Watershed Planning

Assawompset Ponds Complex and Nemasket River

Grown out of an initial floodplain management grant, SRPEDD and its partners are continuing to plan and advance projects that will positively effect river flow, water levels, water quality, fish passage, and recreation in the APC and Nemasket River.

Upper Nemasket Public Workshop Follow Up

Thank you for attending the Upper Nemasket River Enhancement Workshop (6/28/22)!

For the past year, a team of engineers, scientists, and planners, with guidance from a local steering committee, have been modeling and studying a range of alternatives for the Assawompset Pond Dam, the Upper Nemasket River Channel, and the Wareham Street Dam.

On the evening of June 28, 2022, residents from Lakeville and Middleborough came together with the project team to discuss the results of these studies and how they factor in with our hopes for the future of the Upper Nemasket River.

The project team presented the pros, cons, and potential effects of options for enhancing river flow, mitigating flood, and improving habitat, including:

  • Do nothing alternative [existing conditions]
  • Pursue a sediment trap installed into the river
  • Remove the Wareham Street Dam
  • Widen undersized bridges that act as pinch points constraining the river; and
  • Consider alternative designs for the APC Dam

A HUGE THANK YOU to everyone who participated. Your attention and ideas were invaluable to moving forward! If you would like to re-review any of the materials from the meeting, or if you were unable to attend and wish to explore these options, see the document links at right. Some of the material is quite technical - please do not hesitate to reach out to hzincavage@srpedd.org with any questions. We will also post the final project report to this page when it is completed.

Links to Workshop Documents


Presenter leads a presentation in a community meeting room with participants seated at tables
Photo of River Alternatives Summary Table Matrix

There's a lot of great work going on in the APC and Nemasket River to improve the health of the watershed, the water supply, and the protections for residents from floodwaters. There is a specific study of the headwaters and initial strench of the Nemasket River, called the Upper Nemasket Enhancement project. There is a parallel larger-scale project also going on to create an APC-Nemasket Watershed Management Plan. The different geographic scales of the two projects is shown below. Ultimately, the Watershed Management Plan will include the recommendations that come out of the Upper Nemasket Study, but will also cover much larger territory and many other upstream issues.

Two maps clarifying the study area of the APC Managamanet Plan versus the Upper Nemaket River Study Area

The APC and Nemakset River are especially unique resources that deserve careful planning for their protection.

The APC and Nemasket River play numerous important roles for both the natural ecology and the people of southeastern Massachusetts. The APC is the state's largest natural pond system and is the drinking water source for approximately 250,000 people in the cities of New Bedford, Taunton, and portions of other nearby towns. It is a scenic residential and recreation area for pondside communities, spanning the towns of Lakeville, Middleborough, Rochester and Freetown. Water flows out of the Ponds through one principal outlet - the Nemasket River. The Nemasket is the longest herring run in the state of Massachusetts, with fish making an annual trip from Narragansett Bay, up the Taunton and Nemasket Rivers into their breeding grounds at the Ponds. It is a significant habitat area for fish, birds, wetland and mammal species - now including a resurgence of the loon population!

While the Nemasket and APC are precious in so many ways, the management challenge for this system becomes clear when we consider that water quality and flow are affected by land use throughout their combined 44,900-acre watershed area. In equal measure, the waters of the APC and Nemasket River can have some negative effects on surrounding communities during periods of flood and intense storms.

APC & Nemasket Watershed Management and Climate Action Plan

Project Timeline: October 2020 - June 2022

There is so much going on in the APC! Drinking water supplies, essential unique habitat areas, flood risk and recreation rewards... How can all of these interests in and around the APC be managed? How can they be managed today, but also into the future, when more intense rains, drier summers, and hotter temperatures result from climate change and take their toll on this system? With funding from the MVP program, the towns of Lakeville, Middleborough, Rochester, Freetown, Taunton, and New Bedford are working together through the APC Management Team with its team of consultants and the public to tackle this challenge by preparing a APC and Nemasket River Watershed Management and Climate Action Plan.

Follow the link below to the dedicated project page!

Upper Nemasket River Enhancement Plan

Project Timeline: September 2020 - July 2022

Funded through a grant from the Taunton River Stewardship Council, Emily Vogler, Landscape Architect and Professor at RISD, with assistance from SRPEDD, is conducting a public engagement effort aimed at holding a community discussion around possible interventions and trade-offs for improving fish passage, flow, flood management issues on the Nemasket River. Given these three underlying issues, there is an opportunity to bring people together to discuss possible ways to help strengthen the resilience of the local community to future floods, improve the ecological and hydrological connectivity along the river and improve recreational opportunities in the region.

Hydrological & Hydraulic Study

Project Timeline: June 2020 - July 2022

Funded by a SNEP Network Technical Assistance Grant, Horsley Witten Group is performing an H&H study of the Upper Nemasket River corridor, from the head of the Nemasket River at the Assawompset Ponds Complex (APC) in Lakeville downstream to the Wareham Street Dam in Middleborough. The project has three main components.

First, the project team will conduct field assessments and assess existing data, including the outcomes of recent survey work by Outback Engineering.

Second, the project team will refine an existing U.S. Army Corps of Engineers (USACE) Hydraulic Engineering Center (HEC) River Analysis System (RAS) model, which will be able to provide the critical tool to evaluate the hydraulic impacts of the proposed projects in the Nemasket under various hydrologic conditions.

Finally, based on the outcomes of the Nemasket River Community Outreach project described above, the project team will run the model on potential interventions in the Upper Nemasket River system. In this way, the H&H model will immediately be put to use in evaluating potential community-driven restoration projects. It will help to define parameters for combinations of potential grey infrastructure projects (dam repair, dam removal, silt trap construction) and nature-based solutions (floodplain expansion, habitat restoration, wetlands improvements).

Future Project Phases

Next Steps for Six Priority Projects

The APC Floodwater Management Program identified six priority projects that will not only help to address future flooding impacts around the Ponds and Nemasket, but also will improve other conditions such as fish passage, water quality, drought mitigation, and other co-benefits as well. Those six projects are listed below, along with a link to a summary one-pager document that was prepared by the project team to describe next steps.

Hydrological & Hydraulic Study - Funding secured, ongoing project.

APC & Nemasket Watershed Management Plan - Funding secured from the Massachusetts MVP Action Grant Program, project on-going.

Snake River Culvert Replacement - Studying issue and path forward.

Study and Plan to address Sedimentation Issue in the Upper Nemasket at the APC Dam Outlet - next steps to be informed by the H&H Study and other survey work. June 2022 UPDATE - please also explore this resource for current project intended timeline.

Upgrade / Replace Assawompset Pond Dam - next steps to be informed by the H&H Study and other survey work.

Prioritize Wetland Restoration Areas - next steps to be informed by WMOST Model and Watershed Management Plan.