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<br />apply the recommended net application having the lowest deep percolation <br /> <br />during each irrigation. <br /> <br />This level can reduce salt loading by 162,000 tons through reduced <br /> <br />seepage from onfarm ditches, and 50,000 tons from reduced tailwater ditch <br /> <br />seepage but will increase salt loading from deep percolation by 43,000 tons. <br /> <br />The net 169,000 tons, a 37 percent reduction in the salt load delivered to <br /> <br />t~e r~ver, can be achieved at a one-time valley-wide installation cost of <br /> <br />$195,000,000. <br /> <br />Level Three (Maximum Efficiency) - This is similar to level two except <br /> <br />for the addition of automation to the onfarm irrigation system. Assuming <br /> <br />semi-automatic control of time of set the IRMA program used three-hour and <br /> <br />one gallon per minute increments of change to derive the time of set and the <br /> <br />flow rate per furrow needed to apply the recommended net application having <br /> <br />the highest irrigation efficiency during each irrigation. At the request of <br /> <br />t~e local people this level of improvement was examined in more detail, <br /> <br />Structural improvements are the same as in level two except for modifi- <br /> <br />cation in design or quantity needed to accomodate semi-automated controls. <br /> <br />This level can reduce salt loading by 162,000 tons through reduced <br /> <br />seepage from onfarm ditches, 112,000 tons from reduced deep percolation, and <br /> <br />60,000 tons from reduced tailwater ditch seepage. The 334,000 tons, a 76 <br /> <br />percent reduction in the salt load delivered to the river, can be achieved <br /> <br />at a one-time valley-wide installation cost of $275,000,000. <br /> <br />Level Three (Minimum Deep Percolation) - This is similar to level two <br /> <br />except for the addition of automation to the irrigation system. Assuming <br /> <br />the use of semi-automatic controls the IRMA program used three-hour and one <br /> <br />gallon per minute increments of change to derive the time of set and flow <br /> <br />rate per furrow needed to apply the recommended net application having the <br /> <br />lowest deep percolation during each irrigation. <br /> <br />001215 <br /> <br />II-12 <br />