Summary Table of Credits and Lease Payments for 2007

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Readme page for spreadsheet < Colorado PRRIP water accounting 1- 15- 08.x1s> Explanation of Computations, Inputs, and Results for Colorado PRRIP (Platte _ River Recovery Implementation Program) Accounting Procedures for Both Tamarack 1 (shortage reduction at Grand Island) and Colorado's Plan for Future Depletions -CPFD (deficit replacement in May and June) This excel spreadsheet computes Colorado PRRIP water accretion credits and leases from existing augmentation plans according to PRRIP Tamarack I and CPFD accounting procedures. Accretions are groundwater returns to the river resulting from prior recharge. Accretions are computed by the AWAS - Alluvial Water Accounting System model (Glover alluvial aquifer) available from the CSU -IDS website at: http: / /www. ids .colostate.edu /index.html? /projects /splatte/ The basic process for Tamarack 1 is diverting water to groundwater recharge during times of excess to target flows at Grand Island and retiming that water through delayed groundwater returns /accretions into times of shortage at Grand Island. The basic process for CPFD is diverting to groundwater recharge excess waters resulting from Colorado population growth and retime that water through delayed groundwater returns /accretions into times of deficit under CPFD. The times and amounts of excess and deficit for CPFD have been determined by a PRRIP accepted procedure /spreadsheet. An important point is that two separate analysis are done to determine credits for Tamarack 1 and CPFD. Some of the same acre -feet of net recharge are input for both analysis but on the output side where credits for Colorado's PRRIP are determined, the credits for Tam I and CPFD are in separate months with no overlap in a given month. The computations are done in this excel spreadsheet called <Colorado PRRIP Water Accounting >. The Setup page of the spreadsheet is where the following inputs are inserted. Blue outlined blocks and blue text reference areas where inputs. Section A: % days excess in a month at Grand Island, NE as determined from USFWS analysis of actual USGS Platte River flows at Grand Island, NE compared to USFWS target flows. Excess flows are on those days when actual flows are greater than target flows with target flows increased by 10% to account for inaccuracies (i.e., icing) in gage flows. Section B: Monthly acre -feet of accretions from the CPFD spreadsheet that utilizes population increase and water sources. Section C: Monthly acre -feet of net recharge (gross diversion minus pond evaporation) diverted by recharge wells at the CDOW Tamarack Ranch State Wildlife Area for CPFD credit. This was dedicated pumping for CPFD and utilizes first the CPFD accretions listed in Section B before distributing the remainder of Section B to individual recharge /augmentation plans. Section D: % days shortage in a month at Grand Island, NE as determined from USFWS analysis of actual USGS Platte River flows at Grand Island, NE compared to USFWS target flows. Shortages are on those days when target flows are greater than actual flows with actual flows increased by 10% to account for inaccuracies in gage flows.