Phragmites Management along the Muddy River: The Challenge and Evidence of Progress
By Matt Eddy, MMOC Staff
The problems with unchecked Phragmites australis patches in the Back Bay Fens area have been well documented by many, including our own State Senator William Brownsberger. Left unchecked, Phragmites growth narrows the River channel and promotes a build-up of suspended sediment. This decreases the depth of the river and impedes flow.
Funding for Phragmites removal along the eastern bank of the Muddy River (between Mothers Rest and Agassiz Road) was not included in the Federal component of the Muddy River Restoration Project. The US Army Corps of Engineers only funded the parts of the Project associated with flood risk reduction, which included removal of Phragmites on the western bank (adjacent to the Victory Gardens).
In 2022, the Boston Parks & Recreation Department and Brookline Department of Public Works stepped up to allocate funding for expanding the overall area of Phragmites removal. Their goals included greater access by the public to the River’s edge, improved sight lines, and a reduced rate of sedimentation of the River channel.
Boston’s Phragmites removal has been focused especially in the Back Bay Fens area near Mothers Rest and along Agassiz Road. Brookline’s focus is along the downstream section of the Riverway between the Longwood and Fenway T stations.
There’s progress to report!
The yellow line in the middle of the river is a “turbidity curtain” placed to capture Phragmites fragments and minimize sediment flow out of the work area. Since these Google Earth photos were taken in August, 2022, all the Phragmites along the eastern and southern banks of the River has been removed.
View looking towards Mothers Rest Playground, June 2022:
View looking towards Mothers Rest Playground, November 2022:
Back Bay Fens Area, December 2020:
Back Bay Fens Area (much improved!), February 2023:
Root masses and the process of removal
Most of the harvested Phragmites stems and roots are captured by excavators, loaded into trucks, and delivered to incinerators for destruction. Despite the best efforts of the very capable excavator operators, some Phragmites material escapes and floats away. These fragments are retained by turbidity curtains positioned downstream of each work site.
Here’s a view of Phragmites stems caught by the turbidity curtain at the Richardson Bridge, Boylston Street:
Occasionally, during storms or other high water conditions, some masses of Phragmites root material escape these curtains and flow downstream. They can sprout and establish new colonies of Phragmites elsewhere. When MMOC field staff or others see these root balls, they file a report with the US Army Corps to they or their contractors can attempt to capture them.
A floating Phragmites root mass in the Charlesgate area:
The long view: won’t the Phragmites just regrow?
Research suggests that Phragmites may regrow from root masses much deeper than the level at which they are being excavated. Total eradication of Phragmites (or any invasive species, for that matter) is extremely difficult and prohibitively expensive. So instead of eradication, the focus is on managing the problem — addressing the most critical negative consequences of Phragmites growth in a cost-effective manner. This generally involves a combination of mowing, chemical treatment, and seeding of the areas with native species to compete with the Phragmites. Most of this work is scheduled for fall, when Phragmites is most vulnerable to treatment. The Boston Parks and Recreation Department has committed to sustained funding this ongoing management effort.
Note: Phragmites that grows inside the fenced work areas is the responsibility of the Army Corps’ engineering contractor, Charter Contracting. It is Charter’s obligation to treat all invasive species inside the fences before the properties are returned to their owners (Boston, Brookline, and DCR).
Keeping Phragmites in check over the long term requires vigilance. If you notice stems popping up in the Muddy River area, please let the MMOC know. Your report will be delivered to the Army Corps!
Photos: Matt Eddy
