As we enter 2025 and approach the 5^th summer since the founding of the Save Mashpee-Wakeby Pond Alliance, we do so having heard the sobering results of the diagnostic study of the pond, which were presented to the Mashpee Select Board on December 16. We’ve been waiting three years for this study to be completed. Now that we have it, it’s time for action!



This is a longer post than usual, but we hope it will consolidate the key points of the study and presentation. This will allow everyone involved to have a shared understanding of the science and the next steps required to save the pond and continue to mitigate nitrogen loading in the Mashpee River and Popponesset Bay.

If you have not seen the presentation delivered at the 12/16/24 Select Board meeting, please click HERE. The presentation begins with the Estuaries Report at minute 57 and with the Pond Report at the 1 Hour, 12 minute mark. The 168 page report is also available on the front page of the Mashpee Town Website HERE.

At a high level, these are the key facts:

• Mashpee & Wakeby Ponds have been impaired dating back to well before 2001. Both are now considered severely impaired, but Wakeby Pond is worse. 

• The bottom layers of both ponds are anoxic, meaning they are devoid of oxygen and unhealthy for fish. 

• Wakeby Pond receives its largest load of nutrients (both phosphorus & nitrogen) from groundwater and runoff. These come from the areas to the north and northwest of the pond, which is the northernmost part of the Popponesset Bay Watershed. Most of the nutrients, other than the Mashpee northern shoreline, originate in Sandwich.

• The main source of nutrients to Mashpee Pond (75%) come from Wakeby Pond, as the water flows south through the narrows. For most of the homes on Mashpee Pond south of Camp Farley, the groundwater flows away from the pond. This graph from the presentation shows how and from where groundwater flows to Wakeby Pond in dark blue and to Mashpee Pond in dark green:

• Regardless of the directional flow of groundwater, all shoreline homes contribute surface runoff that impacts water quality. The nitrogen from septic systems and fertilizer from all homes, regardless of their location on the ponds enters the Popponesset Bay Watershed, impacting the Mashpee and Santuit Rivers and degrading the bay. Since the head waters of the Mashpee River are at the Southernmost point of Mashpee Pond, a lot of what goes through the watershed from the north ends up travelling down the Mashpee River.

• Phosphorus is the nutrient that drives the development of the pond’s harmful algal blooms that are now occurring regularly in June and sometimes in the fall.

• Nitrogen also enters the ponds, but it is not the critical nutrient contributing to the cyanobacteria problem. The nitrogen, however, does migrate from Wakeby Pond to Mashpee Pond and ultimately to the Mashpee River, adding to the degradation of the estuaries & bays in the Popponesset Bay Watershed.

• The primary external sources of the nutrients to Wakeby come from septic wastewater that has contaminated groundwater. Key contributors are the wastewater from homes on the north and west shores of Wakeby (54%), along with nutrient laden groundwater coming from Pimlico and Peters Ponds (26%). Stormwater run-off, fertilizers and the cranberry bog are also meaningful contributing factors but not as significant as wastewater.

• Wakeby Pond has now received so much phosphorus over time that the largest source of phosphorus contributing to the Cyanobacteria Blooms is already stored in sediment of the pond. The anoxia of the bottom layers of the water column allows for the release of the phosphorus from the sediment, where it feeds the Cyanobacteria. The poor water quality creates a self-sustaining cycle, known as a negative feedback loop, which makes the pond worse.

Considering these facts, the report outlines a myriad of options to manage the nutrients already in the pond and reduce the flow of additional nutrients into the pond. Chief among the actions we can take are the following:

• The primary recommendation of the report is an application of aluminum sulfate (commonly referred to as “alum”) to suppress the internal phosphorus already at the bottom of the ponds (internal source). Alum is a proven tool that chemically binds with the phosphorus to prevent it from becoming available in the water column to serve as food for the cyanobacteria. The process of administering this treatment is complex and requires funding, permitting, and a dosing study to avoid harming the ecosystem. Time to application, if funding is approved, is 3-4 years. The report suggests Wakeby be treated first and carefully monitored to determine if Mashpee needs a treatment as well. It is IMPORTANT TO NOTE that this treatment will only last 10-15 years and will not prevent phosphorus from continuing to enter the ponds. It is a “band-aid” that buys us some time and alleviates the public health hazard associated with toxic cyanobacteria.

• To address the external sources of phosphorus, a combination of tools can be applied and are under consideration by the Town already:

• Explore the design and implementation of an innovative alternative “cluster system” to convert the septic systems of the homes along Pimlico Pond and Cove Roads to a managed treatment site operated and managed by the Town of Mashpee. Members of the Intermunicipal Agreement Team from Mashpee and Sandwich are working closely with our engineers at GHD on this creative solution. Not only will the system be less invasive than town sewer, it will also come at a fraction of the cost and can be deployed relatively quickly. If successful, it is believed to be an approach that could be transferrable to other areas of Mashpee which are hard to sewer. This system will reduce both nitrogen and phosphorus and therefore benefit the ponds, the rivers and the bay, providing water quality benefits to multiple sensitive water resources for the same funds!

• Capitalize on the fully re-designed (100% Permit Ready Plans that were paid for by grant funds) and Conservation Commission permitted Mashpee-Wakeby Boat Ramp. Though the ramp is owned by the State, Mashpee is required to maintain and operate the ramp. It currently has no stormwater system in place, leaving tens of thousands of gallons of dirty water containing rubber, oil, and other pollutants flowing into the pond with each substantial rainstorm. Funding sources for the construction are being sought, including from the State, our own CPC, and grants. Thanks to APCC and Horsley Whitten for tireless work on this project.

• Provide education and incentives to homeowners to reduce nutrient pollution by ceasing all fertilizing, planting native plants, reducing or eliminating lawns and re-directing and slowing down stormwater that runs down their property into the ponds.

Key leaders of our Town’s Wastewater Department and our Sewer Commission believe the data supports this plan. As the clock ticks, our waters worsen and we have no time to waste in implementing the solutions. We look forward to your support in raising your voices and garnering the key votes needed to allow this multi-pronged plan to proceed. Each element of the plan is important and each is needed to address the different contributing parts of the problem.

In the coming weeks, we plan to hold on-line Zoom Meetings to allow for questions from the public. We’ll be sure to keep you apprised of the dates and times.

Sincerely,

Susan Dangel

President, Save Mashpee Wakeby Pond Alliance

The Save Mashpee-Wakeby Pond Alliance is a coalition of concerned neighbors who love Mashpee-Wakeby Pond and are committed to help ensure its preservation, protection, and enhancement as an important recreational and economic focal point for our community. Learn more at:

www.savemashpeewakeby.org