Lower Reservoir Report
Nearby: Swift (Prairie) Mcmullin Bros Upper
Last Updated: December 6, 2025
Lower is a privately owned dam located in Prairie, Montana, designed by USDA NRCS and regulated by the DNRC.
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Summary
Completed in 1962, this earth dam is 29 feet high and spans 300 feet across Timber Creek, providing fire protection, stock, and small fish pond purposes. With a storage capacity of 200 acre-feet and a drainage area of 5.14 square miles, Lower has a low hazard potential and a moderate risk assessment rating.
The dam features an uncontrolled spillway with a width of 150 feet and a maximum discharge of 840 cfs. Although its condition is currently not rated, Lower meets state permitting, inspection, and enforcement requirements. Located in a remote area with no associated structures, this dam serves as a vital resource for water management and environmental conservation in the region.
As a key component of the water infrastructure in the area, Lower plays a crucial role in providing essential services for the local community. With its strategic location, design, and purpose, this dam exemplifies the balance between human needs and environmental stewardship, highlighting the importance of sustainable water resource management in the face of changing climate conditions.
Year Completed |
1962 |
Dam Length |
300 |
Dam Height |
29 |
River Or Stream |
TIMBER CREEK |
Primary Dam Type |
Earth |
Hydraulic Height |
29 |
Drainage Area |
5.14 |
Nid Storage |
200 |
Hazard Potential |
Low |
Nid Height |
29 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Dam Data Reference
Condition Assessment
SatisfactoryNo 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
HighDams 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.
Lower