Ponca Reservoir Report
Nearby: Lake Berry Dam Oscar Micheaux Dam
Last Updated: December 13, 2025
Ponca, also known as Indian Lake, is a Federal-owned irrigation reservoir located in Milks Camp, Gregory, South Dakota.
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Summary
Managed by the Bureau of Indian Affairs, this earth dam structure was completed in 1935 and serves multiple purposes including irrigation, fire protection, and stock or small fish pond. The dam has a structural height of 45 feet and a length of 580 feet, with a storage capacity of 1190 acre-feet.
Despite being a vital water resource for the area, Ponca poses a high hazard potential due to its condition assessment not being available. The last inspection date was in 2012, with an inspection frequency of 5 years. The reservoir is situated on Willow Creek and falls under the jurisdiction of the St. Paul District of the US Army Corps of Engineers. Ponca is crucial for irrigation in the region but requires proper risk management measures to ensure the safety of the surrounding community.
With Dusty Johnson (R) as the Congressional Representative for the area, Ponca faces a very high risk assessment rating of 1. Emergency action plans and inundation maps are not readily available, highlighting the need for improved preparedness and risk mitigation strategies. As water resource and climate enthusiasts, it is essential to monitor and advocate for the maintenance and safety of structures like Ponca to ensure sustainable water management practices and environmental protection in the region.
Year Completed |
1935 |
Dam Length |
580 |
River Or Stream |
WILLOW CREEK |
Primary Dam Type |
Earth |
Nid Storage |
1190 |
Structural Height |
45 |
Hazard Potential |
High |
Nid Height |
45 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Platte Creek Near Platte
|
3cfs |
Niobrara River At Mariaville
|
1650cfs |
Keya Paha R At Wewela Sd
|
54cfs |
Long Pine Creek Near Riverview
|
191cfs |
Keya Paha R Near Keyapaha Sd
|
33cfs |
Niobrara River Nr. Verdel
|
517cfs |
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.
Ponca