Upper Delta Basin Enlargement Reservoir Report

Last Updated: December 13, 2025

The Upper Delta Basin Enlargement, also known as No.


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Summary

1 Tailings, is a privately owned earth dam located in Green River, Wyoming. Completed in 2013, this structure serves the primary purpose of storing tailings material, with a maximum storage capacity of 9992 acre-feet and a structural height of 40 feet. The dam has a fair condition assessment and a high hazard potential, requiring regular inspections to ensure safety.

Managed by the State of Wyoming and regulated by the SEO, the Upper Delta Basin Enlargement plays a crucial role in the management of water resources in the area. Situated along the Green River, it covers a surface area of 652 acres and has a drainage area of 0 acres. Despite its fair condition, the dam is equipped with outlet gates for controlled release of water and a spillway type that is not specified in the data.

Owned by a private entity and designed by Phillip Solseng, the Upper Delta Basin Enlargement is a significant infrastructure project in the region. With a history of inspections and maintenance, this dam continues to contribute to water management efforts in Sweetwater County, Wyoming. As climate change impacts water resources, structures like the Upper Delta Basin Enlargement become essential for ensuring water security and mitigating potential risks.

Year Completed

2013

Dam Length

8900

Dam Height

40

River Or Stream

GREEN RIVER

Primary Dam Type

Earth

Surface Area

652

Hydraulic Height

35

Nid Storage

9992

Structural Height

40

Outlet Gates

None

Hazard Potential

High

Foundations

Soil

Nid Height

40
       
Seasonal Comparison

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Dam Data Reference

Condition Assessment

Satisfactory
No 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

High
Dams 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.