Table 23 



Coos Bay 



Coos Bay, Oregon 



Date(s) 

 1878 



1879 



Construction and Rehabilitation History 



1880 

 1884 



1889 



1891- 

 1895 



1923 



1923- 

 1929 



1924- 

 1928 



1929- 

 1930 



A study was authorized for improvement of navigation at Coos Bay, 

 Oregon. The study recommended construction of a half-tide drift wall 

 or jetty extending seaward from Fossil Point, a second wall (parallel 

 to the first) to confine the channel, and sand fences to prevent 

 wind-blown sand from extending the spit. 



The project was adopted then referred to the Board of Engineers for 

 the Pacific Coast who recommended construction of a spur jetty from a 

 point 250 yd below the northern extremity of Fossil Point. The 

 project was authorized in November 1879. 



Construction of the spur jetty was initiated. 



The spur jetty was constructed at half-tide height to a 1,825-ft 

 length. 



The Board of Engineers recommended that two parallel jetties be con- 

 structed to confine the channel and that work on the spur jetty be 

 stopped. 



The north jetty was constructed to a 9,600-ft length from the high 

 waterline on the seaward side of the north spit. The jetty was of 

 rubble-mound construction on a foundation mattress of pole and brush. 

 Stone used averaged 2 tons with 25 percent weighing 4 to 10 tons and 

 up to 17 tons at the head. The outer 600 ft quickly subsided and was 

 replaced twice by 1900. 



No maintenance work has been done on the north jetty since 1900. The 

 outer 1,000 ft were 12 to 20 ft below mean low water. The north 

 jetty fixed the direction of the channel but was unable to maintain 

 satisfactory depths in the channel. The project was therefore modi- 

 fied to restore the north jetty and construct a south jetty in ac- 

 cordance with the project recommended by the Board of Engineers in 

 1889. 



The north jetty was restored to design height, using 690,212 tons of 

 stone. 



The south jetty was constructed. 



The south jetty was repaired, and a concrete cap was placed on the 

 outer 650 ft of the jetty. 



(Continued) 

 116 



