Due to rapidly rising reservoir levels that could exceed record storage that occurred in 1958, the International Boundary and Water Commission, United States and Mexico, will increase the release of
floodwaters from Falcon Dam at noon on July 14.
Releases into the Rio Grande will increase to 60,000 cubic feet per second (1700 cubic meters
per second) up from the current release of 39,700 cubic feet per second (1125 cubic meters per second). Residents in the Rio Grande Basin, especially those downstream from the dam in Starr County, should continue to monitor National Weather Service warnings and forecasts for updated information and river forecasts concerning flood conditions; they should also heed any guidance from local emergency management officials.
The water elevation at Falcon Reservoir rose 3 feet in 24 hours to 304 feet on July 13 and continues to climb rapidly. The highest level ever recorded at the reservoir was 308 feet on October 19, 1958.
Even with the increased releases out of the dam, a new record could be set. The rapid rise in the reservoir is due to floodwaters entering from the Rio Grande and Salado River, a Mexican tributary, that were heavily affected by precipitation from Hurricane Alex and a subsequent tropical depression.
This water will flow downstream into the Lower Rio Grande Valley where the Commission has a system of flood control levees, diversion dams, and floodways in the Lower Rio Grande Flood Control Project that extends from Peñitas to the Gulf of Mexico. Residents will see a significant increase in flows in the U.S. interior floodway in the next 1-2 days due to diversion of water at Anzalduas Dam. The U.S. Section of the Commission expects floodwaters to rise approximately 3-5 feet along the interior floodway levees, which average 12-14 feet in height.
Diversion of waters into Mexico’s interior floodway at Retamal Dam, located near Donna, TX-Rio Bravo, Tamaulipas, will also continue.
Because of these upstream diversions, the Commission will continue to control floodwaters in the Rio Grande downstream from Retamal Dam to approximately the same levels seen for the past few days.
The U.S. interior floodway includes channels known as the Banker Floodway, Main Floodway, North Floodway, and Arroyo Colorado through portions of Hidalgo, Cameron, and Willacy Counties.
Staff from the U.S. Section of the International Boundary and Water Commission’s Lower Rio Grande Flood Control Project remain in Flood Fight Operations. During this phase of response, crews patrol flood control levees 24 hours per day to identify and respond to any problems that could arise such as erosion along the levees, freeboard encroachment, or seepage on the land side of the levees.
At the Commission’s uppermost reservoir, Amistad Dam, located at Del Rio, Texas-Ciudad Acuña, Coahuila, flood releases continue at the rate of 26,000 cubic feet per second (750 cubic meters per second). The Commission has been releasing floodwaters from Amistad Dam since July 5.
The Commission manages its flood control infrastructure taking into account prudent operation of the reservoirs, existing flood conditions in parts of the Rio Grande and its tributaries in the United States and Mexico, impact to property, and forecasts for additional rainfall in the basin. In accordance with dam operations criteria, the Commission is making controlled releases in order to avoid massive releases that would otherwise be required in the future and to avoid reservoir levels that could affect safe operation of the dams.
Information about Rio Grande flow as well as storage and release data from U.S. and Mexican reser
voirs in the Rio Grande basin is available on the USIBWC web page at: http://www.ibwc.gov/Water_Data/Reports/RG_Flow_data.html.