Grace Main Reservoir Report
Nearby: Grace Dike Soda
Last Updated: December 18, 2025
Grace Main is a privately owned dam located in Caribou, Idaho, serving the primary purpose of irrigation.
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Summary
Built in 1908, this Timber Crib type dam stands at a height of 51 feet and has a storage capacity of 1100 acre-feet. The dam, situated on the Bear River, plays a crucial role in providing water for agricultural needs in the region.
Managed by the Idaho Department of Water Resources, Grace Main is regulated and inspected by various state agencies to ensure its safety and compliance with regulations. With a significant hazard potential and moderate risk assessment, the dam's emergency action plan is periodically reviewed and updated to meet guidelines. The dam has an uncontrolled spillway and a maximum discharge capacity of 12500 cubic feet per second, making it an essential piece of infrastructure for water resource management in the area.
The Federal Energy Regulatory Commission oversees the regulatory aspects of Grace Main, highlighting its importance in both irrigation and hydroelectric purposes. With its location in a picturesque setting surrounded by nature, Grace Main stands as a testament to the vital role dams play in water resource management and climate resilience efforts.
Year Completed |
1908 |
Dam Length |
180.5 |
Dam Height |
51 |
River Or Stream |
Bear River |
Primary Dam Type |
Timber Crib |
Surface Area |
45 |
Hydraulic Height |
38 |
Drainage Area |
4070 |
Nid Storage |
1100 |
Structural Height |
52 |
Hazard Potential |
Significant |
Foundations |
Rock |
Nid Height |
52 |
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.
Grace Main
Black Canyon - Highway 34 to Grace Powerhouse