2023-07-05_HYDROLOGY - M2006078 - Laserfiche WebLink

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2009-2023 Camenish Borrow Pit SWSP, Applegate Group, Inc. Page 2 of 5 July 5, 2023 Depletions Lagged depletions result from past evaporative losses, water that was used for dust control, and water that was lost from mined product. Evaporative losses occurred from the dewatering trench around the excavated area which was approximately 4,000 feet in length and 5 feet wide with a total exposed area of 0.5 acre. The Integrated Decision Support Group Alluvial Water Accounting System ("IDS-AWAS") model was used to lag depletions to the South Platte River. The following parameters were used in the model: a distance from the well to the stream of 11,400 feet, a transmissivity of 50,000 gpd/ft, a specific yield of 0.2, and a no- flow boundary of 13,500 feet. Total lagged depletions since the beginning of the operation through the end of the effect on the stream (February 2007 through January 2037) are 34.66 acre-feet, of which 2.434 acre- feet were replaced under the previous SWSP approval (2007-2009). A summary of the total lagged depletions is shown on attached Table 2. In addition the lagged depletions through December 2022 were compared against the river call to determine the net depletions. That analysis shows that 7.92 acre-feet of the lagged depletions did not require replacement during periods of free river from February 2009 through December 2022. Therefore, this SWSP seeks to replace the un-replaced out-of-priority lagged depletions from the period of February 2009 through January 2037 (the end of the model period). The remaining lagged depletions since the expiration of the previous SWSP are 20.91 acre-feet. These lagged depletions include actual net depletions through December of 2022 plus any remaining future depletions wrapped back into the calendar year 2023. After December 2023, only 2.549 acre-feet of the total 20.91 acre-feet of depletions remain. Since this is only 7.4% of the total depletions which will have occurred to the stream from the operation of this pit, the Applicant proposes to aggregate the 2.549 acre-feet of replacement water and distribute its delivery throughout 2023. A summary of the total lagged depletions and out-of-priority depletions is shown on attached Table 1. Replacement The replacement source for this plan period is excess accretion credits from the 12CW179 augmentation plan leased from Denver Julesburg Water Resource Partners (DJWRP) (WDID 0202634). A copy of the lease is attached. The accretion credits accrue upstream of the Lower Latham Ditch headgate at the South Platte River generally located in the S '/z of Section 35, Township 5 North, Range 66 West of the 6th P.M., which is above any calling rights which could be injured, and were made available starting July 1, 2016. Since such credits were not made available until 2016, excess credits were provided to make up this shortfall. From February 2009 through December 2022, there were 2,594.25 acre-feet of excess DJWRP accretions, of which 61.38 acre-feet were leased to Burnco, therefore leaving 1,926.33 acre-feet of net excess accretions available for use in this SWSP. The Applicant has leased from DJWRP 20.91 acre-feet of replacement water from the period of July 2016 through December 2023 to replace all un-replaced out-of- priority depletions starting in February 2009. A summary of the replacement schedule is shown on attached Table 1. Conditions of Approval This substitute water supply plan is hereby approved in accordance with section 37-90-137(11), C.R.S. and subject to the following conditions: 1. This SWSP is approved with the effective date of July 5, 2023 through December 31, 2023 unless otherwise revoked or superseded by a decree. This SWSP replaces out-of-priority lagged depletions that accrued to the river prior to the effective date of this plan that were not previously replaced