Sculpin: The deepwater sculpin, abundant in Lake Ontario until 1980, was considered extirpated from this lake until caught in waters in 1996, 1998 and 1999. They were caught in Lake Erie as recently as 1995. The cause of the sculpins' population decline is unknown. However, scientists theorize that alewives and rainbow smelt may have contributed to the decline because they eat sculpin eggs and larvae. In addition, alewives and rainbow smelt compete with deepwater sculpins for food.