Delmoe Lake Dam Reservoir Report

Last Updated: December 5, 2025

Delmoe Lake Dam, located in Jefferson County, Montana, stands as a vital structure for irrigation purposes since its completion in 1914.


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Summary

This earth dam, towering at a height of 60 feet, harnesses the waters of Big Pipestone Creek to provide a storage capacity of 9,900 acre-feet, serving the surrounding agricultural lands. The dam's normal storage capacity of 6,585 acre-feet supports a surface area of 310 acres, ensuring water availability for the area's needs.

With a high hazard potential but a satisfactory condition assessment, Delmoe Lake Dam remains a key component of the local water resource infrastructure. The dam is state-regulated, with the Department of Natural Resources and Conservation overseeing its permitting, inspection, and enforcement. The last inspection in 2021 revealed its satisfactory condition, highlighting the importance of regular monitoring and maintenance to ensure its continued functionality. Despite its age, the dam's structure and storage capacity support the region's irrigation needs effectively.

Delmoe Lake Dam's historical significance, coupled with its critical role in water management, underscores the importance of maintaining and monitoring this key structure. As climate change impacts water resources, the dam's ability to store and regulate water flow becomes increasingly crucial. With its location in a high-hazard area, ongoing risk management measures and emergency preparedness are essential to safeguard the surrounding communities and agricultural lands. As a cornerstone of water resource management in the region, Delmoe Lake Dam symbolizes the intersection of human ingenuity and environmental stewardship in ensuring water security for generations to come.

Year Completed

1914

Dam Length

290

Dam Height

60

River Or Stream

BIG PIPESTONE CREEK

Primary Dam Type

Earth

Surface Area

310

Hydraulic Height

60

Drainage Area

22.9

Nid Storage

9900

Hazard Potential

High

Nid Height

60
       
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.