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I I I I I I I I I I I I I I I I I I I 000988 analysis of horizontal and vertical movement trends. Three important factors were revealed. First, the largest flood of record had only minimal effect on the horizontal alignment of the active creek bed. Most of the horizontal move- ment occurred during intermediate flows. Second, the bed level degraded considerably in local areas during major floods and generally aggraded during intermediate flows. Finally, an analysis of the 100 year floodplain revealed that the flow conditions for approximately 6,000 feet upstream of Arapahoe Road are really two separate hydraulically disconnected flood profiles. Using the above findings, various alternatives were developed to sta- bilize the creek bed movement and to increase land utilization. The alter- natives ranged from status quo or do-nothing to channelization and other major structural options. The alternative plans were evaluated and schematic plans prepared and presented to the Technical Advisory Committee and property owners. Individual meetings were then held with each of the major impacted land owners to develop the final selected alternative plan. Pr~liminary design drawings and cost estimates were prepared for the selected plan. In addition, the main- tenance requirements, the impact on water quality and existing wells, and a recreation plan were defined for the selected plan. The selected plan consists of approximately 10,200 feet of channelization upstream of Arapahoe Road and revetments to stabilize the channel in the upper reaches of the study area. Filing of the flood fringe (1/2 foot floodway) allows for the reclamation of 215 acres of floodplain property, which includes the reclaimed area adjacent to the channelization reach. Implementation of the selected plan requires dredge and fill permits (Section 404, Water Qual ity Act) and a Colorado Department of Health Water Quality Certification (Section 401). However, filling of the flood fringe can be done prior to receiving the permits, but there is a high risk of horizontal channel movement eroding the banks of the fill in certain areas because of the lack of bank protection. Since it is unlikely that the entire project would be constructed at once, then phasing of the construction will be required. A detailed discussion of the sequence and constrai nts on the phasi ng is presented inSect i on VI -A of vi