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Northern Colorado Water Conservancy District <br /> N^C W C-D <br /> 220 Water Avenue•Berthoud,CO 80513 •970-532-7700•fax 970-532-0942 <br /> • MEMORANDUM <br /> TO: Mr. Mike Serlet,PE <br /> Colorado Water Conservation Board <br /> 1580 Logan Street, Suite 750 <br /> Denver, CO 80203 ` 44 • <br /> FROM: Jon Altenhofen, PE <br /> Supervisory Water Reso rces Engineer <br /> Northern Colorado Water Conservancy District (NCWCD) <br /> 220 Water Ave.,Berthoud,CO 80513; 970-622-2236;jaltenhofen @ncwcd.org <br /> DATE: April 18,2007 <br /> REF: Accounting for Lower Logan Well Users,Inc. (LLWU) in Support of Request for <br /> Colorado Agricultural Drought Response Grant for 2006 <br /> NCWCD's Augmentation Recharge Accounting (ARA)Program provides accounting services <br /> to augmentation plans in the lower South Platte River in Colorado. As Water Resources <br /> Engineer responsible for the ARA Program, I completed all the accounting necessary for <br /> LLWU operations for 2006. This involved the use of groundwater models (AWAS)to <br /> compute the lagged well depletions and recharge accretions at the nver. Information was <br /> gathered from meter reports for the wells and Water Commissioner records were utilized to <br /> quantify recharge site inflows. <br /> 11111 Monthly updates of the accounting for net effects on the river were submitted to the Division <br /> Engineer to verify that all out-of-priority well depletions were augmented from the LLWU <br /> replacement supplies consisting of Prewitt Reservoir releases, recharge accretions and pumping <br /> of augmentation wells directly back to the river. Inflows to groundwater recharge ponds result <br /> in accretions at the river later in time. Augmentation wells are pumped directly to the river <br /> through ditches and creeks on days of river call to replace the remaining depletions not covered <br /> by recharge accretions and Prewitt Reservoir releases. The use of augmentation wells also <br /> causes depletions in the future that must be replaced if out-of-prionty. <br /> The accounting completed for LLWU for the depletions of member wells is utilized by LLWU <br /> to assess their members at a$ per acre-foot of depletions at the river. LLWU uses these <br /> collected water fees to lease the replacement supplies (i.e., Prewitt Reservoir,recharge <br /> accretions and augmentation wells) developed by LLWU members. The attached Table 1 <br /> (Prewitt Reservoir leases),Table 2 (recharge accretion leases) and Table 3 (augmentation well <br /> Ieases) are the accountings that list the leases of replacement supplies for 2006. <br /> Table 1 for Prewitt Reservoir lists a total Iease of$22,560. The lease rate for Prewitt Reservoir <br /> is$20/ac-ft of net credit where net credit is after river shrink and replacement of Prewitt return <br /> flow obligations. <br /> Table 2 for recharge accretions for April 1,2006 through December 20, 2006 list a total <br /> recharge accretion lease of $236,650. Recharge accretions in 2006 were all leased at$20/ac-ft <br /> for April 1 through December 20. <br /> 110 <br /> 1 <br />