Hnot Ratedley Reservoir Report
Nearby: C. Iverson Jay A. Lake No.5
Last Updated: December 13, 2025
Hnot Ratedley, located in Potter County, South Dakota, is a state-regulated earth dam constructed in 1933 by the Works Progress Administration (WPA).
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Summary
This dam, standing at 46 feet tall with a length of 675 feet, serves the primary purpose of water storage on Cheyenne Creek. With a storage capacity of 4,125 acre-feet and a drainage area of 74 square miles, Hnot Ratedley plays a crucial role in managing water resources in the region.
The dam, classified as having a significant hazard potential, features an uncontrolled spillway with a width of 170 feet and a maximum discharge capacity of 6,500 cubic feet per second. While its condition assessment is currently listed as "Not Rated," the dam undergoes inspections every three years to ensure its structural integrity and functionality. With Dusty Johnson (R) representing the area in Congress, Hnot Ratedley stands as a key infrastructure providing water resource management and flood control benefits to the local community.
As climate change continues to impact water resources, the importance of well-maintained dams like Hnot Ratedley in South Dakota cannot be understated. With its regulated state jurisdiction, the dam ensures proper permitting, inspection, and enforcement measures are in place to manage potential risks and safeguard the surrounding area from flooding events. As enthusiasts in water resource management and climate resilience, understanding the critical role of dams like Hnot Ratedley is essential in promoting sustainable water management practices for the future.
Year Completed |
1933 |
Dam Length |
675 |
Dam Height |
46 |
River Or Stream |
CHEYENNE CREEK |
Primary Dam Type |
Earth |
Hydraulic Height |
46 |
Drainage Area |
74 |
Nid Storage |
4125 |
Outlet Gates |
None |
Hazard Potential |
Significant |
Foundations |
Soil |
Nid Height |
46 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Moreau R Near Whitehorse Sd
|
35cfs |
Oak Cr Near Wakpala Sd
|
10cfs |
Grand R At Little Eagle Sd
|
47cfs |
Bad R Near Fort Pierre Sd
|
7cfs |
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.
Hnot Ratedley