INTERNATIONAL BOUNDARY AND WATER COMMISSION, 

UNITED STATES AND MEXICO

Carlos Marin, United States Commissioner

Presentation to the Good Neighbor Environmental Board

July 24, 2007
MISSION OF THE COMMISSION

The International Boundary and Water 

Commission is responsible for applying the 

boundary and water treaties between the 

United States and Mexico and settling 

differences that arise in their application.
STRUCTURE PER 1944 TREATY 

INTERNATIONAL BOUNDARY 

AND WATER COMMISSION 

(IBWC)

MEXICAN 

SECTION

•Mexican Commissioner

•Secretary

•Two Principal 

Engineers

•Legal Adviser

US

SECTION

•US Commissioner

•Secretary

•Two Principal 

Engineers

•Legal Adviser
IBWC STRUCTURE

 Commission has the character of an 

international organization for joint projects

 Decisions of the Commission are recorded 

in the form of Minutes approved by the two 

governments.

 312 Minutes
IBWC FLOOD CONTROL 

PROJECTS

 Lower Rio Grande

 Presidio, TX

 Rectification Project – El Paso-Cd. Juarez

 Chamizal Project – El Paso-Cd. Juarez

 Canalization Project – Las Cruces-El Paso

 Colorado River – near Yuma-Mexicali

 Tijuana River – San Diego-Tijuana
FLOOD CONTROL TERMINOLOGY

 Levee – en elevated earthen berm parallel to the 

river channel that protects adjacent property 

from floodwaters

 Freeboard – a term that reflects the distance 

from the water surface elevation to the top of the 

levee

 Overtopping – where floodwaters rise above the 

top of the levee

 Interior Floodway – a separate channel off the 

main river channel where floodwaters can be 

diverted to reduce flood flows in the river
FLOOD CONTROL TERMINOLOGY

U.S. Levee Mx Levee

Low Flow Channel
LOWER RIO GRANDE FLOOD 

CONTROL PROJECT

 History

Hidalgo and Cameron Counties coordinated 

with Mexico in 1920s for Rio Grande levees 

and floodways 

IBWC developed and implemented a new 

plan in the 1930s

Additional improvements made in 1950s

Covers 180 river miles from Peñitas, TX to 

Gulf of Mexico
LOWER RIO GRANDE FLOOD 

CONTROL PROJECT

 Hurricane Beulah (1967)

Category 3 storm at Brownsville

35 inches of rain caused widespread flooding 

in Texas and Mexico

Flow of 220,000 cfs at Rio Grande City

Over $1 billion in damage, 58 deaths

Flooded McAllen Airport, Harlingen, Cd. Mier, 

Cd. Camargo, agricultural lands
Harlingen, Texas

1967
Raymondville, Texas 1967
LOWER RIO GRANDE FLOOD 

CONTROL PROJECT

 Minute 238 (1970)

 IBWC agreement to upgrade the Lower Rio Grande 

Flood Control Project

 U.S. and Mexico agreed to a design flood of 250,000 

cfs at Rio Grande City, TX-Cd. Camargo, Tamaulipas

 Some elements constructed jointly; others undertaken 

by each country

 Both countries share flood risks and benefits of flood 

control infrastructure
LOWER RIO GRANDE FLOOD 

CONTROL PROJECT

 U.S. Infrastructure

270 miles of levees

Thousands of acres of interior floodway

Weirs

420 drain structures

180 irrigation structures

10 bridges

Provides flood protection for hundreds of 

thousands of U.S. residents
LOWER RIO GRANDE FLOOD 

CONTROL PROJECT

 Anzalduas Dam

Built and operated jointly by U.S. and Mexico

Located near McAllen, TX – Reynosa, Tamps.

Diverts U.S. share of floodwaters to U.S. 

interior floodway

Diverts irrigation water for Mexico
ANZALDUAS DAM
LOWER RIO GRANDE FLOOD 

CONTROL PROJECT

 Retamal Dam

Built and operated jointly by U.S. and Mexico

Built to limit flood flows at Brownsville, TXMatamoros, Tamps.

Diversion of Mexico’s share of floodwaters to 

its interior floodway
RETAMAL DAM
Main Floodway

North Floodway

Anzalduas Dam Retamal Dam

Arroyo Colorado

McAllen

Harlingen

Brownsville
FLOOD WORKSHOPS

 Binational workshops held annually

 Participation of field office and Headquarters 

staff from both Sections, National Weather 

Service, Conagua

 Flood Operations Manual reviewed for Amistad, 

Falcon, Anzalduas, Retamal Dams

 Flood scenarios are developed and binational 

planning exercises are conducted 

 Ensures preparation for joint operation of dams 

during flood events
ENVIRONMENTAL CONSIDERATIONS

 USIBWC has reduced floodway mowing in the Lower Rio 

Grande to help establish a wildlife corridor, per 1993 

U.S. Fish and Wildlife Service Biological Opinion

 Purchase of conservation easements underway to 

expand wildlife corridor

 Cameron County, river mile 28 to 62.5

 Easements to provide 33 ft. vegetated corridor next to 75 ft. 

cleared bank 

 13 tracts to be acquired by end of the year. 200-300 tracts 

sought.

 Tree planting in Canalization Project

 EIS and stakeholder collaborative process underway in 

Canalization Project considers environmental 

enhancements and flood control improvements
FEMA CONSIDERATIONS

 FEMA is updating flood maps in targeted 

counties nationwide

 Maps will determine mandatory flood insurance 

requirements

 FEMA requires certification that levees can 

withstand the 100-year flood with 3 feet of 

freeboard

 USIBWC has informed FEMA that it cannot 

certify levees in Doña Ana County, NM and El 

Paso, Hidalgo, and Cameron Counties, TX
LEVEE DEFICIENCIES

 USIBWC levees were constructed decades ago; 

with time, they have degraded

 In some areas, levees are no longer high 

enough to contain the design flood

 Lower Rio Grande Flood Control Project

 U.S. levee overtopping for 38 river miles (up to 6 ft), 

freeboard encroachment for 64 river miles

 U.S. floodway overtopping for 2 miles and freeboard 

encroachment for 24 miles

 Mexican levee overtopping for 57 river miles and 

freeboard encroachment for 110 river miles
LEVEE DEFICIENCIES

 Doña Ana County, NM –

1 mile overtopping, 37 

miles freeboard 

encroachment

 El Paso County, TX – 2 

miles of overtopping, 24 

miles of freeboard 

encroachment

 Levees within inches of 

overtopping in El Paso in 

2006 Rio Grande at El Paso, 8/1/06
LEVEE IMPROVEMENT PLAN

 Lower Rio Grande

 $125 million estimated cost

 Annual budget typically $2–5 million

 Work undertaken as funding becomes available

 MOU for Hidalgo County to use bond funds to raise a 

critical 12-mile reach near Mission

 El Paso County

 $20 million estimated cost

 USIBWC in 2007 raised 7.4 miles of levee in east-central 

El Paso

 Additional funds required for sediment removal - $650,000 

acquired by Congressman Reyes in current FY
LEVEE IMPROVEMENT PLAN

 Doña Ana County

 $20 million estimated cost

 Sediment removal at key areas is performed as part 

of annual Operations and Maintenance

 Coordination with Mexico

 Data sharing and cooperation on hydraulic modeling

 Each country required to maintain its own levee 

system to the agreed-upon design flood

 Joint Report of the Principal Engineers for 

improvements in the El Paso-Juarez area
INTERNATIONAL STORAGE DAMS

 Amistad Dam, Del Rio, TX 

– Cd. Acuña, Coah.

 Flood control, water storage, 

recreation, hydro power

 Total capacity 4.9 maf 

(including flood storage)

Amistad Dam

 Falcon Dam, Falcon Heights, TX – Nueva Cd. 

Guerrero, Tamps.

 Flood control, water storage, recreation, hydro power

 Total capacity 3.16 maf (including flood storage)

 Provides water and flood control for Lower Rio Grande
DAM SAFETY

 Routine dam safety inspection done in 2007 

 Conducted by IBWC and technical advisors from 

U.S. Army Corps of Engineers and Conagua

 Dams are ranked per Corps of Engineers Dam 

Safety Action Classes:

 DSAC I – Urgent and Compelling (unsafe)

 DSAC II – Urgent (potentially unsafe)

 DSAC III – High Priority (conditionally unsafe)

 DSAC IV – Priority (marginally safe)

 DSAC V – Normal (safe)
DAM SAFETY

 Report found all dams to be generally well-maintained 

and able to operate under normal conditions

 Amistad Dam 

 DSAC II – Urgent (potentially unsafe)

 Concerns about impact of naturally-occurring sinkholes

 Report recommends that a panel of geotechnical consultants be 

convened starting in the next funding request cycle

 Falcon Dam

 DSAC III – High Priority (conditionally unsafe)

 Concern about foundation seepage

 Report recommends a comprehensive seepage analysis and 

evaluation of dam stability using current analytical methods to 

confirm or change the DSAC
DAM SAFETY

 Anzalduas Dam 

 DSAC IV – Priority (marginally safe)

 Report recommends that IBWC continue to update 

electrical and mechanical systems, remove sediment 

near the dam

 Retamal Dam

 DSAC III – High Priority (conditionally unsafe)

 Concern about central gate oscillation during floods

 Recommends modifying flood operations to reduce 

use of central gate and replacing the gate lifting 

system
RECOMMENDATIONS

 Encourage FEMA to give time for certain levee 

improvements to be completed before Flood 

Insurance Rate Maps are finalized

 Support development and use of more 

sophisticated modeling by FEMA and others to 

more accurately map flood risk

 Encourage local, state, and federal cooperation 

on flood control issues

 Support technical assistance to Mexico for 

needed flood control improvements
INTERNATIONAL BOUNDARY AND WATER COMMISSION, 

UNITED STATES AND MEXICO

U.S. Section

(915) 832-4100

www.ibwc.state.gov