An imminent-failure warning at New Mexico’s McLeod Dam forced evacuations

At 2:01 p.m. MDT on Tuesday, September 29, dam operators and county officials reported the imminent failure of McLeod Dam in southern New Mexico, and the National Weather Service issued a flash flood emergency. Doña Ana County told residents between the communities of Garfield and Salem to evacuate, and orders that evening extended to Hatch, Placitas and Rincon as well.

By 11 p.m. the county had lifted most of them. The dam had not failed catastrophically, but the afternoon exposed how little margin a small earthen structure has when a tropical storm’s moisture reaches the desert.

The flash flood emergency, and the order it carried

A flash flood emergency is the weather service’s most urgent flood product, reserved for a threat to life. The alert covered rural areas between Garfield and Salem, including portions of Highways 187 and 390 and stretches along the Garfield Drain and Garfield Canal, according to Hoodline. The warning was set to run until 4:45 p.m. MDT, a window that shows how short the lead time was between the operators’ call and the point at which downstream residents would have needed to be gone. The county’s notice told people to gather medications, essential items and pets and head south, and warned that “Residents should not wait until conditions worsen to evacuate,” the Albuquerque Journal reported.

Shelters opened at the Radium Springs Community Center on Lindbeck Road, and the American Red Cross sent staff. Carina Gonzalez, the Red Cross community disaster program manager, described it to KRWG as “a safe and warm place for them to stay overnight.” State Representative Nathan Small told the station that “there is water coming over the top of some flood control facilities” and that there was flooding in the village of Hatch.

A small earthen dam and a 2023 inspection rating

AccuWeather described McLeod Dam, which locals also call the Garfield dam, as a 20-foot earthen structure that was overtopped by floodwaters. Earthen dams face two failure modes that matter in a storm: water spilling over the crest and water seeping through the embankment, a process called piping. Neither needs a large reservoir to endanger a valley, and a high hazard potential rating means that a failure would probably cost lives downstream, whatever the structure’s size.

KRWG reported that the National Inventory of Dams lists the structure as rated in “poor” condition after a 2023 inspection, with a high hazard potential classification and no emergency action plan on file. That reading has not been independently verified here, and none of the coverage identifies who owns the dam. New Mexico’s Office of the State Engineer says its Dam Safety Bureau oversees roughly 300 of the state’s more than 600 dams, and that dams with the potential to cause fatalities or property damage must prepare and exercise an emergency action plan.

Piping, pumps and the last evacuation still standing

The county’s account of the afternoon was less dramatic than the early alerts. Spokesperson Ariana Parra told the Albuquerque Journal that the dam had a “very small piping failure,” that the problem “had been mitigated,” and that “no water is exiting from the dam at this point.” Pumps were used to move water downstream and relieve pressure. AccuWeather’s earlier account had said the structure was breached, and the two versions were never reconciled in coverage read for this article.

By 11 p.m., according to KTSM, evacuations were lifted for Salem, Hatch, Garfield and Placitas because “the storms have passed and additional large amounts of rain are not forecasted,” in the county’s words. Rincon, a community of fewer than 300 people, stayed under an evacuation notice because of standing floodwater. County Commission Chairman Manny Sanchez said the Rio Grande near Rincon was “at its banks” and had “hit pretty hard.”

The damage was in the roads. Interstate 25 near Hatch flooded, with water rescues under way, and NM 313 showed debris and road damage at mileposts 11 and 12. Hatch Valley Public Schools canceled Wednesday classes because roads were impassable. Elsewhere in the region AccuWeather reported multiple vehicles trapped by street flooding in Deming, New Mexico, and in Henderson, Nevada. The rain came from a chain of tropical systems: AccuWeather pointed to moisture from former Hurricane Odalys, remnants of Hurricane Polo and an incoming storm from the West, and chief meteorologist Jon Porter called it “the most dangerous flash flooding risk in the last five years or more” in New Mexico. The National Hurricane Center’s advisory on Polo’s remnants that evening listed a wind advisory for southern New Mexico and far western Texas.

The Albuquerque Journal cited the weather service as measuring 1 to 3 inches of rain, well under the 4 to 8 inches AccuWeather had forecast, yet the alarm still went out on the strength of a dam operator’s report. Rain is forecast to continue across the Southwest through Friday.

This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.

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