2013-01-02_HYDROLOGY - M1985026 - Laserfiche WebLink

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Mr. Peter Wayland Challenger SWSP December 31, 2012 Page 2 of 7 System (IDS AWAS) stream depletion model with the following assumptions: • Distance from the centroid to the river; XPond 1 = 642 ft, XPond 2 = 322 ft, Xpond 3 = 263 ft • Alluvial aquifer width (W) = 1,700 ft • Specific Yield (S) = 0.2 • Transmissivity (T) = 67,325 (gpd /ft) The stream depletions model was taken to a steady state condition and show that the stream depletions will equal the yearly evaporation of 52.62 acre -feet at a monthly rate as shown in the attached Table AII.2. Replacement The proposed source of replacement for this pit includes historical consumptive use credit from 7.4 shares of Hill & Brush Ditch water rights from the dry-up of 37 acres of land, and a water lease with the City of Loveland. The applicant has a 25 -year Water lease with the City of Loveland ( "Loveland ") for 100 acre -feet of fully consumable water which is used for replacement purposes for six gravel pits operated by the Applicant, including the Challenger Pit. Loveland will deliver this water to the Big Thompson River approximately 10 miles upstream of the Challenger Pit, at their waste water treatment plant (WDID 0402300). Therefore a transit loss of 2.5% (10 miles @ 0.25% /mile) will be assessed on all releases. Transit losses are subject to change at the water commissioner's discretion. The monthly depletion and replacement requirements, based on an average year are found on the attached Table AII.2. Under the terms of the Loveland lease, replacements can be made using a variety of water owned by Loveland including, but not limited to, Windy Gap reusable effluent, Loveland Storage Reservoir water as decreed in case no. 82CW202A, and Colorado Big Thompson ( "C- BT") Project water. In the event that Loveland plans to use C -BT water as a replacement source, Loveland shall comply with the Interim Rule issued by the Northern Colorado Water Conservancy District ( "Northern District ") in May 2005, regarding the use of C -BT Project water in substitute water supply plans. Prior to the use of C -BT Project water, Loveland is required to notify this office, the division engineer and the water commissioner of the amount of C -BT Project water dedicated to this plan and provide a copy of the Northern District's approval letter as required by paragraph I(g) of the Northern District's May, 2005 Interim Rule. A review of the irrigation practices at Challenger Farm indicates that 20 shares of the Hill & Brush were used to irrigate approximately 100 acres, of which 37 acres have been dried up due to the mining project. The dry up of 37 acres is associated with 7.4 shares of the water right. The average year analysis shows that on an average year the historic net stream depletions as a result of the 7.4 shares are 59.88 acre -feet per year. This would provide a credit of 61.81 acre -feet during the irrigation season, and a return flow obligation of 1.93 acre - feet during the non - irrigation season (see attached Table AII.2). The dry year analysis shows modeled the results of the 2002 irrigation year, which closely resembled the 2012 irrigation year. This analysis showed that on a dry year the historic net stream depletion as a result of the 7.4 shares is only 28.66 acre -feet. This would provide a credit of 33.25 acre -feet during the months of May and June only, and a return flow obligation of 4.59 acre -feet during the remainder of the year (See attached Table AII.3). During a similar future dry year, the current 25 -year lease with Loveland would not be sufficient during the months of July, August, and September. The