2009-08-25_HYDROLOGY - M1987049 - Laserfiche WebLink

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Jeffrey A. Clark August 24, 2009 Page 2 Depletions from past and proposed operations at the pit were lagged to the stream system based on the Glover factors over 36 months. The Glover factors were determined using the Integrated Decision Support Alluvial Water Accounting System (IDS AWAS). The results showed that over 36 months, about 88 percent of the first month's slug depletions would impact the river. The depletions were normalized to 100 percent over the 36 months to determine the lagging for this SWSP. The total lagged depletions during this SWSP period are 111.9 acre-feet (Table 1 B, Column 9). Replacements The Applicant proposes to replace the depletions with 25 shares of Fulton Ditch (out of 70 shares total that the Applicant owns), which are delivered directly to the South Platte River or stored and released later, depending upon season. The Applicant will use the remaining 45 Fulton Ditch shares to replace depletions from the North Tower Pit and Ready Mixed Pit 1, two other gravel pits it owns and operates, managing the 70 shares in a joint operation to cover depletions for all three pits. All the shares are delivered down the lateral that historically served the Bromley Lakes site and will be measured prior to release to the river for replacement of depletions or to storage. The historical consumptive use credit of Fulton Ditch shares is based on 1.76 acre-feet per share as determined in the South Adams County Water and Sanitation District change case engineering report for Division 1 Water Court case no. 2001 CW258. The 25 shares would have a total consumptive use yield of 44 acre-feet. The distribution of these shares is shown as Column 12 on the attached Table 1 B. The historic yield of these Fulton shares will exceed the depletions in the summer months and requires replacement of historic return flows in the winter months. However, the excess yield from the Fulton shares will be placed into storage in Kenneth Mitchell Lake for later release to the river during the fall and winter months, as shown in Tables 1 B and 2. Ready Mixed has obtained an agreement with the City of Brighton to store up to 200 acre-feet of water in the Kenneth Mitchell Lake. Additional replacement requirement will be provided by water that Ready Mixed already has in storage, which is projected to be 110 acre-feet at the beginning of June 2009. Releases from storage for Bromley Lakes Pit replacement are shown in Table 1 B, column 16. The total storage releases are shown in Table 2, Column 6. Ready Mixed portion of the Kenneth Mitchell evaporation was estimated based upon conservative storage projection provided by the City Of Brighton. The balance of the replacement requirements of 8.8 acre-feet will be provided by a lease for augmentation credits with the City of Brighton ("Brighton"). Table 1 B, Column 18 shows the distribution of their respective credits. A copy of the lease with Brighton was provided to this office with this SWSP request and is attached to this letter. The monthly evaporative depletions and proposed monthly replacement requirements can be found on the attached Table 1 B. Conditions of Approval I hereby approve the proposed substitute water supply plan in accordance with C.R.S. §37-90- 137(11), subject to the following conditions: 1. This plan shall be valid from August 1, 2009 through July 31, 2010 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) by June 15, 2010.