2012-03-30_HYDROLOGY - M1999050 - Laserfiche WebLink

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Mr. Jared Dains Timnath - Connell SWSP March 30, 2012 Page 3 The historical consumptive use of the 4.0 Box Elder Ditch shares used on the John Weitzel property is estimated to be 170.72 acre -feet and the return flow obligations for these 4.0 shares for October through April is 89.52 acre -feet. This quantification is based on the average headgate diversions for the Box Elder Ditch for the years 1950 to 2004 assuming 10% ditch loss and 55% field efficiency. The pro -rata historical consumptive use credit for the 2.5 shares is 106.7 acre -feet and the pro -rata return flow obligation for the 2.5 shares for October through April is 55.95 acre -feet. The expected volume of water available for diversion into the recharge pond is 240.73 acre -feet per year. This figure represents the pro -rata average headgate diversion less a 10% ditch loss. A total of 251.57 acre -feet were diverted into the recharge site during the 2011 irrigation season. Additionally, approximately 51.82 acre -feet of free river water was diverted into the recharge pit in January 2012. The lagged accretions from the Timnath - Connell recharge pond were estimated by the Applicant's consultant using the Alluvial Water Accounting System (AWAS) stream depletion model developed by the Integrated Decision Support Group with the following assumptions: • Distance from the gravel pit centroid to the river (X) = 3,000 ft • Alluvial aquifer width (W) = 5,300 ft • Specific yield (S) = 0.2 • Transmissivity (T) = 50,000 (gpd /ft) The lagged accretions to the Cache la Poudre River are estimated to total 239.85 acre -feet for April 2012 through March 2013 (includes carry over from recharge in previous years). The summer and winter return flow obligations from the 2.5 Box Elder Ditch shares will be maintained by this substitute water supply plan. A monthly breakdown of the stream depletions from the mining operation as well as the replacements made by the recharge accretion credits of the Box Elder Ditch shares are shown in the attached Table 6. Conditions of Approval I hereby approve this substitute water supply plan, in accordance with Section 37 -90- 137(11), C.R.S., subject to the following conditions: 1. This plan is approved with an effective date of April 1, 2012 and shall be valid through March 31, 2013 unless otherwise revoked or modified. If this plan will not be made absolute by a water court action by the plan's expiration date, a renewal request must be submitted to this office with the statutory fee (currently $257) no later than February 15, 2013. 2. Well permit 53419 -F was obtained for the current use and exposed pond surface area of the gravel pit in accordance with § 37 -90- 137(2) and (11), C.R.S. 3. The flow into the recharge site must be metered and equipped with a continuous flow recorder unless the water commissioner, in conjunction with the division engineer, determines adequate records may be kept without such equipment. 4. The total surface area of the ground water exposed at the Timnath - Connell Pit must not exceed 8.0 acres, resulting in 19.5 acre -feet per year of evaporative loss. 5. The total amount of ground water used for dust control shall not exceed 0.8 acre -feet per year and the total product mined at the Timnath - Connell Pit site shall not exceed zero tons per year, resulting in 0.0 acre -feet per year lost with the mined product.