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Shoreline Erosion on Sauvie Island, Oregon: Perceptions and Management Practices

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Shoreline Erosion on Sauvie Island, Oregon: Perceptions and Management Practices Shoreline Erosion on Sauvie Island, Oregon: Perceptions and Management Practices by Season Long, MS Candidate (Non-thesis) Marine Resource Management Program College of Oceanic and Atmospheric Science Oregon State University Corvallis Oregon, 97331 Presented June18th,2007 Funding of this project was provided by OSU Sea Grant MASTER'S PROJECT APPROVAL FORM Student information Student na Address: Redacted for Privacy Telephone m Project title:Shoreline Erosion on Sauvie Island, Oregon: Perceptions and Management Practices Defense date: 6/18/07 Project committee members 1) Major project advisor: uE S.Ci'ii'?Al Department:/s - / (j1J /, 1e C / c Signature: Redacted for Privacy 2) Committee member Redacted for Privacy Department:C-ic c Redacted for Privacy Signature: 3) Committee member: J%7/ ,?4/ 2O1- Department: C2/5- a2o2C 77T' Redacted for Privacy ACKNOWLEDGEMENTS I am grateful for the knowledge and support that I have received while perusing my master degree at Oregon State University. I would first like to thank my major advisor Sam Chan for his support, guidance, and encouragement which allowed me to excel in this Master Program. In addition, I would like to thank Jim Good for contributing to my knowledge in the area of Marine Resource Management and for the direction he provided in shaping my project write-up. I would also like to thank Michael Harte for his insight and perspective on the many professional paths that are ahead in my career. I would also like to extend a warm thanks to the residents of Sauvie island, many of whom opened there homes to me, as well as, enriched this project with there personal stories. I would also like to thank Oregon Sea Grant Extension for believing in me and this project enough to provide financial support. Finally, I would like to thank my family and friends for there unwavering love, support, patience, and advice though out this process. I would not have been able to do it without you! 2 Table of Contents Page Acknowledgments .2 Tablesof Contents................................................................................3-5 List of Tables and Figures ...................................................................... 6-7 1.ABSTRACT ........................................................................................ 8 2. INTRODUCTION ............................................................................9-11 3. BACKGROUND ............................................................................. 11-21 3.1 Regional Hydrology and Geology .............................................11-16 3.2 Formation of Sauvie Island ......................................................16-18 3.3 Early Human Settlement ............................................................ 18 3.4 Influence of Flood Control Programs ......................................... 19-2 1 4. SUAVIE ISLAND BANK EROSION ................................................... 22-45 4.1 Primary Factors Contributing to Sauvie Island Erosion ......................23 4.1.1 Impact of Dams ............................................................ 23-25 4.1.2 Flooding Impacts on Erosion ........................................25-26 4.1.3 Vessel Generated Waves ..............................................26-30 4.1.4 Upstream Erosion Control Impacts ...................................30-31 4.1.5 Water Level Changes .........................................................31 4.1.6 Wind Generated Waves ................................................... 32 4.1 .7Cultural Site Disturbances ...............................................32-33 4.2 Secondary Factors Contributing to Sauvie Island Erosion.......................34 4.2.1 Dredging-induced Erosion ........................................... 34-38 4.2.2 Beach Renourishment ...................................................36 4.2.3 Waterway Structures and Erosion ................................. 39-40 4.2.4 Tidal Influence and Erosion ............................................. 41 4.2.5 Wind-Generated Erosion .................................................41 4.3 Interaction of Primary and Secondary Factors ............................. 41-42 4.4 Shoreline Protective Structures ................................................. 42-45 5. RESEARCH DESIGN AND METHODS .............................................. 45-48 5.1 Overview ............................................................................ 45-46 5.2 Property Owner Survey ............................................................ 46 5.2.1 Sample Selection .......................................................... 46 5.2.2 Survey Distribution .................................................. 46-47 5.2.3 Survey Analysis ........................................................... 47 5.3 Government Agency Interviews Concerning Erosion .................... 47-48 5.4 Image Analysis of Erosion .......................................................... 48 6. SURVEY RESULTS ....................................................................... 48-76 6.1 Survey Response and Subsequent Site Visit ................................. 49-50 6.2 Survey Respondent Characteristics .......................................... 51-54 6.3 Shoreline Erosion Concerns and Observed by Respondents ............ 54-58 6.4 Factors Contributing to Shoreline Erosion ..................................... 59 6.5 Other Issues of Concern for Property Owners ............................ 59-60 3 6.6 Shore Protective Structures and their Effectiveness......................60-62 6.7 Respondents and Agency interactions ........................................... 63 6.8 Site Visits to Selected Erosion Areas..........................................63-65 6.1 Government Agency Role in Shoreline Erosion Management...................66-69 6.2 Agency Knowledge of Erosion on Sauvie Island....................................70-73 6.2.1 Federal Agencies The US Army Corps of Engineers...........................................70 6.2.2 State Agencies Department of State Lands (DSL)........................................70-7 1 Oregon Department of Fish and Wildlife...................................71 6.2.3 Local Agencies ColumbiaCounty.................................................................71 Multnomah County ..........................................................71-72 Sauvie Island Drainage Improvement Company..........................72 The West Multnomah Soil and Water Conservation District..........72 Nation Resource Conservation Service......................................73 6.3 Monitoring and Technical Assistance Agencies.....................................73-76 6.3.1 Federal Agencies The US Army Corps of Engineers........................................73-74 Nation Resource Conservation Service (Oregon NRCS)................74 6.3.2 State Agencies Oregon Department of Fish and Wildlife...............................74-75 Department of State Lands.................................................... 75 6.3.3 Local Agencies Sauvie Island Drainage Improvement Company........................ 75 The West Multnomah Soil and Water Conservation District..........75 Columbia and Multnomah Counties........................................ 76 7. AERIAL PHOTO DATA RESULTS................................................... 76-80 7.1 Aerial photosOverview.................................................................................. 77 7.2 ARC GlSlnconsistancies............................................................................... 78 7.3 Aerial Photo Results...................................................................................... 80 8. DISCUSSION................................................................................ 83-90 8.1 Discussion Overview .................................................................. 83 8.2 Columbia River................................................................... 83-86 Columbia River Erosion Interaction........................................ 83 Columbia River Observe Erosion Events.................................. 84 Columbia River Mitigation................................................... 86 8.3 Multnomah Channel Discussion.............................................. 86-90 Erosion Interactions............................................................ 88 ObservedErosion............................................................ 88-89 Mitigation Multnomah Channel Shoreline Erosion..................89-90 8.4 Willamette River Discussion....................................................... 90 9. CONCLUSIONS............................................................................ 90-93 10. RECOMMENDATIONS................................................................ 93-99 10.1 Cooperative Management..................................................... 93-96 10.2 Shore Term Changes .96-97 10.3 Needed Studies .................................................................. 97-98 10.4 Multnomah County Sauvie Island Rural Plan ........................... 98-99 11. WORKSHOP OUTLINE ............................................................. 100-101 12. GLOSSARY ............................................................................. 102-103 13. BIBLIOGRAPHY ..................................................................... 104-107 13. APPENDICES ........................................................................... 108-130 Appendix A) Columbia River, Willamette River, and the Multnomah ChannelErosion Survey ...........................................................
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