Deweese Gp-12 Reservoir Report
Nearby: Deweese #11 Deweese #10
Last Updated: December 21, 2025
Located in Harper County, Oklahoma, Deweese Gp-12 is an earth dam constructed in 1959 by the USDA NRCS.
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Summary
This private structure on Sand Creek serves as a water resource management facility with a storage capacity of 31 acre-feet and a maximum storage of 50 acre-feet. With a dam height of 31 feet and a length of 162 feet, Deweese Gp-12 plays a crucial role in regulating water flow and providing flood control in the area.
This dam, managed by a private owner, has a low hazard potential and is currently rated as "Not Rated" in terms of condition assessment. With a moderate risk assessment score of 3, Deweese Gp-12 is considered to have a moderate risk level. The spillway of this structure is uncontrolled with a width of 21 feet, ensuring proper water release during high flow events. Despite being non-USACE regulated, Deweese Gp-12 contributes significantly to water resource management in the region.
As a vital part of the water infrastructure in Harper County, Deweese Gp-12 provides essential water storage and flood control capabilities. With its strategic location on Sand Creek and its moderate risk level, this earth dam continues to support the community of Fort Supply and surrounding areas in managing water resources and mitigating potential risks associated with flooding.
Year Completed |
1959 |
Dam Length |
162 |
Dam Height |
31 |
River Or Stream |
SAND CREEK |
Primary Dam Type |
Earth |
Surface Area |
3 |
Hydraulic Height |
31 |
Drainage Area |
0.13 |
Nid Storage |
50 |
Hazard Potential |
Low |
Nid Height |
31 |
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.
Deweese Gp-12