Thompson Lake Dam
The water level of Thompson Lake is controlled by the Robinson Mill Dam, a 150+ year old structure
that lies at the outlet of the lake at its northern terminus, in the town of Oxford.
The water level of Thompson Lake is controlled by the Robinson Mill Dam, a 150+ year old structure
that lies at the outlet of the lake at its northern terminus, in the town of Oxford.
Dam Reports provided by the Town of Oxford
Thompson Lake Dam (Robinson Mill Dam)
The water level of Thompson Lake is controlled by the historic Robinson Mill Dam, located at the lake’s northern outlet in Oxford, Maine. Built more than 150 years ago, the dam plays a critical role in protecting water quality, shoreline stability, fish habitat, and recreational use of the lake.
A Brief History of the Dam
Constructed in 1863, the dam was originally built to power the Robinson Mill, a wool textile mill. Its construction raised Thompson Lake’s water level by approximately 10 feet and altered the natural downstream flow. At the time, water level management focused on industrial needs rather than environmental or recreational concerns.
Managing Lake Levels Over Time
By the late 20th century, residents became increasingly concerned about fluctuating water levels and their impacts on shoreline erosion and lake ecology.
In 1993, an engineering consultant worked with the Maine Department of Environmental Protection and local stakeholders to establish a Rule Curve, guidelines for managing seasonal water levels that balanced mill operations with lake protection and property owner concerns.
Transition to Town Ownership
After the Robinson Mill closed and became tax-delinquent, ownership of the dam transferred to the Town of Oxford. With industrial use no longer a factor, the town revisited water level goals.
In 2012, the town asked TLEA to study and recommend lake levels that would:
These recommendations were approved at an Oxford town meeting and remain in effect today.
Seasonal Water Level Guidelines
Under the current guidelines:
These levels are designed to balance ecological health, infrastructure protection, and recreational use.
Dam Condition and Engineering Review
In 2018, concerns about dam condition and unpredictable water levels prompted Oxford to commission an engineering assessment by Maine-based firm MBP. The dam was rated “fair to poor”, with identified issues including:
The report also noted that more frequent extreme weather events could increase the risk of overtopping and potential structural failure.
Renovations and Improvements
Based on engineering recommendations, the Town of Oxford approved dam renovations that began in 2020 and were completed in early 2021. Improvements included:
These upgrades significantly improved the dam’s safety and reliability while reducing the risk of uncontrolled water release.
Additional improvements and long-term funding strategies continue to be evaluated.
Environmental and Community Importance
The condition and operation of the Dam directly affects:
TLEA continues to work with the Town of Oxford and neighboring communities to support responsible dam management and long-term planning.
News Report
WMTW Channel 8 News visited The Robinson Mill on Thompson Lake in Oxford during September of 2025 to report on the future plans for revitalizing the former industrial mill into affordable housing units. Click the link below to watch the report.
Former workers and history buffs say goodbye to Robinson Mill
