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irrigation applications are required. Tile drains were constructed on 400 acres of mesa lands in 1960-61. During 1962, approximately 3,000 acre-feet of tile drainage effluent was returned to the distribution system. The effluent has a dissolved-solids content of approximately 1,800 ppm, based on electrical conductivity measurements. An undetermined amount of ground water beneath the mesa percolates into the Wellton-Mohawk aquifer under a maximum head of about 60 feet. The elevation of the ground water has stabilized during 1961 and 1962. Outside of the tiled area the depth to ground water is 20 to 70 feet. Thus, the use of additional tile in significant quantity does not appear feasible in the immediate future for recovery of mesa drainage water as a source of dilution water. 2. Projected Improvement in Quality of Ground Water. It was recognized early in the investigational program that the quality of ground water in the Wellton-Mohawk aquifer varies widely. Drawing Nos. 998-303-108 and 998-303-109 show the present variations both vertically and horizontally. During the construction of the 49 test wells which penetrated the gravel aquifer, water samples were obtained at different depths. Of the 49 wells tested, eight showed a marked increase in salinity with depth, and three showed a sharp decrease in salinity with depth. The remaining 38 wells show a general increase in salinity with depth, but to a lesser extent than that shown in the eight wells. Discharges from 69 drainage wells have also been sampled periodically 51Epson Perfection 4870 Photo, 400 dpi, 8 bi