Jeffrey #1 Reservoir Report

Last Updated: December 6, 2025

Jeffrey #1 is a private irrigation dam located in Garfield, Montana, along the Big Wild Horse Creek.


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Summary

Built in 1958 by the USDA NRCS, this earth dam stands at 18 feet in height and spans 175 feet in length. With a storage capacity of 167 acre-feet and a drainage area of 12.97 square miles, Jeffrey #1 plays a crucial role in providing water for agricultural purposes in the region.

Managed by the Montana Department of Natural Resources and Conservation (DNRC), Jeffrey #1 has been designated with a low hazard potential and is currently not rated for its condition assessment. Although the last inspection date is not specified, the dam is subject to state regulations, inspections, and enforcement to ensure its safety and functionality. The presence of emergency action plans and inundation maps are not documented, suggesting a potential area for improvement in terms of risk management and preparedness.

Overall, Jeffrey #1 serves as a vital water resource infrastructure in the area, contributing to agricultural irrigation needs and water management along the Big Wild Horse Creek. As climate change continues to impact water availability and quality, maintaining and monitoring dams like Jeffrey #1 is essential for sustainable water resource management in the region.

Year Completed

1958

Dam Length

175

Dam Height

18

River Or Stream

BIG WILD HORSE CREEK

Primary Dam Type

Earth

Hydraulic Height

18

Drainage Area

12.97

Nid Storage

167

Hazard Potential

Low

Nid Height

18
       
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.