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Steamboat Sand and Gravel Pit SWSP Page 4 of 8 <br />March 11, 2015 <br />was 126 acres for the Weiskopf Ditch. The crop irrigated by the ditch was entirely pasture grass. <br />The consumptive use credit associated with the Weiskopf Ditch was calculated using the <br />Modified Blaney - Criddle Method with daily temperature and precipitation data from the nearby <br />Steamboat Springs weather station. TR -21 crop coefficients were used in the Blaney - Criddle <br />analysis. The ditch loss was assumed to be 10% for the Weiskopf Ditch. The maximum <br />irrigation efficiency was assumed 50% reflecting the flood irrigation practices historically used in <br />this area. Based on the soil type and effective root depth, the available soil moisture capacity of <br />the field irrigated under the subject ditch is estimated to be 0.125 inches /inch. The average <br />annual historic stream depletions that occurred due to irrigation of the acreage under the <br />Weiskopf Ditch are estimated to be about 137.74 acre -feet, or 1.09 acre- feet/acre (Table 6). <br />However, as noted above, Alpine does not propose to use any dry-up consumptive use credits <br />under the Weiskopf Ditch during the requested SWSP period, but may propose to utilize dry -up <br />consumptive use credits in future SWSPs. <br />The dry-up areas are in close proximity to Grouse Creek and the Yampa River. These <br />areas are underlain by alluvial sand and gravel deposits which have a high transmissivity of <br />ground water. Therefore, for purposes of this SWSP, you assumed that 100 percent of the <br />historical return flow will accrue to the stream system within the same month that water is <br />applied to the ground, which is consistent with the determination made in the decree in case no. <br />2OO8CW94. <br />Conditions of Approval <br />I hereby approve the proposed substitute water supply plan in accordance with § 37 -90- <br />137(11), C.R.S., subject to the following conditions: <br />This plan is approved with the effective date of February 1, 2015 and shall be valid <br />through January 31, 2016 unless otherwise revoked or modified. If this plan will not be <br />made absolute by a water court action by the plan's expiration date, a renewal request <br />must be submitted to this office with the statutory fee (currently $257) no later than <br />December 1, 2015. <br />2. Well permit 76189 -F was issued for the gravel pit in accordance with § 37 -90- 137(2) and <br />(11), C.R.S., on June 28, 2012, and remains in good standing. <br />3. The total surface area of the groundwater exposed at the Steamboat Sand and Gravel <br />Pit site must not exceed 1 acre in the dewatering trenches, which results in a maximum <br />evaporative annual loss of 1.94 acre -feet. <br />4. The annual water used for dust control at the Steamboat Sand and Gravel Pit site shall <br />not exceed 1.38 acre -feet, the total product mined at the Steamboat Sand and Gravel Pit <br />site shall not exceed 200,000 tons per year, which results in 2.94 acre -feet of water lost <br />with the mined aggregate, and the total amount proposed for irrigation uses shall not <br />exceed 1.16 acre -feet. <br />1313 Sherman Street, Room 821, Denver, CO 80203 P 303.866.3581 F 303.866.2223 www.water.state.co.us �; • G =' �• <br />',1876 `' <br />