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. UPPER GUNNISON RIVER WATER CONSERVANCY DISTRICT Mitigation Proposal Page 7 of! 0 pages consumptive use or stream depletion is ten percent (10%) of the total amount diverted by the well serving the dwelling unit. Therefore, the depletion by wells serving dwelling units utilizing non- evaporative sewage disposal systems amounts to 0.0392 acre-feet per year. The depletion occurs at an uniform rate throughout the year. For wells located in the Slate River drainage serving dwelling units connected to the East River Treatment Plant, the annual consumptive use or stream depletion is 100 percent of the total amount diverted by the well serving the dwelling unit (0.39205 acre-feet per year). This depletion is presently occurring as a result of existing wells diverting from the Affected Reach of the Slate River (See FIGURE 3, above.) 6 For purposes of determining the total amount of replacement water that must be released from Meridian Lake Reservoir in order to replace depletions to the stream at the point of depletion, transit losses will be added to the stream depletion. The District's engineering consultants estimated transit losses based on assumptions regarding reservoir releases during the month of August in a dry year, a period when transit loss would be higher than normal. Based on those calculations, transit losses will be assessed for each well at a rate between 0.9 per cent (.009) and 1.0 per cent (.01) of the water released from the reservoir. . Water users who wish to be included in the Upper Gunnison District's plan for augmentation may purchase Augmentation Certificates which entitles the owner of to the release from Meridian Lake Reservoir in increments of 0.05 acre-feet of water per year (Base Units). Based on current estimates of cost recovery, the District has set the price ofa Base Unit at $1,500.00 if reserved by May 17,2004. Using the calculations above, one Base Unit will provide sufficient replacement water, including transit loss and CWCB winter mitigation (described below), for the annual depletions from in-house use only for a single dwelling unit that utilizes a non-evaporative sewage disposal system. Owners of existing wells whose wastewater is piped to the East River Treatment Plant would have to purchase nine Base Units if required to replace their depletions from domestic indoor use for 365 days per year. At the current price for Base Units, the cost to augment domestic indoor use only for a well serving a single dwelling unit connected to the treatment plant could be $13,500. For virtually all of these existing well owners, local residents who work in the area, such a requirement would make the Augmentation Certificates unaffordable. This situation is the principal reason that the District is requesting that the CWCB approve the acceptance of potential injury to the instream flow rights in the Affected Reach of the Slate River with the mitigation proposed below. . 6 The plan will also permit the purchase of augmentation certificates to replace depletions from diversions for lawn and garden irrigation, commercial and industrial uses, pond evaporation and livestock watering. Replacement water requirements for lawn and garden irrigation and pond evaporation are determined by using consumptive use and evaporation tables approved by the State Engineer. Replacement water requirements for commercial and industrial uses will be determined by the Division Engineer on a case-by-case basis.