The rain-swollen Rio Grande River threatened to push through an earthen dam and cause flooding in El Paso, prompting evacuation orders for residents, officials said.
Up to 6 million gallons of water could rush into El Paso if the 30-year-old dam across the border in Mexico breaks, Mayor John Cook said. "We're talking like a tidal wave hitting El Paso," he said.
About 2,000 people were asked to evacuate and city buses transported those who wanted to leave.
State and federal officials also were working with authorities in Ciudad Juarez, Mexico, to monitor the dam and prepare for a potential emergency.
Water was reportedly coming over the breast of the dam. Further details on the dam's condition were not immediately known.
The area has been deluged by heavy rain this week, soaking mountainside neighborhoods, flooding highways and causing flash floods and rock slides. Thick mud inundated numerous homes and covered some roadways around the city's west side.
The El Paso area has received more than 8 inches of rain this year, almost all of it this week.