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representative of large portions of the SPDSS study area. The specific data needed to complete a <br />thorough analysis include the following: <br />• Monthly pumping data (metered records or power records with certified PCCs) <br />• Acreage and crop type information directly corresponding to the pumping data <br />• Estimated application efficiencies <br />• Multiple years of data covering wet/dry/average periods with unrestricted pumping (no <br />quotas) <br />Until such time that more comprehensive data is available, no adjustment for deficit irrigation is <br />recommended. For the SPDSS, pumping should be estimated using the consumptive use <br />approach with a full supply. <br />Comments and Concerns <br />As flow meter pumping data and power data with certified PCCs are collected under some of the <br />newer decreed augmentation plans, a new source of information may become available for <br />investigating deficit irrigation throughout the SPDSS study area. Based on the analyses <br />performed for this task, we recommend a minimum of 5 years of monthly data be collected prior <br />to reconsidering. We also recommend a representative sample of the study area be analyzed, e.g. <br />wells located on the north and south side of the South Platte River, wells irrigating different crop <br />types, wells serving as the sole source versus supplemental supply, etc. <br />References <br />Troutman, Brent M, Edelmann, Patrick, and Russell G. Dash. Variability of Differences <br />between Two Approaches for Determining Ground-Water Discharge and Pumpage, Including <br />Effects of Time Trends, Lower Arkansas River Basin, Southeastern Colorado, 1998-2002. <br />Available online at http://pubs.usgs.gov/sir/2005/5063. <br />Task 77.doc 8 of 8 <br />