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7.0 IMPACTED STREAM REACHES <br /> The stream reaches impacted by the operation of the project was analyzed and documented in a <br /> memorandum prepared in 2007. Summarized below is the impact stream reach analysis (CDOW, January <br /> 12, 2007). <br /> The following procedure was followed to determine the stream reach impacted by Project operations: <br /> • A modified version of the Revised Tamarack Recharge Model was used as the base model. This <br /> version does not include neighboring operations and maintains a constant ET rate regardless of <br /> depth to groundwater. <br /> • All pre- existing recharge, pumping and calibration data were deleted. Average yearly ET and <br /> precipitation were used for each zone. This model version is a "clean- slate" version of the model <br /> used to estimate aquifer response under specified conditions. <br /> • Zone Budget, a program written by the USGS (Harbaugh, 1990) was used to identify the flows <br /> into and out of the stream boundary. As shown on Figure 3, four stream reaches were created <br /> using Zone Budget: <br /> Reach A (Entire Grid): This stream reach starts approximately 2 miles downstream of the <br /> Harmony Ditch headgate' and ends approximately 2.25 miles downstream of the <br /> Logan /Sedgewick County Line. This stream reach encompasses the entire model grid and <br /> contains approximately 14 miles of stream. <br /> Reach B: This stream reach starts at the western edge of the model grid (2 miles downstream of <br /> the Harmony Ditch headgate') and ends at the Logan/Sedgewick County Line. This stream reach <br /> contains approximately 12 miles of stream. <br /> Reach C: This stream reach starts at the Crook Road (Highway 55) and ends at the <br /> Logan/Sedgwick County Line and contains approximately 9 miles of stream. <br /> Reach D (Tamarack Ranch SWA): This stream reach starts at the Crook Road (Highway 55) <br /> and ends at the Red Lion Road (Road 93). This reach includes the main portion of the Tamarack <br /> Ranch SWA and contains approximately 6.5 miles of stream. <br /> The following scenarios were run using these Revised Tamarack Recharge Model versions: <br /> Scenario 1: All wells pumping their full decreed rate for 90 days. During this model run four of <br /> the recharge wells became dry and stopped pumping. These four wells are all located in the <br /> group of 11 located in the center of the Tamarack Ranch SWA. The pumping rates for these <br /> wells were decreased to allow continued pumping. <br /> Scenario 2: All wells pumping the same rate as in Scenario 1 but for 120 days. This scenario <br /> was run to determine that the well impacts have reached a quasi- steady state by 90 days and that <br /> there are no significant changes if the pumping period is extended. <br /> Scenario 3: Ponds are recharging at the same rate as pumped in Scenarios 1 and 2 but decreased <br /> by five percent to account for evaporation losses. Recharge wells are not operated under this <br /> • <br /> 1 Note this distance incorrectly listed as 0.6 miles in CDOW's April 24, 2004 memorandum. <br /> 16IPage <br />