Marys Lamb Reservoir Report
Nearby: Phillippi #1 Soda Creek
Last Updated: December 5, 2025
Marys Lamb is a privately owned earth dam located in Capitol, Montana, along TR-Box Elder Creek.
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Summary
Built in 1945 by the USDA NRCS, this dam serves multiple purposes including fire protection, stock watering, and small fish pond management. With a height of 14 feet and a length of 900 feet, Marys Lamb has a storage capacity of 136 acre-feet and a drainage area of 0.38 square miles.
Managed by the Montana Department of Natural Resources and Conservation (DNRC), Marys Lamb is classified as a low hazard potential structure with a condition assessment of "Not Rated." Despite lacking specific information on inspections and emergency action plans, the dam is regulated, permitted, inspected, and enforced by the state government. The dam's location in Carter County, Montana, under Congressional District 00, is overseen by Representative Greg Gianforte (R).
Although Marys Lamb has not been rated for its condition, it remains an essential water resource structure for the local community's fire protection and agricultural needs. With its historical significance dating back to World War II, the dam continues to play a vital role in managing water resources and supporting the surrounding ecosystem along TR-Box Elder Creek in Montana.
Year Completed |
1945 |
Dam Length |
900 |
Dam Height |
14 |
River Or Stream |
TR-BOX ELDER CREEK |
Primary Dam Type |
Earth |
Hydraulic Height |
14 |
Drainage Area |
0.38 |
Nid Storage |
136 |
Hazard Potential |
Low |
Nid Height |
14 |
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.
Marys Lamb