Eagle Dam Removal
Feasibility Assessment
Feasibility Assessment
Project Overview
CRWA is working with the Town of Wrentham to assess the feasibility of removing Eagle Dam, an outdated structure in poor condition that presents a hazard to downstream residents and infrastructure, and is detrimental to local wildlife. This project is funded by a Municipal Vulnerability Preparedness (MVP) grant awarded to the Town in 2019.
History
Eagle Brook connects Wrentham’s Lake Pearl to the Mill River, which flows into the Charles River. The small dam on the uppermost section of the brook dates back to the early 1800s when a corn mill was constructed on the site. A few decades later Red Dam was constructed a few hundred yards upstream to create Lake Pearl, which residents now use for recreation. Since the construction of Eagle Dam, there are believed to have been at least three dam breaches at the site: in 1876, which was reported to cause significant downstream damage, in 1968, and most recently in the early 2000s.
Current Conditions
Today, Eagle Dam is owned and maintained by the Town of Wrentham. The Town engages a firm to conduct regular safety inspections of the dam as required by the state. A recent dam safety inspection found the dam to be in “poor condition”: failure of the spillway, which was never professionally repaired after the most recent breach; severe erosion of the embankment; and overgrowth of vegetation, including large trees, which can impact the structural integrity of a dam. The report recommended the Town either breach (or remove) the dam to eliminate the risk of failure, which would provide an opportunity to restore natural stream conditions, or repair the dam--the status quo is not an option. Due to the dam’s condition, its close proximity to State Route 140, and the increased frequency of extreme rain events, the Town is working to address this hazard.
In 2019, the Town partnered with CRWA to take advantage of state funding through the Municipal Vulnerability Preparedness program to explore dam removal. There is no state funding available for dam repair; if the Town elects to repair the dam it will need to be funded by the Town or private interests. The small impoundment behind the dam does not have any public access for canoeing or other recreation at this time. Historical records indicate that Atlantic salmon once made their way up Eagle Brook. However, due to this dam and many others along the Charles, there are no longer Atlantic salmon, but the dam still presents a barrier to native fish that reside in the brook.
History
Eagle Brook connects Wrentham’s Lake Pearl to the Mill River, which flows into the Charles River. The small dam on the uppermost section of the brook dates back to the early 1800s when a corn mill was constructed on the site. A few decades later Red Dam was constructed a few hundred yards upstream to create Lake Pearl, which residents now use for recreation. Since the construction of Eagle Dam, there are believed to have been at least three dam breaches at the site: in 1876, which was reported to cause significant downstream damage, in 1968, and most recently in the early 2000s.
Current Conditions
Today, Eagle Dam is owned and maintained by the Town of Wrentham. The Town engages a firm to conduct regular safety inspections of the dam as required by the state. A recent dam safety inspection found the dam to be in “poor condition”: failure of the spillway, which was never professionally repaired after the most recent breach; severe erosion of the embankment; and overgrowth of vegetation, including large trees, which can impact the structural integrity of a dam. The report recommended the Town either breach (or remove) the dam to eliminate the risk of failure, which would provide an opportunity to restore natural stream conditions, or repair the dam--the status quo is not an option. Due to the dam’s condition, its close proximity to State Route 140, and the increased frequency of extreme rain events, the Town is working to address this hazard.
In 2019, the Town partnered with CRWA to take advantage of state funding through the Municipal Vulnerability Preparedness program to explore dam removal. There is no state funding available for dam repair; if the Town elects to repair the dam it will need to be funded by the Town or private interests. The small impoundment behind the dam does not have any public access for canoeing or other recreation at this time. Historical records indicate that Atlantic salmon once made their way up Eagle Brook. However, due to this dam and many others along the Charles, there are no longer Atlantic salmon, but the dam still presents a barrier to native fish that reside in the brook.
Feasibility Assessment
The goal of the initial feasibility assessment is to identify any major barriers to dam removal. The project team, made up of CRWA, Wrentham DPW and a technical consultant, engaged extensively with the Historical Commission to better understand the historical and cultural significance of the dam. It was through this and other research that the team learned the dam had already been breached three times. Sediment samples were collected upstream of the dam and while pollutants were observed, as they typically are in urban rivers, nothing was found at levels that would preclude a dam removal. The team also explored upstream and downstream water quality and bathymetry. Upstream water quality was observed to be very poor, which is not uncommon for water behind a dam as it becomes stagnant and inhospitably warm for many native creatures. The team conducted modeling of river flow with and without the dam to identify any potential flooding issues from either keeping or removing the dam. Modeling indicates this area is quite prone to flooding during a large rain event (both with or without the dam) but needs further refinement.
Due to the condition of the dam, the threat of a sudden dam failure that could cause severe flooding is a concern. The Town also sent a survey to dam abutters to get their feedback about the dam. To date, no major technical barriers to dam removal have been identified, but additional community conversations are necessary before any decisions can be made.
Due to the condition of the dam, the threat of a sudden dam failure that could cause severe flooding is a concern. The Town also sent a survey to dam abutters to get their feedback about the dam. To date, no major technical barriers to dam removal have been identified, but additional community conversations are necessary before any decisions can be made.
Next Steps
- Conduct more robust hydrologic and hydraulic modelling
- Engage with abutters, community members, and MassDOT (who manages state Route 140)
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