John Thornhill Dam Reservoir Report
Last Updated: December 5, 2025
John Thornhill Dam, located in Tifton, Georgia, was completed in 1966 by the Natural Resources Conservation Service and serves as a crucial irrigation resource along Tr-Mill Creek.
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Summary
This earth dam stands at 16 feet in height and spans 850 feet in length, with a storage capacity of 103 acre-feet. Despite its low hazard potential, the dam boasts a moderate risk level due to its proximity to a residential area and agricultural land.
The dam's primary purpose is irrigation, supporting the local agricultural community in Turner County. Operated privately, John Thornhill Dam is not regulated or inspected by any state agency. With a spillway width of 40 feet and a maximum discharge of 300 cubic feet per second, the dam ensures controlled water flow and minimizes the risk of flooding downstream. Although the condition assessment is currently not available, the dam remains a vital water resource for the region, highlighting the importance of sustainable water management practices in the face of climate change.
Year Completed |
1966 |
Dam Length |
850 |
Dam Height |
16 |
River Or Stream |
Tr- Mill Creek |
Primary Dam Type |
Earth |
Drainage Area |
0.25 |
Nid Storage |
103 |
Hazard Potential |
Low |
Nid Height |
16 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Flint River At Ga 32
|
4340cfs |
Little R At Tifton Worth Co Line Rd
|
0cfs |
Muckalee Creek At Ga 195
|
419cfs |
Flint River At Albany
|
3510cfs |
Kinchafoonee Creek Near Dawson
|
531cfs |
Turkey Creek At Byromville
|
10cfs |
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.
John Thornhill Dam