2013-04-16_HYDROLOGY - M1981058 - Laserfiche WebLink

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Mr. Mark A. McLean, P.E. DeBeque Pit SWSP April 12, 2013 Page 3 May 2013 through April 2014 and 159.12 for the period of May 2014 through April 2015 (Table 2). The model includes actual depletions due to mining and exposed water surface area through December 2012 and projected depletions for the 2013 and 2014 plan years. Included in the 2013 and 2014 plan years are also depletions to the stream resulting from projected pumping of 67 acre -feet from the existing pond in May and June of each year from dewatering at the site when mining is proposed to resume 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 40.7 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. In addition a dewatering credit of 67 acre -feet is claimed during May and June 2013 and May and June 2014. Previously, the Lathams dedicated 2 shares of the Larkin Ditch to the augmentation plan decreed in Case No. 2005CW76, which were associated with 6 acres of dry-up and a historical consumptive use of 12.7 acre -feet per year. This SWSP includes historical consumptive use credits from an additional 4.1 shares resulting in a total of 6.1 shares. Dry-up of 19.1 acres is required for use of the 6.1 shares. Mining activities are reported to have resulted in dry-up of 20.1 acres as shown in the attached Figure 3. Additional dry-up of 2.8 acres has occurred between the ditch and mine area and may be claimed in future plans. The consumptive use credit associated with the 6.1 shares of the Larkin Ditch was calculated for the period 1972 through 2000 using the Modified Blaney - Criddle Method with daily temperature and precipitation data from the nearby Palisade weather station. Delivery of the replacement water will be made in the same manner as described in Case No. 2005CW76. Specifically, 10 percent of the prorata ditch diversion for 6.1 shares will be diverted in the Larkin Ditch to replace ditch losses. The remaining 90 percent of the prorata diversion for the subject shares will be returned and measured to the Colorado River at or near the ditch headgate. Note that a comprehensive stream depletion analysis considering return flow lags may be necessary for approval of a plan for augmentation. The Larkin Ditch (senior right) water right was decreed in Case No. CA1927 for 25 cfs for irrigation purposes, and the First Enlargement of the Larkin Ditch (junior right) was decreed in Case No. W -176 for 12.5 cfs for irrigation purposes. The Lathams' 20.5 shares equate to a flow of 5.74 cfs of senior rights and 2.87 cfs of junior rights. The junior water right in the Larkin Ditch (appropriation December 31, 1950) was historically called out by the Grand Valley water right. Historically the water rights within the lower Colorado River Basin that are junior to the Grand Valley water right have been allowed to divert without curtailment because of releases of water from the Historic Users Pool ( "HUP ") in Green Mountain Reservoir. Once the junior water in the Larkin Ditch is changed for augmentation purposes it will no longer benefit from the Green Mountain Reservoir releases under the HUP. Therefore the junior water in the Larkin Ditch cannot be used as a replacement source in this SWSP, unless the water is in priority. For the purpose of this SWSP you are proposing to use only the consumptive use credits available from the change of senior water rights in the Larkin Ditch (priority no. 2). The dry year average annual historical stream depletion from the senior water right in the Larkin Ditch is estimated to be about 40.7 acre -feet (Table 3). The amount dedicated to this SWSP equates to 1.708 cfs of the senior right! Note: According to Table 5 of the decree entered in Case No. 2005CW076, the historical consumptive use credit from 6 acres of dry-up under the Larkin Ditch is 12.2 acre -feet per year. The 6 acres of dry-up produces a consumptive use credit that exceeds the estimated depletions for the