Harlowton Sewage Lagoon Reservoir Report
Nearby: Jawbone Dam #2 Jawbone Dike #1
Last Updated: December 5, 2025
The Harlowton Sewage Lagoon, located in Shawmut, Montana, is a vital water resource management facility owned by the local government.
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Summary
This sewage lagoon plays a crucial role in treating wastewater and protecting the environment by ensuring compliance with state regulations and permitting requirements. Completed in 1958, this earth dam structure has a height of 10 feet and a storage capacity of 190 acre-feet, serving as a key component in the management of wastewater in the region.
Situated near the Musselshell River offstream, the Harlowton Sewage Lagoon covers a surface area of 19.7 acres and has a drainage area of 21.2 acres. Despite its low hazard potential, the facility has not been rated for condition assessment since its last inspection in 1979. While there have been no reported modifications or assessments in recent years, the lagoon continues to serve its primary purpose effectively. With a normal storage capacity of 129 acre-feet and a maximum discharge rate of 6 cubic feet per second, the facility plays a critical role in maintaining water quality and environmental sustainability in Wheatland County, Montana.
The Harlowton Sewage Lagoon stands as a testament to responsible water resource management in the region, with a focus on environmental protection and regulatory compliance. As a state-regulated facility under the jurisdiction of the Department of Natural Resources and Conservation (DNRC), the lagoon serves as a model for efficient wastewater treatment and disposal. Despite its age, the facility's low hazard potential and continued operation underscore its essential role in safeguarding public health and the environment through effective water management practices.
Year Completed |
1958 |
Dam Length |
4565 |
Dam Height |
10 |
River Or Stream |
MUSSELSHELL RIVER OFFSTREAM |
Primary Dam Type |
Earth |
Surface Area |
19.7 |
Hydraulic Height |
10 |
Drainage Area |
21.2 |
Nid Storage |
190 |
Hazard Potential |
Low |
Nid Height |
10 |
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.
Harlowton Sewage Lagoon