Gambo Reservoir Report
Nearby: Mallison Falls Dundee
Last Updated: December 14, 2025
Gambo, also known as Newhall Dam, is a private hydroelectric structure located in Windham, Maine along the Presumpscot River.
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Summary
Built in 1911, this concrete gravity dam stands at 24 feet tall and spans 350 feet in length, with a storage capacity of 1261 acre-feet. Operated under the oversight of the Federal Energy Regulatory Commission (FERC), Gambo serves as a low hazard dam with a moderate risk assessment rating.
With a normal storage capacity of 1000 acre-feet and a maximum discharge rate of 10,135 cubic feet per second, Gambo plays a vital role in regulating water flow and generating hydroelectric power in the region. The dam features an uncontrolled spillway with a width of 259 feet and three slide gates for outlet control. Despite its age, the structure has not undergone recent condition assessments, and its emergency action plan status remains unclear.
As a key player in the New England District, Gambo stands as a testament to early 20th-century engineering and continues to contribute to the region's water resource management and energy production efforts. Enthusiasts of water resources and climate will find this historic dam a fascinating example of sustainable infrastructure that has stood the test of time.
Year Completed |
1911 |
Dam Length |
350 |
Dam Height |
24 |
River Or Stream |
Presumpscot River |
Primary Dam Type |
Concrete |
Surface Area |
151 |
Drainage Area |
493 |
Nid Storage |
1261 |
Outlet Gates |
Slide (sluice gate) - 3 |
Hazard Potential |
Low |
Nid Height |
24 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Presumpscot River At Westbrook
|
-999999cfs |
Saco River At Cornish
|
1020cfs |
Androscoggin River Near Auburn
|
2700cfs |
Mousam River Near West Kennebunk
|
44cfs |
Saco River Near Conway
|
315cfs |
Nezinscot River At Turner Center
|
43cfs |
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.
Gambo
Gambo Road Gorham