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I !I I I I I I I I I I I I I I I I I I I 2. Augmentation purposes. Central Colorado Water Conservancy District provided data for the development of this demand scenario and target release schedule where the primary use would be for augmenting out of priority depletions primarily for irrigation. 3. Minimum instream flows. The Greenway Foundation and the City of Littleton provided data which allowed for development of a demand scenario and target release schedule for maintaining minimum instream flows. 4. South Metro Water Users (M&I and conjunctive use). This is a group of primarily municipal water supply agencies and cities that are active in the South Metro Water Supply Study. These entities have generally expressed an interest in using reallocated Chatfield storage space in conjunction with a groundwater source of supply for M&I and conjunctive use. Data were supplied by these entities for developing a demand scenario and a target release schedule. 5. Mixed Use. A combined group of Central Colorado Water Conservancy District, Greenway Foundation and the City of Littleton were used to develop a scenario to explore the feasibility of operating reallocated Chatfield Reservoir storage for the benefit of all three interests. Demand scenarios and target release schedules were developed by combining scenarios 2 and 3, listed above. A spreadsheet model was developed to analyze the potential use of the reallocation pool under the fifteen possible modes of operation (i.e., five demand scenarios with three possible storage pools). Using a daily time step, this model computed the inflow to the allocated storage pool, prorated evaporation, demand releases, spills and final storage. The model was used to analyze: I. The adequacy of the available water rights to effectively use the reallocated storage space, 2. The potential of the reallocated Chatfield Reservoir storage space to meet the demand release schedules for the various entities and 3. Effects on reservoir water surface elevation fluctuation from operation of the reallocated storage space to meet the target releases with inflows diverted under the priorities of available water rights. The most important result from the model studies is that the water rights available to Denver Water, Central Colorado Water Conservancy District, the Greenway Foundation, City of Littleton, and South Metro Water Users were sufficient to efficiently use the reallocated reservoir storage space under all pool sizes. Model results indicating the frequency that target release schedules were met for each entity for the three reallocated storage pools are presented in Table ES-l below. P:\Data\GEN\CWCB\Chatfield\Report12.02\RevisedChatReport 1 03\Report2-Q3.doc 3