Contents - Previous - Next

This is the old United Nations University website. Visit the new site at

9. Field excursion reports

Local Excursions

Excursion to the Papago Indian Reservation

On Friday 5 January, the Working Group visited the Papago Indian Reservation west of Tucson. Serving as guides were Mr. Bill Tatom, Project Officer, Sells Agency, Bureau of Indian Affairs, Professor Gary Nabham, Department of Plant Sciences, University of Arizona, and Professor Agnes Aamodt, College of Nursing, University of Arizona, an anthropologist who lived for one year in one of the Indian villages passed on the excursion.

The Reservation has been established on what was always Indian land and covers 1.2 m ha. Its government centre is at Sells (Fig. 2). The route passed through Sells, stopping first at the Papago Cattle Development Station five kilometres beyond it. Here the party was met by Mr. Cecil Williams, Chairman of the Tribal Council, who spoke to the group about their problems and achievements.

The present population of Papago Indians is about 12,000 on the Reservation and 4,000 off it, with 94 per cent full bloods. The population shows a very high rate of natural increase, 2.8 per cent per annum, and more than 48 per cent of the population is aged below 18 years. Unemployment is high, around 40 per cent, but was considerably higher before the implementation of federal aid programmes over the past five years. Out-migration to the city is significant, particularly among the young, although many return. There has been a big increase in federal government funding over the past five years and the present estimated annual grant is US$15 million, or about US$1,000 per head.

Fig. 2. Post-meeting excursion to irrigated lands in southwestern Arizona

The community is divided into 11 districts, and the chairman and vice-chairman of each district committee serve on the Tribal Council. However, the administration of the Reservation rests with the Bureau of Indian Affairs, most of whose officers are "Anglos," and federal administrative policy is sometimes seen as being in conflict with individual Indian rights.

Up to five years ago much of the Reservation was remote, but there are now many paved roads, and road and housing construction is carried out by the Reservation's own construction company. Many of the houses seen incorporated traditional elements, such as screened off areas for outdoor living. Modern construction of rammed earth and cement walls has developed from the original adobe materials.

Most of the Indians still speak the Papago language although many cultural traits have been lost. They retain valuable knowledge of the uses of desert plants, and gathering food, for example fruit and blossoms of the saguarro cactus, used for ceremonial wines etc., remains important. The use of native vegetation is regulated by tribal ordinances which determine where plants can be picked; for example certain villages have traditional areas.

Discussions with the Project Manager at the Cattle Development Station focused on problems of range management. There are grassland communities within the desert shrubland pastures, but these have been decreasing over the course of time under livestocking. The range is communally owned, but livestock are under private ownership and 90 per cent of the cattle are owned by 10 per cent of the population. Large feedlots have been constructed at the station, and the Indians grow their own hay and forage crops. The station provides a cattle-marketing facility and in addition offers training programmes for farm mechanics, agricultural managers, extension officers and veterinary aides. There was some discussion concerning possible conflict between the traditional culture and changes in attitude induced by training and development programmes. Much of the capital for this project has come from federal funding, but there remains a shortage of operational money. A giant US$5 million eggmarketing project is being considered.

The original Papago settlements were dependent on floodfarming where, in good years of several floods, crops were watered by diverting floodwaters out of a wash across the field. To increase economic stability and improve water supplies, the Papago Farms were established in the far west of Pima County near the Mexican border. These are sited on a main wash coming in from Mexico and supported by a large groundwater reservoir which extends across into Mexico, where it is also exploited by Mexican Papagos. The principal crops grown under supplemental irrigation are cotton, grain sorghum, and wheat. The farms also have an experimental plot of jojoba, the native plant which produces a bean rich in oil rivalling that of the sperm whale in quality.

On the way to the farms the party passed the village of Schuchuli which is now dependent on solar power. A photovoltaic cell system providing 17 kwh of electricity was installed by NASA at a cost of between US$300,000 and 400,000. Besides providing domestic lighting and power for pumping, it works several small refrigerators and the community washing and sewing machines. The project is an interesting example of problems of communication between technicians and local villagers in introducing a new technology. Apart from initial maintenance problems and teething troubles, a lack of understanding of the facility and its limitations by the villagers has led to some disappointments, notably over restrictions on the amount of power available.

After a stop at the Quijotoa trading post, where Papago and other native American artifacts, notably traditional basketware, are sold to tourists, the party headed north into new territory. A detour through Santa Rosa showed one of the larger Papago communities, which has a boarding school for children from remote villages. This was an area of floodfarming up to the last decade, involving the diversion of summer floodwaters over adjacent fields.

The route north passed by the Lakeside Copper Mine, from which the Papago community receives royalties, but which is temporarily closed because of low prices.

The last stop was at the Tat Momolicot Dam on the Santa Rosa Wash, which supports large-scale commercial agriculture as at the Papago Farms.

Excursion to the Environmental Research Laboratory

A half-day field excursion on Monday 8 January included a visit to the Environmental Research Laboratory of the University of Arizona. The laboratory, under the direction of Professor Carl N. Hodges, became well-known for the development of cheap inflatable plastic greenhouses in which a controlled saturated atmosphere can be maintained by evaporating seawater or other salt water. In this way the water requirement of plants is reduced by about 90 per cent, which makes desalinization of seawater a much more economic proposition as a supply. Intensive production of a wide range of fruit and vegetables has been developed on a commercial basis in these structures, which have been built by the laboratory for Abu Dhabi and other extreme-arid countries.

The party then journeyed south from Tucson to the "Continental Area." named after the Continental Rubber Company which grew guayule for rubber there during the Second World War. Like jojoba, guayule is a native desert plant with very low water requirements. The Continental Area is now occupied by extensive pecan orchards under irrigation along both banks of the Santa Cruz River. The economic, social and political aspects of the pecan orchards, and of irrigated agriculture in general in the Tucson region, were the basis for interesting comments by Dr. Thomas W. Maddock, Jr., who was the guide for this portion of the excursion.

Post-meeting Excursion to Irrigated Lands along the Salt, Gila and Lower Colorado Rivers, 10-12 January 1979

On Wednesday 10 January, about 20 members of the Working Group left on a three-day excursion to examine problems of irrigation forming in southwestern Arizona. Their guide, who added very greatly to the value of the excursion, was Dr. Thomas W. Maddock Jr., a native Arizonan who has spent some 40 years working for the United States Government in irrigation development and water management. During that period he was employed by the Water Resources Branch of the US Geological Survey and by the Bureau of Reclamation, where he became Director of Research. Since his retirement he has been a research professor with the Department of Hydrology at the University of Arizona. Dr. Maddock has provided the report on which this account is largely based.

The party drove northwestwards from Tucson into the valley of the Santa Cruz River (Fig. 2). The area is the site of the Cortaro Farms Irrigation Project, one of the first major irrigation projects in Arizona based on pumped groundwater, which has been in continuous operation since about 1916. It was hard hit by the agricultural depression of the 1920s, and was then taken over by the bond holders, since which time the project has been financially successful. Until the 1940s, power for pumping was provided by a project owned steam plant. The original depth to watertable was probably less than five metres, but is now much greater.

On the descent from the Picacho Pass leading into the Casa Grande Valley, evidence of ground subsidence caused by lowering of the watertable through pumping could be observed. At the railroad junction of Picacho, the excursion headed north along Route 87 through the Randolph Irrigation District, once dependent on pumping water using electrical power and now largely abandoned. Being situated on a very slight rise between headwater tributaries of the Gila River, it receives no recharge from irrigation water or from floods in the watercourses which head in the mountains to the northeast.

North of Randolph, a visit was made to the Casa Grande Ruins, remains of pre-Columbian dwellings in an area that was formerly irrigated from the Gila River. In the 1920s this area was covered with a dense growth of phreatophytes, mostly mesquite, that have now disappeared with the advent of pumping and lowering of the watertable.

Further north, the route followed the upper Gila River, through an area irrigated by its waters. This is an Indian irrigation development, being part of the Gila River Indian Reservation.

At the headquarters of the Salt River Project at Tempe, there was an audio-visual presentation of the history of the Project. This scheme originated in 1903 when the founders of the Salt River Valley Water Users' Association pledged their lands as collateral for a loan to build Roosevelt Dam and related facilities. The project, which began as an irrigation district, is now an organization in which electric-power generation by hydra and thermal plants greatly exceeds in importance water management for irrigation. A portion of the revenues from the provision of electric power goes to support water operations, thereby keeping water costs low. The provision of domestic and industrial water supplies has become increasingly important with the marked growth of Phoenix since the Second World War, and much irrigated land has gone out of production through competition for urban land use and the increasing costs of pumping from a falling watertable. Under a contract between the City of Phoenix and the Salt River Project in 1952, the City pays the Project the annual assessment for urban acreage which is no longer irrigated, and the water to which this urban acreage was entitled is in turn delivered by the Project through its transmission system to the Phoenix Water Filtration Plant.

The Case Grande drainage and the headwaters of the Salt River system have built up an enormous area of alluvium from which rise small mountain chains. From the northwest, several washes draining alluvium-filled tectonic basins converge on the Gila River where it enters a more incised course above Gila Bend. The alluvial tracts end here, at the Gillespie Dam. The annual run-off from this area is close to 2500 x 106 m, all of which is used for irrigation except in infrequent sequences of years of high rainfall, when reservoirs overflow. In addition, an equal amount of groundwater is pumped annually for irrigation.

The Gillespie Dam is a diversion dam built around 1920 to replace an earlier structure built around 1890, but irrigation began in this region as early as 1865. All the favourable sites above Gillespie Dam, the lowest diversion site, had been identified and occupied by 1895, and the alluvial lands were fully appropriated for irrigation by 1928. With increasing discharge of waste water from the growing urban complex, important changes are taking place in the hydrological balance downstream from Phoenix. The small irrigation systems below the Agua Fria are expanding, as the urbanization of the Salt River Valley increases and with it the return from the single major sewage-disposal plant in the very lowest part of the valley. On the other hand, groundwater levels continue to fall in the upper part of the valley.

From Gillespie Dam, the route passed south through the Gillespie Irrigation District, where cotton is the principal crop but which also has some important cattle-feeding operations. From Gila Bend, the excursion then passed directly through the desert to the lower Colorado River and Yuma.

On the second day, guided by Mr. Edward M. Hallenbeck, Director of the Yuma Project of the US Bureau of Reclamation, the party drove through part of the Yuma Mesa Irrigation Project, sited on a terrace above the floodplain and using water pumped from an irrigation system heading at Imperial Dam on the Colorado River. The group then passed through the Yuma Irrigation Project in the floodplain, which receives gravity-fed water from the Colorado River, and continued south to the Mexican border. Here the party saw the installations for the protective and regulatory groundwater pumping programme which extends on both sides of the border in the vicinity of San Luis. Approximately 46,000 m of groundwater will be pumped by the United States towards its share of the water historically delivered as treaty water to Mexico across the Arizona Sonora border.

After travelling along the eastern levee of the Colorado River, which in this sector was dry, the party reached the Morelos Dam, where water is diverted to the Mexicali Valley of Mexico.

Under the Treaty of 1944, the Mexican share of the Colorado River flow was established at 1850 x 106 m per year but, after 1961, with reduced flows in the lower Colorado River and the return of saline irrigation drainage water from the WelltonMohawk Project, the water reaching Mexico had become so saline as to create an international problem. The most saline water can now be bypassed above the Morelos Dam to the Santa Clara Slough at the head of the Gulf of California, but in order to meet its obligation to Mexico, and in the face of water shortage in the Colorado Valley, the United States is preparing to build a desalting plant near Yuma at a cost of US$200 million and with an annual operating cost of US$10 million. This will allow it to meet an agreement, under Minute 242 (1972), that water supplied to Mexico shall be within 140 ppm of the salinity of water at Imperial Dam. Near Morelos Dam the excursion passed the site for the proposed desalinization plant, and the party then visited the pilot plant for an extensive tour of the facility and its control-test mechanisms.

The party then drove upstream to imperial Dam, the takeoff point of the All-American and Wellton-Mohawk canals and the lowest US diversion on the Colorado River. The party crossed the river here and visited the sluice works and desilting basins.

The third day was devoted to a visit to the Wellton-Mohawk Irrigation and Drainage District with Mr. Harold Prichett, Project Leader, who discussed various problems in the area. Water diverted at Imperial Dam is lifted through three pumping stations to irrigate land along the lower Gila River between 25 and 70 km east of Yuma. After a precarious early history based on the interception of local floods by the diversion dams, this irrigation area developed on the basis of pumped groundwater but, in the absence of recharge, both water and soil salinity increased rapidly and from 1952 onwards Colorado River water was imported as a solution. With increased recharge from the irrigation water, problems of high watertables and secondary salinization soon occurred and it became necessary to remove the excess groundwater by pumping. This drainage water, which was mainly saline, was discharged into the Gila River and so into the Colorado, where after 1961 it adversely affected the quality of water diverted at Morelos Dam for irrigation in Mexico. Most of this water will now be treated in the Yuma Desalting Plant.

In a tour of part of the Wellton-Mohawk District, participants saw the modern procedures of land levelling using machines controlled by laser beams as part of measures to make more efficient use of irrigation water, and automatic systems of water distribution on the farm operated by electricity

Major crops of the Wellton-Mohawk District include alfalfa hay, shipped to dairies in Los Angeles and Phoenix and to feedlots in central Arizona; hard red wheat of million quality and a lesser amount of barley, both of which can be doublecropped with grain sorghum; Bermuda grass seed; cotton; and truck crops, including lettuce and melons. There is an important demand for seasonal labour from Mexico. There are large cattle feedlots within the area, such as that of the McElhany Cattle Company east of Wellton, and sheep from summer ranges are grazed during the winter months.

After the party left the Wellton-Mohawk Project, a visit was made to Painted Rock Dam, a flood-control structure on the Gila River which protects Yuma and the Wellton

Mohawk Project. The dam is an immense earth-filled structure which had never captured much water before the winter floods of 1978-1979. At the time of the excursion it was holding so much water that the visitors were not allowed to go up on to the dam as planned. This was an indication of the unusually wet conditions in the southwestern United States in 1978 and early 1979. The dam is not simply a storage structure, but continues to pass through a certain amount of water, which can cause problems to local traffic fording the Gila River.

From Painted Rock Dam a direct route was taken back to Tucson.

Contents - Previous - Next