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1-7 Briefly, the entities commented and chose the following: 1. City of Wheat Ridge. The City Council adopted the estimated optimum combination alternate for use in Phase B of this study. 2. City of Lakewood. The City recommended that for the reach of Lena Gulch above Maple Grove Reservoi r, the estimated optimum combination alternative be util ized; and for the reach below Maple Grove, a grass-l ined channel be uti 1 izecl. 3. Jefferson County. The Board of County Commissioners adopted the estimated optimum combinatIon a-ternate for use in Phase 8 of this study. Also, detention ponds in the vicinity of Interstate 70 should be studied. 4. City of Golden. The City recommended that for the reach of cena Gulch from U.S. Highway No.6 to Zeta Street, the improved flood plain alternate be util ized, and the sedimentation basin located upstream of Zeta Street be subject to County Con:rol. The master plan chosen by the local entities was then developed. This included final ization of the hydroiogical ane hydraul ical analysis of Lena Gulch for the lOa-year storm. This inforMation is presented on appropriate mapping in Volume 11 of this Report. Table 1-5 presents the master plan cost estimate. An evaluation of Maple Grove Reservoir was undertaken. This study indicated that Maple Grove Reservoir plays a major role in the hydrological runoff process of Lena Gulch beside. being a key component of the Con- solidated Mutual Water Company (Consolidated) for water supply. This study found that Maple Grove Reservoir (MGR) diminishes peak runoff floVI5 downstream during storms of lOa-year or less f-equency. Additionally, analysis showed that the flood star-age capacity and spillway flow characteristics are fairly optimal from a channel viewpoint. That is, it was calculated that embankment enlargement and alternation of spill- way characteristics to further reduced flood flow were not economically sound. The State Engineer of Colorado deter-min'2d that MGR is a moder-ate hazard dam, and has required that MGR's spillway discharge capacity be enlarged_ Various entities, the Urban Drainage and Flood Cvntrol District and Cans01 idated requested that an analysis be m':-Ide to identify facts regard- ing spi llway improvement, flood control benefi ts, "later supply benefits, and alternate water supply and flood cootrol options. It has been estimated that it would cost $600,000 to improve Maple Grove Reservoir's inadequate spillway, The analysis of Maple Grove Reservoir as a flood control structure and as a water "upply faci I i ty has shown that the final distribution of spillway improvement costs is a negotiable matter between Canso 1 idated and the UD&FCO.