2019-08-27_HYDROLOGY - M1989120 - Laserfiche WebLink

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Amended Aggregate Industries South Platte Combined SWSP August 27, 2019 Plan I Ds 3614, 47731 3624, 47721 4616, 3437, 3376, 3650, 3668, and 5475 Page 11 of 21 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. The decree entered in case no. 2016CW3186 relied on a parcel-specific analysis of the historic consumptive use of the subject water rights, with a study period of 1950 through 2001. The total shares include 4/6t" (0.667) of a share historically used to irrigate the Broncucci (aka Wattenberg) Property. An average of 42 acres of pasture grass were irrigated by controlled flood irrigation. The engineering study commissioned by Westminster for case no. 2016CW3186 found the average historical consumptive use for the 0.667 Brighton ditch shares used on the Broncucci Property to be 82.5 acre-feet. The other 0.371 shares were historically used to irrigate the Haake Property, along with 5.75 shares of the New Brantner Extension Ditch Company. Irrigated portions of the Haake Farm ranged from 92.3 to 111.8 acres from 1950-2001. 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 49 and 61 acres of furrow irrigated corn and flood irrigated pasture grass were irrigated by both the combined Brighton Ditch and New Brantner Ditch water supplies. The engineering study commissioned by Westminster for case no. 2016CW3186 found the average historical consumptive use attributable to the 0.371 Brighton Ditch shares used on the Haake Property to be 67.85 acre-feet. The total average historical consumptive use for the subject 1.038 shares is therefore 150.35 acre-feet per year (144.85 acre-feet per share). Aggregate will utilize the entire 1.038 shares for use in this plan. The use of the Brighton Ditch shares in this plan must comply with the terms and conditions of the 2016CW3186 decree, including the volumetric limits identified in paragraph 35.D of the decree and summarized in the table below. Apr May Jun Jul Aug Sep Oct Annual Max Monthly and Annual Limits 59.7 96.3 96.3 106.6 97.8 56.8 52.3 458.0 20-Year Limits 458 11073 11355 11598 1,375 879 425 7,163 For the purposes of this SWSP, you have estimated the expected credit for the Brighton Ditch shares from a dry-year farm headgate delivery (using a 25% ditch loss, consistent with case no. 2016CW3186) of 334 acre-feet per share, or 343.60 acre-feet for all 1.038 shares for the period of April through October. This amount is less than the 20-year average annual limit of 358.15 acre-feet (7,163 acre-feet : 20 years), and therefore is acceptable. Actual deliveries, which were lower than projected deliveries, were used for the months of March, April, and May 2019, resulting in a revised projected consumptive use credit of 272.83. The historical return flows associated with the 1.038 shares that are the subject of this SWSP must be maintained in accordance with the return flow factors identified in paragraph 35.F of the decree entered in case no. 2016CW3186. The return flow obligations will be accounted for and replaced under this SWSP. The revised total consumptive use credit for 2019 is projected to equal 154.55 acre-feet, which is less than the dry-year yield of 170.88 acre-feet. Aggregate anticipates utilizing the augmentation structures on the Brighton Ditch operated by the City of Aurora for the delivery of these shares.