Upper Rock Creek Reservoir Report

Last Updated: December 5, 2025

Upper Rock Creek, also known as Rock Creek/Atlantic City Mine, is a private-owned water resource located in Fremont County, Wyoming.


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Summary

This dam, constructed in 1961 by C E Spurlock, stands at a height of 101 feet and has a capacity of 3158 acre-feet. With a significant hazard potential and a fair condition assessment, the dam is closely regulated and inspected by the Wyoming State Engineer's Office to ensure its safety and functionality.

The primary purpose of Upper Rock Creek is classified as 'Other', with a controlled spillway type and a maximum discharge of 2200 cubic feet per second. The dam plays a crucial role in water management, flood control, and irrigation in the region, covering a drainage area of 3.5 square miles. Despite its very high risk assessment ranking, the dam's emergency action plan status and risk management measures are currently not available, posing potential challenges in emergency response and mitigation efforts.

For water resource and climate enthusiasts, Upper Rock Creek offers a fascinating case study of dam infrastructure in a rural setting. Its strategic location in Atlantic City, Wyoming, along the Rock Creek stream, showcases the intersection of human-made structures with natural water systems, highlighting the importance of sustainable management practices and risk assessment in safeguarding critical water resources in the face of climate change and increasing environmental pressures.

Year Completed

1961

Dam Length

720

Dam Height

101

River Or Stream

ROCK CREEK

Primary Dam Type

Earth

Surface Area

68

Hydraulic Height

91

Drainage Area

3.5

Nid Storage

3158

Structural Height

101

Outlet Gates

Valve - 2

Hazard Potential

Significant

Foundations

Rock, Soil

Nid Height

101
       
Seasonal Comparison

Weather Forecast

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.