Nelson Dike D Reservoir Report

Last Updated: December 6, 2025

Nelson Dike D is a vital offstream storage reservoir in Phillips County, Montana, designed by the Bureau of Reclamation in 1922 for irrigation purposes.


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Summary

With a dam height of 14 feet and a storage capacity of 85,175 acre-feet, this Earth-type dam plays a crucial role in managing water resources in the region. Situated in the city of Saco, this reservoir receives diversions from the river or stream, serving as a key infrastructure for agriculture in the area.

Managed by the Bureau of Reclamation, Nelson Dike D has a high hazard potential and is subject to regular inspections to ensure its structural integrity and safety. While its spillway type is listed as "None," the reservoir's maximum storage capacity of 85,175 acre-feet provides crucial water resources for irrigation purposes, with a normal storage capacity of 79,224 acre-feet. The reservoir covers a surface area of 4,560 acres and has a drainage area of 35 square miles, highlighting its importance in water management and agriculture in the region.

Given its significant role in irrigation and water resource management, Nelson Dike D stands as a testament to the Bureau of Reclamation's commitment to sustainable water infrastructure development. As a key component in the region's water supply system, this offstream storage reservoir in Montana continues to play an essential role in supporting agriculture and ensuring water security for the community of Saco and beyond.

Year Completed

1922

Dam Length

380

Dam Height

14

River Or Stream

OFFSTREAM STORAGE RESERVOIR RECEIVING DIVERSIONS F

Primary Dam Type

Earth

Surface Area

4560

Hydraulic Height

13

Drainage Area

35

Nid Storage

85175

Structural Height

5

Hazard Potential

High

Foundations

Rock

Nid Height

14
       
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.