Mary No. 1 Reservoir Report
Nearby: White Pine Cone No. 2
Last Updated: December 5, 2025
Mary No.
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Summary
1 is a privately owned earth dam located in Carbon County, Wyoming, along the North Fork Watkins Creek. Built in 1948 by designer Jame T Fletcher, this dam serves primarily for irrigation purposes, with a storage capacity of 140 acre-feet and a maximum discharge of 0. The dam stands at a height of 38 feet with a hydraulic height of 35 feet, stretching 450 feet in length. Despite its low hazard potential, the dam is currently assessed to be in poor condition, highlighting the need for maintenance and improvements.
With its uncontrolled spillway and one outlet valve, Mary No. 1 has a surface area of 10 acres and serves as a vital resource for fire protection, stock, and small fish pond irrigation in the region. The dam's condition assessment conducted in July 2021 revealed a moderate risk level (3), prompting the necessity for risk management measures to ensure the safety and functionality of the structure. Despite being state-regulated and permitted, the dam's poor condition underscores the importance of regular inspections and maintenance to mitigate potential risks and ensure its long-term reliability.
As water resource and climate enthusiasts, it is essential to monitor and support the upkeep of crucial infrastructure like Mary No. 1 to sustainably manage water resources and adapt to changing environmental conditions. By recognizing the significance of dams like Mary No. 1 in facilitating irrigation and other essential purposes, we can work towards enhancing their resilience and effectiveness in the face of evolving challenges posed by climate change and water scarcity. With proper maintenance and risk management measures, Mary No. 1 can continue to play a vital role in supporting agricultural activities and ecosystem health in the region.
Year Completed |
1948 |
Dam Length |
450 |
Dam Height |
38 |
River Or Stream |
NORTH FORK WATKINS CREEK |
Primary Dam Type |
Earth |
Surface Area |
10 |
Hydraulic Height |
35 |
Drainage Area |
0.9 |
Nid Storage |
140 |
Structural Height |
38 |
Outlet Gates |
Valve - 1 |
Hazard Potential |
Low |
Foundations |
Soil |
Nid Height |
38 |
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.
Mary No. 1