2011-12-07_HYDROLOGY - M1981058 - Laserfiche WebLink

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Mr. Mark A. McLean, P.E. December 5, 2011 DeBeque Pit SWSP Page 2 documentation to identify what water rights or other permanent water source will be dedicated to the SWSP to assure that all permanent depletions from either an unforeseen abandonment of the site by the Applicant or as a result of long term ground water exposure after completion of mining and reclamation will be replaced so as to prevent injury to other water rights In accordance with approach no. 4, you have provided an affidavit dated November 7, 2011 that dedicates 6.1 shares of Larkin Ditch water (2 shares were already dedicated to this pit in the augmentation plan approved in case no. 2005CW076) as replacement water solely for this SWSP for as long as there are depletions at this gravel pit site or until such time as another replacement source is obtained. A copy of the affidavit is attached to this letter. For the purposes of this SWSP, this affidavit will be accepted for the dedication of the shares; however, if the State Engineer determines that a different affidavit or dedication process is necessary to assure proper dedication of the shares, additional information may be required prior to future SWSP approvals. Depletions The anticipated net depletions for this plan are 27.29 acre -feet per year for up to 5.6 acres of water surface exposed after December 31, 1980. The exposed ground water area during the period of this SWSP will not exceed 5.6 acres based on 3.6 acres of the existing pond and not more than 2 acres exposed in the dewatering trenches. According to the information submitted, no water surface was exposed within the reclamation permit boundary prior to January 1, 1981. You have provided a monthly breakdown of the annual depletions made up of 17.9 acre -feet of evaporative loss, 2.5 acre -feet of water used and consumed for dust control, and 10.29 acre -feet of water lost with the mined product (which represents 350,000 tons of mined product). A phreatophyte credit of 3.4 acre -feet has been applied to this plan, reducing the evaporative loss to 14.5 acre -feet per year. The applicant received a decree in Case No. 2005CW76 on September 3, 2008 for an underground water right, a change of water right and a plan for augmentation which provides for augmentation of evaporation from the existing 3.6 -acre ground water pond. This decree describes the post- mining augmentation at the DeBeque Pit for the existing 3.6 -acre groundwater pond, quantifies the historical phreathophyte credit at the site and quantifies the historical consumptive use associated with the 20.5 shares of Larkin Irrigation Company stock owned by Thomas F. and Ginger L. Latham (the "Lathams ") The IDS AWAS stream depletion model was used to determine the lagged depletions to the Colorado River. The aquifer characteristics used in the model are based on the lagging parameters decreed in Case No. 2005CW76 and they are: transmissivity (T) = 50,880 gallons per day per foot and specific yield (SY) = 0.2, the distance of the exposed ground water to the stream =150 feet, and the location of the parallel impermeable boundary was estimated to be 2,000 feet from the stream. The lagged stream depletions for the period of this SWSP are estimated at 27.33 acre -feet for the period May 2010 through April 2011 and 27.28 for the period of May 2011 through April 2012 (Table 1). Replacement Kirkland will make replacement for out of priority depletions affecting the Colorado River during the historical call period from April 1 through October 31 of each year using 38.7 acre -feet of historical net stream depletions during April through October from the dry-up of 19.1 acres of land historically irrigated with 6.1 shares in the Larkin Ditch. Kirkland has entered into an agreement with the Lathams under which additional historical consumptive use credit from Larkin Ditch will be dedicated to this SWSP.