Pear Lake Dam Reservoir Report

Last Updated: December 5, 2025

Pear Lake Dam, located in Twin Bridges, Montana, is a privately owned structure primarily used for irrigation purposes along Birch Creek.


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Summary

Built in 1904, this earth dam stands at 19 feet tall and spans 397 feet in length, with a storage capacity of 481 acre-feet. Its uncontrolled spillway has a width of 25 feet, allowing for a maximum discharge of 378 cubic feet per second.

This dam, under the jurisdiction of the Montana Department of Natural Resources and Conservation, has been deemed to have a high hazard potential due to its location and structural characteristics. While its condition is currently not rated, regular inspections are conducted to ensure its safety and functionality. Despite its age, Pear Lake Dam continues to serve its intended purpose efficiently, contributing to the agricultural water needs of the surrounding area.

With its rich history and vital role in water resource management, Pear Lake Dam stands as a testament to early irrigation efforts in Montana. As climate change poses new challenges to water availability and usage, the maintenance and regulation of such dams become increasingly important in ensuring sustainable water management practices for future generations.

Year Completed

1904

Dam Length

397

Dam Height

19

River Or Stream

BIRCH CREEK

Primary Dam Type

Earth

Surface Area

43

Hydraulic Height

15

Drainage Area

2

Nid Storage

481

Structural Height

19

Outlet Gates

Uncontrolled

Hazard Potential

High

Nid Height

19
       
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.