Exhibit B

To accompany memorandum dated August 23, 1964. COLORADO RIVER SALENITY PROBLEM ESTIMATED SALINITY AT NORTHERLY BOUNDARY - REDUCTIONS IN MEXICALI IRRIGATED AREA UNDER VARIOUS OPERATIONS OF DRAINAGE IN THE WELLTON-MOHAWK DISTRICT assumed Drainage Operations Wellton-Mohawk District°ellton-Mohawk Drainageœolorado River @ Northerly Boundary«eduction in Irr. Area, Mexicali Valley. P. P. M. Tons¬alt. Balance©. P. M.­otal…25 Increase Over Salt…20Acre…25 Reduction…25 Reduction to Index¬ummer Winter Tons Balance©rior 1961¬alt Balance 1. Prior to 1961 conditions no drainage from the District.…9900 900 1,640,000 2. Tile Drainage Effluent - 2, 320 ppm’,320 550,000 1.0:1‘,130 1,180 2,150,000 0Ÿrom 1961 Conditions 18,000 4 0 3. Tile Drainage Tile Effuent“,000 ppm Mesa Wells“,000 ppm“,000 710,000 1.3:1‘,240 1,280 2,330,000 8Ÿrom Salt Balance Conditions 8,000 6 2 4. Tile Drainage Tile Effluent”,000 ppm Mesa Wells: Summer“,700 ppm Winter“,100 ppm“,810 910,000 1.6:1‘,330 1,350 2,510,000 17‘4,000 7 3 5. Tile Drainage Tile Effluent•,000 ppm Mesa Wells: Summer“,700 ppm Winter“,100 ppm”,440 1,060,000 1.9:1‘,410 1,420 2,660,000 24’1,000 9 5 assumption: a. Diversion to Wellton-Mohawk would be 450,000 acre-feet annually, salt content 900 p. p. m. b. The annual quantity of effluent from a tile drainage system - 175,000 acre-feet, of which 110,000 acre-feet would come from tile in the Valley and 65,000 acre-feet from wells at toe of Mesa. c. Seasonal distribution of Drainage Returns - 25 percent would return during winter months, 75 percent in summer months in line with the pattern of percolation losses developed in the February 1963 report by U. S. B. R. d. Reduction in Irrigated Acreage in Mexicali Valley due to increased leaching waters necessary to avoid per acre yield reduction with increase in salinity of irrigation water. Percentage reductions refer to the total irrigated area of Mexicali Valley, 443,000 acres in 1963.Microtek ScanMaker 9800XL, 400 dpi, 8 bit, 11,650,048 byte