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Karen Beattie has studied the ecology of Nantucket for 30-plus years. But even she’s blown away by the process of restoring Windswept Bog.
“Setting the stage for nature to come in and take over and do the rest of the work ... it’s really awe-inspiring,” she said. “I’m looking forward to seeing how the site responds.”
As vice president of science and stewardship at the Nantucket Conservation Foundation, Beattie’s been with the project from the start, working with a “dream team” of experts and relying on funding from the U.S. Fish and Wildlife Service and others.
Together, they’ve returned a century-old cranberry bog on the island off Cape Cod, Massachusetts, to a naturally functioning wetland that will serve people and wildlife for generations.
Responding to changing conditions
Harvested for thousands of years by the native Wampanoag people, cranberries are one of the few crops that thrive in Nantucket’s sandy, nutrient-poor soil. They’ve been grown commercially for more than 150 years and once offered residents a source of income outside the tourist season.
The Nantucket Conservation Foundation owns both historically significant cranberry bogs on the island: Milestone and Windswept. Milestone was once the largest contiguous cranberry bog in the world. The foundation has continued production there since acquiring the property in 1968.
The 40-acre cranberry bog at Windswept produced for about a century, including after purchase by the foundation in 1980. In 2018, however, leadership decided to cease cranberry operations due to economic and environmental concerns.
Cranberries rely on traditional seasons to thrive. The plants need cold winters to generate blossoms and fruit. If spring-like weather comes early, they may produce premature blossoms that are killed by sudden, late-spring frosts. And the berries rely on cold fall nights to create their deep-red color just prior to harvest.
Shifting environmental conditions have reduced production in Massachusetts and brought increased competition from Canadian growers.
“Our climate is now more like New Jersey, or even Delaware and areas farther south,” said Beattie. “This has also brought a whole new suite of insects and fungi.”
As a natural basin, Windswept Bog collects runoff from surrounding roads, residential septic systems and lawns. That runoff contains pollutants like fertilizers and bacteria. Fertilizers were also applied directly to the bog during cranberry cultivation.
A healthy wetland would have filtered out pollutants. Instead, layers of sand applied over decades to encourage cranberry growth let runoff flow quickly through Windswept into Polpis Harbor and eventually Nantucket Harbor, where high levels of bacteria and nitrogen threaten the island’s scalloping and boating industries.
Restoration to a naturally functioning wetland addresses all of these issues.
“We felt it would be the right thing to do for the property itself,” Beattie said. “We wanted to restore ecological services, but the other thing was this site is a really important property of ours and provides a lot of public access, use and enjoyment on behalf of the public.”
In addition to the bog, the 231-acre property includes more than 100 acres of natural wetlands and about 80 acres of upland habitat. It’s also connected to several thousand additional acres of protected land. As part of the project, low-profile boardwalks were built so hikers and birdwatchers can explore the restored bog without harming sensitive plants.
Finding funding
Cranberry farming began in Massachusetts, in the early 1800s. More than 13,000 acres in the state’s southeast are still managed for cranberries, the largest food crop. But adjusting to changing economic and environmental conditions isn't easy.
While the Commonwealth of Massachusetts supports farmers in improving the efficiency of their bogs, it also created the Cranberry Bog Restoration Program in 2018. Jessica Cohn is an ecological restoration specialist with the Massachusetts Department of Fish and Game’s Division of Ecological Restoration, which oversees that program.
“There was an unfortunate perfect storm in the cranberry industry, with out-of-state competition, challenges with water resources, and a desire by some growers to stop farming cranberries in Massachusetts,” Cohn said. “The state realized there could be a lot of land in transition.”
Abandoned cranberry bogs tend to become upland habitats, rather than revert to their wetland beginnings. The program offers farmers the option of taking bogs out of production and restoring them to functioning wetlands that provide wildlife habitat, water filtration and coastal resilience. Interested landowners can apply for technical assistance and funding to move a bog from a highly altered landscape to a more natural one.
“It creates a good partnership from the front end, done with a lot of hope and excitement about honoring the land and returning it to a healthy state,” Cohn said.
Massachusetts has restored nearly 500 acres of wetlands and more than 10 miles of stream through seven completed cranberry bog projects. Seventeen more are in various stages of planning, design, permitting and construction.
The Division of Ecological Restoration chose Windswept Bog as a priority restoration project in 2020, granting the Nantucket Conservation Foundation and project partners more than $1.6 million.
In 2024, the Service awarded a $1 million National Coastal Wetlands Conservation Grant to the project. These grants conserve, restore and enhance coastal wetland ecosystems and nearby uplands. Since 1992, we’ve granted more than $530 million, contributing to the long-term conservation and restoration of 600,000 wetland acres.
National Coastal Wetlands Conservation Grants are just one funding source under the Sport Fish Restoration Act, which turned 75 in 2025. Manufacturers and importers of sport-fishing equipment, electric motors, fishing tackle, yachts and pleasure craft pay taxes and import duties on their products, and recreationists pay taxes on fuel for motorboats and small engines. Together, these revenues have provided $12 billion to states to ensure Americans have the best sport fisheries in the world.
“Coastal wetlands provide valuable habitat for countless species of wildlife, including some at risk of becoming threatened or endangered,” said Chris Dwyer, biologist with the Office of Conservation Investment in the Service’s Northeast Region. “They also absorb stormwaters and buffer wave action that might otherwise cause flooding and erosion.”
National Coastal Wetlands Conservation Grants of $1 million have supported cranberry bog restoration in Massachusetts from the beginning:
- Eel River Headwaters, in Plymouth, was the state’s first project, completed in 2010, before the formal program was created. It restored 40 acres of wetland, 1.7 miles of stream and 20 acres of upland.
- Tidmarsh Farms — the largest freshwater wetland and river restoration undertaken in Massachusetts — followed in 2016, restoring 610 wetland acres and 3.5 miles of stream in Plymouth.
- Cold Brook, in Harwich, was completed in 2024, restoring 46 wetland acres and one mile of stream, and Mill Brook Bogs, in Freetown, will begin construction in 2025.
The U.S. Environmental Protection Agency’s Southern New England Program and the Richard King Mellon Foundation also provided funding to support restoration of Windswept Bog.
Renewing Windswept
For cranberry production, Windswept Bog’s 40 cultivated acres were divided into 14 units by berms containing water-control structures. Ditches drained the surface, as did a one-to-three-foot layer of sand built up over a century. Upland plants had begun to take root.
Over two phases, in 2024 and 2025, crews from SumCo Eco-Contracting carried out design plans developed by engineers from Fuss & O’Neill. To restore more natural water movement through the site, they removed more than 2,500 feet of berms and 28 water-control structures, filled ditches, and dug up the sand layer. They also “roughened” the surface, breaking up the cranberry mat to release seeds of native wetland plants, lying dormant below.
“If you can get the hydrology right, the plants start to recover, and eventually the soils and peat start rebuilding,” Cohn said.
Some sand from the bog was placed in adjacent upland areas to create sandplain grassland habitat, a regionally rare habitat found on Nantucket. Foundation staff harvested seeds from native grassland plants on its other properties — capturing local varieties — to replant the upland.
“This is the first large-scale habitat restoration project we’ve undertaken,” Beattie said, “and I’ve learned so much from working with this team of experienced people. It’s kind of jaded me in terms of future projects and expectations of perfection.”
Tracking change, charting a course
Funding from the state supported monitoring of the site before, during and after restoration. The foundation’s ecology staff studied wildlife and plant populations, surface and groundwater flow, and water quality. Results from pre-construction monitoring guided the timing of restoration activities.
“Our team did a lot of research into the property to understand it better before we actually put any shovels in the ground,” Beattie said.
Turtles were fitted with radio transmitters so researchers could track their use of the bog. Data showed the animals were active there in the spring, summer and fall but traveled to nearby wetlands to hibernate in winter.
To protect the turtles and nesting songbirds, work was limited to winter. Splitting it across two years allowed researchers to observe a growing season in between, which led to changes in Phase II. They were excited to see turtles return to the bog after Phase I.
“We always set aside funds for monitoring for learning,” Cohn said. “We like to check up on our sites at specified time periods to learn what’s going on. We want to make sure what we’re doing is actually helping and find ways to make it better, more efficient.”
Looking to the future
Within a decade, Windswept Bog should be a functioning freshwater wetland serving the wildlife and people of Nantucket. But the sea is creeping closer.
Though Windswept is half a mile from the coast now, the National Oceanic and Atmospheric Administration predicts saltwater will reach its northwestern quadrant by 2100. The restored bog will give coastal salt marsh salt marsh
Salt marshes are found in tidal areas near the coast, where freshwater mixes with saltwater.
Learn more about salt marsh habitat, which is becoming scarce, a place to go as it retreats from rising seas.
In the distant future, Windswept Bog's freshwater wetland plants will likely be replaced by salt-tolerant ones, and the habitat will shift to salt marsh, absorbing waves and storm surge from an encroaching ocean.
“When we intervene with restoration, we set the site back on a trajectory of a healthy wetland,” Cohn said, “and healthy wetlands are more resilient to change.”
Windswept Bog, in its various incarnations, has served Nantucket for millennia. Thanks to everyone involved in its restoration, it should continue to do so for a long time to come.
