JOINT PROJECTS OF THE UNITED STATES
AND MEXICO CONSTRUCTED THROUGH
THE International Boundary and Water Commission

 Following are descriptions of each of the joint projects that the Governments of the United States and Mexico planned, designed, constructed, operated and maintained through the International Boundary and Water Commission. They are described in the order of their geographic location.

 1.
Rio Grande
  Gaging   and Water Accounting

Implementation of the 1944 Water Treaty requires that the IBWC keep a record of the Rio Grande waters belonging to each country. The Treaty requires the IBWC to take into account the measurement of the allotments stipulated in the Treaty, the regulation of the waters in storage, the consumptive uses, the withdrawals, the diversions and the losses. To do this, the Treaty provides that the IBWC shall construct, operate and maintain on the channel of the Rio Grande and, through each Section, on the measured tributaries in its country, all gaging stations and mechanical apparatus necessary to make computations and obtain the necessary data for such records. Implementation of the United States part of these activities was authorized by the American-Mexican Treaty Act of September 13, 1950 as amended.

The IBWC operates and maintains 17 gaging stations on the main channel of the Rio Grande. The United States Section operates and maintains 12 gaging stations on the measured tributaries in its country. The Mexican Section operates and maintains eight gaging stations on measured tributaries in its country. In addition, the United States Section operates 66 gaging stations on the United States diversion and return flow channels. Further, each Section of the IBWC gages the spring inflows from its side to the river downstream of the international Amistad Dam on the Rio Grande. Also, the United States Section operates 13 gaging stations for flood warning and operation of the flood regulation storage in the international Amistad and Falcon reservoirs on the Rio Grande. The two Sections exchange and review the stream flow data they collect.

The data form the basis for joint accounting by the two Sections of the waters belonging to each country. The national ownership of waters has been so determined since 1953.

The IBWC also measures the deliveries of the Rio Grande waters made to Mexico under the 1906 Convention.

The collated stream gaging records and records of waters in storage, of rainfall and evaporation stations, and of the measurements of the quality of water are published annually in IBWC bulletins in English and in Spanish, entitled "Flow of the Rio Grande and Tributaries and Related Data."

Copies of the bulletins in English may be obtained from the United States Section Office in El Paso, Texas.

 2.
  Chamizal Boundary Settlement Project

In accordance with the terms of the Convention of 1963 for "Solution of the Problem of the Chamizal," the IBWC relocated the channel of the Rio Grande between the cities of El Paso, Texas and Ciudad Juárez, Chihuahua. The United States Congress authorized the United States part of this project by the American-Mexican Chamizal Convention Act of April 29, 1964. The project was undertaken in 1966 and   completed in 1969.

United States President Lyndon B. Johnson and Mexican President Gustavo Diaz Ordaz formally approved the relocation of the international boundary and the transfer of lands as provided for in the Chamizal Convention on October 28, 1967 at a   ceremony   at the Chamizal Monument in Juárez, Chihuahua. Presidents Johnson and Diaz Ordaz again met in El Paso-Juárez on December 13, 1968 to commemorate completion of the relocated channel and related works provided for in the Convention.

The channel was relocated so as to transfer from the north to the south side of the river a total of 630.34 acres (255.09 hectares) and to keep on the north side 193.16 acres (78.17 hectares). The relocation required the joint construction of 4.4 miles (7km) of concrete-lined new channel and construction of three vehicular bridges an two railroad bridges over the new channel. The improved channel also provides the cities of El Paso and Juárez long-needed protection from Rio Grande floods. The two Governments shared the costs equally. The two Governments also share equally the costs of maintaining and operating the new Rio Grande channel between the two cities and maintenance of one vehicular bridge.

For the relocation of the river channel and transfer of lands to the Mexican side of the river free of private titles, the United States Government through the United States Section had to acquire some 1,200 residential and 186 commercial, as well as industrial and public properties. Also, the Section relocated 11.7 miles (19 km) of railroad facilities and 1.7 miles (3 km) of irrigation canal, and constructed three new port of entry inspection facilities. Of the 193.16 acres (78.17 hectares) ceded by Mexico to the United States: (1) 55 acres (22.26 hectares) are used for a National Park commemorating the settlement of the Chamizal; (2) 60 acres (24.28 hectares) are used for a new high school, Bowie High School; and (3) the remaining 78.16 acres (31.6 hectares) are used for the new United States port of entry facilities at the Bridge of the Americas. As a complementary measure for the City of El Paso, the United States Congress also appropriated funds to cover a part of the cost of construction of a border highway in El Paso, Texas, parallel to the river boundary for a distance of 13 miles (19km).

The Mexican Government has developed schools, parks and recreational facilities on lands transferred to Mexico.

 3.
  Rio Grande Rectification Project

The Convention of February 1, 1933 provided for rectification of the Rio Grande through the highly developed El Paso-Juárez Valley a distance of 86 miles (137 km). The Convention charged the then International Boundary Commission (IBC) with its implementation. The United States part was funded by Appropriation Acts in 1937, 1938 and 1939. Its purpose was to stabilize the international river boundary between the United States and Mexico in this Valley and to provide flood protection for its suburban and agricultural lands. The project was started in 1934 and completed in 1938.

The Rectification Project straightened the river and in the process shortened its meander length from 155 miles (249 km) to 86 miles (137 km) between El Paso and Fort Quitman. The Joint Commission cut a new channel along the axis of the meanders of the old river channel in such a way that the number of acres transferred from one country to the other was equal, so that there was no lass or gain of territory by either country. Exactly 5,121 acres (2,072.40 hectares) were exchanged in 178 parcels of land. A floodway about 590 feet (180 meters) wide with a capacity of 11,000 cfs* (311.49 cms*) was formed by the construction of levees with the channel generally located midway between the levees. The IBWC maintains three bridges across the Rio Grande as part of the project. As a part of the project, 100,000 acre-feet (123 million cubic meters) of flood control storage was provided on the Rio Grande at Caballo Dam constructed 108 miles (173 km) upstream from El Paso by the United States Bureau of Reclamation. The two countries divided the cost of the international rectification project at 88 percent for the United States and 12 percent for Mexico, on the basis of the relative benefits that would accrue at that time to each country from the rectification.

Since its initial completion in 1938, the Rio Grande Rectification Project has provided a stable international boundary through the El Paso-Juárez Valley and has controlled eight river floods, which otherwise would have caused widespread damage in both countries. It has permitted the   development   of extensive residential and industrial areas near the river in both countries.

  4. 
Boundary Preservation Project

To implement Article IV of the 1970 Boundary Treaty, the two Governments approved in 1979 an IBWC recommended joint project for works to restore and preserve the Rio Grande's character as the international boundary in a 199-mile (320 km) reach from a point near Fort Quitman to Hacienditat, Texas about five miles (8 km) upstream of Presidio, Texas-Ojinaga, Chihuahua. The United States portion of the project was authorized by the American-Mexican Treaty Act of October 25, 1972 Construction of the project began in 1980 and it is expected to be completed in 1983.

The project works consist of restoration of the channel of the Rio Grande at locations where it is so clogged with silt and so overgrown with vegetation that the location of the river channel and international boundary, is difficult to find. The channel is being restored to a cross-section having an average depth of six feet (1.8 m), a bottom width of 16.4 feet (5 m) and a top width of about 38 feet (11.6 m). A cleared floodway 56 feet (17.1 m) wide is being provided on each bank of the channel. The project will improve the river's wildlife habitat in that area.

The two Governments are sharing the cost of the project through an equal division of the work, with each Section performing the work required in its country, under the supervision of the IBWC. The two Governments will also share equally the cost of maintaining of the project with each Section assuring performance of work in its country.

 5.
1970 Treaty Projects to Resolve Boundary Differences

The 1970 Boundary Treaty settled all then pending boundary disputes and uncertainties. The most significant dispute remaining after the Chamizal Settlement involved the location of the boundary in the are of Presidio, Texas and Ojinaga, Chihuahua. The river channel was jointly relocated to approximate conditions existing prior to the dispute which arose from changes in the course of the river in 1907. The IBWC was charged with its implementation. The American-Mexican Treaty Act of October 25, 1972 authorized the United States Section's participation. The project was undertaken in 1975 and completed in 1977.

The river was relocated in two reaches by construction of a new channel 4.7 miles (8 km) in length in one reach and 3.6 miles (6 km) in the other. The relocated channel was aligned in the reach above Presidio-Ojinaga so as to transfer from north to the south side of the river 1606.19 acres (650 hectares) and in the second reach downstream from the two cities so as to transfer from the south to the north side 252 acres (101.98 hectares). It is an earth channel with dimensions patterned after the natural channel. The United States acquired 1,969.22 acres (796.92 hectares) of agricultural land for transfer of lands to Mexico and for half of the river relocation.

Also, the channel of the Rio Grande in the hidalgo-Reynosa area was relocated to transfer from Mexico to the United States 481.68 acres (194.93 hectares) by constructing a new earth channel 1.6 miles (3 km) in length. This transfer was made in exchange for the transfer from the United States to Mexico of two tracts of land, the Horcon Tract and Beaver Island, located south of the Rio Grande, comprising 481.68 acres (194.93 hectares).

The total costs of these two relocations were equally shared by the two Governments, with the United States performing the greater part of the work required in the Presidio-Ojinaga area, and Mexico performing the work required in the Hidalgo-Reynosa area and a small part of the work required in the Presidio-Ojinaga area.

 6.
Presidio-Ojinaga Valley Flood Control Project

With the resolution of the Presidio-Ojinaga boundary dispute, the IBWC under the 1944 Water Treaty, recommended and the two Governments approved a joint report for control of Rio Grande floods in the Presidio-Ojinaga Valley to guard against such serious losses to agricultural lands as occurred from floods in 1932, 1938, 1942, 1944, 1958, 1968 and 1974. The United States part was authorized by the Act of October 25, 1972. Construction began in 1975 and was completed in 1977.

The project, undertaken in accordance with a joint plan prepared by the IBWC, consists of levees and a cleared area on each side of the river to form an international floodway about 15 miles (24 k) in length through the Presidio-Ojinaga Valley, to provide protection against a flood of 42,500 cfs (1,203 cms). The two Governments shared the costs equally with each of their respective Sections constructing the works on its side of the river and each maintaining the works on its side.

 7.
International
  Amistad (Friendship) Dam   and Reservoir Project

Amistad Dam is one of the major storage dams jointly constructed by the two Governments on the Rio Grande under the 1944 Water Treaty, through their respective Sections of the IBWC, for control of floods and to enable each country to conserve and utilize its allotted share of the water of the river. The dam is located about 12 miles (19 km) upstream from Del Rio, Texas and Ciudad Acuna, Coahuila, and just downstream from the mouths of two large flood-producing tributaries, the Pecos and Devils Rivers. The United States part of the construction, operation and maintenance was authorized by the Act of Congress of July 7, 1960. Its construction was started in 1964 and completed in 1969.

Before construction, on October 24, 1960 United States President Dwight D. Eisenhower and Mexican President Adolfo Lopez Mateos met at Ciudad Acuna, Coahuila near the dam site and agreed that construction of Amistad Dam should proceed. During its construction, on December 3, 1966, United States President Lyndon B. Johnson and Mexican President Gustavo Diaz Ordaz met at the Dam. On September 9, 1969 United States President Richard M. Nixon and President Diaz Ordaz   dedicated Amistad Dam.

The dam stands 254 feet (77.4 meters) above the riverbed and consists of a concrete gravity spillway section within the river canyon flanked by earth embankments. The total length of the Dam is 6.1 miles (10 km) with 1.8 miles (3 km) on the United States side and 4.3 miles (7 km) on the Mexican side. The dam created a reservoir with a total capacity of 5,250,00 acre-feet (6,475,000,000 cubic meters) of which 3,505,000 acre-feet (4,324,000,000 cubic meters) are for conservation of waters for release as required for beneficial uses downstream in the two countries. The remaining storage capacity, amounting to 1,744,000 acre-feet (2,152,000,000 cubic meters) is for control of floods. The spillway capacity is 1,507,000 cfs (42,674 cms).

 In accordance with the 1944 Treaty, each Government independently determined the conservation storage capacity it needed in the reservoir, resulting in the United States having 56.2 percent and Mexico 43.8 percent of the total conservation capacity.

The total cost of construction of the dam was divided between the two Governments in the same proportions as provided in the Treaty.

The dam was jointly planned and constructed by the two Governments through their respective Sections of the IBWC under its supervision. &nbs; Under jointly agreed upon design criteria, each Government prepared the plans for its assigned part of the dam with the United States part performed for the United States Section by the United States Army Corps of Engineers, Southwest Division. Each constructed, through its contractors, the part of the dam corresponding to its share of the costs, in accordance with the allocation of work items determined and coordinated by the IBWC.

The two Governments, through their respective Sections of the IBWC, jointly operate and maintain the dam, dividing the costs in the same proportion as was the construction, and effecting the division by each performing work corresponding to its share of the costs. Water releases are made from each country's share of the waters in conservation storage to meet its downstream requirements, as requested by the appropriate domestic authority. In the United States, the authority is the Texas Department of Water Resources. Water releases for control of floods are determined jointly by the two Sections of the IBWC.

Since operation began in 1968, Amistad Reservoir has effectively controlled floods in the years 1971, 1972, 1974, 1976 and 1978, and conserved the waters which with those conserved in Falcon Reservoir, have provided a full supply for downstream users along the United States and Mexican banks of the river.

The 1944 Treaty provides that public use of the water surface of lakes formed by international dams shall be free and common to both countries. This makes the reservoir, in effect, an international recreation lake for the peoples of both countries. On the United States shore, the United States National Park Service operates a National Recreational Area. On Mexico's shore, its authorities have provided similar recreation facilities.

As a part of the construction of Amistad Dam, power penstocks were installed and sites were excavated on each side of the dam for future hydroelectric power plants. The United States Section has under construction on the United States side a plant for generating its share of the hydroelectric energy that can be generated, as stipulated in the 1944 Treaty. It will consist of two generating units, each of 33,000 kilowatt capacity, and is scheduled for operation in 1983.

Mexico is undertaking construction of a similar plant on its side of the dam for generation of its 50 percent share of the energy potential. The releases of water for energy generation are secondary to the releases of water for domestic and municipal uses and for agriculture and stockraising.

 8.
International
  Falcon Dam and Reservoir   Project

Falcon Dam is the second of the major storage dams that the two Governments have jointly constructed on the Rio Grande under the 1944 Water Treaty through their respective Sections of the IBWC for control of floodwaters and to enable each country to conserve and utilize its allotted share of the waters of the river. The dam is located about 75 miles (121 km) downstream from Laredo, Texas and Nuevo Laredo, Tamaulipas. The United States part of the construction, operation and maintenance was authorized by the American-Mexican Treaty Act of September 13, 1950. Construction was started in 1950 and   completed in 1953.

Falcon Dam is an earth and rock embarkment structure with a concrete spillway. It has a maximum height above the riverbed of 150 feet (45.72 m). It has a total length of 5 miles (8 km) of which 2 miles (3 km) are on the United States side and 3 miles (5 km) are on the Mexican side. The reservoir has a total capacity of 3,978,416 acre-feet (4,907,000,000 cubic meters) of which 2,667,000 acre-feet (3,291,000,000 cubic meters) are for conservation of floodwaters, for release as required for beneficial uses downstream in the two countries. The remaining storage capacity amounting to 1,310,828 acre-feet (1,616,888,800 cubic meters) is for control of floods. The spillway capacity is 456,000 cfs (12,900 cubic meters).

As in the case of Amistad Dam, each Government independently determined the conservation capacity it needed in the reservoir. The determinations resulted in the United States having 58.6 percent and Mexico 41.4 percent of the total conservation capacity. Again, the total cost of construction of Falcon was shared by the two Governments in the same proportion as stipulated in the Treaty.

The dam was jointly planned and constructed by the two Governments through their respective Sections, with each performing through its contractors the items of work corresponding to its share of the costs. The design of Falcon Dam was performed for the two Governments by the United States Department of the Interior, Bureau of Reclamation, under the joint criteria adopted by the IBWC and its supervision. As at Amistad Dam, the works constructed by the United States constructors and the Mexican contractors were jointly coordinated and supervised by the IBWC.

As a part of construction of the dam, each Government constructed on its side and at its expense, a   plant   for the generation of one-half of the available hydroelectric energy as prescribed by the 1944 Treaty. Each plant consists of three generators, each of 10,500 kilowatts. Energy generation is incidental to releases of water for downstream uses.

Operation and maintenance of Falcon Dam is performed jointly by the two Governments through their respective Section of the IBWC, with costs divided in the same proportion as was the construction, and effected by each performing work corresponding to its share of the costs. Releases are made from each country's share of the waters in conservation storage to meet its downstream requirements as requested by the appropriate domestic authority. In the United States, the domestic authority is, as in the case of Amistad Dam, the Texas Department of Water Resources. Releases for flood control at Falcon Dam are determined jointly by the IBWC.

Falcon Dam has provided a regulated water supply for domestic, municipal and irrigation uses downstream in both countries without a serious shortage since storage began in 1953. In its first year of operation in 1954, Falcon Reservoir completely contained the highest flood of record in the Rio Grande, which otherwise would have caused devastating damages downstream in the highly-developed Lower Rio Grande Valley in both countries. In 1967, it completely contained the portion of the "Hurricane Beulah" flood originating upstream of the dam, which otherwise would have caused far more extensive damages than occurred. Falcon Reservoir's 40 mile-long (64 km) reservoir provides water recreation for increasing numbers of visitors from both countries. The State of Texas operates a state park along a part of the United States shore.

 9.
Lower Rio Grande Flood Control Project

The Governments of the United States and Mexico pursuant to an agreement reached in 1932, developed through the IBWC (then IBC) a coordinated plan for an international project for protection of the Lower Rio Grande Valley in the United States and Mexico against the river's floods. The project is located in the delta of the Rio Grande, situated in Hidalgo, Cameron and Willacy Counties in the State of Texas and in the State of Tamaulipas in Mexico. Emergency construction of works on the United States side was performed under the National Industrial Recovery Act of June 13, 1933. The United States part of the international project was authorized by the Act of August 19, 1935, as amended. The works initially planned in the United States were completed in 1950. The project was improved after the floods of 1958 and 1967.

In the   delta   of the Rio Grande, the main channel of the river has never been capable of carrying to the Gulf of Mexico more than a small part of the river's floodwaters. Under natural conditions the river's floodwater spread over much of the delta, finally draining by separate overflow channels in the United States and Mexico to the Gulf. Such spreading of floodwaters seriously threatened the agricultural and urban development of the delta lands in both countries. On the United States side, Cameron and Hidalgo County authorities undertook the construction of levees along the river and off-river floodways utilizing the natural overflow channels, but it was recognized that a complete solution required international coordination. This was provided for in the 1932 agreement. The principal features of the coordinated plan were the construction of levees on each side of the river and improvement in each country of its natural off-river floodways to convey safely to the Gulf of Mexico the river's floodwaters in excess of the capacity of the river channel in the vicinity of the cities of Brownsville, Texas and Matamoros, Tamaulipas. The plan was jointly recommended by the IBC and approved by the two Governments for its implementation through their respective Sections.

On the United States side, the United States Section adopted and implemented the plan for control of Rio Grande floods which had been undertaken. Pursuant to a requirement in the authorization by Congress, the rights-of-way for the project were donated to the United States Government by the counties. In the years 1933 to 1950, each Government through its Section extended, raised and strengthened the levees in its country. The part of the project on the United States side was improved in the years 1959 to 1961 in the light of the experience gained in the 1958 floods. Improvements included the joint construction by the two Governments through the IBWC of   Anzalduas Diversion Dam   on the Rio Grande west of Mission, Texas to effect and control diversions of floodwaters from the river into the United States off-river floodways.

The rains attending "Hurricane Beulah" in 1967 resulted in unprecedented floods from tributaries to the Rio Grande below Falcon Dam which caused extensive damages in the City of Harlingen and in the McAllen area, and to farmlands on the United States side. Similar damages were suffered on the Mexican side. In 1970, the IBWC recommended and the two Governments approved a coordinated plan of improvements to the project to protect against floods as occurred in 1967. The project is designed to safely carry a flood of 240,000 cfs (6,796 cms). The levees were strengthened and works were constructed to assure diversion from the river by each Government of 50 percent of the floodwaters in excess of the safe capacity of the river channel in the Brownsville-Matamoros area. For this purpose the diversion works to the United States off-river floodways were improved, and the two Governments jointly constructed through the IBWC the   Retamal Diversion Dam   located south of Donna, Texas to effect and control flood diversions to the Mexican off-river floodways. As improved, the Lower Rio Grande Flood Control Project on the United States side includes 102.1 miles (164 km) of river   levees   and 119.9 miles (193 km) of off-river improved floodways which are bordered by 167.5 miles (270 km) of levees to carry to the Gulf of Mexico the United States half of the Rio Grande floodwaters.

For the United States, the project has provided full protection against 13 Rio Grande floods since 1930 and protect most of the are from serious flooding from the river in 1967. As now improved, the part of the project in the United States provides a high degree of protection against Rio Grande floods for the Lower Rio Grande Valley of Texas, which has a population of 450,000 and includes 730,000 acres of highly productive irrigated agricultural lands. Similar benefits accrue to the Mexican side of the Lower Rio Grande Valley.

 10.
Lower Rio Grande Water Quality Improvement Project

In 1965, the IBWC recommended and the two Governments approved a joint project for improvement of the quality of the waters of the Lower Rio Grande. United States participation in the project was approved by the Congress by the Act of September 19, 1966. Construction began in 1966 and was completed in 1969.

In the early 1960's, serious increases were observe in the salinity of the waters of the Lower Rio Grande at Anzalduas Dam, upstream from the points of major diversions to irrigated lands in the United States and Mexico. The increases were most serious at times of low flows and often damaged crops. A joint investigation by the IBWC disclosed that the principal source of the increase in salinity was the inflow from the Morillo Drain which enters the Rio Grande from Mexico just upstream from Anzalduas Dam. The salt content of these inflows, which consist of gravity drainage waters from irrigation in Mexico, often exceeded 10,000 part per million.

The works recommended and built to resolve the problem consist of a pumping plant and structures to divers the flows of the Morillo Drain before they reach the Rio Grade, to a drainage channel on the Mexican side, extending about 75 miles (121 km) southeastward and discharging directly to the Gulf of Mexico.

The construction was performed by Mexico under the joint supervision of the IBWC.

The project has reduced the salt burden of the waters of the Rio Grande at Anzalduas Dam b7 280,000 tons per year since operation began in 1970. The reduction in salinity has been beneficial for the irrigated agricultural production and for domestic and industrial uses in the Lower Rio Grande Valley in both countries.

The total cost of the project was shared equally by the two Governments as are the operation and maintenance costs on the basis that the improvement in the quality of the waters of the Rio Grande benefitted users in both countries. The benefitted water users in the Lower Rio Grande Valley of Texas paid one-half of the United States part of the construction costs and they also pay one-half of the United States part of the operation and maintenance costs.

 11.
Boundary Mapping - Rio Grande

The 1970 Boundary Treaty charges the IBWC with delineation of the international boundary with appropriate precision on maps or aerial photographic mosaics of the Rio Grande and for this purpose to make surveys as frequently as it may consider justifiable but at intervals not greater than 10 years. It further provides that each Government shall bear half of the costs and other expenses as determined by the IBWC and approved by the two Governments for these surveys and maps. United States Section participation in this joint project was authorized by the American-Mexican Treaty Act of October 25, 1972. This project covers a distance along the Rio Grande of 1,254 river miles (2,019 km).

The first surveys pursuant to the 1970 Treaty were performed during the years 1972-1975. They consisted of controlled aerial photographic mapping of the river resulting in maps of a scale of 1:20,000 on which the boundary was jointly delineated as the middle of the river by engineers of the two Sections. The maps were completed and adopted by the IBWC on September 23, 1976. The costs were shared equally by each Government performing one-half of the work through its Section of the IBWC.

Copies of the maps may be reviewed in the Headquarters of the United States Section and Mexican Section of the IBWC in El Paso, Texas and Ciudad Juárez, Chihuahua, respectively. In the United States, copies of the maps may be obtained through the United States Geological Survey, Denver, Colorado. The next river boundary surveys are scheduled for 1981-1983.

 12.
Rio Grande Water Quality Monitoring

Since 1935 the IBWC has collected samples and made analyses of the waters of the Rio Grande for quality. The United States Congress authorized United States participation in the program by the Act of August 19, 1935.

With increasing growth of urban communities along the 1,254-mile (2,019 km) river boundary formed by the Rio Grande and the attendant increasing discharges by municipalities and industries of waste waters into the river, there has been increasing need to monitor jointly the quality of the boundary water to detect and define problem areas where corrective actions are needed.

The current monitoring program of the IBWC provides for monthly sampling and analysis of waters of the Rio Grande at 25 points located downstream from border cities, at the international reservoirs, at points of major inflows, and of major diversions.

The analysis of samples at certain points includes complete chemical analysis and at others, determination of the sanitary quality. Samples of inflows to the reservoirs are measured for their sediment content. The data are exchanged by the two Sections of the IBWC, are reported to the appropriate agencies of the two Governments, and published in the annual Water Bulletins of the IBWC.

The sampling and analysis by the United States Section are performed as a part of a cooperative program with the United States Geological Survey Department of the Interior, and the Texas Department of Water Resources and in coordination with the United States Environmental Protection Agency.

The results show that the sanitary quality of the waters of the Rio Grande in the international boundary reach is generally in accord with standards of the two Governments, except in the area of Laredo, Texas-Nuevo Laredo, Tamaulipas, where the waters have sanitary conditions that present a hazard to the health and well-being of the inhabitants of either side of the border. The IBWC has this border sanitation problem under study pursuant to the terms of Minute No. 261 approved by the two Governments for the solution of the Border Sanitation Problems.

 13.
Unilateral Projects Assigned to the United States Section
to Carry Out Treaty Obligations with Mexico

The United States Congress by the Acts of August 29, 1935 and June 4, 1936 authorized the United States Section of the then IBC to construct, operate and maintain two projects to facilitate compliance with the Convention of 1906 for the distribution between the two countries of the waters of the Rio Grande above Fort Quitman. The first is the American Dam and Canal Project located just upstream of El Paso, Texas and the second is the Rio Grande Canalization Project which extends from the American Dam upstream a distance of 106 miles (171 km) to near Caballo Dam in New Mexico.

 a.   American Diversion Dam and Canal Project

The American Diversion Dam, located on the Rio Grande entirely in the United States just upstream from the point where the Rio Grande becomes the international boundary, together with the 2.1 mile (3 km) American Canal, provide the physical works to effect distribution between the United States and Mexico of the waters of the Rio Grande under the 1906 Convention. The dam and canal were constructed in the years 1937 and 1938.

The waters for the United States are diverted to the American Canal on the United States bank and are conveyed by that canal a distance of 2.1 miles (3 km) to the headworks of the irrigation project in the United States. The diversion dam and canal are operated and maintained by the United States Section. Releases from Elephant Butte Dam are made by the United States Bureau of Reclamation of the Department of the Interior.

 b.   Rio Grande Canalization Project

The Canalization Project included acquisition of rights-of-way for the river channel and adjoining floodways and improvement of the alignment and efficiency of the river channel for conveyance of deliveries to Mexico, pursuant to the 1906 Convention, as well as of deliveries to the United States Rio Grande Project. The channel's capacity varies from 3,000 cfs (85 cms) near Caballo Dam to 1,200 cfs (34 cms) near the American Dam. The channel is flanked by cleared floodways formed by levees for control of floodwaters. The channel and floodway have a capacity varying from 22,000 cfs (623 cms) in the upper reaches to 17,000 cfs (481 cms) in the lower reach. It is operated and maintained by the United States Section. It has safely carried through the highly-developed irrigated lands in the Rincon and Mesilla Valleys in New Mexico the floods of 1941, 1942, 1944, 1950, 1958 and 1962, preventing extensive damages.

The Project was reexamined in 1974 to determine its adequacy for flood protection in view of the increased urban and suburban development which had occurred in the Valleys since the project was constructed and the consequent higher degree of protection warranted. The findings were that the degree of control of floods afforded by the project had been significantly in creased as a result of the many arroyo control dams subsequently built by the Soil Conservation Service of the United States Department of Agriculture on the flood-producing tributary arroyos. For this reason, the degree of control afforded by the project was found to be commensurate with the increased developments except in two reaches, one near Anapra, New Mexico and the other near Anthony, New Mexico where the levees were raised and the channel widened in 1976 and 1977.

International Boundary and Water Commission
United States Section
4171 North Mesa, Suite C-310
El Paso, TX  79902-1441
1-800-262-8857

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