Mclean (Toole) Reservoir Report
Nearby: Rocky Mountain High Potter (Toole)
Last Updated: December 21, 2025
Mclean (Toole) is a privately owned dam located in Toole, Montana, near the city of Shelby.
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Summary
Built in 1950 by the USDA NRCS, this earth dam stands at 27 feet in height and spans 276 feet in length. Its primary purpose is for fire protection, stock, or as a small fish pond, with a storage capacity of 123 acre-feet and a drainage area of 4.69 square miles along the Sand Coulee river.
Managed by the DNRC, Mclean (Toole) is regulated and permitted by the state of Montana for inspection, enforcement, and permitting. The dam has a low hazard potential and is currently rated as "Not Rated" for its condition assessment. With a moderate risk assessment rating of 3, the dam does not have an Emergency Action Plan (EAP) in place at this time, but is considered to meet guidelines for risk management. The dam's spillway is uncontrolled with a width of 100 feet, and it has a maximum discharge capacity of 250 cubic feet per second.
Overall, Mclean (Toole) presents an interesting case study for water resource and climate enthusiasts, showcasing the intricate regulatory framework and risk management considerations involved in the operation and maintenance of a privately owned dam in Montana. The dam's historical significance, combined with its unique purpose and design features, offers a valuable insight into the intersection of water resource management, infrastructure development, and environmental conservation efforts in the region. Its location within the Omaha District and Congressional District 00 of Montana, represented by Greg Gianforte, further emphasizes the importance of collaboration between federal, state, and local agencies in ensuring the safety and sustainability of our water resources.
Year Completed |
1950 |
Dam Length |
276 |
Dam Height |
27 |
River Or Stream |
SAND COULEE |
Primary Dam Type |
Earth |
Hydraulic Height |
27 |
Drainage Area |
4.69 |
Nid Storage |
123 |
Hazard Potential |
Low |
Nid Height |
27 |
Seasonal Comparison
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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.
Mclean (Toole)