Century Bog, a 75-acre stretch of fields and woods across Plymouth and Wareham, looks more like a construction site than a former cranberry bog.
Excavators have churned up soil, ripped out pine trees and broken up buried plastic piping. In their place are wide moats of thick, sloppy mud, so dark they're nearly black.
"It looks like a bomb has gone off right in front of us here," said Alex Hackman, director of ecological restoration at Mass Audobon. "But what's actually happening here is that it's being prepared for restoration."
Hackman is part of a team working to restore Century Bog into the natural wetland that was there before the farm. The farm's last owner, the A.D. Makepeace Company, sold the land to the state in 2010, fully retiring the bogs a few years later. The land was then protected as part of the Red Brook Wildlife Management Area, but all of the farm infrastructure was left behind.
Restoring the wetland, said Hackman, means "all the ditches will be eliminated, all the dams removed, the soil will be uncompacted, so it can hold more water [and] fill up like a bathtub."
The Century Bog project is part of a wider trend across Massachusetts, as a growing number of cranberry farmers are retiring their bogs. According to the U.S. Department of Agriculture, the number of retired bogs grew 40% between 2017 and 2022; research from the Woodwell Center for Climate Research has projected that 20% of all remaining bogs in the state are highly likely to retire within the next decade.
"There's just a lot of momentum right now," said Hackman.
As the cranberry industry developed in Massachusetts, farmers wanted water, and so they built their farms on wetlands; Century Bog, specifically, operated as a commercial cranberry farm for more than 150 years. The original farmers leveled the ground, buried the wetlands, and constructed an irrigation system to control the flow of water. They also spread a thin layer of sand over the landscape, to encourage cranberry growth and to reduce pests and weeds.
Every few years, they'd add a few centimeters more.
"But over 150 years, feet of sand get added," said Hackman. At Century Bog, the average was two feet. It's the addition of sand that primarily dries out of the landscape, moving the surface farther away from the groundwater.
"That's why you get pine trees here [now], and not cattails, for example," he said.
All that sand would have been too expensive to remove completely. Instead, the construction crews mixed the sand into the soil as they dug up the buried wetland peat. Later, Hackman's team will add some plants and debris to encourage the stream that runs through the site to bend and curl; they want the water to slow down, saturate and stay.
But mostly, the regeneration of the site will be driven by native seeds dormant in the wetland soil.
"Almost all the plants that recolonize the restored bog surface are from a native seed bank," said Chris Neill, a scientist at the Woodwell Center for Climate Research. "Some of them might be decades old."
They are also much more diverse. Neill has worked on wetland restorations for years; at the Coonamessett restoration site in Falmouth, completed several years ago, he's seen a dramatic jump in the different plant species.
"Before restoration [there were] maybe 15 species in one of our three by three meter plots," he said. "After restoration, the average was 35 species."
That boost to biodiversity is one reason the state government wants to see more of these restorations. Since 2018, the Massachusetts Department of Ecological Restoration has run a dedicated cranberry bog program; last year, the Healey administration set biodiversity targets for the next several decades, as well as a goal to restore 75% of the state's most important habitats by 2050.
At Century Bog, the restoration is expected to help more than 60 species the state says have the greatest need for conservation; it will also restore the habitat of a unique brook trout, called a salter, found in both fresh water and salt water habitats.
Other elements of the projects are more directly beneficial to people. Wetlands absorb nitrogen that gets into waterways from agriculture runoff and sceptic systems. Without wetlands, that nitrogen flows to the ocean where it fuels worsening algae blooms. Wetlands are also a tool for flood management, as climate change makes storms in Massachusetts more erratic.
"Part of the solution is to actually build wetlands in places that would act as natural sponges," said Linda Deegan, a scientist at the Woodwell Center for Climate Research and McNeil's colleague. "So if there's a really heavy rainstorm, the water can now come down and flood out into the wetlands and spread out instead of being confined to a narrow channel and just rushing downstream."
Perhaps the most direct benefit, though, is to the cranberry farmers themselves.
"There have been growers retiring bogs for generations," said Brian Wick, executive director of Massachusetts Cranberries, a nonprofit supporting the local industry. "But it certainly has picked up in these last several years because of the opportunities that are there."
Wick said cranberry farming is still a strong, and iconic, industry in Massachusetts, generating about $1.7 billion in annual economic activity. But farmers are facing several external pressures.
"Overall, I would say things are challenging economically," said Wick. Costs are going up for both farmers and consumers, while farmers simultaneously face competition out of state, from newer, more efficient, and often more productive farms.
Climate change is also making the conditions for farming more difficult, as the state experiences droughts more often.
And then, there's the issue of time. Many of the state's cranberry farmers are aging, and may not currently have an exit strategy.
"It's a common problem in agriculture across the country that the next generation has more options … so [they] might not be willing or able to take over the farm," said Wick. Cranberry bogs also have limited options for switching crops, or selling for development, because as former wetlands, they're prone to flooding.
"So retiring it permanently [for restoration] and getting some cash to do that, provides basically a retirement."
The wetland restoration process is slow. It took Hackman and his partners about a decade to secure the funding for Century Bog, and crucially, to secure the funding to begin the construction phase. The land will initially spring back quickly, but it will be another 7 to 10 years before this restoration is considered "complete," according to Hackman.
Massachusetts has more than 13,000 acres of cranberry bogs across the state. Hundreds of acres have been restored to wetlands so far; another 11 projects are in the pipeline.
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