Josh Flynn, CEO of Seabreeze Property Services, stands Thursday in a salt storage structure at the company’s Portland location. Warming Maine winters have led to an increase in salt usage, raising environmental concerns. Shawn Patrick Ouellette/Staff Photographer

Mainers are no strangers to winter road hazards. Bad weather brings dangerous driving conditions. Rock salt eats up undercarriages and metal infrastructure. Springtime thaws bring frost heaves and potholes.

For generations, those headaches were at least fairly predictable. But as global climate change warms the state’s winters, erratic, severe weather will likely mean more damaging potholes and water pollution from excessive salting to keep up with more frequent ice storms.

In the last full week of February, temperatures went from far below freezing to a record high of more than 60 degrees in Portland. Temperatures crashed again immediately thereafter, and a snowstorm slammed into southern Maine that weekend.

Are those erratic swings a harbinger of winters to come? There’s no easy answer, but a warming climate means more uncertainty, said Maine State Climatologist Sean Birkel.

“We should use caution in ascribing weather events in any individual season to climate change, but the overall trend over several decades is clear,” he said. “The winters have warmed considerably. With these more extreme weather patterns it is consistent with the overall changing climate that we are seeing more winters like this.”

Erratic freeze-thaw cycles combined with added rainfall can create spring-like conditions in the middle of winter, adding seasonally early damage to Maine roads from potholes and frost heaves.

“We are seeing more fluctuation in temperature above and below freezing – it just keeps bouncing around,” said Brian Burne, highway maintenance engineer at the Maine Department of Transportation. “I can absolutely say those types of fluctuations in temperature, added with rain that saturates the soil and freezes it again, is more damaging to the road.”

A car drives past a pothole on Forest Avenue in Portland on Feb. 22. Shawn Patrick Ouellette/Staff Photographer

‘REALLY VEXING ISSUE’

The extent to which warming trends are damaging Maine roadways is unclear. There’s been limited research, but early results from of recent study by Minnesota’s Department of Transportation found no evidence of more frequent freeze-thaw events in that state.

New England has lost three weeks of winter in the past century, and “mud” days have increased by up to a few weeks per year, said Sarah Nelson, director of research at the Appalachian Mountain Club. Winter isn’t just warmer, it is prone to extreme highs and lows, a trend termed “winter weather whiplash” by a research group Nelson is part of.

“It is not just that winters are getting shorter and we are losing snow cover, but there is a sense of a lot more variability,” Nelson said. “Increasing variability in weather is one of the signs of climate change. It is that unexpected condition at the wrong time of year that can cause these kind of impacts (to roads and infrastructure).”

Changing winter weather has meant more ice, sleet and freezing rain in southern Maine, and more water pollution from added tons of rock salt dumped on roads, driveways and parking lots. Salt is an effective deicer and is widely used across the country. It is also toxic to freshwater ecosystems and a dangerous pollutant in drinking water sources.

“This has been an issue that has been on our radar for more than a decade,” said Wendy Garland, environmental assessment director at the Maine Department of Environmental Protection. “We are seeing that our streams and waters are getting saltier over time.”

A large pothole on Somerset Street in Portland. MaineDOT highway maintenance engineer Brian Burne says there is no question that warming winters are accelerating seasonal damage to Maine roads. Derek Davis/Staff Photographer

In 2020, Maine ordered 535,000 tons of rock salt – 780 pounds for every person in the state, according to estimates in an unpublished MaineDOT study. Salt spread on pavement or stored uncovered eventually seeps into waterways and groundwater. Chloride from salt deposits can sit underground for years, slowly leaking into nearby waterways, especially in the summer when groundwater, not runoff, feeds flowing streams.

In small urban waterways near heavily salted areas, dragonflies, mayflies, stoneflies and other critical organisms can’t survive because the water is too salty, a problem that causes a chain reaction across the environment.

“That is the base of the food chain and a source of food for fish. It’s representative of the health of the ecosystem,” Garland said. “If sensitive organisms can’t live in the stream because of the toxic level of chloride, it is going to throw off the whole ecosystem.”

Salt contamination poses a threat to drinking water, too. The scale of the problem is unclear, but MaineDOT estimates it replaces 15 private wells per year damaged by state road runoff. Salty water can elevate high blood pressure, leading to higher chances of heart attacks and strokes, among other health impacts.

Chloride-impacted water also corrodes water lines and equipment and can activate toxic heavy metals such as lead, mercury and cadmium in soil and water pipes. Chloride pollution is so pernicious because it’s nearly impossible prevent runoff into local waterways, and once it is in the environment, it cannot be removed.

“We need our roads to be safe in the winter, but unlike some other types of pollutants, there are not strategies to remove salt from runoff,” Garland said. “We can just use less of it – it’s a really vexing issue.”

A car drives past a large pothole on Somerset Street in Portland. Research is underway to assess the impact of warming Maine winters on roadway damage. Derek Davis/Staff Photographer

SALT USE UNSUSTAINABLE

Instead of reducing salt use, Maine may be on its way to spreading even more. Over the past 15 years, the amount of road salt used each year by MaineDOT has increased by about 40 percent on average, with significant annual variations.

Drivers’ heightened expectations for safe roads in all weather has encouraged the use of more salt, but so has a shifting climate and increasing frequency of messy, slippery winter storms. In a big snowstorm, road crews use relatively little salt because they can plow the light, dry snow instead.

Mixed precipitation events – storms that combine rain, snow, sleet and ice – are more common now, especially in densely populated southern Maine, Burne said. If you want to keep roads open during that mess, he said, salt is the only option.

“We feel like there are more ice storms in the winter, (and) that affects how we treat roads,” Burne said. “You can take a couple feet of a nor’easter and that dry snow is pretty easy to drive on. Just having more ice events affects us dramatically. As we have seen a warming trend and more icing in recent years, we have seen a corresponding increases in salt use.”

Snow and rain accompanied by near-freezing temperatures have become more common in southern Maine over the past 30 years, according to unpublished research for the transportation department by Shaleen Jain, chair of the Civil and Environmental Engineering Department at the University of Maine.

“As far as treacherous conditions, what we see is in the upper half of the state and the lower half of the state, there is a substantial increase in the number of these events,” Jain said.

It will take more research into hourly temperature and precipitation data to determine how storms mix snow, rain, freezing rain and sleet, but the trend seems clear, he said.

“The freezing rain days have actually increased in the south(ern) and the northern parts of the state, and the snow days around freezing temperatures have increased almost throughout the state,” he said.

Jain’s research is part of an upcoming report for MaineDOT that could give local and state policymakers a blueprint for future winter maintenance. The state transportation department, which has adopted technology and practices to limit salt use, only takes care of about 20 percent of roads. Roughly 80 percent are the purview of local governments with varied salting practices, equipment expectations and budgets.

“It is one of those challenging sustainability dilemmas,” Jain said. “Salt use allows for our economy and communities to have uninterrupted access to roads and enhances our mobility. At the same time, the salts migrate into our streams and groundwater.”

Josh Flynn, CEO of Seabreeze Property Services, stands beside some of his Portland company’s road equipment in November. Flynn says raised consumer expectations for safe roads and other paved surfaces have contributed to the increase in salt use. Gregory Rec/Staff Photographer

LOWERING EXPECTATIONS

Josh Flynn feels something’s changing, too. The CEO of Seabreeze Property Services, one of the biggest plowing contractors in Maine, said his salt use has soared in recent years, driven partly by more frequent ice events but also the driving conditions customers want.

“The expectations have changed as much as the weather,” Flynn said. “Whether it is slip-and-fall litigation or the idea that people have forgotten it snows in Maine, our salt usage has increased because people want clear and black pavement in the middle of a storm.”

Without addressing the constant threat of lawsuits if someone slips in an icy strip mall parking lot, or the perception that a pavement isn’t safe unless it’s coated with visible salt crystals, the amount of salting will keep going up as Maine gets more and more mixed storms, Flynn said.

“As the weather keeps changing and trending towards ice, it is going to continue to get more difficult,” he said. “I know people are going to start to want to see something different, but it is going to be a hard conversation.”

A large pothole at the intersection of Congress Street and Franklin Street in Portland exposes the underlying cobblestones. Ben McCanna/Staff Photographer

Maine currently has no statewide salt reduction strategy. New Hampshire, on the other hand, has worked on the issue for nearly a decade. Despite the state’s efforts, the scale of chloride pollution grows. In 2008, New Hampshire recorded 19 chloride-impaired water bodies – by 2020, that number had jumped to 50.

“We are seeing chloride trends in lakes, and it is very alarming,” said Stephen Landry, watershed management section supervisor at the New Hampshire Department of Environmental Services.

In 2013, New Hampshire started its Green SnowPro Certification training program for commercial applicators. The course explains best practices, such as using brine, which uses up to 50 percent less salt than rock salt, and installing technology to spread just enough deicer for safety. Certified operators and their clients are granted limited liability for slip-and-fall lawsuits.

About 600 operators a year get trained in the program, and it will be extended to municipal drivers in the near future, Landry said. The state lays down about 400,000 tons of road salt a year.

Even with those efforts, the only solution is using less salt, getting the public to understand what’s at stake, and lowering expectations for winter road safety.

“If you look at (the) winter severity index, we see the same trends in New Hampshire – we are having more ice events as a result of climate change,” Landry said. “The only thing we can do is put down less salt. That is the real key to this; people’s expectation of what is safe has to change.”