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<br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />Drip irrigation is the predominant practice used within the District on bell peppers and mature <br />green tomatoes. It is also used on onions, asparagus, and other high value crops. A typical drip <br />system in the Imperial Valley uses buried drip tape with an expected life of five to ten years. The <br />acreage under drip irrigation could be expanded significantly over four to five years. Drip <br />irrigation systems require an increased level of management from its water users. Typical water <br />orders for drip irrigation systems range from one to five cubic feet per second (cfs) and are <br />accommodated within IID's current rules. <br /> <br />A large increase in the drip irrigation acreage may result in a system capacity problem for IID's <br />operations. A preliminary analysis of six IID laterals indicated that 40 to 65 percent of the <br />irrigated land along anyone lateral could be converted to drip or any other alternative method <br />requiring daily or near daily operation, without causing capacity problems. It was further <br />determined that, based on an average delivery of five cfs for a drip or other alternative irrigation <br />practice (such as a linear tracking sprinkler system), no more than 50 percent of the irrigated <br />acreage District-wide could be converted to methods requiring daily or near daily operation. <br />Simultaneously delivering smaller flow rates to more deliveries will cause capacity problems on <br />most IID laterals. <br /> <br />To determine the potential on-farm water conservation resulting from additional drip irrigation, <br />tailwater for predominant practices on major IID crops were compared to the same values for <br />other irrigation practices. This allowed, the potential water savings to be estimated. IID's <br />Irrigation Management Unit (IMU) provided values for the amount of tailwater occurring with <br />the various irrigation practices used in the Imperial Valley. <br /> <br />The conservation savings attributed to drip irrigation were assumed to equal the amount of the <br />tailwater associated with the particular crop's current irrigation practice. For example, if all the <br />major vegetable crops were converted from their current irrigation practice to drip, a total of just <br />over 80,000 acre-feet per year (0.91 AF/AC) is estimated to be saved. <br /> <br />Draft: Subject To Revision 12/21/95 <br /> <br />47 <br />