Agate Dam Reservoir Report
Last Updated: December 6, 2025
Agate Dam, located in Sioux County, Nebraska, is a federal-owned structure designed by the USDA NRCS for fire protection, stock, and small fish pond purposes.
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Summary
Completed in 1936, this earth dam stands at a height of 20 feet and spans 696 feet in length, with a storage capacity of 206 acre-feet. The dam's primary source agency is the state of Nebraska, and it is regulated by the Nebraska Department of Natural Resources.
Despite its low hazard potential, Agate Dam has been assessed as being in poor condition as of August 2019. The dam's inspection frequency is every 5 years, with the last inspection conducted in August 2019. The dam lacks an emergency action plan and updated emergency contacts, raising concerns about its readiness in the event of a disaster. While the risk assessment and management measures for the dam are currently unknown, its location on TR-Long Branch Creek and its purpose for fire protection highlight its importance in water resource management and climate resilience efforts in the region.
Water resource and climate enthusiasts interested in Agate Dam will find it to be a crucial asset for fire protection and water storage in Sioux County, Nebraska. With a storage capacity of 206 acre-feet and a maximum discharge of 5800 cubic feet per second, the dam plays a significant role in managing water resources in the area. However, its poor condition assessment and lack of updated emergency preparedness raise concerns about its long-term sustainability and resilience to climate-related challenges. As efforts to address these issues continue, Agate Dam remains a focal point for enhancing water resource management and climate adaptation strategies in the region.
Year Completed |
1936 |
Dam Length |
696 |
Dam Height |
20 |
River Or Stream |
TR-LONG BRANCH CREEK |
Primary Dam Type |
Earth |
Surface Area |
13.7 |
Hydraulic Height |
20 |
Drainage Area |
1.2 |
Nid Storage |
206 |
Structural Height |
20 |
Hazard Potential |
Low |
Foundations |
Soil |
Nid Height |
20 |
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.
Agate Dam