Lower Glasston Dam Reservoir Report
Last Updated: December 5, 2025
Lower Glasston Dam, also known as Walvoord Lake Dam, is a privately owned structure located in Sweet Grass, Montana, along the Sweetgrass Canal.
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Summary
Completed in 1912, this earth dam stands at a height of 30 feet, serving primarily for irrigation purposes. With a storage capacity of 7,317 acre-feet, the dam covers a surface area of 571 acres and plays a crucial role in water resource management in the region.
Despite its historical significance, Lower Glasston Dam is facing challenges in terms of its condition assessment, marked as poor with a high hazard potential. The last inspection in July 2021 revealed the need for improvements to ensure the dam's safety and functionality. The dam is regulated by the Montana Department of Natural Resources and Conservation (DNRC), with state permitting, inspection, and enforcement in place.
For water resource and climate enthusiasts, Lower Glasston Dam represents a key piece of infrastructure in the irrigation system of Montana. As discussions around dam safety and resilience continue, attention to the maintenance and potential upgrades of this structure will be essential to ensure its long-term viability and the protection of surrounding communities and ecosystems.
Year Completed |
1912 |
Dam Length |
1240 |
Dam Height |
30 |
River Or Stream |
SWEETGRASS CANAL |
Primary Dam Type |
Earth |
Surface Area |
571 |
Hydraulic Height |
28.5 |
Nid Storage |
7317 |
Structural Height |
30 |
Hazard Potential |
High |
Foundations |
Rock, Soil |
Nid Height |
30 |
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 Glasston Dam