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. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . included information on the current facilities, the water providers' plans for meeting existing and future demands, and basic planning data such as annual distributions of water supply usage and peaking factors. Water demands are presented in summary form as Chapter 2 of this report. In addition, Appendix 2 contains the data acquisition swnmary reports for each of the eleven providers. A regional ground water model was prepared by Hydrosphere Resource Consultants, Inc. ("Hydrosphere") to predict the decline in regional ground water heads in each of the four aquifers of the Denver Basin over the study period. As described previously, water levels in the Arapahoe Aquifer have been steadily decreasing over the past twenty years, impacting the water supplier's ability to produce water from this resource. Therefore, a major component of this study is to predict the falling regional head in each of the aquifers over time so that estimates can be made of well production in the future. The local well analysis predicts the production rate of each well, based upon the regional head data, and predicted well-to-well interference. HRS Consultants ("HRS") prepared the local well analysis. The local well analysis is a spreadsheet simulation of the production rate in a well, using the Theim approach. The Theim approach recognizes the layering within each aquifer and assesses the production from each layer of the aquifer based on the regional heads. The local well analysis also includes a Theis analysis of the interference produced though adjacent wells. The estimated production rates in each aquifer are then used to predict the number of wells required by each water provider to produce the pumping requirements for each ten-year period. The results of the local well analysis are then input to the infrastructure plan and costing model for each alternative. Modeling of the Denver Basin aquifers is a very difficult issue. The model covers an area of 6700 square miles with limited data, requiring numerous assumptions in setting up and calibrating the model. A Peer Review Panel was established at the beginning of the ground water study to review the work of Hydrosphere in the regional modeling and the work of HRS in completing their Local Well Analysis. This Peer Review Panel met several times with the Consultants during the course of the study, and provided considerable input that resulted in revisions and additions to the Consultants' work that improved the modeling and analyses. The Peer Review Committee included the following members: Brian 1. Ahrens Edward (Ned) Banta John D. Van Bredehoeft George Chadwick John Halepaska John Hendrick Jim Jehn Theresa Jehn-Dellaport David Little Isabel McGowan Scott Mefford Colorado Division of Water Resources US Geological Survey Private Consultant Chadwick Associates John C. Halepaska & Associates, Inc. Centennial Water & Sanitation District Jehn Water Consultants, Inc. Jehn Water Consultants, Inc. Denver Water Private Consultant Hydrokinetics Page 1-18