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Executive Summary <br />transferable is an irrigator's historic consumptive use, not the anlount of water diverted. <br />Increasulg irrigation efficiency is likely to reduce losses fronl deep percolation and <br />runoff, but it nlay or may not nlaterially affect the amount of water consunled by the <br />plant. Much of the water lost to these ulefficiencies will return to the river or <br />groundwater system for use by downstream water diverters. The reliance upon <br />irrigation return flows is a coninlon occurrence uz Colorado and downstreanl water <br />rigllts 1lolders that relied upon historical return flows are entitled to protection fronl <br />uljury t11at could occur when a water right is changed. For this reason, the law and <br />customs in Colorado are clear that water nlade available fronl reduced diversions is not <br />available to t11e original appropriator for irrigation of additional acreage or transfer to <br />ofller uses. For agricultural water conservation measures to be successful, these aspects <br />of water in Colorado must be considered. <br />Reductions in crop consumptive use (conserved consumptive use water) only occur <br />when: 1) Irrigated acres are decreased, 2) crop selection is changed fronl a summer crop <br />to a cool season crop, 3) crop selection is cllanged to one with a shorter growing season, <br />4) deficit irrigation is practiced, applying sonle anlount less than full or historical <br />evapotranspiration over the growing season, or 5) evaporative losses fronl the field <br />surface are reduced as a result of conservation tillage, mulching, and or drip irrigation. It <br />is important to recob ize that reducing agricultliral water consumptive use will limit <br />crop yields and may increase producer exposure to risks suc11 as irrigation systenl <br />failure, pests or drought. Implenlenting water conservation nleasures usually results u1 <br />increased equipnlent, labor, aild nlanagenlent costs t11at nlust be borile eifller by fl1e <br />irrigator or by those w11o benefit from the conserved water. <br />Increased and enhanced use of irrigation water conservation measures may be beneficial <br />u1 certain areas of Colorado if the basin scale impacts are evaluated as part of the <br />adoption process. Increased agricultural water conservation could potentially result in a <br />voluntary reduction in the diversion of water to the farm, creatulg benefits such as <br />inlproved water quality, allowing nlore water to renlain in the streams, reduced <br />waterlogging of soils, and reducing energy costs for punlping, but may not result in <br />water that can be legally transferred to other uses. If the use of water conservation <br />nleasures can inlprove water supply availability without causuzg uljury to downstreanl <br />users or t11e environment, then t11e result nlay be improved water supplies for <br />agriculture and other uses. <br />T11e Colorado Ag Water Alliance believes that water conservation is only one <br />conlponent in nleeting Colorado's future water needs. Better use of existing surface and <br />groundwater storage resources and t11e developnlent of new storage to meet fi.iture <br />denlands and for drought years will be required to nleet both existulg agricultural <br />shortages and future M&I demands. In order for agricultural water conservation to play <br />a nleaningful role in meeting the State's future water needs, a nunlber of legal and <br />adnunistrative issues must be resolved and sufficient financial incentives offered to <br />nutigate the increased risk and loss of productive capacity that occur under reduced <br />water supplies. Furthermore, an in-depth basin-by-basin analysis of agricultural water <br />conservation will need to be conducted to gauge the opportwlities to obtain transferable <br />water within tlle constrauzts of our interstate conlpacts and priority systenl. <br />DRAFT ES-2 <br />