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The Lower Rio Grande Rehabilitation Project has rehabilitated the diversion, distribution, and drainage systems of La Feria and Mercedes Divisions to permit more efficient operation and maintenance of works. Rehabilitation work also was done to reduce seepage losses from the canals and laterals and to provide drainage relief from a design storm that would produce 2.6 inches of runoff.
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La Feria Division has about 35,000 irrigable acres of land in the extreme western half of Cameron County, Texas. The lands are on the Rio Grande delta plain about 25 miles inland from the gulf coast. Rehabilitation of the diversion and distribution facilities involved lining 21 miles of canals and laterals; repairing 35.1 miles of formerly unlined canals and laterals; placing 54.5 miles of pipeline, including replacing 9.6 miles of lined laterals in poor condition with pipeline; repairing or replacing structures; repairing or replacing pumping installations; enlarging the existing storage basin to 2,000 acre-feet capacity; cleaning vegetative growth from all unlined canals and laterals; and providing maintenance roads. Drainage system work included reconstructing the drainage pumping plant, cleaning and clearing all drains and ditches, enlarging or replacing some drainage structures, and providing maintenance roads along 153 miles of drainage system. Providing maintenance roads permits the use of mechanical maintenance equipment instead of manual labor.
The irrigation works include an inlet channel from the Rio Grande about 7 miles south of La Feria, Texas, a riverside pumping plant, one large and several small relift pumping plants, and approximately 161 miles of canals and laterals. The river pumping plant receives diverted river flows through an inlet channel 1,000 feet in length and about 80 feet in average width. All water diverted from the Rio Grande is lifted an average of 20 feet at the main pumping plant from the inlet channel to the distribution system. Following the first lift, the irrigation system involves one large relift pumping plant located on the main canal at the northeast comer of the storage basin and two small relift pumping plants on the lateral system. A diked area on the north bank of the Arroyo Colorado 5.5 miles north of the main pumping plant serves as a storage and desilting basin. The main canal functions as a supply canal to the storage basin, the second lift pumping plant, and to the laterals serving the gravity-fed lands of the division. The main canal has a total length of 17.6 miles. From the river pumping plant, the canal extends northward 5.3 miles to a siphon crossing of the Arroyo Colorado and the storage basin and then extends 12.2 miles to the north boundary of the division.
The siphon crossing of the Arroyo Colorado is the only major structure on the main canal and consists of a monolithic concrete box 450 feet long, 7- by 7-feet inside dimensions, with inlet and outlet transitions about 15 feet long. The system of laterals is laid out to conform to the water-service units created by topographic features of the area. About 68 percent of the lands are served through the second lift pumping plant near the storage basin. After water passes through the plant, service is by gravity . The lateral system consists of 144 miles of laterals and pipeline. A network of 153 miles of drainage ditches and the Tio Cano drainage pumps serve the district land.
The Mercedes Division occupies the southeast corner of Hidalgo County, Texas, and a strip 7 miles long in the western part of Cameron County. It includes the towns of Mercedes, Weslaco, Elsa, Edcouch, several suburban areas, and rural centers of population. The division encompasses 90,000 acres of land, including about 72,000 irrigable acres. Rehabilitation of the diversion and distribution system involved lining 136 miles of canals and laterals, repairing 94 miles of presently lined canals and laterals, placing 21 miles of pipeline, repairing or replacing structures as required, repairing or replacing pumping installations, enlarging the existing storage and desilting basin to a capacity of 4,500 acre-feet, cleaning vegetative growth from all unlined canals and laterals, and providing maintenance roads.
Drainage system work included clearing and cleaning of all drains and ditches, enlarging or replacing drainage structures, and providing maintenance roads along 250 miles of drainage system. Water to serve the division`s land is diverted from the Rio Grande about 7 miles south of Mercedes, Texas, to the pumping plant through an inlet channel 1,200 feet long and 100 feet in average width. All of the water diverted from the river is lifted at the main pumping plant approximately 20 feet from the inlet channel to the distribution system. Several relift pumping plants serve the higher lands. The distribution system consists of 13.5 miles of canals, 6.5 miles of unlined laterals, 53.8 miles of concrete lined laterals, and 248.9 miles of concrete pipelines. A diked area just north of the river pumping plant serves the division as a storage and desilting basin. Releases to the main canal are made through a gated control structure. The main canal serves the laterals on the gravity-fed lands and the North Weslaco Relift Pumping Plant.
There are three major structures on the main canal. At the crossing of the main floodway, there are two separate reaches of siphon with a 1,000-foot earth canal section intervening. Both of these siphons are of monolithic fourbarrel construction; each barrel is 7 feet 9 inches in diameter. The Anacuitas Arroyo is crossed by a 416-foot continuous concrete U-section flume 6 feet in depth and partitioned into three channels, each of which is 5 feet 10 inches in width. A 750-foot-long, 12-foot-diameter concrete pipe conveys the main canal across Lake Campacaus and the north floodway. The division`s drainage system consists of a 250-mile network of drainage ditches connected with outflow channels to the main and north floodways. Six drain pumps lift the collected drainage flows to the floodways.
First permanent settlements in the Lower Rio Grande Valley were established by the Spanish Crown in 1749 to secure its claim to the territory. Early agriculture was restricted to subsistence crops since transportation to outside markets was not available. Livestock raised on the open range were driven overland or to ports for marketing outside the valley. Land grants followed in a few years and settlement expanded, although limited to scattered small farms and ranches. Construction of a railroad southward into the valley in 1904 opened a market for agricultural products and initiated a period of intense land development and agricultural expansion. Settlement of the present La Feria area was started about 1908 by La Feria Mutual Canal Company. Small tracts of land were sold by the company to farmers with the agreement that they would purchase their water at an annual rental. Three years earlier a similar sales program had been started by the American Rio Grande Land and Irrigation Company in what is now the Mercedes Division area.
Since 1896, various groups have made numerous investigations of the water supply, soils, drainage (surface and subsurface), and flood-control problems of the Lower Rio Grande Valley. Necessarily, the more recent studies have been primarily concerned with problems of ensuring the availability of an adequate water supply to the valley, delivery of that supply to the land, and removal of excess water to assure continued productivity. The boards of directors of La Feria and Mercedes Divisions recognized that the irrigation systems were almost a half century old, that operation and maintenance costs were mounting rapidly, that the flow of the Rio Grande had been over appropriated, and that the then-existing facilities were not making the most effective use of the water available, and requested that the Bureau of Reclamation make a general investigation. In accordance with the request and under a program jointly financed by those interests and the Bureau of Reclamation, four alternative diversion plans to deliver Lower Rio Grande flows to existing distribution systems were studied. A report on the investigations, dated May 21, 1954, found all plans feasible and recognized the need for rehabilitation of the existing distribution systems and for construction of main drain outlets. A plan of rehabilitation for the Mercedes Division was completed in January 1956, and for La Feria Division in January 1957. Definite plan reports for both divisions were prepared in April 1959 and July 1960, respectively.
The Mercedes Division was authorized by Public Law 85-370 (72 Stat. 82), approved April 7, 1958. La Feria Division was authorized by Public Law 86-357 (73 Stat. 641), approved September 22, 1959.