Nilan East Dam Reservoir Report
Last Updated: December 23, 2025
Nilan East Dam, located in Augusta, Montana, stands as a crucial structure for irrigation purposes along TR-Elk Creek.
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Summary
Built in 1951, this earth dam reaches a height of 51 feet and spans 1010 feet in length, with a storage capacity of 15,600 acre-feet. The dam's spillway, measuring 72 feet wide, operates as uncontrolled. Despite its high hazard potential, the dam has been assessed as satisfactory in condition, with the last inspection conducted in October 2021.
Situated within Lewis and Clark County, Nilan East Dam plays a vital role in water resource management, holding a normal storage capacity of 10,092 acre-feet and serving as a lifeline for agricultural activities in the region. Administered by the State of Montana and regulated by the Department of Natural Resources and Conservation (DNRC), the dam undergoes regular inspections, enforcement, and permitting processes to ensure public safety and compliance with state regulations. With a moderate risk rating of 3, the dam is monitored closely for any potential issues or emergencies.
Congressional District 00 in Montana, represented by Greg Gianforte (R), oversees Nilan East Dam's operations and maintenance. The dam's location at S20 20N 7W, with a drainage area of 3.55 square miles, underscores its strategic significance in water storage and distribution. As a focal point for water resource and climate enthusiasts, Nilan East Dam serves as a testimony to sustainable water management practices and the critical role of infrastructure in supporting agricultural livelihoods and environmental sustainability in the region.
Year Completed |
1951 |
Dam Length |
1010 |
Dam Height |
51 |
River Or Stream |
TR-ELK CREEK |
Primary Dam Type |
Earth |
Surface Area |
525 |
Hydraulic Height |
51 |
Drainage Area |
3.55 |
Nid Storage |
15600 |
Hazard Potential |
High |
Foundations |
Rock, Soil |
Nid Height |
51 |
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.
Area Campgrounds
| Location | Reservations | Toilets |
|---|---|---|
Nilan Reservoir FAS
|
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Willow Creek FAS
|
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Double Falls Campground
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Nilan East Dam