Guelff Reservoir Report
Last Updated: December 6, 2025
Guelff is a privately owned earth dam located in Dawson County, Montana, serving multiple purposes such as fire protection, stock watering, and small fish pond management.
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Summary
Built in 1946 by the USDA NRCS, the dam stands at a height of 15 feet and has a storage capacity of 77 acre-feet. Situated on the TR-Yellowstone River, Guelff is regulated by the Montana Department of Natural Resources and Conservation (DNRC) and is subject to regular inspections and enforcement measures to ensure its safety and compliance with state regulations.
With a low hazard potential and a moderate risk assessment rating, Guelff provides essential water resources for the surrounding area while also posing manageable risks. The dam features an uncontrolled spillway with a width of 60 feet and a maximum discharge capacity of 600 cubic feet per second. Despite not having a formal condition assessment, Guelff remains operational and fulfills its intended functions effectively. The dam's location in the Omaha District and under Congressional District 00, represented by Greg Gianforte, highlights its importance within the local and federal regulatory framework.
As a key infrastructure for water management in Dawson County, Guelff serves as a vital resource for the community's agricultural and environmental needs. Its historical significance, functional design, and regulatory oversight make it a noteworthy site for water resource and climate enthusiasts interested in understanding the intersection of public and private ownership in managing water supplies. Guelff's role in providing water for fire protection, livestock, and recreational purposes underscores the importance of sustainable water management practices in the region.
Year Completed |
1946 |
Dam Length |
200 |
Dam Height |
15 |
River Or Stream |
TR-YELLOWSTONE RIVER |
Primary Dam Type |
Earth |
Hydraulic Height |
15 |
Drainage Area |
1.64 |
Nid Storage |
77 |
Hazard Potential |
Low |
Nid Height |
15 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Yellowstone River At Glendive Mt
|
6000cfs |
Beaver Creek Nr Trotters
|
0cfs |
Yellowstone River Near Sidney Mt
|
6130cfs |
Redwater River At Circle Mt
|
1cfs |
Little Missouri River At Medora
|
64cfs |
Powder River Near Locate Mt
|
231cfs |
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.
Area Campgrounds
| Location | Reservations | Toilets |
|---|---|---|
Glendive Campground
|
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Jaycee West City Park
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Makoshika State Park
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Pine-on-the-Rock Campground
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Intake Dam FAS
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Guelff