Big Dumb Bunny Reservoir Report

Last Updated: December 5, 2025

Big Dumb Bunny is a privately owned earth dam located in Cascade, Montana, along Spring Creek.


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Summary

Completed in 1972, this dam serves multiple purposes including fire protection, stock, and a small fish pond, with a primary height of 16 feet and a storage capacity of 235 acre-feet. The dam has a low hazard potential and is currently rated as "Not Rated" for condition assessment.

Owned and regulated by the Montana Department of Natural Resources and Conservation (DNRC), Big Dumb Bunny is subject to state jurisdiction, permitting, inspection, and enforcement. The dam is situated in Congressional District 00 of Montana, represented by Greg Gianforte (R), and falls under the oversight of the Omaha District of the US Army Corps of Engineers. Despite lacking detailed information on maintenance and emergency preparedness measures, the dam's location and purpose make it a notable feature for water resource and climate enthusiasts interested in Montana's water infrastructure.

With its unique name and multiple functions, Big Dumb Bunny stands out as a charming yet essential piece of water infrastructure in the heart of Montana. Its significance lies not only in providing valuable services like fire protection and stock maintenance but also in contributing to the local ecosystem through the creation of a small fish pond. As water resource and climate enthusiasts explore the diverse landscape of Montana, this dam on Spring Creek offers a captivating glimpse into the intersection of human engineering and environmental conservation in the Big Sky Country.

Year Completed

1972

Dam Length

700

Dam Height

16

River Or Stream

SPRING CREEK

Primary Dam Type

Earth

Hydraulic Height

16

Nid Storage

235

Hazard Potential

Low

Nid Height

16
       
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.