Flood Control Levee Systems
Under the terms of the 1944 Treaty relating to the Tijuana River, the IBWC in 1967 (IBWC Minute 225 of June 19, 1967) recommended to the two Governments and they approved a joint project for the control of floods on the Tijuana River in the United States and Mexico for protection of developments near the boundary in the City of San Diego, California and in the City of Tijuana, Baja California. A joint project was essential because coordinated flood control works were required in each country to protect developments in the other country. That project provided for 2.7 miles (4.3 kilometers) of a concrete-lined channel south of the boundary in Tijuana, veering westwardly to then continue for 6 miles (9.7 kilometers) to the Pacific Ocean. The part of the project in the United States was modified in 1977 to the present stilling basin configuration (IBWC Minute 258) to conform to a change in land use planning in San Diego.
The project consists of concrete-lined channel for the Tijuana River in Mexico extending from the boundary upstream 2.7 miles (4 km), and of a concrete and rock-lined channel in the United States extending from the boundary downstream 0.9 miles (2 km). The downstream portion of the channel in the United States is a flared section to reduce the velocity of flows before discharging into the natural channel below the project. The channel and bordering levees were constructed pursuant to jointly approved design criteria and plans to contain a flood of 135,000 cfs (3,823 cms). The levees in the United States tie into high ground on the north to protect the community of San Ysidro, and on the south to protect the South Bay International Wastewater Treatment Plant and the City of Tijuana. The U.S. levee on the north bank of the river is 2.0 miles in length, and the U.S. levee on the south bank of the river is 1.9 miles in length. Each Government constructed and maintains at its cost the part of the project in its territory under the supervision of the IBWC.
For the United States part of the project the State of California and the City of San Diego acquired and furnished the rights-of-way for the channel and the levees. The United States Section contracted with the United States Army Corps of Engineers, Los Angeles district, to prepare the plans and supervise the construction of the United States part.
In 1980, the Tijuana River flood control system safely carried through its structures the highest flood flows in the Tijuana River since at least 1916, averting within the limits of the project property damage and probably life in the United States and Mexico.
The United States Section was authorized to construct its portion of the international flood control project by the Act of Congress of October 10, 1966, as amended by the Act of Congress of September 28, 1976. The latter was necessary to allow the United States Section to purchase the land needed for the smaller project. The project was completed in early 1979.
Tijuana River Basin
The Tijuana River drains a 1,730 square mile (4,480 km) basin situated partly in the United States and partly in Mexico. Originating in Mexico, the river crosses the international boundary into the United States near San Ysidro, California, then flows westerly in a broad flood plain about 5.3 miles (9 km) to discharge into the Pacific Ocean at a point about 1.5 miles (2 km) north of the boundary.
The United States Section of the International Boundary & Water Commission (USIBWC) operates and maintains three flood control systems on the Rio Grande. These flood control systems are: the Upper Rio Grande Flood Control System, Presidio Valley Flood Control System, and the Lower Rio Grande Flood Control System.
The Upper Rio Grande Flood Control System consists of 223 miles of flood control levee alongside 197 miles of the Rio Grande from Caballo, New Mexico to Little Box Canyon, Texas; located about 10 miles downstream of Fort Quitman, Texas. The Rio Grande runs 106 miles from Caballo to the downstream end of American Dam in El Paso, Texas, where it becomes the international boundary about 16 miles south from the New Mexico – Texas state line. This 106-mile stretch of the Rio Grande is referred to the Canalization Project segment and is bounded by 130 miles of levees; 57 miles on its west side and 73 miles on its east. The Upper Rio Grande Flood Control System continues downstream for another 91 miles from El Paso to Little Box Canyon. This stretch of the Rio Grande is referred to as the Rectification Project segment and is confined by approximately 93 miles of river and spur levees on the U.S. floodplain. The Upper Rio Grande Flood Control System protects approximately 1 million U.S. residents in the following metropolitan statistical areas: Las Cruces, New Mexico and El Paso, Texas.
The Presidio Valley Flood Control System is located upstream of Big Bend National Park in Texas. This flood control system consists of 15 miles of levee on U.S. floodplain that parallels the Rio Grande. The Rio Conchos, the main Mexican tributary from the state of Chihuahua, enters the Rio Grande at Presidio, where it increases normal flow by 10 to 20 times. The design flood for the Rio Grande is 3600 cfs above the confluence with the Rio Conchos and 42,000 cfs below. The Presidio Valley Flood Control System provides flood protection to roughly 52 square miles of urban and agricultural land in Presidio; a Texas town of nearly 5000 residents.
The Lower Rio Grande Flood Control System contains 270 miles of U.S. flood control levee along the Rio Grande, interior floodways, and the Arroyo Colorado in Texas. Flood control works along the Rio Grande include 102 miles of levees and floodplain from Peñitas, Texas to beyond Brownsville, Texas. The interior floodway, which starts 13 levee-miles downstream from Peñitas at Anzalduas Dam, is about 70 miles long and is bounded by 143 miles of levees; 68 miles on the right side and 75 miles on the left side. The Arroyo Colorado, a 53-mile natural channel that breaks-off the interior floodway, is confined by high ground and 25 miles of levee; 10.5 miles on the left side and 14.6 miles on the right side. The Lower Rio Grande Flood Control System provides protection to the following metropolitan statistical areas: Brownsville-Harlingen, Texas and McAllen-Edinburg-Mission, Texas. Approximately one million U.S. residents live in the Lower Rio Grande Valley. Due to its proximity to the Gulf of Mexico and related tropical weather systems, the Lower Rio Grande Valley is prone to hurricanes and annual flood events.
Currently, the USIBWC is in the process of rehabilitating or improving deficient segments within the Upper Rio Grande, Presidio Valley, and Lower Rio Grande Flood Control Systems. This is being accomplished in a phased approach through the agency's annual construction appropriation. In 2009, the American Recovery and Reinvestment Act (ARRA) supplemented our resources to address a significant portion of high-priority levee segments in the three Rio Grande Flood Control Systems. The ARRA provided for construction of approximately 236.5 miles of infrastructure improvements via 16 contracts.
Master schedules, providing the status of the planned and on-going improvements, may be accessed at the following links:
- Projects funded by the ARRA Appropriation: ARRA Progress Schedule.
- Projects funded by the annual Appropriation: RGF Progress Schedule.
Lower Rio Grande
The interior floodway, which starts 13 levee-miles downstream from Peñitas at Anzalduas Dam, is about 70 miles long and is bounded by 143 miles of levees; 68 miles on the right side and 75 miles on the left side. The Arroyo Colorado, a 53-mile natural channel that breaks-off the interior floodway, is confined by high ground and 25 miles of levee; 10.5 miles on the left side and 14.6 miles on the right side. The Lower Rio Grande Flood Control System provides protection to the following metropolitan statistical areas: Brownsville-Harlingen, Texas and McAllen-Edinburg-Mission, Texas. Approximately one million U.S. residents live in the Lower Rio Grande Valley. Due to its proximity to the Gulf of Mexico and related tropical weather systems, the Lower Rio Grande Valley is prone to hurricanes and annual flood events.
Hydraulic Model of the Rio Grande and Floodways within the LRGFCP