Ordinance No. 20513 - Laserfiche WebLink

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Current Floodplain Form and Function Historical placement of fill (Figure 13) and riprap armoring on the riverfront has channelized the Willamette River by changing and straightening the natural waterway. As a result, the floodplain has been decreased from 7.5 acres in 1910 to the current 1.5 acre area, for a total loss of 6 acres of floodplain onsite. Now the average slope of the bankline is 34 -44 %; dramatically steeper than the historical average of 8 -13 %. Consequently, the water storage capacity was five times greater historically than the current conditions and represents the carrying capacity of the natural resource according to Statewide Planning Goal 5. Further, this historical floodplain area is an integral part of the layers of Eugene's history embedded in the site, contributing to the sites identity as emphasized in the Guiding Principles for master planning. Full restoration of this historical floodplain would require excavation and removal of approximately 24,000 cubic yards of fill material from the Riverfront. The increased elevation created by this fill has eliminated riparian bottomland, which significantly diminishes the aquatic functions from reference conditions. Restoring the floodplain would support the objective of "connecting the river to the city and the city to the river," while maintaining a public river edge. Fill removal also serves the Rivers to Ridges plans to "enhance floodplains for their habitat, flood protection, water quality, recreation, and scenic values." Further, the Statewide Planning Goal 5 encourages protection of historically and ecologically unique natural areas and management of water levels for fish, wildlife, 15 Figure 13. Fill Placement on EWEB site.