2021-06-01_HYDROLOGY - M1977436 - Laserfiche WebLink

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Aggregate Industries South Platte Combined SWSP June 1, 2021 Plan IDs 3614, 4773, 3624, 4772, 4616, 3437, 3376, 3650, 3668, 5475, 5829, Et 6090 Page 11 of 23 Thornton Lease Aggregate has a perpetual lease of 10.53 acre-feet of fully consumable effluent from the City of Thornton, which will be released from the Metro Wastewater Treatment Plant at a rate of 0.035 cfs daily from November Vt through March 315t Fulton Ditch Aggregate owns a total of 96 shares in the Fulton Ditch Company, consisting of 62 shares obtained from Cooley Gravel, 22 shares from CAMAS, 6 shares from CEtM Aggregates, and 6 shares from Hill Et Peterson. For 2021, Aggregate intends to utilize their 62 Cooley Gravel shares for replacement under this SWSP. (The 22 CAMAS shares, 6 CEtM Aggregates shares, and 6 Hill Et Peterson shares will be leased to others for irrigation purposes). Prior to 1977, the 62 Cooley Gravel shares were used in two blocks: 30 of the shares were owned by the Montandon Trust and used for the irrigation of 48.7 acres, and 32 shares were owned by the Palombos and used for the irrigation of 31.1 acres. The shares were purchased by Walt Flanagan Et Company in 1977 and little is known about the use of the shares after that time. The historical consumptive use analysis utilized a parcel-specific analysis for the period of 1919 to 1977. A total of 40 shares were used on the Montandon parcel prior to 1964, with 10 shares being sold off in 1964. The historical consumptive use analysis assumed that the subject 30 shares irrigated 75% of the Montandon parcel (36.5 acres) prior to 1964 and 100% of the parcel (48.7 acres) from 1964 to 1977. The crop mix for the Montandon and Palombo parcels was assumed to reflect the mix of crops for the Fulton Ditch as a whole as identified in the 1956 CDSS irrigated lands GIS layer, consisting of 44% alfalfa, 26% corn, 15% dry beans, 13% pasture grass, 1% small grains, and 1% sugar beets. The applicant previously utilized an assumed ditch loss of 20% and irrigation efficiency of 65%. For the purposes of this SWSP, the applicant has provided a revised analysis utilizing an assumed irrigation efficiency of 50%. Based on the above, the historical consumptive use of the 62 Cooley Gravel shares is estimated as 1.5 acre-feet per share. Return flow obligations were allocated as 50% surface return flows and 50% subsurface return flows. The 62 shares to be used for replacement purposes under this SWSP will be delivered through the augmentation station owned by the South Adams County Water Et Sanitation District located just downstream of the ditch headgate. The expected consumptive use credit for the 62 Fulton Ditch shares for 2021 has been estimated from a dry-year farm headgate delivery of 2.64 acre-feet per share or approximately 164 acre-feet for all 62 shares. After accounting for return flow obligations, the total consumptive use credit for the 62 shares is projected to equal 96.28 acre-feet in 2021. In the event the Fulton Ditch goes into Sections, the Applicant has sufficient alternative replacement supplies in the form of shares in the Brighton Ditch, as described below, to make up any temporary shortfalls. Brighton Ditch Pursuant to a March 4, 2010 Water Lease with the City of Westminster (Amended January 14, 2020), Aggregate has the right to use 1.038 shares in the Brighton Ditch Company owned by the City of Westminster for augmentation purposes. Aggregate has extended the lease through June 30, 2022. The subject 1.038 shares were changed in case no. 2016CW3186 from irrigation use to direct flow and storage or all beneficial uses of the municipal water system of Westminster. The use of the subject shares for replacement purposes in this SWSP was not decreed in case no. 2016CW3186; however, the decree entered in case no. 2016CW3186 included a provision that Aggregate's continued use of the subject shares be governed by the terms and conditions of the decree.