County Line Detention Dam Reservoir Report
Last Updated: December 7, 2025
Located in Sierra County, New Mexico, the County Line Detention Dam serves as a critical flood risk reduction infrastructure along the Rio Grande.
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Summary
Completed in 1956 by the USDA NRCS, this earth dam stands at a height of 32 feet and a length of 650 feet, with a capacity to store 182 acre-feet of water. Despite its importance in mitigating flood hazards, the dam is currently assessed to be in poor condition, with a high hazard potential, highlighting the urgent need for maintenance and rehabilitation.
Managed by local government authorities and regulated by the Office of the State Engineer, the County Line Detention Dam plays a crucial role in protecting the unincorporated residents in the area from potential flooding events. With a spillway width of 200 feet and a maximum discharge capacity of 11,408 cubic feet per second, the dam's effectiveness in managing floodwaters is evident. However, the dam's poor condition underscores the necessity for proactive risk management and maintenance strategies to ensure its continued functionality and safety for the surrounding communities.
As climate change continues to exacerbate extreme weather events, the County Line Detention Dam stands as a vital infrastructure for flood risk reduction in the region. With a moderate risk assessment and a history of poor maintenance, stakeholders must prioritize the rehabilitation and upkeep of this essential structure to safeguard lives and property in Sierra County. Collaborative efforts between government agencies and local communities will be crucial in addressing the dam's current condition and ensuring its resilience in the face of future climate challenges.
Year Completed |
1956 |
Dam Length |
650 |
Dam Height |
32 |
River Or Stream |
RIO GRANDE - TR |
Primary Dam Type |
Earth |
Hydraulic Height |
26 |
Drainage Area |
1.3 |
Nid Storage |
182 |
Structural Height |
37 |
Outlet Gates |
Needle - 0 |
Hazard Potential |
High |
Foundations |
Soil |
Nid Height |
37 |
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.
County Line Detention Dam
Caballo Reservoir