Castor Reservoir Report
Nearby: Tomeyer #1 Olie
Last Updated: December 6, 2025
Located in Toole, Montana, the Castor dam was completed in 1914 and serves multiple purposes including fire protection, stock, and a small fish pond.
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Summary
With a height of 30 feet and a storage capacity of 92 acre-feet, this earth dam on the TR-Marias River is regulated by the Montana Department of Natural Resources and Conservation.
The dam has a low hazard potential and is currently rated as "Not Rated" in terms of condition assessment. Despite not having a recent inspection date, the dam is under state jurisdiction with permitting, inspection, and enforcement responsibilities falling under the DNRC. The primary purpose of the Castor dam is to provide essential services while ensuring the safety and sustainability of water resources in the area.
Representing a piece of Montana's water infrastructure history, the Castor dam stands as a testament to early 20th-century engineering efforts. With its strategic location in Loma and its vital role in providing water resources for fire protection and livestock, the dam continues to be a significant asset in the region's water management efforts.
Year Completed |
1914 |
Dam Length |
300 |
Dam Height |
30 |
River Or Stream |
TR-MARIAS RIVER |
Primary Dam Type |
Earth |
Hydraulic Height |
30 |
Nid Storage |
92 |
Hazard Potential |
Low |
Nid Height |
30 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Marias River Near Chester Mt
|
249cfs |
Marias River Near Shelby Mt
|
305cfs |
Teton River Near Dutton Mt
|
83cfs |
Cut Bank Creek At Cut Bank Mt
|
138cfs |
Lake Creek Near Power Mt
|
30cfs |
Marias River Near Loma Mt
|
335cfs |
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.
Castor