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One of the more challenging features of the District is its three-dlmensionc',l "geometry", both surface shape and topography, as well as subsurface characteristics. Because of its. long "skinny" configuration, the ratio of miles of ditch to service area is rather high; a shape closer to square or clrcular would be more efficient. The general uphill slope, and rather steep lands adjacent to the Gila River valley made rel ift pumps necessary, and also contributed to potential drainage problems where varying field elevatlons adjoin. At this time, the District is comprised of approximately 57,600 irrigable acres in the valley and 7,400 acres on the mesa. DRAINAGE GENERAL BACKGROUND A very important factor in the appl ication of irrigation water, especially from rlvers dralning semi-arid areas such as the Colorado River basin, is the presence of salt. Unl ike sea water, which has a salt content of 33,~)0 parts per mill ion, the water accumulating beneath irrigated fields may have a salt content of a much lesser, yet highly damaging, concentration. The salts, of many different types, arrive as part of the irrigation water. They have been 'dissolved from natural sources in the soil and rock of the watershed, and wash into streams with each rain or snowmelt. The use of water by growing plant~, whether in a natural or cultivated setting, concentrates these naturally occurring salts. Additional natural salts are added as irrigation water moves through the soil profile to the water table. The Colorado River at Glenwood Springs, Colorado has a sRlt concentratlon of approximately 250 ppm. By the time the river reaches Lake Mead (behind Hoover Daml, its salt content is 7~) ppm. At the present time, this increase is perhaps SOX naturally occurring, and about SOX due to return flows from upstream irrigators and other water users. Irrigated areas must have either natural or artificial drainage to get rid of excess water that would waterlog the land, and also to dispose of the salts which accumulate as a result of the crop's use of the water through evapotranspiration. In sufficient concentration, all salts, even fertil izers, can be injurious to some degree to all plants, to some more than to others. Salt can be tasted in drinking water at a level of about 1500 ppm. NEED FOR DRAINAGE The Bureau of Reclamation did not provide a return flow system as part of the original construction of this project. Although it was anticlpated that one would eventually be