Duncan Reservoir Report
Nearby: Menardi & White Moncreiffe
Last Updated: December 5, 2025
Duncan is a privately owned Earth dam located in Sheridan, Wyoming, along the Jennings Gulch river.
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Summary
Built in 1939 by designer Paul F. Anderson, this dam stands at a height of 33 feet and has a reservoir storage capacity of 59 acre-feet. Despite its low hazard potential, recent inspections have rated its condition as poor, highlighting the need for maintenance and potential repairs to ensure its long-term safety and functionality.
Situated in a picturesque setting with a surface area of 5 acres, Duncan serves as a vital water resource for the surrounding area. The dam's primary purpose, categorized as 'Other', underscores its importance in managing water flow and storage. Although currently in a state of disrepair, Duncan's historical significance and contribution to the local ecosystem make it a valuable asset that warrants attention and preservation efforts.
With Liz Cheney representing Congressional District 00, Wyoming, where Duncan is located, there is a clear opportunity for advocacy and support for the dam's restoration and upkeep. As water resource and climate enthusiasts, it is crucial to recognize the role of structures like Duncan in sustainable water management and to advocate for the necessary resources and interventions to safeguard these critical assets for future generations.
Year Completed |
1939 |
Dam Length |
270 |
Dam Height |
33 |
River Or Stream |
JENNINGS GULCH |
Primary Dam Type |
Earth |
Surface Area |
5 |
Hydraulic Height |
28 |
Nid Storage |
59 |
Structural Height |
33 |
Outlet Gates |
Slide (sluice gate) - 1 |
Hazard Potential |
Low |
Foundations |
Soil |
Nid Height |
33 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Piney Creek At Kearny
|
113cfs |
Rock Creek Near Buffalo
|
70cfs |
South Piney Creek At Willow Park
|
0cfs |
Goose Creek Near Acme
|
123cfs |
Tongue River At Monarch
|
383cfs |
Prairie Dog Creek Near Acme
|
19cfs |
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.
Duncan