The perennial winter gripes over road salt – too much, too sparse, too frequent, too seldom – tend to melt away as soon as the springtime sun peaks over the horizon. But though annoyances and safety concerns may fade, the salt itself doesn’t, as scientists told lawmakers this week. It runs into streams and ponds, turning these freshwater reserves brackish, and it leaches into soil, altering the acidity and rich biological system within.
Legislators on the Senate Natural Resources Committee aim to address these concerns with S.29, a bill to establish a voluntary certification program to improve salt application practices. It seeks to expand resources for municipalities and companies that apply salt to roadways, sidewalks or parking lots for winter de-icing or summer dust control. The bill outlines a series of standards for certification and balancing safe conditions for water and land with those of drivers.
“I think there is an opportunity here to save money, to help biodiversity, native plants and animals, as well as protect people who are applying salt,” said Sen. Anne Watson, D/P-Washington, who sponsored the bill, in an interview.
All members of the Natural Resources Committee have also cosponsored the bill. The bipartisan support made the bill appealing to consider early in the legislative session as new committee members settle in, Watson said.
“As a new committee, I wanted to make sure that we had something we could work on together that would likely have broad support,” she said.
The bill would establish a voluntary program for training and certification, to be renewed annually, modeled after New Hampshire’s Green SnowPro Program.
As it stands now, the bill includes limited liability provisions so that certified salt applicators, or the property managers who hire them, are not liable for damages that could arise from snow and ice hazards, when best management practices are followed, as outlined by the training.
“People want to oversalt beyond what is a safe level because of that potential (liability) risk. But if we can establish that these are the best management practices, then, as long as you are doing those things, it should be sufficiently safe and there’s no need to go beyond that. So we can reduce the amount of salt we need to use. It’s less salt in the environment and less expense,” Watson said.
The current bill calls for guidance on when and how salt should be applied, with the hope of reducing use, particularly on roads closest to streams and ponds where it may eventually end up in larger rivers and Lake Champlain.
In Vermont, 15 out of 18 tributaries to Lake Champlain saw increases in chloride concentration (salt, of course, is sodium chloride) since 1990. Those increases have ranged across waterways from 41% to 163% in some places, said Matthew Vaughan, the chief scientist at the Lake Champlain Basin Program during his Tuesday testimony to the committee.
Vaughn explained that chloride levels around 10 milligrams per liter are considered natural background levels, while 20 mg/l is considered elevated and by 35 mg/l, scientists see reductions to biodiversity.
Increasing salinity in waterways has significant environmental impacts: Denser, saltier water sinks to the bottom of lakes creating a stratified pool, which reduces the mixing of surface and deep water and can lead to harmful, low oxygen levels.
Salt also slows growth and reproduction rates of aquatic life, from creatures as small as zooplankton to fish and amphibians. The loss of zooplankton and other microorganisms is especially detrimental to an ecosystem because it means there is less food available all the way up the food chain. So waterways with elevated salt levels see reduced biodiversity overall.
Sunnyside Brook in Colchester, one of the streams most affected by salt runoff, has routinely tested for chloride concentrations above 230 milligrams per liter, according to a 2024 Department of Environmental Conservation report to the EPA. That concentration of chloride is EPA’s threshold for chronic toxicity to aquatic life. The report also noted the stream has seen significant declines in mayflies and other similarly sensitive insects, which are used as indicators of overall ecology health, in the past decade. Over 72% of the brook’s surrounding area is developed, meaning it is likely to see higher rates of road salt application.
But establishing exactly how much salt has been applied – and where – is a challenge for lawmakers, ecologists and even salt applicators alike. While VTrans and some municipalities have the technology to capture rates of salt application, many towns do not have salt trucks that can control or report how much salt has been dropped on a road. And the state has no way of when owners of parking lots or other private landowners sprinkle salt.
Adding requirements to measure the amounts of dropped salt would be challenging for many applicators that don’t have the advanced technology, Phil Sexton, a seasoned salt applicator who runs a similar reduction program in the Adirondacks, said in his Tuesday testimony to the committee.
“It’s like asking someone to follow the speed limit without a speedometer,” he said.
The committee flagged this challenge and others around record-keeping requirements for discussion in the coming weeks.
