Article

Great Meadow Wetland Rehab to Reclaim More Natural Flow

Acadia National Park’s largest and much-manipulated wetland is intricately tied to its urban surroundings. Energized by recent federal funding, an ambitious plan seeks to restore it to a more natural state while protecting neighbors from damaging floods.

By Jason Flynn and Lauren Gibson

Three people kneeling on wet ground surrounded by small green and pink flags where plugs have been planted around them. One is pressing the soil around a newly planted sedge while the others are using different tools to dig small holes.
Schoodic Institute employees, Alex Cisneros Carey, Sophie Gronbeck, and Taylor Palmer, planting native grasses in a Great Meadow restoration study plot.

Image credit: Friends of Acadia / Sam Mallon


Acadia National Park staff members watched in disbelief as heavy machinery ripped up pieces of the park’s main road.


A Manipulated Landscape

Located in a glacially carved, u-shaped valley, the Great Meadow is filled with shallow marsh grasses, alder and sweetgale shrubs, and red maple trees. Monitoring data show that most of the wetlands in Acadia are in good condition, but the Great Meadow isn’t. Invasive plants, hydrological (water-flow) disruptions, and stressors like trails, culverts, and roads have diminished its wetland functions.

Expansive, vibrant green meadow backed by rounded mountains.
Sitting between Dorr and Champlain mountains, the Great Meadow is Acadia’s largest freshwater wetland.

Image credit: NPS

Prior to European colonization, Indigenous groups collectively known as the Wabanaki lived in the vicinity of what is now Acadia National Park. They used the coastal area for subsistence hunting, fishing, and gathering. The Wabanaki were highly mobile and skilled navigators, crossing saltwater bays and traveling on rivers in seafaring canoes. The Great Meadow and associated springs may have provided them with drinking water and a carry trail for passage through Mount Desert Island’s steep hills and dense forests. Today, the Wabanaki and the National Park Service are piloting a co-stewardship approach to managing resources while reconnecting the Wabanaki people to the park landscapes containing culturally significant plants.


These landscape alterations created artificial boundaries in and around the wetland, setting the stage for decreased wetland function.


In 1909, George B. Dorr purchased a natural spring, now known as Sieur de Monts Spring, acquiring surrounding areas to prevent development. Subsequently, Dorr drained, filled, and manipulated the Great Meadow, physically transforming the landscape for his Wild Gardens exhibits. In 1916, Dorr donated the land to the National Park Service for what was then known as Sieur de Monts National Monument and became the park’s first superintendent.

The park subsequently modified the vehicle and pedestrian paths around the Great Meadow, abandoning the roads that Dorr had constructed. John D. Rockefeller, Jr., in conjunction with the National Park Service, developed the Park Loop Road between 1935 and 1940. The road follows the northern and eastern perimeter of the Great Meadow. These landscape alterations created artificial boundaries in and around the wetland, setting the stage for decreased wetland function.

Signpost with three signs pointing towards different Acadia roads and trails, half submerged. The flooding hides all of the ground in the vicinity, with trees and shrubs breaking the surface, along with some tilted, maybe floating wood boardwalks.
Submerged Hemlock Path sign. In the background are remnants of the raised Jessup Path boardwalk, which was damaged when the Great Meadow flooded.

Image credit: Friends of Acadia / Julia Walker Thomas

Compromised Capacity

When summer park visitors walk out onto the dry and cracked soils of Great Meadow, it’s plain to see that something is wrong. In its current state, the wetland doesn’t respond naturally to rain events. Past ditching and channelization of Cromwell Brook, the wetland’s main waterway, causes the wetland to drain faster, reducing its holding capacity. Trails and abandoned roads that bisect the wetland impede the natural flow of water, creating drought conditions during dry periods and extended flooding during heavy rain or snow. These extreme fluctuations in water level threaten the park’s historic and natural resources. They favor disturbance-tolerant plants, reducing the diversity of species in the wetland. And they reduce recreational access and compromise visitor safety.


Maintaining infrastructure that supported the very conditions we were trying to prevent felt a lot like chasing your tail.


Botanical surveys indicate that the areas around Great Meadow and Sieur de Monts have the highest concentration of invasive plant species in the entire park. The park’s Invasive Plant Management Team began to actively monitor and treat invasives in the Great Meadow watershed in 1993. But in spite of continued removal, many remain. Glossy buckthorn, in particular, is especially persistent. Vegetation crews have to work over 100 hours a year just to keep it at current levels in the Great Meadow.

Low-angle view of a man in a brimmed hat, orange vest, and heavy-duty rubber gloves leaning down to the ground to pull out a plant with both hands.
Acadia National Park employee Jim Burka removing invasive glossy buckthorn in the Great Meadow. Vegetation crews have to work over 100 work hours a year just to keep this persistent plant at current levels.

Image credit: Friends of Acadia / Ashley L. Conti

In most cases, healthy wetlands within Acadia are naturally acidic and nutrient-poor. These conditions promote the development of sphagnum, also known as peat moss, which is a good indicator of wetland health. But Great Meadow has a low percentage of sphagnum, which means there’s a high concentration of inorganic soil. Inorganic soil is mainly mineral matter. Water moves through it more quickly than through organic soil, further reducing the wetland’s capacity to retain water.

The U.S. Geological Survey’s 2016 analyses of Great Meadow indicated that the undersized outlet culvert at the Park Loop Road was the primary cause of the wetland’s poor hydrology. Even when functioning properly, the culvert caused flooding at Sieur de Monts. Managing the culvert was time-intensive and expensive, and its existence led to more non-native plant species and less sphagnum. Plus, maintaining infrastructure that supported the very conditions we were trying to prevent felt a lot like chasing your tail. We needed a big change.

Compacted social trails beside a waterway, along where the water passes under via a narrow stone culvert. Visitors and a dog are heading back towards cars parked along the road.
The Park Loop Road culvert at the outlet of the Great Meadow is the primary cause of the wetland’s poor hydrology. When water levels are extremely low, the soils become dry and cracked. Park visitors then walk into the wetland, which erodes soils and harms sensitive plants.

Image credit: NPS

Back to Nature, by Design

With federal funding from the Bipartisan Infrastructure Law, the park and its partners hired an engineering firm to help them understand the downstream impacts from wetland restoration and a new culvert design, particularly on Bar Harbor. The engineers’ model incorporated existing point data from the park’s rain gauge, continuous historic stream flow data, wetland water-level measurements, and topographic LiDAR and survey data. It used U.S. Army Corps of Engineers Hydraulic Engineering Center River Analysis software to extrapolate these discrete results to the entire watershed.

This enabled park staff to compare water levels in the Great Meadow to those downstream of the new culvert for different culvert configurations and restoration methods. Our goal was to select a road crossing that reduced peak flooding in Sieur de Monts, prevented damage to historic structures, and avoided impacts to infrastructure outside the park. The engineers used an iterative design process for creating the new culvert, where they repeatedly tested, analyzed, and refined successive prototypes until the design met the desired specifications.


The stream-simulation bottom would mimic a natural channel so that fish and other aquatic animals could cross through easily.


Satellite image of the oval-shaped wetland with red-to-blue overlay indicating water velocity and pink dashes around all sides indicating culvert locations. Flow is mostly slow, but there are areas leading to some of the culverts where peak flow is high.
A software-generated model of the Great Meadow shows water flow through the wetland. Areas of increased flow (shaded yellow to red) associated with road and trail culverts (pink lines) cause scouring and erosion. Historic wetland ditching accelerates the lowering of water levels, and abandoned roads impede flow. The model helped identify places where targeted actions could improve wetland health.

Image credit: VHB / Dave Cloutier

They concluded that the best solution would be a 12-foot box culvert with a 10-foot stream-simulation bottom. The stream-simulation bottom would mimic a natural channel so that fish and other aquatic animals could cross through easily. The flow through the channel would match the existing peak flow downstream. The design specs included repairing the stream channel immediately upstream and downstream from the crossing. This would create a floodplain to further dissipate energy from large storm events and help maintain a stable channel. The restoration would employ engineering with nature principles, using root wads and live staking to stabilize the new stream banks.


Upstream of the restored floodplain, the design called for a nature-like earthen berm.


Upstream of the restored floodplain, the design called for a nature-like earthen berm at the transition from wetland back to stream. Dave Cloutier, a senior water resource engineer on the project, said the berm was designed “to improve hydrology of the Great Meadow by reducing the severity of water level fluctuations.” The structure would enable the wetland to retain water in smaller rain events (the old culvert allowed the wetland to drain) and permit the controlled release of water from the wetland during heavier rain, preventing downstream flooding.

Diagram of planned vegetation around the new culvert. On the meadow side, there's an expanded floodplain surrounded by dots indicating shrub plantings. On the other side there's a forested floodplain where trees and understory plants will go.
The new culvert design called for extensive revegetation. Contractors worked closely with park staff to identify locally sourced native plants and seed mixtures. They also saved the topsoil and reused it during rehabilitation to preserve the native seed bank.

Image credit: VHB


The more sphagnum, the more water the wetland retains; the more water retained, the more sphagnum.


“With a more natural flow pattern in Great Meadow,” said Kate Miller, a quantitative ecologist who works for the National Park Service, “we expect to see increased peat buildup, greater plant diversity, and overall improved function.” Greater water retention will create a positive feedback loop, further stabilizing the hydrology: the more sphagnum, the more water the wetland retains; the more water retained, the more sphagnum.

A Shared Understanding

To augment the improvements in hydrology from the new culvert, we looked at the web of abandoned roadbeds and ditches that crisscrossed the Great Meadow. These past manipulations were for accessing and draining the wetland. Working with engineers, park staff devised a series of purges for the raised earthen roadways and plugs for the associated drainage ditches.Plans in hand, we consulted the Army Corps of Engineers, discussing permanent and temporary impacts and construction phasing and requirements. We also consulted the Maine State Historic Preservation Office, as some of the old roads, such as the Jessup and Hemlock Paths, are part of the Mount Desert Island Hiking Trail System, which is on the Natural Register of Historic Places. We developed treatments that preserved the integrity of the trails, while adding improvements to the wetland.


The park and its partners have worked to reframe how staff look at the landscape and to incorporate generational Indigenous knowledge.


Acadia National Park, Friends of Acadia, and Schoodic Institute have been working to develop new and meaningful relationships with the Wabanaki people. Acadia National Park’s program lead for Resource Management, Rebecca Cole-Will, has been collaborating with the Wabanaki to identify culturally significant plant species in the park. These conversations stemmed from the 2015 regulation change that permitted Indigenous gathering of plants by federally recognized tribes. The park and its partners have worked to reframe how staff, including project team members, look at the landscape and to incorporate generational Indigenous knowledge into the wetland restoration project.

Young person in a bright orange hoodie holding the roots of a small shrub in a wooded area littered with shovels, backpacks, colored flags, and other trappings of restoration work.
Elena Sparrow of the Wabanaki Youth in Science program collaborated with the Acadia vegetation crew and the Schoodic Institute in 2023, planting native species in the Great Meadow.

Image credit: Friends of Acadia / Sam Mallon

The project team examined its assumptions about the Great Meadow, deciding it was time to slow things down and hold back on some of our planned actions. There were many more questions for us to consider: Did every change to the wetland occur after European colonization? Were we seeing every aspect? Who should identify pre-colonial or overlooked landscape features? How could we protect Indigenous cultural and intellectual property and the rights and interests of the Wabanaki? How could we protect their knowledge and cultural practices from misuse? Were we changing conditions that would favor culturally significant species? Were there culturally significant species that should be in the wetland but were long gone?


Co-stewardship with the Wabanaki means developing a shared understanding of what Great Meadow restoration is going to look like.


Co-stewardship with the Wabanaki means developing a shared understanding of what Great Meadow restoration is going to look like. We’re conducting additional surveys of the project area for rare plants and those with ethnobotanical importance. We’re giving Tribal members the time they need to reconnect with the landscape. And we hope to have future discussions with Wabanaki knowledge holders about culturally important plants that may face negative impacts from climate change.

Serving the Public

Restoring the Great Meadow doesn’t mean recreating the wetland that existed before Dorr bought the land. We’re not returning it to some historic state. It’s about creating conditions for the wetland to naturally rebuild its own functions and resiliency and preventing catastrophic downstream impacts. In order to do that, we have worked to understand its existing conditions, its stressors, and how change will affect it. This work, strengthened by partnerships and realized through structural changes made with the help of the infrastructure funding, benefits local Mount Desert Island communities and park visitors.

Two people in full NPS uniform. Director Sams, on the left, listens as Cole-Will talks and gestures, with the meadow and mountains behind them.
National Park Service Director Chuck Sams (left) and Acadia National Park Chief of Resource Management Rebecca Cole-Will discussing the importance of partnership and what ecological restoration in the Great Meadow means for addressing the impacts of climate change.

Image credit: Friends of Acadia / Ashley L. Conti

In addition to designing the new culvert, we’ve used Bipartisan Infrastructure Law funds to develop vegetation restoration experiments that test the effectiveness of seeding native plants for halting non-native plant invasions, which is crucial for wetland water retention. The tests are adaptable, so we can incorporate the lessons we learn from one set of tests when we design the next set. “These experiments should help us determine if competition can slow down the growth of invasive shrubs, allowing [the Invasive Plant Management Team] breathing room,” said Jesse Wheeler, the park’s vegetation program manager.


Investing in more appropriate infrastructure for the wetland through recent federal funding will save on long-term operation and maintenance costs.


Annual precipitation in Acadia National Park has increased by about 6 inches since many of the park’s roads and trails were built. Scientists predict the area’s future climate will be hotter, with more frequent and intense precipitation. We have already seen more frequent flooding in the cultural landscapes at Sieur de Monts, including the Nature Center and Wild Gardens, and in the associated trail system in Great Meadow. This has led to limited visitor services, longer visitor use closures, and increased costs. With the help of the infrastructure funds, we’re proposing significant changes to existing trails. One such change is to add purges (large perpendicular ditches) across the trails to support wetland connectivity. Another change is to construct a boardwalk-style trail, compliant with the Americans with Disabilities Act, over the purges and above the flooded wetland. This will provide trail access to more people more of the time.

Brown building with sandbags in front of its two sets of doors, surrounded by water.
The Sieur de Monts Nature Center during Great Meadow flooding.

Image credit: Friends of Acadia / Julia Walker Thomas

The Great Meadow wetland restoration project will also help reduce overall park costs. Year after year, the park cleaned the undersized, clogged culvert in Great Meadow, but we couldn't do it before every storm. As storms became more frequent and intense, damage to historic structures and recreational assets increased. Investing in more appropriate infrastructure for the wetland through recent federal funding will save on long-term operation and maintenance costs for buildings, roads, and trails.

This hasn’t been an easy or quick path to follow. It has taken preparation, patience, and teamwork. We’ve had to be adaptable as the project evolves. But though our goals, timelines, and products may change, we’re developing deeper long-term relationships, gaining more meaningful results, and serving the public in more ways than we could ever have imagined.

About the authors

Flynn outside in a yellow safety vest looking at paperwork.
Jason Flynn is an environmental protection specialist at Acadia National Park. Image credit: Friends of Acadia / Julia Walker Thomas
Gibson outside by the ocean, smiling for the camera.
Lauren Gibson is the Wild Acadia coordinator at Friends of Acadia. Image courtesy of Lauren Gibson.

Acadia National Park

Last updated: August 30, 2024