gates. From the intake structure the canal follows the left bank of the river 2 miles downstream to discharge into the stilling basin of the main canal for the El Paso Valley portion of the United States Bureau of Reclamation project.

The canal consists of 7,760 feet of open, concrete-lined, trapezoidal section and 2,714 feet of closed conduit section. Its designed capacity is 1,200 second-feet. For more than half of the length of the American Canal the flanking mesas and foothills of the Franklin Mountains extend almost to the Rio Grande, so that only a narrow strip is available for the canal along the highway and railroad already occupying the low ground.

Construction of the American Dam and Canal feature was completed in 1938 at a cost to the Government of $667,398.

(c) Rio Grande rectification project

(Authorized by Treaty of February 1, 1933.)

Location. The rectifed channel is 85.6 miles in length, extending from El Paso, Tex., to the lower end of the El Paso-Juarez Valley, at the head of Quitman Canyon. General conditions.-The project, authorized by the treaty of 1933 with Mexico and completed in 1938, accomplished the shortening of the international portion of the river through the El Paso-Juarez Valley from its natural meandering course 155.2 miles in length to a straightened course 85.6 miles long, which together with the same length of adjoining leveed floodways eliminated a serious flood hazard to the cities of El Paso, Tex., and Ciudad Juarez, Mexico, and the irrigated lands in both countries downstream therefrom, which include 178,000 acres. It further stabilized the international boundary in this portion of the river and provided incidental irrigation and drainage benefits to the adjoining lands. The rectified channel was so located that the areas cut from the United States exactly balance those cut from Mexico. The areas cut from each country were ceded to the other. In all there were 178 of these areas, known as parcels, of which 85 were ceded by the United States to Mexico, 69 were ceded by Mexico to the United States, and 24 remained in the floodway channel. In each case, the total area ceded was 5,121 acres. The 1933 convention provides further that the permanent international boundary shall be the middle of the deepest channel within the levees of the rectified channel.

Caballo Dam, an integral part of the rectification project, was constructed by and is operated and maintained by the Bureau of Reclamation, in accordance with the Interdepartmental Agreement between the Secretaries of State_and Interior, dated August 27, 1935. Located 112 river miles upstream from El Paso, Tex., and 27 miles downstream from Elephant Butte Dam, Caballo Dam controls about one-half of the direct tributary drainage area of the Rio Grande between Elephant Butte Dam and El Paso, Tex. The Inter-departmental Agreement provides that 100,000 acre-feet of the total 346,000 acre-foot capacity of Caballo Reservoir shall be reserved for flood control, and that so far as can be accomplished within this regulated capacity, releases from the reservoir shall not exceed 11,000 cubic-feet per second. The plan, developed by the Commission and included as a part of the rectification project, provided for flood storage only at Caballo Dam but, as constructed, it also provides, separate from the rectification project, conservation capacity necessary for development of firm power at Elephant Butte Dam. Caballo Dam is operated and maintained by the Bureau of Reclamation. The total cost of construction of the portion of the works assigned to and performed by the United States under the terms of the Convention of February 1, 1933, amounted to $4,043,020, exclusive of the cost of Caballo Dam.

Since completion of the project it has safely carried past the cities of El Paso and Juarez, and in the channel through the irrigated lands below in both countries, floods in 1938, 1941, 1942, 1944, and 1950 which would have otherwise caused widespread serious damage. In addition there were passed safely through the lower end of the rectification project floods originating from arroyos in that area in the years 1940, 1941, 1945, 1946, 1948, 1950, 1951, and 1953, which otherwise would have caused considerable local damage.

*

*

*

*

The maintenance and operation of the El Paso Rio Grande projects comprising the canalization project, American Dam and Canal, and the rectification project, heretofore described, which includes a total of 195 miles of channel, 177 miles of floodway, and 215 miles of levees, comprise principally the keeping of the floodways and river channel cleared of vegetation, revetment of the channel to maintain the position of the river which, in the case of the rectification project, forms the boundary, and secure the levees against erosion, and maintenance of the levee, levee road, slopes, and removal of material discharged into the river by arroyos,

to assure that the project will accomplish its intended purpose of safely carrying flood flows through the area. During the years 1954 and 1955, when the operation and maintenance funds available were reduced to $404,128 and $371,344, respectively, experience demonstrated that the projects could not be maintained in a manner which would assure their proper functioning. Major items of work which were deferred in fiscal year 1954 include the placing of 5 miles of river bank revetment and the resurfacing of 8 miles of levee road, while in fiscal year 1955 there will be deferred 11 miles of river bank revetment and 18 miles of levee road resurfacing. Moreover, funds made available in previous years have not permitted the replacement of heavy duty equipment, now 18 to 20 years old and no longer economical of operation. It is proposed to replace such equipment over a 5-year period at a cost of $99,000 per year, $12,000 are requested annually to permit payment of hourly wages at the rates prevailing in the area, $41,256 are required annually to restore to normal standards maintenance of the projects, and $92,400 required annually over a 6-year period to complete 235 miles of river banks that require revetting. These items, essential for the establishment of the project on a sound and efficient operating basis, make necessary an increase in the amount of $244,656 over the 1955 allotment, making the total amount needed for the fiscal year 1956-$616,000.

The purchase of the new heavy equipment will permit the effecting of an annual reduction in the maintenance costs beginning in 1957 and increasing the annual saving to $40,000 after the end of the 5-year replacement period. The revetment placement program is scheduled to be completed within 6 years, following which a further reduction may be effected in the amount of $72,000 annually. In the event funds are not made available for new heavy equipment, the annual cost of operation and maintenance will increase progressively.

Lower Rio Grande flood control project

(Authorized by international agreement in 1932, and Public Law 46, approved April 25, 1945)

Location.-The Lower Rio Grande flood control project, located in both the United States and Mexico, extends from the town of Penitas, Tex., to the Gulf of Mexico, a distance of about 180 river miles. It is situated within the fertile alluvial delta of the Rio Grande which includes highly developed agricultural areas in both countries. The principal towns in the United States are Brownsville, Harlingen, and McAllen Tex., and in Mexico, Reynosa and Matamoros, Tamaulipas. General conditions. In this region the Rio Grande discharge is extremely erratic, varying from periods of little flow to floods of 200,000 second-feet which may originate below Falcon Dam. The channel of the Rio Grande in its delta diminishes in capacity as it approaches the Gulf such that at Brownsville, it will carry only about 30,000 cubic feet per seond. Before levees and floodways were constructed, overflows from the channel, situated on the highest part of the delta, spread away from the river over the fertile delta lands finally collecting in natural depressions and discharging into the Gulf.

Following a disastrous flood in 1922, Cameron and Hidalgo Counties be an a system of protective works based upon a plan proposed by the United States Bureau of Reclamation and approved by the State reclamation engineer. The plan proposed was basically the same as has since been constructed. The work was carried to partial completion by 1930, at a cost to the counties of over $5 million. It had then become evident that the problem could only be completely solved with the cooperation of Mexico. Therefore, the International Boundary Commission, in 1930, was authorized to review the original plan and to develop an international plan for flood control. The plan developed included the construction of river levees in both countries and interior floodways in both countries, located along natural depressions through which floodwaters in excess of the river floodway capacity would be conducted to separate outlets into the Gulf of Mexico. To effect the diversion of floodwaters, two diversion dams were proposed. The report of the Commission was approved by both Governments, but Mexico withheld approval of construction of diversion dans pending agreement on the equitable division of waters in the international streams. The 1944 water treaty now constitutes this agreement.

The original plan was modified in the light of changes which occurred in the hydraulic characteristics of the river. The modified plan provides for the construction of a single diversion dam at the Anzalduas site, a short distance downstream from the Mission Inlet to the United States floodway. All the works contemplated under the modified plan have been completed except Anzalduas Dam and the appurtenant works outlined herein before as a part of "Construc

59824-55-36

tion." That portion of the lower Rio Grande flood-control project already completed embraces a levee system 88 miles in length along the left bank of the river and 137 miles of leveed interior floodways through which overflow waters of the Rio Grande may be safely passed through the valley eastwardly to the Gulf of Mexico. It further includes structures to control the distribution of waters between the floodways, and numerous small irrigation and drainage structures through the levees.

As a part of the project work, 63,597 linear feet of riverbank revetment have been constructed, of which 42,830 linear feet are now located on the present riverfront. Of this length, 15,873 linear feet were constructed and placed under the Rio Grande bank-protection project. In the latter category, 25 percent of the cost of bank-revetment works placed for the protection of private works located near the river is paid by the private interests.

The cost to date to the United States for construction of its portion of the lower Rio Grande flood-control project has amounted to $10,595,177. Since construction, Rio Grande floods occurring in 1935, 1936, 1938, 1939, 1941, 1942, 1944, 1945, 1946, 1948, 1949, and 1951 have been passed through the valley without damage to the land and properties protected.

The maintenance and operation of the lower Rio Grande flood-control project consists principally of reconditioning of the levees due to damages caused by heavy rain and wind erosion; clearing of levee and floodway areas; cleaning and repairing of the riverbank revetment; and maintenance of Government-built structures through the levees. Experience gained during 1954 and the current year shows that on this project, as on the El Paso-Rio Grande projects, the funds made available were insufficient to properly maintain and operate the project. Portions of the maintenance items have had to be wholly deferred, and such work as was performed was in a major part below the standard necessary to assure proper functioning of the project. To continue this practice will not only jeopardize the purpose of the project, but will result in higher costs to the Government. Moreover, as in the case of the El Paso projects, funds made available in previous years for the lower Rio Grande project have not permitted the replacement of heavy-duty equipment which is no longer economical of operation.

For the fiscal year 1956, it is proposed to (a) restore to normal standards the maintenance of the project which will cost $142,062 in excess of the amount allotted in 1955, (b) catch up on items of work wholly deferred in recent years which will cost an addtional $18,000, (c) begin a 5-year program of replacement of heavyduty equipment at a cost of $22,000 annually, and (d) increase the wages paid to hourly employees to that necessary to meet the prevailing wages paid in the area, which will cost $19,000. These items, essential for the establishment of this project on a sound and efficient basis, make necessary a total increase of $201,062 over the amount allotted in 1955, making the total amount needed for fiscal year 1956, $434,400.

The purchase of the new heavy equipment will permit an annual reduction in the normal operation and maintenance costs beginning in 1957 and increasing the annual savings to $21,300 at the end of the 5-year period. In the event funds are not made available for replacement of the heavy equipment, the annual cost of normal operation and maintenance will increase progressively.

Falcon Dam and powerplant

(Authorized by 1944 water treaty and Public Law 312, approved October 5, 1949.)

Location. The international Falcon Dam and powerplant is situated on the Rio Grande 75 miles downstream from Laredo, Tex., 125 miles upstream from Brownsville, Tex., and 229 miles southwest of San Antonio, Tex.

General conditions.-Falcon Dam, completed in November 1953, is the first of the major storage dams which the Governments of the United States and Mexico agreed in the 1944 treaty to jointly construct and operate and maintain through the International Boundary and Water Commission. The treaty provides that the costs of operation and maintenance as well as the cost of construction of the dam shall be prorated between the two Governments in proportion to the capacity allotted to each country for conservation purposes in the reservoir, 58.6 percent to the United States and 41.4 percent to Mexico. The treaty further provides with respect to the powerplant at the dam that the hydroelectric energy shall be shared equally and that the cost of operation and maintenance as well as construction shall be divided in like proportion.

The joint operation and maintenance of Falcon Dam and Reservoir and powerplant by the United States and Mexico through the International Boundary and Water Commission is accomplished by close coordination between and overall

direction by the respective superintendents at the dam of the United States and Mexican section of the Commission under the general supervision of this international body. The division between the two sections of the work involved in the operation and maintenance is accomplished as it was in the construction of the dam and powerplant by allocation to each section of the Commission of a part of the work items in such manner that the cost of the work performed by each Government will conform to the treaty provisions.

Subject to possible future reallocation by the Commission, the operation and maintenance by the United States section includes the portion of the works located in the United States comprising the portion of the earth dam in this country; the outlet works consisting of a concrete gravity dam and four 13-foot penstocks with appurtenant control works and bypass lines; the concrete spillway structure controlled by six 50- by 50-foot fixed wheel gates and with appurtenant hoisting equipment; and the powerhouse located in the United States which contains 3 vertical-shaft Francis-type turbines, each of which will develop 14,750 horsepower at rated head of 100 feet and three 3-phase, 60-cycle generators, each rated at 10,500 kilowatts, together with appurtenant control regulating equipment, switchyards, and local substation. The operation and maintenance of the reservoir monuments and buoys, which mark the jurisdictional line between the United States and Mexico, are a part of the responsibility of the United States section. In this connection and for the purpose of removing trash and debris from the reservoir and for reservoir-survey purposes, a Higgins work boat is operated and maintained by the section.

For the direct supervision and administration of the operation and maintenance of the works jointly with Mexico, there are located at the dam on the United States side an administration building, garage, warehouses, rent houses for employees, and water and sewage-treatment works, other utilities, roads, fences, etc., which require maintenance by the United States section.

Since the initial generation of power did not begin until the second quarter of the current fiscal year 1955, it is estimated that the $205,000 available for the operation and maintenance of the dam and powerplant will be sufficient for this year. For 1956 when power will be generated throughout the year, the total estimate for operation and maintenance is $233,000.

International gaging stations

(Authorized by the Water Treaty of 1944.)

Since 1889 on the Rio Grande and since 1902 on the Colorado River, the United States and Mexico have been engaged in joint water measurement activities. The prime purpose of the present stream gaging program of the Commission is to secure a joint record mutually acceptable to both the United States and Mexico, of the flow of the Rio Grande and of the Colorado River in their boundary sections, of the tributaries thereto, and of related hydrologic data, in order to provide the basis of the determinations of the national ownership of the boundary waters available at any given time, in accordance with the allocations to each country stipulated in articles 4 and 10 of the 1944 water treaty. For this purpose the treaty provides in articles 9 (j) and 12 (d) that the Commission shall construct, operate, and maintain gaging stations on the boundary portion of the main channel of the Rio Grande and on the Colorado River and that each section of the Commission shall construct, operate, and maintain gaging stations on tributaries located in its own country. The present program also includes stream gaging on the Tijuana and other international streams.

The records secured also figure importantly in recommendations and decisions on the control of works constructed and development of works to be constructed, under the 1944 treaty, on the international reaches of the Rio Grande, Colorado River, Tijuana River, and other international streams. Another important attendant purpose of the program is the collection of natural resources information on these international streams and measured tributaries. Analysis of these data provide valuable' information on stream flows, evaporation, rainfall, wind, humidity, sediment loads, sanitary and chemical qualities of the international waters. These data are essential to other Government agencies, State and local authorities, and farmers.

At the present time there are 45 stream gaging stations operated and maintained by the Commission on the Rio Grande and its tributaries. The United States Section operates 10 stations on the United States tributaries and 18 on the main stream. The Mexican Section operates 9 stations on the Mexican tributaries

and 8 on the main stream. On the Colorado River 2 gaging stations are operated by the United States Section and 3 on tributaries thereto. The Mexican Section operates 1 gaging station on the Colorado River, 1 on the Tijuana River, and 3 on the Santa Cruz River.

The storage of international waters, which began in Falcon Reservoir on the Rio Grande in August 1953, poses unique operation problems from a water control and regulation standpoint, in that waters of both the United States and Mexico are stored in a single reservoir and continuous determination and record of the ownership of the waters in storage is essential. Also required are flow forecasts, including flood volume forecasts, and hydroelectric energy production forecasts. These are made jointly by the United States and Mexican Sections of the Commission.

In connection with the unprecedented flood of June 1954, the hydrographic personnel of the Commission came importantly into play in promptly securing and furnishing to the officials in both countries flood warnings, including data and forecasts as regards the probable stages and discharges of the flood as well as securing the data which permitted optimum realization of regulation benefits at Falcon Dam and Reservoir and enabled determination of the national ownership of the floodwaters.

A total of 35 field employees is now engaged in the gaging station program along the Rio Grande and on the Colorado River and other international steams. Douglas-Agua Prieta sanitation project

(Construction authorized by act of August 19, 1935, operation and maintenance authorized by Public Law 786, approved September 13, 1950.)

The Douglas-Agua Prieta sanitation project was developed as the result of reports made by the Public Health Department of Mexico and residents of Agua Prieta, Sonora, that the dumping of improperly treated sewage from Douglas. Ariz., across the boundary line constituted a menace to the public health.

Douglas, Ariz., and Agua Prieta, Sonora, are adjoining border cities separated only by the international boundary line. The slope of the topography in the area is such that the sewage from the United States flows to Mexico. The municipal sewer system of Douglas, Ariz., consisted of about 20 miles of sewer lines which discharged into a large septic tank. An outfall line from the septic tank conveyed the sewage effluent to the boundary line where it was emptied into an open ditch located in Mexico. For a number of years the sewage effluent had been used for irrigation purposes by Mexican farmers. Treatment of the sewage in the septic tank on the United States side was inadequate and health authorities of the State of Arizona and of the United States, as well as the Mexican Government, agreed that the public health was endangered by these conditions.

Upon agreement of the Governments of the United States and Mexico, instructions were issued to the Commissioners of the International Boundary and Water Commission for each Section to conduct studies, ground surveys, and investigations to cover the problem fully and to prepare a report thereon. These studies culminated in the report of the Commission, submitted to the two Governments in May 1941, which recommended the construction of a sanitation project designed to correct the unsatisfactory conditions at that point. An appropriation of $90,000 for the United States portion of the project was set up in the 1943 budget, but work on the project was postponed for the duration of the war. Early in the summer of 1947 the project was completed at a cost to the United States of $185,000.

Operation and maintenance of the international plant by the adjoining towns has not been satisfactory. For this reason agreement with Mexico is now pending looking to joint operation by the Commission which it is anticipated will be consummated during the current year. Under date of June 9, 1952, the United States Section, pursuant to Public Law 786, negotiated an agreement with the city of Douglas whereby the Commission would operate and maintain the plant with the city of Douglas contributing 75 percent of the cost of such operation and maintenance of the share allocated to the United States, but not to exceed an annual contribution of $4,500. The total estimated annual cost to the United States is $6,000.