Soft Maple Spillway Reservoir Report

Last Updated: December 16, 2025

Located in Lewis, New York, the Soft Maple Spillway is a privately owned hydroelectric dam that was completed in 1926.


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Summary

With a dam height of 15 feet and a length of 173 feet, the spillway has a storage capacity of 2678 acre-feet and a maximum discharge of 31,000 cubic feet per second. The spillway is a concrete gravity dam with a multi-arch core type and sits on a rock foundation, serving the primary purpose of hydroelectric power generation.

The Soft Maple Spillway is situated on the Beaver River and is regulated by the Federal Energy Regulatory Commission. It has a low hazard potential and a moderate risk assessment rating. The spillway features an uncontrolled spillway type with a width of 144 feet and is associated with a total of 8 structures in the area. The last inspection of the spillway was conducted in June 2018, with a frequency of every 3 years.

For water resource and climate enthusiasts, the Soft Maple Spillway offers a fascinating glimpse into the history and technology of hydroelectric power generation in New York. Its unique design and location make it a valuable asset in the region's energy infrastructure, showcasing the importance of sustainable water resource management and the integration of renewable energy sources in combating climate change.

Year Completed

1926

Dam Length

173

Dam Height

15

River Or Stream

Beaver River

Primary Dam Type

Concrete

Surface Area

400

Drainage Area

240

Nid Storage

2678

Hazard Potential

Low

Foundations

Rock

Nid Height

15
       
Seasonal Comparison

Weather Forecast

Dam Data Reference

Condition Assessment

Satisfactory
No 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

High
Dams 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.