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St C BY4-245-J2 • !d 4L • vlAA. JUJL•+LLr iL <br /> AMAZON CHANNEL MAINTENANCE STUDY <br /> However, the Portland District of the COE has recognized these problems and concerns regarding <br /> their maintenance requirements and is currently preparing a new guideline for selective vegetation <br /> management on flood control structure. This new guideline should be out for public review by <br /> December, 1992. The COE's new guideline will attempt to provide an acceptable balance between the <br /> primary or intended purpose of flood control and other secondary purposes such as wetland <br /> preservation, fish and wildlife habitat and water quality. <br /> STUDY RECOMMENDATIONS <br /> 1. The channel maintenance activities scheduled for the reach between SPRR and BeItline can <br /> be delayed at least one year with a minimal risk of additional flooding. This maintenance <br /> reprieve will provide the City with the time needed to implement the following <br /> recommendations. <br /> 2. Obtain new topographical maps of the Amazon Channel floodplain area from SPRR to Bailey <br /> Hill Road. The City may want to include the study area downstream of SPRR that will be <br /> affected by the City's 'Amazon Widening Project' (Reference 4). The maps should be at 10 _ <br /> 200 feet scale with two foot contours minimum. Spot elevations or interpolated one foot <br /> contour will be required in extremely flat areas. <br /> 3. Conduct more detailed hydrologic studies of the flooding in the lower Amazon ChanneL <br /> These studies should address the complex relationships between flood discharge, flood storage <br /> volume and the location of the 100-year floodplain boundaries and the sensitivity of if value <br /> to these relationships. These studies will provide a detailed risk assessment of affected <br /> properties if alternative channel maintenance practices are developed and implemented. <br /> 4. Working with the new COE vegetation management guideline, develop alternative channel <br /> maintenance practices that support the selected floodplain risk obtained from item 3 above <br /> and balance the conflicting issues regarding the primary and secondary functions of the <br /> Amazon Channel. <br /> • REFERENCES <br /> 1. City of Eugene, West Eugene Wetlands Special Area Study - Draft Plan, Prepared by City of <br /> Eugene and Lane Council of Governments, March, 1991. <br /> 2. OTAK, Inc, Amazon Channel Study, prepared for the City of Eugene's Department of Public <br /> Works, January, 1990. <br /> 3. Federal Emergency Management Agency, Flood Insurance Study for City of Euz,ene. Oregon, <br /> September, 1986. <br /> 4. Cit T Eugene, Amazon Widening Project -A Proposal to Restore Wetland, 1991. <br /> 5 <br />