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<br />44 <br /> <br />Salinity concentration of the drain flow in the 70's averaged <br />about 3600 mg/L, During 1978-1988 an irrigation efficiency <br />improvement program reduced the inflow about 100,000 acre-feet, <br />reduced farm delivery about 100,000 acre-feet, and reduced the <br />drain flow about 100,000 acre-feet, <br /> <br />The salinity concentration of the Colorado River at Imperial Dam <br />changed from about 900 to 685 mq/L and the drain flow changed <br />from about 3600 to 3100 mq/L in 1980 and has remained almost <br />constant till 1989 (Figure 1). <br /> <br />The objective of the irrigation improvement project in Wellton- <br />Mohawk is to reduce the volume of return flow to a desalting <br />plant treating drainage flow, The salt budgets are only shown to <br />illustrate what happens to salt loading and salinity <br />concentration when irrigation improvement are made, A simplified <br />water and salt budget for the Wellton-Mohawk Irrigation Project <br />displays the significant reduction in return flow (about 50%) and <br />reduction in salt pickup in the drain flow (70%) due to <br />irrigatiop improvements: <br /> <br />1970-1977 1978-1988 <br />Water Salt Water Salt <br /> mg/L mg/L <br /> 850 685 <br /> 3600 3150 <br />ac-ft tons ac-ft tons <br />----- ----- <br />500,000 600,000 400,000 370,000 <br />210,000 1,030,000 120,000 520,000 <br /> 430,000 150,000 <br /> <br />Inflow(Imperial) <br />Outflow (Drain) <br /> <br />Inflow Diversion <br /> <br />Outflow Drain <br /> <br />Salt Pickup <br /> <br />----------------------------------------------------------------- <br />