La Mesilla Site 1 Dam
La Mesilla Site 1 Dam is an earth dam located in Rio Arriba County, New Mexico, built in 1970. It carries a High hazard potential classification and has a poor condition assessment.
About La Mesilla Site 1 Dam
The primary purpose of La Mesilla Site 1 Dam is flood risk reduction. The dam is designed to control downstream flooding by temporarily storing excess water during storms and releasing it at a controlled rate. The dam is owned by La Mesilla Community Ditch (local government). It impounds the Arroyo Pira near La Mesilla.
The dam stands 33 feet tall and stretches 910 feet across, creates a reservoir covering 11 acres, has a maximum storage capacity of 309 acre-feet, and collects water from a drainage area of 0 square miles. Completed in 1970, the structure is well into its service life at over 50 years old.
This dam carries a high hazard potential classification, which means that a failure or uncontrolled release of water would likely cause loss of human life. This classification reflects the consequences of failure, not the likelihood — it indicates that people live or work in the area downstream. Its condition is rated poor, meaning the dam has recognized safety deficiencies that require remediation to address risks. Notably, no emergency action plan is currently on file for this high-hazard dam. The most recent inspection on record was 05/04/2020.
At 33 feet, this dam is taller than 78% of dams nationwide.
Living Downstream
If you live or work downstream of this dam, consider taking these steps: learn your local evacuation routes, check whether your county emergency management office has a dam failure inundation map, and sign up for local emergency alerts. The New Mexico dam safety program can provide more specific information about emergency planning for this structure.
Search for dams near your address to see all dams in your area with hazard classifications and safety data.
Location
| State | New Mexico |
| County | Rio Arriba |
| Nearest City | La Mesilla |
| River/Stream | Arroyo Pira |
| Coordinates | 35.95707, -106.06126 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 33 ft |
| Dam Height | 33 ft |
| Dam Length | 910 ft |
| Year Completed | 1970 (56 years old) |
Storage & Hydraulics
| NID Storage | 309 acre-ft |
| Max Storage | 309 acre-ft |
| Surface Area | 11 acres |
| Drainage Area | 0 sq mi |
| Max Discharge | 170 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Flood Risk Reduction |
| Owner | LA MESILLA COMMUNITY DITCH |
| Owner Type | Local Government |
| Hazard Classification | High |
| Condition Assessment | Poor |
| Last Inspection | 05/04/2020 |
| Emergency Action Plan | No |
Identifiers
| NID ID | NM00235 |
| Federal ID | NM00235 |
| More Info | State Dam Safety Program |