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0 On -Site Hydrologic Effects: <br />Programs capable of reducing average annual target flow shortages by 7,000 ac -ft/yr have <br />been evaluated for each water management alternative: conservation cropping, deficit <br />irrigation, land fallowing, and on -farm changes in irrigation techniques. Each of these <br />projects has been analyzed independently of each other. Ultimately, only one of these <br />projects or a combination of these projects would be implemented for a total yield of <br />7,000 ac -ft/yr in accordance with Nebraska's estimate of the maximum yield attributable <br />to water management that could be available to the Program. <br />Estimates of on -site yield and timing were based on the Final Report. Each water <br />management alternative is described in more detail below. <br />Option 1: Conservation Cropping <br />The representative conservation cropping program evaluated focuses on a conversion <br />from continuous corn cropping to an alternating rotation of corn and soybeans. The <br />distribution of land involved in conservation cropping in each reach was based on the <br />distribution of acres irrigated with surface supplies. The number of acres that were <br />assumed to be included in a conservation cropping program are summarized in the <br />following table. The acreage is based on the assumption that the full water supply and <br />associated reductions in consumptive use consist of storage water. Many acres below <br />Lake McConaughy receive storage water primarily as a supplement to natural flow <br />supplies. To the extent that storage is used to supplement natural flow supplies, the <br />acreage included in a conservation cropping program and the yield it can produce may <br />need to be adjusted. This applies to all water management options. <br />Table III -7 <br />Conservation Cropping Program <br />Reach <br />Acres Included in <br />Program (ac) <br />16 <br />3,200 <br />17 <br />7,200 <br />18 <br />9,300 <br />19 <br />11,000 <br />Total <br />30,700 <br />Although a significant portion of the acreage included in this program is in reaches 18 <br />and 19, which are within or near the end of the critical habitat, the savings in <br />consumptive use may be stored in the EA as space is available. Releases from the Lake <br />McConaughy EA will flow through the entire critical habitat, therefore, the yields have <br />not been discounted. This applies to all water management programs. <br />On -farm consumptive use savings from implementing an alternating corn and soybean <br />rotation are estimated to be three inches per acre per year. The tables below show the <br />proposed average monthly reductions in diversions and the reductions in on -farm <br />deliveries for each reach. Although the reductions in diversions were assigned to a reach <br />\\DN00 \E- DRIVE\PROJECTS\Platte \Work Products\Task 9 \wapc report (Version 7).doc 24 <br />