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period, or should represent the best available data at key locations in the basin. The <br />SPDSS Feasibility Study estimated approximately 75 key gages. <br />2.2 Fill missing records on a monthly basis for the key streamflow gages using the techniques <br />developed/utilized during the CRDSS and RGDSS modeling efforts. Linear regression <br />with upstream, downstream, or nearby gages was generally used to fill missing data in <br />previous CDSS efforts. <br />Deliverables: <br />2.1, 2.2 A technical memorandum describing the key streamflow gage selection and filling <br />process. The memorandum will include a table of selected key gages, their percent <br />complete, the independent gage used for filling, and the regression statistics <br />(regression equation and r~ value). The memorandum will also include maps showing <br />the location of key streamflow gages. <br />A data file of historic filled streamflow gage estimates (*.rih) formatted for use in the <br />surface water modeling efforts. <br />Tasks 3 and 55 -Identify Key Diversion Structures <br />Background: <br />The goal of the historic crop consumptive use analysis is to account for 100 percent of the crop <br />consumptive use in the basin by representing 100 percent of the irrigated acreage. There are <br />over 8,000 individual irrigation structures in the basin (SPDSS Feasibility Study, October 2001). <br />Therefore, larger structures and structures of administrative importance are represented <br />"explicitly" as key structures, while smaller structures can be aggregated and modeled together <br />without significantly reducing the accuracy of the results. <br />Objective: <br />To identify the key diversion structures accounting for approximately 85 percent of the net <br />absolute decreed water rights in Division 1 and Water District 47 in Division 6. This is <br />estimated to represent approximately 85 percent of the diverted water within each basin. This <br />approach is consistent with the approach used for CRDSS and RGDSS. Key structures will be <br />the focus of the initial service area coverage developed by the GIS contractor. <br />Approach: <br />3.1 Identify initial key diversion structures that account for approximately 85 percent of the <br />net absolute decreed water rights using the methodology developed for CRDSS and <br />RGDSS. The total number of key structures is initially estimated to be approximately <br />320. The following procedure will be used to identify key diversion structures: <br />Identify net absolute water rights per structure. Separate structures by water district <br />(tributary) and rank structures within each water district according to net total <br />absolute water rights. Select initial key structure cutoff value based on the 85 percent <br />recommendation (SPDSS Feasibility Study, October 2001) for each water district. <br />The purpose of ranking by water district allows recognition that structures on <br />tributaries may have smaller total water rights but are key in administration. <br />SPDSS Consumptive Use and Water Budget Component <br />