Mouth of the Columbia River Jetties Major Rehabilitation

1. Mouth of the Columbia River Jetties Major Rehabilitation

4. 1965 2005 1939 1917 MCR North Jetty - Construction and Repair History (Receded approximately 1800’ in length since 1916)

5. 2007 2006 1982 MCR South Jetty - Construction and Repair History (Receded approximately 5000’ in length since 1885 - 1913) 1961- 1962 1931-1934 1913 1886

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

8. = reliability-based decision point

9. Reach of North Jetty NOT Repaired Since 1917 Original Construction 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) MCR Jetty Breach Feb 2006 Severe Deterioration of Jetty Heads

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

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

12. MCR North Jetty Repaired in 2005 Sep 2002

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

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

16. North Head Shoreline 1913 Benson Beach * North Head 1939 Shoreline 1913 head of jetty in 2002 * Shoreline receded 2,000 ft since 1939 North Jetty * 2002 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. = spur groin 120 110 90 100 80 70 60 50 40 30 20 N 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 Vicinity13 Runs of Salmonids Chinook Salmon

24. Juvenile Fish Studies North Jetty Disposal Site Jetty A

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

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

27. ESA Species in Project VicinitySteller Sea Lions

29. Other Species of Concern California Sea Lion Dungeness Crab