Jolly Bob Downs Reservoir Report
Nearby: Bob Downs Sherrill Rufus No 2
Last Updated: January 3, 2026
Jolly Bob Downs is a private earth dam located in Vinson, Oklahoma, along TR-Grape Creek.
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Summary
Built in 1978 by the USDA NRCS, this dam stands at a height of 29 feet and has a maximum storage capacity of 50 acre-feet. With a controlled spillway and a low hazard potential, Jolly Bob Downs serves multiple purposes, including flood control and water conservation.
Managed by the OWRB and regulated by the state of Oklahoma, Jolly Bob Downs undergoes regular inspections, with the last one conducted in August 2006. Despite its age, the dam is in good condition and poses a low risk to the surrounding area. It has one valve outlet gate and a very high risk assessment rating of 1, indicating its critical importance in managing water resources and mitigating potential flood risks in the region.
Overall, Jolly Bob Downs is a crucial structure in the water resource management infrastructure of Harmon County, Oklahoma. With its strategic location and impressive capacity, this earth dam plays a vital role in safeguarding the local community and the environment from the impacts of extreme weather events and ensuring a sustainable water supply for the region.
Year Completed |
1978 |
Dam Length |
552 |
Dam Height |
29 |
River Or Stream |
TR-GRAPE CREEK |
Primary Dam Type |
Earth |
Surface Area |
1 |
Hydraulic Height |
25 |
Nid Storage |
50 |
Structural Height |
29 |
Outlet Gates |
Valve - 1 |
Hazard Potential |
Low |
Foundations |
Soil |
Nid Height |
29 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
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.
Jolly Bob Downs