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Ms. /Dana Comanicru RE. Upper Poudre River SWSP Renewal September 26, 2006 Page 3 of 5 diverted a total of 309 acre-feet into the rechazge site between April 20 and October 2, 2005 and a total of 58.1 acre-feet into the recharge site between April 27 and August 2, 2006 (Table No. 3). Lafazge may only claim up to 240.3 acre-feet for the farm headgate delivery from these shazes. The farm headgate delivery contains the historic consumptive use credit and the winter return flows. Although Lafarge rechazged slightly more and in a different timing than the average farm headgate diversions in 2005, they will only claim up to the previously approved 240.3 acre-feet. During 2006, Lafarge only recharged 58.1 acre-feet, which is approximately 24.2 percent of the required 240.3 acre-feet (58.1/240.3). As shown in Table No. 4, Lafazge reduced the amount of historic consumptive use credit and winter reiurn flows in the rechazge model for 2006 by the same proportion (24.2%* 128.4). The amount used in the model for 2006 is 31 acre-feet, which is a decrease from the average 128.4 acre-feet. Since Lafarge anticipates a full delivery in Water Year 2007, the monthly timing of 128.4 acre-feet was used in the recharge model to determine the lagged timing of the historic consumptive use credit. Augmentation by Recharge Lafarge delivers the full headgate delivery of the 5.75 shares into a rechazge site. A recharge model determines the timing of the lagged consumptive use credit from the shares as it reached the Poudre River. A copy of the recharge model run is included in Appendix D. The recharge model uses the following assumptions: • The centroid of the rechazge site is approximately 2,300 feet from the Poudre River. • The transmissivity is 160,000 gaUday/ft. This value was assumed to be the same as the transmissivity of a pump test well in the area. Source: Groundwater Circulaz No. 11, Loc. B8- 69-27bba. • The specific yield is 0.2, which is typical for an alluvial aquifer. • The location of the pazallel impermeable boundary is a distance of 6,500 feet from a live stream. Source: USGS Depth to the Water Table in the Boulder-Fort Collins-Greeley Area, Front Range Urban Comdor, Colorado. Table No. 5 includes the results of real-time historic consumptive use credit realized by the Poudre River from recharge for Water Year 2007, which is 96.9 acre-feet. Accretions from Dewatering Water The SEO is concerned with the lagged effect to the stream system from dewatering operations and later allowing a groundwater lake to fill. The SEO will allow accretions to the river, which result from dewatering, to be claimed as credit to offset depletions that occur due to the mining operation and the dewatering operation. The Overland Ponds and North Taft Hifl Expansion Sites have now reached equilibrium or steady state conditions and no longer have an accretion to the river that can be claimed as a credit. Appendix E contains a copy of the stream depletion models. The operations at the Home Office Pit have continuously dewatered directly back to the Poudre River since the 1970's. -Due to the long period of continuous dewatering, this site has reached a state of equilibrium or steady state conditions and there is no longer a net accretion to the river. If changes in