Nelson Dike A Reservoir Report
Nearby: Nelson Dike B Nelson Dike C
Last Updated: December 6, 2025
Nelson Dike A, located in Saco, Montana, is a federal-owned offstream storage reservoir primarily used for irrigation purposes.
°F
°F
mph
Wind
%
Humidity
Summary
Built in 1922 by the Bureau of Reclamation, this earth dam stands at 11 feet high and stretches over 2031 feet in length, with a storage capacity of 85,175 acre-feet. The reservoir covers a surface area of 4560 acres and serves a drainage area of 35 square miles.
With a high hazard potential, Nelson Dike A has a notable risk assessment rating of 2, indicating the need for vigilant monitoring and management. Despite its age, the condition assessment of the dam is listed as "Not Available," emphasizing the importance of regular inspections and maintenance. The last inspection date was in August 2020, with an inspection frequency of once per year. While an Emergency Action Plan (EAP) has been prepared, it was last revised in July 2014.
The dam is under the jurisdiction of the Bureau of Reclamation, which also handles funding, design, construction, regulation, inspection, and operation of Nelson Dike A. With no state permitting or enforcement requirements, the federal agency is responsible for ensuring the safety and functionality of this crucial water resource infrastructure in Montana. For water resource and climate enthusiasts, Nelson Dike A represents a significant piece of the region's irrigation infrastructure with its historical importance and ongoing role in agricultural water supply.
Year Completed |
1922 |
Dam Length |
2031 |
Dam Height |
11 |
River Or Stream |
OFFSTREAM STORAGE RESERVOIR RECEIVING DIVERSIONS F |
Primary Dam Type |
Earth |
Surface Area |
4560 |
Hydraulic Height |
6 |
Drainage Area |
35 |
Nid Storage |
85175 |
Structural Height |
11 |
Hazard Potential |
High |
Foundations |
Rock |
Nid Height |
11 |
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.
Nelson Dike A