Big Creek Lake Reservoir Report

Last Updated: December 5, 2025

Big Creek Lake, located in Stevensville, Montana, is a private reservoir with a primary purpose of irrigation.


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Summary

The dam, built in 1892 by the USDA NRCS, is a concrete gravity structure standing at 12 feet high and 65 feet long. The lake has a storage capacity of 2,904 acre-feet, covering a surface area of 242 acres and serving a drainage area of 50 square miles.

Despite its age, Big Creek Lake is state regulated, with the DNRC overseeing permitting, inspection, and enforcement. The spillway, with a width of 145 feet, is uncontrolled, and the hazard potential is deemed significant. While the condition assessment is not rated, the emergency action plan was last revised in August 2021, indicating a proactive approach to risk management. With moderate risk identified, the reservoir remains a crucial water resource in the region.

Water resource and climate enthusiasts will be drawn to Big Creek Lake for its historical significance and operational importance in the irrigation sector. Its location in the beautiful Ravalli County, surrounded by the Big Creek stream, adds to its appeal for those interested in sustainable water management practices. As a key feature in the local landscape, the reservoir serves as a testament to the ingenuity of early dam engineers and continues to play a vital role in supporting agricultural activities in the area.

Year Completed

1892

Dam Length

65

Dam Height

12

River Or Stream

BIG CREEK

Primary Dam Type

Concrete

Surface Area

242

Hydraulic Height

12

Drainage Area

50

Nid Storage

2904

Structural Height

12

Hazard Potential

Significant

Nid Height

12
       
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.