Greybull Sewage Treatment Lagoon Reservoir Report

Last Updated: December 5, 2025

Greybull Sewage Treatment Lagoon, located in Greybull, Wyoming, is a crucial facility owned by the local government and regulated by the Wyoming State Environmental Quality Office.


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Summary

Designed by Thomas D. Crank and completed in 1960, this Earth-type dam stands at a height of 8 feet and has a storage capacity of 152 acre-feet. The lagoon serves as an offstream water resource for the area, with a surface area of 31 acres and a drainage area of 0.

Despite its satisfactory condition assessment, the Greybull Sewage Treatment Lagoon poses a significant hazard potential, with a high risk rating of 2. The facility is inspected every five years, with the last inspection taking place in May 2020. It features controlled outlet gates and no spillway, emphasizing the need for efficient management and maintenance to prevent any potential risks or emergencies. Overall, Greybull Sewage Treatment Lagoon plays a vital role in managing sewage and wastewater in the region, highlighting the importance of water resource infrastructure for environmental protection and public health.

Year Completed

1960

Dam Length

4800

Dam Height

8

River Or Stream

OFFSTREAM

Primary Dam Type

Earth

Surface Area

31

Hydraulic Height

5

Nid Storage

152

Structural Height

8

Outlet Gates

Other Controlled - 1

Hazard Potential

Significant

Foundations

Soil

Nid Height

8
       
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.