The Herring Ponds Watershed Association Board of Directors (BOD) received a draft of the Herring Ponds Management Plan and Diagnostic Assessment in late August. The BOD appointed a Review Committee consisting of Paul Denoncourt, Tom O’Brien, Jerry Levine, Brian Harrington, Jack Kedian, Geri Williams, Lee Pulis, Jim Smith, and Don Williams to study the 125-Page report, look for questions and help bring the report into its final form for presentation to our membership.
The Review Committee has held four meetings in which questions were generated for both our Plymouth Department of Marine and Environmental Affairs (Kim Tower and David Gould) and our consultant (Ed Eichner). These questions were presented to David and Kim and ideas for moving forward were discussed.
The Review Committee has received written responses from both the DMEA and from the Consultant and has individually reviewed them. In addition, an updated draft Management Plan which outlines long term, interim and short-term goals has been received and reviewed by the Review Committee. The Management Plan outlines actions that the Town/HPWA and other project partners can implement to reduce the watershed pollution, specifically total phosphorus, in the interim while awaiting long term management options. The options have been listed and we are looking into option details including how to monitor option progress, option expense and option maintenance requirements.
Plans for the immediate future include a meeting of the Review Committee to discuss the recently received answers to DMEA and consultant questions, then a meeting with Review Committee, DMEA and Consultant to talk about pros and cons of the listed options.
The Study indicates that Little Herring Pond (LHP) is nutrient rich; however, it has acceptable water quality due to the short residence time (amount of time the water/phosphorus remains in the pond). LHP releases the phosphorus load to Great Herring Pond (GHP) via Carters River, especially during the summer months, has a long residence time (acts like a sink) where the phosphorus load accumulates. This is what can feed cyanobacteria and create blooms. The Study indicated a reduction of phosphorus coming into GHP needs to be managed to meet an acceptable water quality goal. The study indicates the largest source of phosphorus is from septic systems. The Town and project partners will seek funding to conduct a feasibility assessment of sewering 250-300 homes on the west sides of LHP and GHP.
Unfortunately, the cost of sewering that many homes is very expensive, both for the Town of Plymouth and for the individual homeowners. In addition, such a project requires planning and engineering time so that it would likely take a decade or more to enact.
The threat of yearly cyanobacteria blooms shutting down our pond for a decade or so is not acceptable, and the consultant has added several options that singly will not achieve our phosphorus level goal but collectively might suffice to stop cyanobacteria blooms. The final Management Plan will outline a process for implementing the best possible options, given our watershed’s unique characteristics.
The Water Quality Plan was extremely useful in identifying these unique characteristics. They include:
- 87% of LHP phosphorus is from septic systems while 41% of GHP phosphorus load is from septic systems
- 47% of the phosphorus in GHP comes from LHP via the Carters River
- All homes in the watershed have septic systems, which leach phosphorus into the groundwater as the septic systems are meant to treat bacteria and not phosphorus
- Ground water flows from northwest to southeast, meaning that homes on the west banks of GHP and LHP have a greater influence on phosphorus pollution
- Measurement of LHP and GHP outlet stream flow rates and of cyanobacteria (it is always present at some level in ponds) will help evaluate our progress and direct us toward a new or additional remedy
- The bowl shape of both LHP and GHP basins may increase the importance of runoff as a source of pollution
When the Water Quality Report is “finalized” (January 2023, most likely), it will be presented (via Zoom) to our membership with an opportunity for questions and dialogue with the consultant. Plymouth and the consultant will then work closely with HPWA to start, monitor, and adjust the chosen programs to ensure the best result while we move toward sewering of the recommended watershed homes.
Don Williams, President
Water Quality Plan Review Committee
Herring Ponds Watershed Association