Sandstone No. 1 Reservoir Report

Last Updated: December 13, 2025

Sandstone No.


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Summary

1 is a privately owned earth dam located in Johnson, Wyoming, along the Sandstone Draw. Completed in 2005, the dam stands at a height of 39 feet and serves multiple purposes including fire protection, stock water supply, and a small fish pond. With a storage capacity of 74 acre-feet and a surface area of 3.85 acres, the dam plays a crucial role in water resource management in the area.

The dam's low hazard potential and fair condition assessment make it a reliable structure for the local community. Equipped with a valve outlet gate and an uncontrolled spillway, Sandstone No. 1 has undergone regular inspections, with the last assessment conducted in September 2017. The dam is regulated, permitted, inspected, and enforced by the Wyoming regulatory agencies, ensuring its safety and compliance with state standards.

Despite its moderate risk assessment, Sandstone No. 1 continues to provide essential water resources for fire protection, livestock, and recreational fishing. Its strategic location and design make it a valuable asset for water supply and management in the region, showcasing the importance of effective dam infrastructure for climate resilience and water security.

Year Completed

2005

Dam Length

392

Dam Height

39

River Or Stream

SANDSTONE DRAW

Primary Dam Type

Earth

Surface Area

3.85

Hydraulic Height

34

Drainage Area

0.22

Nid Storage

74

Structural Height

39

Outlet Gates

Valve - 1

Hazard Potential

Low

Foundations

Rock, Soil

Nid Height

39
       
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.