2024-06-18_HYDROLOGY - M2019028 - Laserfiche WebLink

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Holcim South Platte Combined SWSP June 18, 2024 Plan IDs 3614, 4773, 3624, 4772, 4616, 3437, 3376, 3650, 3668, 5475, 5829, Ft 6243 Page 13 of 26 Treatment Facility extending downstream to a point at or above the Lupton Bottom Ditch headgate. The point of depletion is downstream of the Lupton Bottom Ditch headgate. The Applicant must notify the Water Commissioner at least 48 hours prior to making replacement deliveries at a location other than the Hite Treatment Facility. Thornton Lease Holcim 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 1st through March 31st Fulton Ditch Holcim 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 C&tM Aggregates, and 6 shares from Hill Ft Peterson. For 2024, Holcim intends to utilize their 62 Cooley Gravel and 22 CAMAS shares for replacement under this SWSP. (The 6 C&tM Aggregates shares and 6 Hill &t 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 Ft 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 an 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. Holcim has provided a memorandum dated December 29, 2022 with a historical consumptive use analysis of the 22 CAMAS shares. The historical consumptive use analysis utilized a parcel-specific analysis for the period of 1919 to 1971. The shares were purchased by Adams Aggregate in 1971 and little is known about the use of the shares after that time. A total of 45 shares were used on the CAMAS parcel during the study period to irrigate an average of 81.9 acres of alfalfa and pasture grass. The parcel contained primarily loam soils and an average water holding capacity of 1.5 inches per food was assumed. For the purposes of this SWSP, the Applicant has assumed an irrigation efficiency of 50%. Based on the above, the historical consumptive use of the 22 CAMAS shares is estimated as 1.52 acre-feet per share. Return flows were allocated as 75% surface return flows and 25% subsurface return flows. The historical return flows from the Cooley Gravel shares and the CAMAS shares were added together to develop a single set of return flow factors. The 84 shares to be used for replacement purposes under this SWSP will be delivered through the augmentation station owned by the South Adams County Water Ft Sanitation District located just downstream of the ditch headgate. The expected consumptive use credit for the 84 Fulton Ditch shares for 2024 has been estimated to be 2.40 acre-feet per share or approximately 202 acre-feet for