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from 1979 through 2003, with around ten to fifteen years of data for any given well. The <br />SEO provided datasets in the form of: <br />• Estimated historical pumping which had been converted from power records <br />using the PCC method with assigned PCCs, and <br />• Theoretical pumping which had been based on a consumptive use analysis (IWR) <br />with acreages and crop types assigned to each well, divided by application <br />efficiencies ranging from 60% to 70%. <br />The historical estimated pumping was divided by the estimated pumping to determine the <br />percent deficit irrigation. A sample of the results is provided in Figure 2 below, with <br />each time series representing results from an individual well (well permit ID's were <br />omitted for confidentiality). These data provided a representative sample of the twenty- <br />one wells that were investigated. As shown, the results did not reveal consistent patterns <br />across years for a given well or by comparing a given year among different wells. <br />zoo% <br /> <br />180% <br /> <br />v 160% <br /> <br />E <br />' <br />a <br />~ 140% - <br />0 <br />E <br />a <br />v <br />120 <br />i <br />s <br />E <br />N <br />W <br />A 100% <br /> <br />U <br />a <br />° so% <br /> <br />- <br /> ` \ <br />°- 60% ~ - <br />0 <br />c <br />v <br />° <br />` <br />40% <br />w <br />a <br />20% <br /> <br />0% <br /> <br />1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 <br />Figure 2. Deficit Irrigation Estimates Using Annual Data Provided by the SEO <br />Conclusions <br />An appropriate data set that could be used to quantify deficit irrigation was not identified. The <br />comparison of pumping records to estimated IWR is sensitive to the crop type, acreage, and <br />application efficiency. While there is consensus that deficit irrigation likely occurs, there is also <br />consensus that it is likely to occur at different levels depending on soil type, climatic conditions, <br />time of growing season, crop type, and whether the well serves as a sole source or supplemental <br />supply. Data is not available at this time to provide a thorough investigation that is <br />Task 77.doc 7 of 8 <br />