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<br />Mrs. Judy Sappington <br />State Engineer's Office <br />August 25, 1992 <br />Page 6 <br />3. Timing of Replacement <br />The site is approximately 300 feet from the Cache La Poudre River. <br />Consequently, the time lag of the depletions to the river was not <br />assumed to be instantaneous. Timing of the depletions was found by <br />using the computer model, 'Analytical Stream Depletion Model', by <br />Dewayne R. Schroder from the State Engineer's Office. <br />Values for the input parameters and results of the computer model <br />are attached with this letter. The well location was assumed to be <br />at the center of the proposed lakes. The impermeable boundary was <br />located on a USGS topographic map. <br />The USGS publication, 'Pumping Tests in Colorado - Colorado Ground <br />Water Circular No. 11' was used to estimate the value of <br />transmissivity. A pump test was done on a well located in Section <br />34, Township 6 North, Range 66 West and the transmissivity was <br />determined to be 120,000 gpd/ft. This same value was used for the <br />evaluation of the subject operation in Section 35. <br />A value of 0.2 was used for Specific Yield which would be typical <br />of an alluvial aquifer. <br />The depletions at the pit were converted from acre-feet per month <br />to gallons per minute for use with the computer model. Table No. <br />5 lists the results from the depletions analysis. The annual <br />depletions at the river for the first year are 6.9 acre-feet. By <br />year five the annual depletions at the river are the same as the <br />depletions at the pit of 19.6 acre-feet. <br />It is proposed in this plan that all replacements are made to the <br />stream during the irrigation season as shown on Table No. 9 as a <br />result of the dry-up of ten acres of pasture grass. <br />D. ADJACBNT HELLS <br />Attached with this letter is a copy of the Permitted and Decreed <br />Water Well Map and list of wells provided with the MLRD Exhibit G <br />information. Wells within quarter/quarter sections which <br />potentially could be within 600 feet of the proposed gravel pit <br />have been plotted on the map. Also provided with this letter are <br />the tabulations for well permits and water rights in the vicinity. <br />Specific locations were plotted if distances from section lines <br />were provided. <br />