Cooper #20 Reservoir Report
Nearby: Oknoname 059030 Cooper #16
Last Updated: December 21, 2025
Cooper #20 is a privately owned earth dam located in Harper, Oklahoma, along the SAND CREEK river.
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Summary
Constructed in 1960 by the USDA NRCS, this dam stands at a height of 25 feet and has a length of 467 feet, with a storage capacity of 79 acre-feet. The dam's primary purpose and design details are not specified, but it is classified as a low hazard potential structure with a moderate risk assessment rating.
Despite being unregulated by the state and having no associated inspection or enforcement agencies, Cooper #20 remains a significant landmark in the region. With its uncontrolled spillway and minimal drainage area of 0.59 square miles, this dam serves as a vital component in managing water resources in the area. With a risk management rating of moderate and a condition assessment of "Not Rated," the dam's overall safety and structural integrity remain a subject of interest for water resource and climate enthusiasts.
Year Completed |
1960 |
Dam Length |
467 |
Dam Height |
25 |
River Or Stream |
SAND CREEK |
Hydraulic Height |
25 |
Drainage Area |
0.59 |
Nid Storage |
79 |
Hazard Potential |
Low |
Nid Height |
25 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Cimarron River Near Buffalo
|
75cfs |
North Canadian River At Woodward
|
59cfs |
Cimarron R Near Buttermilk
|
43cfs |
Bluff Creek Nr Buttermilk
|
43cfs |
Cimarron River Near Waynoka
|
133cfs |
North Canadian River Near Seiling
|
101cfs |
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.
Cooper #20