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. and corresponding lower pumping rate. In this situation, water level in the well has dropped to the bottom of the screen and the well is unable to produce at the desired production rate, even though there is still water in the cell. In order to achieve the desired production, additional wells will need to be installed, each pumping at a lesser rate, with less drawdown at the wells. . To perform a preliminary analysis of pumping costs, we need estimates of pumping water levels in wells to calculate lift and to project when additional wells may be required to meet the proposed pumping rates. For the deeper aquifers, installation of supplemental wells can be expensive. For planning purposes, the number of wells and timing of installations are both important. Methods to approximate water levels in pumping wells based on water levels in model cells are described in Trescott et. al (1976) and Prickett (1967). These methods are limited to strictly confined or unconfined conditions. In the Denver Basin, we expect aquifers to start under confined conditions and then convert to unconfined conditions as pumping progresses. It is not clear how to treat this with the existing analytical methods. 5.0 Overview of Analytical Approach The Arapahoe aquifer is a prime water producer over much of the basin. We have concentrated our analysis on this aquifer. Three well sites were chosen for detailed analysis. Well information is presented in Table 5,1 and well locations are shown in Figure 5.1. Wells have been chosen in several areas of the basin so that results can be applied to other wells. Our analysis uses the results of Banta's SIMGRO simulation to establish regional water levels over time. In order to produce a consistent analysis, we have used the pumping rates from Banta's model in our analysis of pumping water levels. At each site. the analysis included the following steps: . J. Determine simulated pumping rates for the sites from Banta (1989). 13