The year 2025 was an exciting period of progress for Wigwam Pond! Following the recommendations put forth in the 2023 Wigwam Pond Public Access and Recreation Plan, the Town of Dedham Conservation Division worked with Water & Wetland, a pond management company, to advance invasive species management around Wigwam Pond. Before beginning this project, Water  & Wetland obtained an Order of Conditions from the Dedham Conservation Commission and a Massachusetts Department of Environmental Protection State Pesticide Use Permit.  These are standard permits for performing any invasive treatment work in a sensitive resource area such as a pond or wetland, and include conditions such as time of year restrictions, safe pesticide use protocols, and notification requirements.

Aerial view of Wigwam Pond before invasive special removal (Photo by Town of Dedham, taken on December 9, 2025)

After acquiring the required permitting, Water & Wetland conducted a pre-treatment survey in April 2025 to establish baseline conditions at Wigwam Pond. The survey revealed extensive growth of two invasive aquatic plants, Eurasian milfoil and fanwort, along with dense stands of Phragmites (common reed) surrounding the pond’s shoreline.

These invasive species pose serious threats to the pond’s ecological health. As the plants grow, die, and spread, the plant matter gradually fills in the pond, making it increasingly shallow and more vulnerable to eutrophication (an overabundance of nutrients like nitrogen and phosphorus). This creates a harmful cycle: nutrient-rich waters fuel excessive algae and plant growth, which in turn worsens water quality. Invasive plants also grow and spread rapidly, forcing out native vegetation that local wildlife depend on for food, shelter, and habitat.

 To address these concerns, beginning in May 2025 Water & Wetland applied Sonar, a non-toxic herbicide treatment, to target dense aquatic vegetation. At that time, nearly 95 percent of the pond’s surface was covered by invasive vegetation and dense mats of filamentous algae (often called pond scum). A follow-up visit in June showed encouraging results, with algae coverage reduced to approximately 40–50 percent. To ensure long-term effectiveness, two additional herbicide treatments were completed in June and July, resulting in near-complete removal of the targeted aquatic invasive plants.

Dense stands of invasive Phragmites (common reed) at the southern corner of the pond during invasive removal operations (Photo by Town of Dedham, taken on December 9, 2025)

In August 2025, the focus shifted to the shoreline, where dense stands of Phragmites were treated. Biologists accessed the shoreline using a Marsh Master, an amphibious all-terrain vehicle designed to safely navigate wetland environments. The Marsh Master is typically operated by two trained staff members from Water & Wetland and allows access to parts of the pond that would otherwise be inaccessible by boat or foot. The herbicide was carefully sprayed directly onto the Phragmites, while native vegetation, such as cattails, was intentionally avoided. August is the most effective time to treat Phragmites, as the plant is in full bloom and readily transports the herbicide to its roots, reducing the likelihood of regrowth the following year.

Phragmites (common reed) at the southern corner of the pond following mowing operations with the Marsh Master (Photo by Town of Dedham, taken on December 17, 2025)

The team returned to Wigwam Pond in December to cut and mulch treat Phragmites stands, focusing on a large section of the pond’s southern shoreline. Additional cutting is planned for 2026, a management approach that helps create space for native plants to reestablish during future growing seasons. 

Looking ahead, the Town will continue working with Water & Wetland to manage invasive species and monitor water quality at Wigwam Pond. As the pond’s health continues to improve, the Town will begin exploring Phase 2 and Phase 3 of the Wigwam Pond Public Access and Recreation Plan, which include enhancing existing access and identifying future access points and connections around the pond. In the long term, the Town envisions an accessible perimeter boardwalk trail that would unlock the full recreational and educational potential of this special natural resource.

 We are excited by the progress achieved in just over a year and proud to be one step closer to achieving the long-term vision for Wigwam Pond! If you have any questions about invasive species, ecological improvements at Wigwam Pond, or want to learn more about the Wigwam Pond Recreation and Access plan, please reach out to the Conservation Division of the Planning, Zoning, and Natural Resources Department at dedhamconservation@dedhamma.gov.