Nelson Dike C Reservoir Report

Last Updated: December 6, 2025

Nelson Dike C is a significant offstream storage reservoir located in Saco, Montana, owned and operated by the Bureau of Reclamation.


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Summary

Built in 1915, this earth dam stands at 28 feet high and serves primarily for irrigation purposes, with a storage capacity of 85,175 acre-feet. The dam spans a length of 434 feet and covers a surface area of 4,560 acres, receiving diversions from the surrounding area for water storage.

With a high hazard potential due to its location and design, Nelson Dike C has undergone modifications in 2018 to reinforce its foundation. Despite its age, the dam remains in good condition, with regular inspections carried out by the Bureau of Reclamation. As part of the larger water management infrastructure in the region, Nelson Dike C plays a crucial role in ensuring reliable water supply for agricultural irrigation in Phillips County, Montana.

As a key component of the Bureau of Reclamation's operations, Nelson Dike C highlights the importance of maintaining and monitoring water resources in the face of climate challenges. With its strategic location and significant storage capacity, this reservoir exemplifies the agency's commitment to sustainable water management practices in the region, ensuring water security for both agricultural and environmental needs.

Years Modified

2018 - Foundation

Year Completed

1915

Dam Length

434

Dam Height

5

River Or Stream

OFFSTREAM STORAGE RESERVOIR RECEIVING DIVERSIONS F

Primary Dam Type

Earth

Surface Area

4560

Hydraulic Height

23

Drainage Area

35

Nid Storage

85175

Structural Height

28

Hazard Potential

High

Foundations

Rock

Nid Height

28
       
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.