Jackson (Madison) Reservoir Report

Last Updated: December 5, 2025

Jackson (Madison) is a privately owned earth dam located in Norris, Montana, within Madison County.


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Summary

Built in 1959 for irrigation purposes, the dam spans 315 feet in length and stands at a height of 34 feet, with a hydraulic height of 15 feet. The reservoir created by the dam has a storage capacity of 87 acre-feet, with a normal storage level of 56 acre-feet and covers an area of 6.4 acres.

Despite its age, Jackson (Madison) dam is in poor condition and has a high hazard potential, according to a recent assessment. The dam is regulated by the Montana Department of Natural Resources and Conservation, with state permitting, inspection, and enforcement in place. The last inspection was conducted in August 2015, with a scheduled inspection frequency of 5 years. The spillway of the dam is uncontrolled, with a width of 25 feet.

Given its moderate risk rating, there is a need for improved risk management measures to address the dam's poor condition and high hazard potential. Climate enthusiasts monitoring water resources in the area should be aware of the potential risks associated with Jackson (Madison) dam and the importance of regular inspections and maintenance to ensure public safety and the integrity of the structure.

Year Completed

1959

Dam Length

315

Dam Height

34

River Or Stream

BRADLEY CREEK

Primary Dam Type

Earth

Surface Area

6.4

Hydraulic Height

15

Nid Storage

87

Hazard Potential

High

Nid Height

34
       
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.