Peterson No. 1 Reservoir Report
Last Updated: December 7, 2025
Peterson No.
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Summary
1 is a privately owned irrigation dam located in Weston, Wyoming, along the Black Thunder Creek. Built in 1976 by designer J.H. Coffman, this earth dam stands at 20 feet high and spans 615 feet in length, with a storage capacity of 246 acre-feet. Despite its low hazard potential, the dam is currently in poor condition, as assessed during the last inspection in July 2017.
The dam features an uncontrolled spillway with a width of 400 feet and is equipped with a single slide (sluice gate) outlet. While it is regulated by the State of Wyoming and subject to regular inspections, the dam's risk assessment indicates a moderate level of risk. It is crucial for water resource and climate enthusiasts to monitor the maintenance and management of Peterson No. 1 to ensure its continued safety and functionality for irrigation purposes, acknowledging its importance in the local water infrastructure.
Located in Edgemont, SD, within the Omaha District and Congressional District 00 of Wyoming, Peterson No. 1 plays a vital role in the water supply system of the area. With its historical significance dating back to the 1970s, this dam serves as a key asset for agricultural activities in the region, highlighting the intersection of water resource management, infrastructure maintenance, and climate resilience in the face of evolving environmental challenges.
Year Completed |
1976 |
Dam Length |
615 |
Dam Height |
20 |
River Or Stream |
BLACK THUNDER CREEK |
Primary Dam Type |
Earth |
Surface Area |
39 |
Hydraulic Height |
15 |
Nid Storage |
246 |
Structural Height |
20 |
Outlet Gates |
Slide (sluice gate) - 1 |
Hazard Potential |
Low |
Foundations |
Soil |
Nid Height |
20 |
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.
Peterson No. 1