Flash Flood — Eddy, New Mexico

2004-04-03 to 2004-04-04 · near Whites City, Eddy, New Mexico

Event narrative

During the evening of April 3rd, a National Weather Service spotter reported Dark Canyon Road, five miles east of State Highway 137, was under seven feet of water. Additional flooding over southwestern portions of Carlsbad was reported by local law enforcement and the public. Just after midnight, early Sunday morning, U.S. Highway 285 became impassable due to flooding ten miles northwest of Carlsbad. Flooding along County Roads 658 and 672 southwest of Carlsbad resulted in several evacuations and helicopter rescues during the early morning hours on Sunday along Dark Canyon Draw. As late as Sunday afternoon, flooding of low-lying areas around Carlsbad continued along the Pecos River, as well as along Dark Canyon, Dagger, Rocky Arroyo, and Hackberry Draws.An Eddy County flood survey revealed that three different factors contributed to the record flooding in and near Carlsbad. Flood waters from Rocky Arroyo Draw fed into the Pecos River north of Avalon Reservoir. This flow along with heavy rainfall from thunderstorms resulted in a required release of water from the Avalon Reservoir. Radar estimated rainfall totals of three to four inches near and west of Avalon Reservoir between 900 PM MST on April 3rd through 100 AM MST on Sunday, April 4th. Releases from the reservoir began near 800 PM MST on April 3rd, with a measured peak rate of 14,800 cfs (cubic-feet per second) at around 400 AM MDT Sunday morning. This release of water eliminated the potential danger of a dam failure, but resulted in the washout of Callaway Drive just downstream from the release point on Avalon Reservoir. The second factor contributing to the record flooding was extremely high flow through the Dark Canyon Draw into downtown Carlsbad. Radar estimated rainfall totals of one to three inches over and southwest of Dark Canyon Draw during the evening and overnight hours of Saturday April 3rd. This rainfall led to catastrophic flash flooding along the Dark Canyon Draw from southwest portions of Carlsbad into the downtown area. A wall of water moved down Dark Canyon Draw at approximately 130 AM MST Sunday morning. The third factor that contributed to the flooding was the failure at several points of the Carlsbad Irrigation District (CID) canals. These CID channels, used primarily to irrigate area alfalfa fields, began failing due to runoff crossing perpendicular to the CID channels. This runoff was due to 8-12 inches of rainfall in the previous three days. Erosion of the channels began occurring due to the high volume of water flowing over them. As the channels finally failed, water flowed into adjacent neighborhoods. The community hardest hit by this runoff was the La Huerta neighborhood in northeastern Carlsbad. As a result of this flooding, 6 to 12 inches of water was left standing throughout most of the La Huerta area with higher amounts at isolated points.

Source: NOAA Storm Events Database, event_id 5392950. Narrative written by the NWS forecast office that issued the report.