BURLINGTON — Vermont’s dirt roads span 8,534 miles — more than the straight-line distance between Burlington and San Francisco three times over. They contribute to the state’s rustic charm, bring tourists looking for gravel biking and are beloved by rural residents.
They are also particularly vulnerable to floods. Runoff from any type of road can harm water quality, but Vermont has some 1,300 more miles of dirt than pavement — and those dirt roads are subject to easy erosion.
With the state’s increase in flooding, those old roads are hitting waterways and their ecosystems hard.
And the state is pretty much stuck with them. “Putting in paved roads is very expensive, and we just don't have that kind of funding in Vermont to want to do that,” said Jim Ryan, former manager of the Vermont Municipal Roads Program with the Department of Environmental Conservation.
But there are ways to improve those roads that reduce pollution and strengthen against floods.
Like paved roads, dirt roads are essentially impervious, meaning they do not absorb water, said Beverly Wemple, a University of Vermont professor who helps lead the college’s Water Resources Institute. When it rains, water washes across those surfaces, eroding sediment and running into ditches or bodies of water.
Phosphorus likes to bind to sediment, meaning it gets swept away too. In excess, it fuels harmful algae blooms — as is the case in Lake Champlain, where runoff has deposited high levels of the nutrient. Large sections of the lake are on the federal impaired waterways list.
Phosphorus aside, those sediments can hurt aquatic ecosystems where plants and animals struggle to survive in water choked with dirt and debris.
Wemple’s research helped bring attention to dirt road runoff at a time when Vermont was focusing more and more on water quality.
A 2008 lawsuit alleging poor pollution control forced federal and state officials to revise plans for Lake Champlain. State lawmakers passed the Vermont Clean Water Act in 2015, anticipating stricter standards. Those came a year later when federal officials tightened limits on phosphorus in the lake.
People wanted a better understanding of where the phosphorus was coming from.
Funded by the Lake Champlain Basin Program, Wemple studied the impact of Vermont's transportation network on water quality.
Tropical Storm Irene hit while research was underway, allowing Wemple’s team to also see what happens to Vermont’s roads when they flood, she said.
The study, released in 2013, proved erosion from dirt roads was a significant source of sediment in waterways — and confirmed phosphorus attached to the sediment was polluting Lake Champlain. It also included research on ways to keep water off roads and reduce runoff.
“That research essentially gave us the first piece … of scientific evidence of the importance of our road network as a source of pollutant transfer but also of the potential for some fairly straightforward practices to minimize that pollutant runoff,” Wemple said.
After the new phosphorus regulations, the state created a permit program that set road standards for towns. It aimed to reduce erosion contributing to phosphorus pollution. The Department of Environmental Conservation and Agency of Transportation run the program.
Towns must record the condition of their roads and key characteristics — such as whether they connect to water and whether they use storm drains, or ditches and culverts, for drainage. Over half the roads in Vermont connect to waterways, the state says.
The Agency of Natural Resources says open-drainage roads — those with culverts and ditches — are often gravel and produce the most phosphorus. Those roads are where the bulk of the standards are applied.
Towns must upgrade roads not up to code. For a dirt road, this usually means improving drainage: lining ditches with stones and vegetation to filter out sediment.
There are also improvements to the road itself. Crowning a road, or lowering the sides so the high point is in the middle, helps it shed water, as does removing berms and ruts that trap water. Another element: properly sizing culverts, the tunnels that allow water to pass underneath roads.
“We were able to document that many of these practices are quite effective in both reducing erosion and making the transportation network more flood resilient,” said Wemple.
Through the Agency of Transportation’s Better Roads Program, towns can apply for grants to cover projects.
Making improvements also helps protect from floods, said Ryan. Working as a deputy stream engineer in the aftermath of Irene, and doing “flood forensics” after the 2023 floods, he found that up-to-standard roads came away in better shape.
We hear anecdotally … that it looks like places where we've upgraded the storm water infrastructure on roads, there were fewer damages.Beverly Wemple, University of Vermont Water Resources Institute
Where there was damage, the culprit was most frequently culvert size, he said. Often the issue stemmed from small culverts under driveways or over intermittent streams. In heavy rain, culverts have to handle more water than usual. If they’re too small, they flood or get blocked by debris, leading to a domino effect where one failed culvert takes out several others down the road, Ryan said.
Municipalities are slowly updating their roads. Ryan said Vermont towns have an average of 25 miles of roads running directly into waterways and are upgrading about a mile a year.
Flood resilience can get a boost right away, but maintenance is ongoing.
“There's no finish line there. The road grader always has to go out and put a proper crown on the road, remove the grader berm, lower the road's shoulders and clean out the ditches,” Ryan said.
His observations are set to be tested: Wemple just began a two-year study on the impact of the road permit program on flood resilience in 2023 and 2024.
“We hear anecdotally … that it looks like places where we've upgraded the storm water infrastructure on roads, there were fewer damages,” she said. “But we don't have the scientific evidence to back that up yet.”
Wemple said people often ask, Should we just pave the roads?
One factor is uncertainty about which is worse for water quality. Wemple said there’s not much difference between paved and unpaved.
But there’s also what she called “the societal question.”
“Many of us in Vermont are quite attached to our rural landscapes and those unpaved roads,” she said. “And if we paved them, people would drive a lot faster. And we'd lose some of that rural ideal that we are really attached to.”
Eric Barker lives on a dirt road in Underhill close to where he grew up. When he chose where to raise his family, a dirt road was a priority.
“I don't even think we looked at a single lot on pavement,” he said.
His driveway requires a lot of care, and his car has gotten stuck in the mud at inopportune times, but he said it’s worth it.
“I think you have to have the right vehicles, and I think you have to have the right mentality,” he said. He values the privacy his home allows for his family — and the sparse traffic.
Dirt roads also draw tourism. Waterford resident Fritz Fay is president of Northeast Kingdom Gravel. The organization’s mission is to bring dollars to the Kingdom by mapping gravel biking routes and attracting tourists.
The sport has exploded in recent years — and Fay said Vermont, with its sprawl of dirt roads, is ready made for it.
Big events and concentrated trails can overwhelm small towns, and locals often resent that, Fay said, but gravel biking is gentler.
The NEK has witnessed that scenario in East Burke with the popular Kingdom Trails. Gravel biking brings in a few people at a time across multiple towns, Fay said.
“It’s scattered, and that’s an advantage,” he said.
The benefits go beyond drawing cyclists, though.
“If all these roads were paved, it'd be one less kind of unique thing to come to Vermont (for),” he said.
The Community News Service is a program in which University of Vermont students work with professional editors to provide content for local news outlets at no cost.
