7-Up Sea Reservoir Report

Last Updated: December 5, 2025

Located in Fallon County, Montana, the 7-Up Sea reservoir is a private-owned irrigation dam completed in 1949 by the USDA NRCS.


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Summary

The dam is situated along the TR-Lame Jones Creek and serves as a vital water resource for agricultural purposes in the area. With a height of 25 feet and a length of 350 feet, the dam has a storage capacity of 90 acre-feet, providing a reliable water source for irrigation needs.

Managed by the Montana Department of Natural Resources and Conservation (DNRC), 7-Up Sea is regulated, inspected, and enforced to ensure its structural integrity and operational efficiency. The dam has a low hazard potential and is not currently rated for its condition assessment. With a maximum discharge capacity of 600 cubic feet per second and a spillway width of 60 feet, the dam is designed to manage water flow effectively and mitigate potential risks associated with heavy precipitation events.

Despite not being rated for condition assessment, 7-Up Sea plays a crucial role in supporting agricultural activities in the region. With its state-regulated status and ongoing inspection and enforcement measures, the dam exemplifies responsible water resource management practices in the face of changing climate conditions. Enthusiasts interested in water resources and climate resilience will find 7-Up Sea to be a fascinating case study in sustainable irrigation infrastructure development and maintenance.

Year Completed

1949

Dam Length

350

Dam Height

25

River Or Stream

TR-LAME JONES CREEK

Primary Dam Type

Earth

Hydraulic Height

25

Drainage Area

0.36

Nid Storage

90

Hazard Potential

Low

Nid Height

25
       
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.