La Mesilla Site 1 Dam Reservoir Report

Last Updated: December 5, 2025

The La Mesilla Site 1 Dam, also known as the Rc&D Project Measure 243, is a crucial piece of infrastructure in Rio Arriba, New Mexico, designed by the USDA NRCS to address flood risk reduction along the Arroyo Pira.


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Summary

Completed in 1970, this earth dam stands at a height of 33 feet and spans 910 feet, with a storage capacity of 309 acre-feet. Despite its essential role in protecting the surrounding area from flooding, the dam is currently assessed as being in poor condition with a high hazard potential.

Located in the city of La Mesilla, the dam is regulated and inspected by the Office of the State Engineer, demonstrating the state's commitment to ensuring its safety and effectiveness. With a moderate risk assessment rating, there is a recognized need for risk management measures to be implemented and for the dam to undergo necessary maintenance and improvements. As water resource and climate enthusiasts, it is vital to monitor the condition of structures like the La Mesilla Site 1 Dam to protect communities and ecosystems from the impacts of extreme weather events and changing climate patterns.

Year Completed

1970

Dam Length

910

Dam Height

33

River Or Stream

ARROYO PIRA

Primary Dam Type

Earth

Surface Area

11

Drainage Area

0.31

Nid Storage

309

Outlet Gates

Uncontrolled

Hazard Potential

High

Foundations

Unlisted/Unknown

Nid Height

33
       
Seasonal Comparison

Weather Forecast

Dam Data Reference

Condition Assessment

Satisfactory
No 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

High
Dams 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.