Surface Water Management

COCKREHAM ISLAND BUY-OUT FEASIBILITY STUDY

The Cockreham Island Flood Hazard Reduction Buy-Out Study: Cockreham Island is located between the Towns of Lyman and Hamilton, in Skagit County, Washington, and is adjacent to the Skagit River. With its significant history of flooding and flood-related damages, a group of landowners, who collectively own a large portion of Cockreham Island, requested that Skagit County inquire about the possibility of a buy-out of island properties.

This study has been presented by GeoEngineers, Inc.

FINAL REPORT

LIST OF FIGURES

Figure 1. Vicinity Map
Figure 2. Site Map (29MB)
Figure 3. Properties (28MB)
Figure 4. Smaller Creeks and Levee (29MB)
Figure 5. Geology
Figure 6. Valley Slope
Figure 7. Channel Character (25MB)
Figure 8. Complimentary Bends (28MB)
Figure 9. Old and Potential Paths
Figure 10. Recommended Meander (29MB)
Figure 11. Buyout Priorities

APPENDICES:

APPENDIX A –HYDROLOGY AND HYDRAULICS

Figure A-1 Cross Sections and Contours (25MB)
Figure A-2 Digital Terrain Model (37MB)
Figure A-3 1-year Flow Inundation Map (23 MB)
Figure A-4 2-year Flow Inundation Map (22MB)
Figure A-5 5-year Flow Inundation Map (20MB)
Figure A-6 10-year Flow Inundation Map (20MB)
Figure A-7 25-year Flow Inundation Map (20MB)
Figure A-8 50-year Flow Inundation Map (20MB)
Figure A-9 100-year Flow Inundation Map (22MB)

APPENDIX B – BENEFIT COST ANALYSIS

Figure B-1 Structures (22MB)
Figure B-2 Cost Effective Parcels at 3% Discount Rate
Figure B-3 Cost Effective Parcels at 7% Discount Rate
Figure B-4 Total Existing Ecosystem
Figure B-5 Total Proposed Ecosystem
Figure B-6 Cost Effective Parcels at 3% Discount Rate
Figure B-7 Cost Effective Parcels at 7% Discount Rate
Figure B-8 Cost Effective Parcels at 3% Discount Rate
Figure B-9 Cost Effective Parcels at 7% Discount Rate

APPENDIX C – LAND MANAGEMENT SUITABILITY

Figure C-1 Habitat Restoration
Figure C-2 Agricultural Observation
Figure C-3 Public Access and Recreation
Figure C-4 Combined Management Plan

APPENDIX D – FUNDING SOURCE EVALUATION