2017-03-02_HYDROLOGY - M1977436 - Laserfiche WebLink

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South Platte Combined Replacement Plan Page 9 of 19 March 1, 2017 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 historic 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 historic 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. A ditch loss of 20% and irrigation efficiency of 65% were utilized for the analysis, which appear reasonable based on review of aerial photos and topography. Based on the above, the historic consumptive use of the 62 Cooley Gravel shares is estimated as 1.87 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 2017 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 113 acre-feet in 2017. 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, Aggregate has the right to use 1.038 shares in the Brighton Ditch Company owned by the City of Westminster for augmentation purposes. The 2016 SWSP request included an updated HCU analysis for the subject shares prepared by Ecological Resource Consultants, Inc. ("ERC"), using a study period of 1950-2001. The total shares include 416th (0.667) of a share historically used to irrigate the Wattenberg (aka Broncucci) Property. An average of 42 acres of pasture grass were irrigated by controlled flood irrigation. Using a Blaney-Criddle analysis the crop irrigation requirement for the 42 acres was determined to be 103.38 acre-feet. Assuming a 25Y, ditch loss and 50% irrigation efficiency the average historic consumptive use for the 0.667 Brighton ditch shares was found to be 100.04 acre- feet. The other 0.371 shares were historically used to irrigate the Haake Property, along with 5.75 shares of the New Brantner Ditch. During the study period, between 10.7 and 11.3 acres of dry beans (prior to 1960) and corn (1960 on) were irrigated by the Brighton Ditch shares only; 20 acres of pasture grass and between 14.2 and 20.1 acres of dry beans (prior to 1960) and corn (1960 on) were irrigated by the New Brantner Ditch shares only; and between 26 and 35 acres of pasture grass and 24 to 35 acres of dry beans (prior to 1960) and corn (1960 on) were irrigated by both the Brighton Ditch and the New Brantner Ditch shares. Using a Blaney-Criddle analysis the crop irrigation requirement was determined to be 17.50 acre-feet for the area irrigated only by the Brighton Ditch shares, 77.18 acre-feet for the area irrigated only by the New Brantner Ditch shares, and 118.63 acre-feet for the area irrigated by the excess water from both the Brighton Ditch and the New Brantner Ditch shares. The amount of Brighton Ditch water used to meet the crop irrigation requirement on the area irrigated by both sources was calculated by multiplying the total crop irrigation requirement by the percentage of Brighton Ditch water in the excess water. Based on a 0-V C0 o Office of the State Engineer A ' . 1313 Sherman Street, Room 821, Denver, CO 80203 P 303.866.3581 www.water.state.co.us 1876 "'