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Inc <br />Mr. Kim Lawrence <br />July 7, 1998 <br />Page 4 <br />3. REPL4CEMENT WATER <br />Replacement water for depletions associated with mining from Sections 1 and 2 will consist of leased <br />water from Stromquist Farms and non-irrigated grass consumptive use credits associated with the land <br />being mined just north of Weld County Road 24 and just east of Weld County Road 93/0. Hall-Irwin <br />has available for its use the water rights that historically irrigated the Booth Land and Livestock <br />Company farm. These water rights, however, are not part of this substitute supply plan. Enclosed is a <br />map (Appendix C) that shows: 1) the fields within the mine property, 2) the ditch water used to irrigate <br />each field, and 3) the crops grown on each field. Table 5 summarizes the water rights owned by the <br />Booth Land and Livestock Company. In the future it is likely that Hall-Irwin will utilize a portion of the <br />water rights listed on Table S as replacement sources for a substitute supply plan and/or as <br />augmentation replacement sources for a permanent augmentation plan. <br />The field where the Section 1 pit will be mined was a 27.2 acre non-irrigated grass field. Mr. Don <br />Hepp, who has farmed portions of the Booth farm since 1967, confirmed that this field has a high <br />groundwater table and that no irrigation water has been applied to this field. The gross potential <br />consumptive use of pasture grass was computed using the Blaney-Griddle Methodology for the years <br />1950 through 1996 and weather data from the Longmont 2ESE Station. The results of the Blaney- <br />Criddleanalysis are summarized on Table 6. The average annual potential gross consumptive use for <br />pasture grass between 1950 and 1996 was 26.5 inches. <br />Based on results from the Colorado Springs non-irrigated lysimeter tests, we conservatively assumed <br />that 90 percent of the precipitation was effective in meeting the potential consumptive use water <br />requirement of the non-irrigated grass. The monthly effective precipitation was then computed as the <br />minimum of: 1) the monthly gross potential consumptive use of grass, or 2) 90 percent of the monthly <br />precipitation. Thus, of the 13.37 inches of average annual precipitation, 9.36 inches is effective in <br />meeting the potential consumptive use for grass. Table 7 summarizes the consumptive use credit <br />computation for non-irrigated pasture grass when gravel mining occurs. <br />Included in Appendix D for your reference is a copy of an aerial photograph of the Booth farm taken <br />in the fall of 1997, which demonstrates there was grass growing on the 27.2 acre parcel. Mining of the <br />Section 1 pit will remove approximately 12.5 acres of the 27.2 acre grass field. Thus, an average <br />annual credit of 9.75 acre-feet (12.5 acres * 9.36 inches/12 inches/1 foot) will be used to offset gravel <br />mining depletions associated with Section 1 mining. Mining of the Section 2 pit will remove an <br />additional 7.6 acres of grass from the 27.2 acre field. Thus, the total average annual consumptive use <br />credit for grass increases from 9.75 acre-feet during mining of the Section 1 pit to 15.68 acre-feet <br />during mining of the Section 2 pit. <br />The net depletions at the Hall-Irwin Shores pit will be the total depletions associated with gravel <br />mining less the consumptive use credits attributable to non-irrigated pasture grass. The net depletions <br />for the Section 1 gravel pit mining operations are summarized on Table 8 and the net depletions for -- - -- <br />Section 2 gravel pit mining operations are summarized on Table 9. <br />Since the gravel mining operations are approximately 5,100 feet away from St. Vrain Creek (wash <br />pond to St. Vrain Creek), a stream depletion analysis (Appendices E and F) using the.State Engineer's <br />