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. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , I of water supplies in a year where supplies are below the average has significant impacts to in- stream flows, the environment, recreational activities, and to the tourism industry in general. On the other hand, in times of high water yields, when the supplies are above the average yield, additional water supplies could be made available to the metropolitan area with much less impact to the environment. Hence, this study looks at developing additional renewable surface supply yield when water supplies are available above the average yield, through a junior water right. In water supply development to date, water suppliers could not make use of these wet year supplies without very large storage facilities such as Two Forks, because of the need to deliver water supply to its customers every year. However, the non-tributary ground water supplies are available to the South Metro Area to meet demands when no water supplies are available from the surface water system. Therefore, this plan would utilize renewable surface supplies to the extent they are available in wet years, and the non-tributary ground water supplies in dry years. The importation of additional renewable water supplies will extend the life of the non-tributary aquifer system. This identifies two components of conjunctive use, the surface water supplies and the ground water supplies. The renewable water supplies must be captured, stored, and diverted to the South Metro Area during the wet year scenario. This will require an extensive system of storage, conveyance, diversions, treatment, and distribution. The construction of these types of water supply systems in sensitive mountain areas and with the prospect of trans-basin diversions would be very difficult from environmental, permitting, and financial perspectives. Instead, the proposal by the participant water providers is to request Denver Water's cooperation in use of their existing facilities in the Blue River and Upper South Platte River Basins and potentially their facilities for treatment and distribution in the metropolitan area. Denver Water's raw water systems would be used to deliver the additional wet year water to the vicinity of the Foothills Water Treatment Plant, and the treated water system could be used to deliver these flows to a distribution system of the participant water providers. In this manner, both the environmental permitting of new facilities and the cost of constructing these facilities can potentially be avoided, understanding that existing permits may require revision, and additional environmental analysis will be required to address the mitigation of further depletions in both the Blue River and South Platte River systems. This plan appears much more viable than the permitting and construction of new facilities. The costs involved would be for the lease or use of existing facilities rather than capital costs of new facilities. Under this plan, additional renewable water supplies would be delivered to the South Metro water providers. The providers would use the additional surface supplies directly for water supply, or could store this water either in surface water reservoirs or by injection into the deep non-tributary aquifers for use at a later time. This plan of conjunctive use relies heavily on the use of Denver Water's existing infrastructure for raw water deliveries from the South Platte and Blue River Basins. The plan also relies upon Denver Water having capacity to deliver flows during peak runoff periods, and proposes to effectively "borrow" water from Denver Water storage reservoirs. Denver Water has required that the plan not affect in any way its ability to obtain its full yield from its water rights through buildout of Denver Water's service area Page 1-15