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I I I I I I I I I I 1.2 Proposed Study Effort 1.2.1 GENERAL STUDY SCOPE The study effort will build upon what was learned in the Reconnaissance Study (905 (b) Report), The primary study objective is to determine the most beneficial plan to reduce the flood threat to Greeley and improve the riparian ecosystem of the Cache la Poudre River. Based upon the results of the Reconnaissance Study, is anticipated that flood damages can be reduced by increasing stream channel conveyance, lowering flood peaks by storing part of the excess flow in designated areas of the flood plain and removing some property from the floodway, Channel conveyance can be improved by buying and removing some property from critical reaches of the floodway and moving existing sand berms further from the center ofthe river. Widening the floodway will build upon the City's on-going effort to improve the channel capacity of bridge crossings in Greeley, Where the floodway can be widened, efforts will be made to improve both the environment in the reach and provide a public access corridor. Gravel pits and old oxbows offer potential as storage areas for flood flows, In addition, unoccupied flood plain property, such as the old sugar plant reservoir site east of 6th Avenue near the mouth of Eaton Draw, could also be used for flood storage, The flood storage areas will also be evaluated for their potential to improve riparian habitat along the Cache la Poudre River in Greeley, wetland habitat for migratory bird species and for public access via the regional trail system, The initial focus ofthe study will be to identify flood reduction alternatives that are likely to have favorable benefit / cost ratios, Additionally, ecosystem restoration efforts that are the most productive will be identified at that time. For both the flood damage reduction and ecosystem improvement efforts, typical tasks will include defining the problem and opportunities, forecasting the future conditions without a project and formulating alternative plans. This initial focus is referred to as "Decision Point 1" and an incremental cost estimate has been prepared for that part of the study. Specific tasks that will be addressed for Decision Point 1 include defining of stage, frequency,damage curves along key river reaches, determining the shape of major historical flood hydrographs, trends in flooding with time and identifying specific channel reaches and storage areas for ecosystem restoration, An economic analysis will be conducted, including the existing condition expected annual damages for floods of all frequencies, The existing ecosystem w\ll be documented, and a dominant coveHype map developed for the project reach, If desirable flood damage reduction and ecosystem restoration measures are identified for Decision Point I, then the study will continue to its conclusion through the process of evaluating the alternatives against the "without project" alternative, comparing the alternatives and selecting a plan, When Decision Point I is reached, the scope of the 6