1. Mouth of the Columbia River Jetties Major Rehabilitation

4. MCR North Jetty - Construction and Repair History 1917 1939 19652005 (Receded approximately 1800’ in length since 1916)

5. MCR South Jetty - Construction and Repair History 19131886 1931-1934 1961- 1962 1982 2006 2007 (Receded approximately 5000’ in length since 1885 - 1913)

6. Design Development Least cost, most reliable repair, environmentally acceptable. Jetty cross section options: –Dimensions: crest elevation, crestwidth, sideslope –Material types: stone, concrete, combination Due to the variability in design climate and repair history, design applications will vary: –Between the three structures –Along the length of each structure. Both physical and two numerical modeling are used to assess and fine tune the designs.

7. Physical Modeling of Cross Design Options – Optimize Reliability Jetty Resilience Compromised by Wave Action

8. = reliability-based decision point

9. Reach of North Jetty NOT Repaired Since 1917 Original Construction Severe Deterioration of Jetty Heads MCR Jetty Breach Feb 2006 Threatened Jetty Section Progressive Damage 2005 North Jetty = 58,000 tons Armor Stone (5-12 tons) 2006 – 2007 South Jetty = 160,000 tons Armor Stone (5-30 tons)

10. Sand infill from north side through damaged structure. Submerged head of north jetty helping to hold Peacock Spit and Benson Beach.

11. Major Rehab Considerations Engineering Features –Lagoon Fill –Spur Groins –Capping

12. Repaired in 2005 Sep 2002 MCR North Jetty

14. 12 m 10 m 8 m 14 m SOUTH JETTY 6 m MCR Navigation channel Existing spur groins on south jetty.

15. North Jetty South Jetty Clatsop Spit MCR Channel Peacock Spit NJS Use the NJS to reduce the scour rate along the southern toe of the north jetty (place 0.2 - 0.5 Mcy/yr) Use the SWS to feed material onto Peacock Spit and Sustain the sediment budget north of MCR (place 1.5-2.5 Mcy/yr): SWS

16. 1939 Benson Beach Shoreline 1913 North Head * * hea d of jett y in 200 2 2002 North Head Shoreline receded 2,000 ft since 1939 North Jetty Shoreline 1913 * As shoals recede, jetties become vulnerable to foundation scour and wave attack

17. South Jetty Head – 4000 ft loss in length

18. Major Rehab Alternatives Scheduled Repair Immediate Rehab –Minimum Template –Large Template –Composite Template Scheduled Rehab

19. N 20 3040 5060 70 80 90 100 110 120 = spur groin NORTH JETTY MAJOR REHABILATION

20. Selected Plan Reliability: Major feature restoration consisting of structural work on Corps operated and maintained facility Goal: Develop the most cost-effective reliable structure that serves the purpose for the navigation channel

21. Applicable Environmental Laws NEPA (National Environmental Policy Act) –Mitigated FONSI Environmental Assessment CWA (Clean Water Act) CZMA (Coastal Zone Management Act) ESA (Endangered Species Act) –Biological Assessment –Biological Opinion Marine Mammal Protection Act Magnuson-Stevens Act

22. Potential Impacts Listed Species and Critical Habitat Impacts to Aquatic Organisms Impacts to Commercial and Recreational Fisheries Essential Fish Habitat Cultural Resources Socio-Economic Section 404 Waters and Wetlands

23. ESA Species in Project Vicinity 13 Runs of Salmonids Chinook Salmon

24. Juvenile Fish Studies North Jetty Disposal Site Jetty A

25. ESA Species in Project Vicinity Pelagic Mammals and Turtles Right Whale Green Sea Turtle

26. ESA Species in Project Vicinity Birds (Pelican, Eagle, Murrelet, Plover) Pelican Plover Eagle Murrelet

27. ESA Species in Project Vicinity Steller Sea Lions

29. Other Species of Concern Dungeness Crab California Sea Lion