Jessup Mill Pond Dam Reservoir Report

Last Updated: December 5, 2025

Jessup Mill Pond Dam, located in Creston, Montana, is a Federal-owned structure with a primary purpose of water supply.


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Summary

Built in 1941 by URS Corporation, this Earth-type dam stands at a height of 27 feet and spans a length of 290 feet, creating a reservoir with a normal storage capacity of 205 acre-feet on Mill Creek. The dam has been modified in 2004 for foundation, hydraulic, seismic, and structural improvements.

Despite being deemed in satisfactory condition as of the last assessment in October 2019, Jessup Mill Pond Dam carries a high hazard potential and is classified as having a very high risk level. The dam is equipped with a controlled spillway and slide gate outlet gates, with a maximum discharge capacity of 2078 cubic feet per second. While the dam has not been regulated or inspected by the state, the Fish and Wildlife Service, the primary federal agency involved, is responsible for the dam's operation, design, construction, regulation, and inspection.

Given its critical role in water supply and the potential risk associated with its operation, Jessup Mill Pond Dam serves as a focal point for water resource and climate enthusiasts interested in understanding the complexities of managing and maintaining dams in a high-hazard environment. The dam's location in Flathead County, Montana, and its association with the Seattle District of the US Army Corps of Engineers further underline the importance of monitoring and ensuring the safety and stability of this vital infrastructure.

Years Modified

2004 - Foundation, 2004 - Hydraulic, 2004 - Seismic, 2004 - Structural

Year Completed

1941

Dam Length

290

Dam Height

27

River Or Stream

Mill Creek

Primary Dam Type

Earth

Surface Area

23

Hydraulic Height

26

Drainage Area

1.25

Nid Storage

390

Structural Height

28

Outlet Gates

Slide (sluice gate)

Hazard Potential

High

Foundations

Soil

Nid Height

28
       
Seasonal Comparison

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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.