Lake Winthrop Dam Reservoir Report
Nearby: Factory Pond Dam Houghton Pond Dam
Last Updated: February 3, 2026
Lake Winthrop Dam, located in Holliston, Massachusetts, was completed in 1966 and serves as a vital recreational resource for the community.
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Summary
This earth dam, with a height of 4.6 feet and a hydraulic height of 3 feet, creates a stunning lake with a surface area of 131 acres and a maximum storage capacity of 405 acre-feet. The dam is regulated by the Department of Conservation and Recreation, ensuring its safety and compliance with state guidelines.
Despite its significant hazard potential and poor condition assessment, Lake Winthrop Dam remains a popular spot for outdoor enthusiasts seeking leisure activities such as boating and fishing. The dam's uncontrolled spillway type and moderate risk assessment highlight the importance of regular inspections and maintenance to prevent potential emergencies. With Katherine M. Clark as the congresswoman representing the area, efforts to improve the dam's condition and ensure public safety are ongoing.
While Lake Winthrop Dam poses challenges due to its condition and hazard potential, it continues to be a treasured destination for residents and visitors alike. With its rich history dating back to the 1960s, the dam stands as a testament to the importance of water resource management and climate resilience in the face of changing environmental conditions. As efforts to enhance its safety and functionality progress, Lake Winthrop Dam remains a symbol of the community's commitment to preserving and enjoying its natural surroundings for generations to come.
Year Completed |
1966 |
Dam Length |
300 |
Dam Height |
4.6 |
River Or Stream |
UNNAMED BROOK |
Primary Dam Type |
Earth |
Surface Area |
131 |
Hydraulic Height |
3 |
Drainage Area |
1.7 |
Nid Storage |
405 |
Hazard Potential |
Significant |
Foundations |
Unlisted/Unknown |
Nid Height |
5 |
Seasonal Comparison
Hourly Weather Forecast
Nearby Streamflow Levels
Charles River At Medway
|
100cfs |
Lake Cochituate Outlet At Framingham
|
8cfs |
Sudbury River At Saxonville
|
233cfs |
Charles River At Dover
|
273cfs |
West River Below West Hill Dam
|
1cfs |
Neponset River At Norwood
|
15cfs |
Dam Data Reference
Condition Assessment
SatisfactoryNo existing or potential dam safety deficiencies are recognized. Acceptable performance is expected under all loading conditions (static, hydrologic, seismic) in accordance with the minimum applicable state or federal regulatory criteria or tolerable risk guidelines.
Fair
No existing dam safety deficiencies are recognized for normal operating conditions. Rare or extreme hydrologic and/or seismic events may result in a dam safety deficiency. Risk may be in the range to take further action. Note: Rare or extreme event is defined by the regulatory agency based on their minimum
Poor A dam safety deficiency is recognized for normal operating conditions which may realistically occur. Remedial action is necessary. POOR may also be used when uncertainties exist as to critical analysis parameters which identify a potential dam safety deficiency. Investigations and studies are necessary.
Unsatisfactory
A dam safety deficiency is recognized that requires immediate or emergency remedial action for problem resolution.
Not Rated
The dam has not been inspected, is not under state or federal jurisdiction, or has been inspected but, for whatever reason, has not been rated.
Not Available
Dams for which the condition assessment is restricted to approved government users.
Hazard Potential Classification
HighDams assigned the high hazard potential classification are those where failure or mis-operation will probably cause loss of human life.
Significant
Dams assigned the significant hazard potential classification are those dams where failure or mis-operation results in no probable loss of human life but can cause economic loss, environment damage, disruption of lifeline facilities, or impact other concerns. Significant hazard potential classification dams are often located in predominantly rural or agricultural areas but could be in areas with population and significant infrastructure.
Low
Dams assigned the low hazard potential classification are those where failure or mis-operation results in no probable loss of human life and low economic and/or environmental losses. Losses are principally limited to the owner's property.
Undetermined
Dams for which a downstream hazard potential has not been designated or is not provided.
Not Available
Dams for which the downstream hazard potential is restricted to approved government users.
Lake Winthrop Dam
Ashland State Park Boat Launch