This story was originally produced by the New Hampshire Bulletin, an independent local newsroom that allows NHPR and other outlets to republish its reporting.
Steep, rocky, and unforgiving: Among hikers, New Hampshire’s trail network has a reputation.
“When the trails … in New Hampshire were laid out, they were laid out to maximize adventure, challenge,” said Matt Moore, senior operations manager for Appalachian Mountain Club Trails.
It’s common for trails in the White Mountains to follow direct routes up slopes, eschewing twists and turns, or switchbacks, that would moderate their ascents. The trail crews that charted these routes in the 1920s and 1930s often crafted them with string, using lengths to mark a straight path up the slope, Moore said.
That approach created some iconic routes up and down the region’s famous peaks — but it also established trails that tend to be aligned with the path of rainfall runoff.
That means trails in New England are particularly susceptible to erosion to begin with, Moore said. And as climate change continues to make rain events more intense, that creates a growing problem for hikers and trail crews alike.
“Climate change is intensifying and accelerating a problem that we already had,” Moore said.
Heavy trail usage compounds the issue.
Up to 1,000 people hiking on the Franconia Ridge on a peak day, for example, is “the kind of usage that I’m sure the original builders never could have envisioned,” Moore said. “They were coming up here in horse-drawn carriages.”
Now, hikers travel to the White Mountains in droves on Interstate 93 and other major roads. All that foot traffic compacts the soil lining trails, further lowering the grade of the trail bed and allowing water to pick up more speed as it channels through.
This can create massive ditches that are difficult to traverse and unappealing to the eye, Moore said. Soil compaction around trails can kill trees by constricting their roots; when runoff displaces sediment from trails, it can find its way into mountain streams.
So how are trail crews responding?
The most permanent and effective solution for the worst cases typically involves rerouting trails, Moore said. Trading a steep grade for length — say, by introducing switchbacks — decouples a footpath from the path of runoff, lessening the amount of erosion it will see.
Some hikers balk at the idea of changing trail routes, Moore said.
“People have mixed feelings about it,” he said. “People say, ‘I liked the challenge of the old trail.'”
Moore says the trails that are relocated are examples of worst-case erosion problems: deep ditches and compacted soils that make for a “devastated area” around the footpath where there once was wilderness.
The other reality, he said, is that relocation projects are expensive and time-consuming — meaning that while relocation is an effective solution to erosion, it’s not one that can be implemented everywhere it may be needed.
“Relocating to sustainable grades would offer us, yeah, a more sustainable solution,” Moore said. “But obviously we’re not going to be able to relocate these thousands of miles of trails to sustainable grades.”
When relocation isn’t possible, crews may also “harden” a trail, such as by constructing a stone staircase. But this is similarly labor-intensive, time-consuming work, so crews must concentrate their efforts on the “worst case” trails, Moore said.
Recent significant trailwork projects include the hardening of the Old Bridle Path on Mount Lafayette, where trail crews constructed staircases, and the ongoing relocation of the Falling Waters Trail to mitigate erosion, Moore said. The Falling Waters Trail is not yet reopened; its relocation — a significant undertaking — is expected to be complete “in the next few years,” Moore said.
But across the vast majority of trails, Moore said, climate mitigation is taking a more understated form: water bars, and an immense mobilization of volunteers to help maintain them.
A water bar is a ridge constructed across a trail, such as with a log or stones, to divert streams of water. By interrupting the flow of runoff, these simple structures help lessen erosion and catch sediment, Moore said.
Volunteers help clean sediment buildup from alongside water bars and place it back on the trail. Last year, Appalachian Mountain Club volunteers cleaned and maintained about 5,000 water bars on trails that the club maintains, Moore said.
“The maintenance of these water bars, that is the primary (solution) for the next 30 to 50 years,” Moore said.
Over that period, professional trail crews like those that Moore oversees will continue to target the trails most affected by climate change for larger-scale improvements, he said.
While some may worry at the prospect of route changes, Moore said it’s this work that will be most effective at keeping trails in the Northeast hikeable. After all, it’s becoming increasingly apparent that if people don’t change routes, climate will.
