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I I I I I I I I I I I I I I I I I I I Alternatives Two through Four utilize a detention facility with a controlled outflow discharge. The estimated stored volume in the detention facility varies from 310 acre-feet to 600 acre-feet. The design concept limits the stored depth to seven feet or less. Alternative Five is the preferred alternative. This alternative intercepts the flow above County Road 66 and routes it, undetained into Boxelder Creek. In addition to facilities to get the flow to Boxelder Creek, improvements are planned along an approximate three-mile reach of the creek, through town and south of town, in Larimer County. 1) Alternative One - No Action The No Action alternative means that the existing conditions will remain in the future. This means that the FEMA identified floodplain will remain thus causing future payments of floodplain insurance premiums, limiting land values and causing increased construction costs for the limited development that will take place within the floodplain Mitigating the floodplain is the purpose of the study therefore; no action is considered a non-option for purposes of this report. Costs and benefits are provided for this alternative later in the report. 2) Alternative Two - Diversion to Boxelder Creek A graphic of Alternative Two is shown on Exlubit One. This alternative temporarily impounds an estimated 310 acre-feet of water in a detention facility north of Larimer County Road. The exact location of the detention facility is not known at this time. It is anticipated that the detention facility will be a secondary use of a private land owners field. An up front one-time easement fee will be paid to the landowner for the opportunity to build improvements on his property and for maintaining said improvements. At times when water inundates the private crop, the owner will be paid the market value of said crop. The roadbed of Larimer County Road 66 will be raised to function as a levee to divert water into the detention facility. It is anticipated that the Town will pay for the raising of the road embankment and reconstruction of the road because the existing road meets county requirements and the planned improvements are needed to meet project requirements. A detention facility outlet structure and diversion canal are used to route water to Boxelder Creek. For purposes of this study, 400 cfs is the outflow routed to Boxelder Creek, using a typical diversion ditch as seen in Figure I. The use of a detention facility is not desired because of potential negative effects to county residents in the upper Coal Creek Basin This alternative includes improvements along Boxelder Creek to pass the increased flow while keeping the water surface elevation the same so adjacent property owners are not impacted. The planned improvements include bridge improvements, channel excavation 7