Charles River Dam

Natick Dam pic by drone

The dam spanning the Charles River in South Natick was constructed in 1934, and is owned and maintained by the Town of Natick. The dam is regulated by a permit issued by the Department of Conservation and Recreation’s Office Dam Safety (DCR-ODS) and is considered a High Hazard dam due to the potential for loss of life and significant property damage in the event of dam failure.

Dam History and Current Use

A dam/impoundment structure has been present in this area of the Charles River since the 1700s. Historic documents indicate a timber dam that once served local mills was destroyed by a flood in the early 1930s and replaced in 1934 with the current configuration: an earthfill embankment, stone masonry, and concrete structure. Today, the impoundment formed by the dam creates a pond area that is used for aesthetic and recreational purposes. The dam serves no functional purpose and does not provide flood control.

Residents who are interested in learning more about the dam’s history, are encouraged to review the research published by Charlotte Diamant, a student at Wellesley College available here.

Project Goal

The Code of Massachusetts Regulations (302 CMR 10.13) states that a dam owner is responsible for damage to the property of others and any injuries resulting from the operation or failure of a dam. For this purpose, the Town of Natick utilizes the services of a professional consultant to perform biennial safety and condition inspections of the South Natick Dam.  Due to the extensive mature tree growth on the earthen dam, the condition of the dam has consistently been rated as "Fair", and removal of the trees has been recommended in order to minimize the risk of dam failure.

Based on these inspections and per the guidance of DCR-ODS, rehabilitating or removing the dam was identified as a priority in the Town of Natick’s 2010 Hazard Mitigation Plan, 2018 Hazard Mitigation Plan Update and 2017 Community Resilience Building Report. In response, Town Meeting allocated funds to rehabilitate the structure. 

Project Efforts to-Date

Rehabilitation Analysis

In 2019, the Town of Natick engaged a dam engineering consultant to provide engineering and design services to rehabilitate the South Natick Dam. The rehabilitation project was expected to include retaining the dam’s current configuration and spillway elevation. Rehabilitating the dam would involve the removal of all trees and woody vegetation, re-grading earthen embankment slopes, installing riprap slope protection, repairing the concrete spillway and retaining walls and replacing the currently inoperable low-level outlet gate structure. During public meetings, residents raised concerns regarding the removal of 60 trees located on the dam’s right embankment and attendees asked the Town to consider alternative solutions that would preserve the area’s aesthetics and recreational function, but reduce public safety risk. The Town agreed to consider restoring the river as an alternative, which would require breaching or removing the concrete spillway.

River Restoration Analysis

As a first step in evaluating the feasibility of a dam decommissioning/river restoration option, the Town engaged a consultant to obtain and analyze sediment samples upstream and downstream of the dam. Laboratory results found the sediments’ quality would not be an impediment to the spillway’s removal should that option be chosen.

Following the favorable sediment results, in early 2020, the Town received a grant from the Massachusetts Executive Office of Energy and Environmental Affairs to further evaluate the feasibility of breaching the dam and restoring the associated river channel. The Town has contracted with a consultant to complete this work and findings from this analysis should be available in July 2020. At that point in time, the Town anticipates conducting an extensive public outreach program to inform next steps.