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54.2 A memorandum describing the changes over time by county and basin. The <br />memorandum will include a recommendation for crop categories, by county and historic <br />period, to use in the irrigated acreage assessment. <br />Task 58 -Review Previous Estimates of Potential CU <br />Objective: <br />Review and document previously generated estimates of potential crop consumptive use in the <br />SPDSS study area for verification and comparison purposes for the different modeling time <br />periods. <br />Approach: <br />58.1 Gather appropriate data and literature from previous studies of potential and supply- <br />limited crop consumptive use in the South Platte and North Platte River basins. Sources <br />for data include the USGS, the USBR, CSU, LRE's library, and LRE's collection of <br />water right transfer decrees and supporting engineering reports. In addition, supporting <br />documents from other key court cases will be identified and reviewed. <br />Deliverables: <br />58.1 A draft memorandum summarizing historic CU estimates and techniques. The <br />memorandum will include maps showing the geographic areas represented by the <br />estimates. <br />Task 59, 60, 61, and 73 -Collect Applicable Information, Develop Locally Calibrated <br />Blaney-Criddle Coefficients, and Estimate Potential CU at Climate Stations <br />Background: <br />The modified SCSBlaney-Criddle consumptive use methodology estimates potential <br />consumptive use on a monthly basis using monthly average temperature and daylight hours. <br />Because this data is readily available for long study periods, the methodology is widely used and <br />recommended for use in the SPDSS. However, Blaney-Criddle crop coefficients available from <br />the SCS publication Irrigation Water Requirements Technical Release No. 21 (TR-21) were <br />developed to represent general conditions around the west and may not represent local conditions <br />in the South Platte or North Platte River basins. Therefore, consistent with the approach taken <br />for RGDSS, locally calibrated Blaney-Criddle crop coefficients will be developed for SPDSS. <br />Because of the relatively large extent of the SPDSS study area, up to three locally calibrated <br />coefficients maybe required and developed for each major crop type. <br />Objective: <br />Collect/review results of lysimeter studies for development of crop coefficients within the <br />SPDSS study area. Collect/review results of previous studies that developed locally calibrated <br />(including high altitude) crop coefficients. Sources for data include the USGS, CSU, NCWCD, <br />SEO, water court decrees, and LRE's collection of water right transfer decrees and supporting <br />engineering reports. Review the modified Kimberly-Penman monthly analysis methodology <br />developed by Colorado State University for Northern Colorado Water Conservancy District's <br />SPDSS Consumptive Use and Water Budget Component l3 <br />