Ambnot Rated No.1 Reservoir Report
Last Updated: December 8, 2025
Ambnot Rated No.1 is a privately owned dam located in Mellette, South Dakota, along the tributary of the Little White River.
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Summary
Constructed in 1968, this earth dam stands at 26 feet high and stretches 485 feet in length, with a storage capacity of 24 acre-feet. Despite being rated as "Not Rated" in terms of condition assessment, it poses a low hazard potential.
Managed by the South Dakota Department of Environment and Natural Resources (DENR), Ambnot Rated No.1 is subject to state regulation, permitting, inspection, and enforcement. The dam's primary purpose and associated structures remain unspecified, reflecting its relatively low profile in terms of both risk assessment and emergency preparedness. Its location and design suggest a focus on local water resource management rather than major flood control or hydroelectric power generation.
With a maximum discharge capacity of 470 cubic feet per second, Ambnot Rated No.1 serves as a modest but essential piece of infrastructure within the St. Paul District of South Dakota. As a potentially overlooked component of the state's water resource system, this dam provides an intriguing case study for climate and water resource enthusiasts interested in the management and regulation of smaller-scale dams in rural settings.
Year Completed |
1968 |
Dam Length |
485 |
Dam Height |
26 |
River Or Stream |
TRIB. LITTLE WHITE RIVER |
Primary Dam Type |
Earth |
Hydraulic Height |
26 |
Nid Storage |
24 |
Hazard Potential |
Low |
Nid Height |
26 |
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.
Ambnot Rated No.1