Chapman Dam Reservoir Report
Nearby: L Hance Wetland Reserve Dam Theresa
Last Updated: January 11, 2026
Chapman Dam, located in Nelson Corners, St.
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Summary
Lawrence County, New York, is a privately owned concrete dam completed in 1971 for recreational purposes. Standing at 16 feet high and 60 feet long, the dam holds a storage capacity of 1800 acre-feet and covers a surface area of 320 acres, making it a popular destination for outdoor enthusiasts and nature lovers. The dam is situated on Grass Creek and is regulated by the New York State Department of Environmental Conservation, ensuring proper inspection, permitting, and enforcement measures are in place to maintain its safety and functionality.
Despite its low hazard potential and moderate risk assessment rating, Chapman Dam has not been conditionally assessed or rated. The last inspection on record dates back to June 1994, highlighting the need for a more recent evaluation to ensure the dam's structural integrity and safety standards. With a maximum discharge capacity of 560 cubic feet per second and an uncontrolled spillway width of 20 feet, Chapman Dam plays a crucial role in water resource management and flood control in the region. As a significant feature in the local landscape, efforts to update its emergency action plan, risk management measures, and hazard assessment are essential for the continued sustainability of this vital water infrastructure.
Year Completed |
1971 |
Dam Length |
60 |
Dam Height |
16 |
River Or Stream |
GRASS CREEK |
Primary Dam Type |
Concrete |
Surface Area |
320 |
Drainage Area |
6.26 |
Nid Storage |
1800 |
Hazard Potential |
Low |
Nid Height |
16 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
West Branch Oswegatchie R Nr Harrisville Ny
|
1220cfs |
Oswegatchie River Near Heuvelton Ny
|
1250cfs |
Black River At Watertown Ny
|
6200cfs |
Oswegatchie River Near Oswegatchie Ny
|
997cfs |
Beaver River At Croghan Ny
|
999cfs |
Raquette River At South Colton Ny
|
1010cfs |
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.
Chapman Dam
Lake of the Woods