2011-05-06_HYDROLOGY - M1977559 (7)

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Heidi Frey May 6, 2011 Page 3 System (IDS AWAS). Valco's annual operations at this pit are similar year -to -year, allowing us to develop a consistent pattern of depletions based on the lagging pattern determined by AWAS. For this SWSP, Valco proposes to replace the depletions to the Arkansas River based on the pattern used in the previous SWSP and shown in Table 3. 3. Water Replacements: For this SWSP, Valco proposes to use the same replacement sources and methodology as in the previous SWSP. These replacement sources include Rocky Ford Ditch credits, Canon City and Oil Creek (CC &OC) Ditch credits, Pueblo Board of Water Works (PBWW) lease water, and Lower Arkansas Water Management Association ( LAWMA) shares. a. CC &OC Ditch Credits: Valco owns 26 shares in the CC &OC Ditch. In previously approved SWSPs, historic consumptive use credits were calculated based on 25 CC &OC Ditch shares and totaled 38.34 acre-feet per year. For this SWSP, Valco proposes to continue using the previously calculated historic consumptive use of 38.34 acre -feet per year for the 25 CC &OC Ditch shares. These shares will provide augmentation water for the Canon City East Pit and Rocky Ford East Pit. As required in the previous SWSP, an augmentation station will measure the ditch credits returned to the Arkansas River. The augmentation station consists of a ramp flume, pressure transducer and data logger in the CC &OC Ditch lateral that runs parallel to MacKenzie Avenue. Valco is the last user under this lateral, which outlets directly to the Arkansas River. The consumptive use credits will be measured through the augmentation station and reported to the SEO with the monthly accounting. b. Rocky Ford Ditch Credits: Valco owns two shares in the Rocky Ford Ditch, which they have used for augmentation purposes under an SWSP for many years. The net annual yield of these two shares is 25.72 acre -feet, which is used to off -set depletions at Valco's Rocky Ford East Pit. For this SWSP, Valco will deliver these shares directly to the Arkansas River using the City of Aurora's augmentation station. The City of Aurora will include the delivery of Valco's shares in its water accounting for this augmentation station. The lagged depletions at the Rocky Ford East Pit will be reduced by irrigation - season credits associated with the historic consumptive use of these shares. Non - irrigation season depletions associated with these shares will be replaced with PBWW lease water. vww.bbawater.com c. PBWW Lease Water: Valco has a 15 year lease (through June 15, 2013, extendable for one 10 year period through 2023) for 150 acre -feet per year of consumable water obtained from PBWW. Similar to the previous SWSP, PBWW lease water will be used to off -set depletions at the Canon City East Pit and Rocky Ford East Pit. The leased water may come from any available PBWW source, and PBWW will apply the appropriate transit losses from the source to the appropriate pit. Most likely, PBWW will make releases from sources at or below Pueblo Reservoir. Accordingly, the accounting forms simply show the amount of augmentation water needed from the PBWW lease and specific transit losses are not shown. d. LAWMA Shares: Valco owns 8 common LAWMA shares and 90 preferred LAWMA shares. These shares are used to off -set depletions at the Lamar East Pit. The yield from the 8 common LAWMA shares varies from year to year depending on the percent allocation set by the LAWMA Board of directors. For 2011, the common share allocation