Yaquina Bay North Jetty, Oregon 



Yaquina Bay is a tidal estuary located on the Oregon coast approxi- 

 mately 177 km (110 miles) south of the Washington State line. The pres- 

 ent navigation project consists of a navigation channel maintained to a 

 depth of -12.2 m (-40 ft) mllw at the entrance and protected by two paral- 

 lel rubble-mound breakwaters, which are separated by a distance of about 

 305 m (1,000 ft). A layout of the project is illustrated in Figure 11. 

















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Figure 11. Layout of Yaquina Bay jetties 



Since initial authorization of the Federal navigation project over 

 100 years ago, the two jetties protecting the entrance channel have under- 

 gone a series of extensions and repairs. The north and south jetties have 

 been extended three times to their present authorized lengths of 2,130 m 

 (7,000 ft) and 2,620 m (8,600 ft), respectively. Since its final extension in 

 1972, no additional repair work has been required on the south jetty; how- 

 ever, the north jetty has required two rehabilitations since its final exten- 

 sion in 1966. In both instances, severe wave conditions hammered the 

 seawardmost 137 m (450 ft) of the structure below the water level, posing 

 a hazard to navigation and creating increased dredging requirements. Dur- 

 ing the most recent repair, in 1988, the seawardmost 30.5 m (100 ft) of the 

 jetty was armored with 29,485-kg (32.5-ton) stone. The next 30.5 m 

 (100 ft) was armored with 23,405-kg (25.8-ton) stone, and the landward- 

 most portion of the rehabilitation was armored with 16,330-kg (18-ton) 

 stone. The crest was 9.1 m (30 ft) wide and had an elevation of +6.1 m 

 (+20 ft). Side slopes were 1V:2H. 



14 



Chapter 2 Project Descriptions and Inspection Results 



