Table 22 



Columbia River flt The Mouth 



Astoria, Oregon 



Date(s) Construction and Rehabilitation History 



1882 A study was authorized for improvement of navigation at the mouth of 

 the Columbia River. The study, submitted in 1882, recommended con- 

 struction of a south jetty approximately 4.5 miles long. 



1884 Construction of the south Jetty was authorized. 



1885 Construction of the south jetty was initiated. 



1893 The Board of Engineers recommended increasing crest elevation of the 

 jetty to +12 ft mlw at the shore, sloping to +10 ft mlw at a distance 

 of 1.125 miles from shore, then sloping to +4 ft mlw at the outer 

 end. Also recommended was the construction of 4 groins on the north 

 side of the Jetty. 



1895 The south jetty was completed, including the recommendations made in 

 1893. Jetty length was 22,440 ft and required 945,923 tons of stone. 



1899 The channel depth decreased as the channel shifted to the north. A 

 new study was authorized for stabilization of the channel at -40 ft 

 mllw. 



1903 The report authorized in 1899 was submitted for study. The report 

 recommended extending the south Jetty 2.5 miles westerly and con- 

 structing a north jetty to extend westerly from Cape Disappointment. 



1903- The extension to the south Jetty was constructed. The extension was 

 1913 12,514 ft long and required 4,837,311 tons of stone. 



1913- The north jetty was constructed to a crest elevation of +28 to +32 ft 

 1917 mllw, a crest width of 25 ft, side slopes of 1:1.5, and length of 

 approximately 2.5 miles. 



I93I- The inner 3-3 miles of south Jetty were rehabilitated with 

 1937 2,207,613 tons of stone. 



1937 The outer 300-ft portion of the south jetty was repaired during 



1931-37 with 10,636 tons of stone. The outer 500 ft were impregnated 

 with 12,737 tons of asphaltic mix with 18 percent asphalt and 82 per- 

 cent beach sand. 



1938- The north Jetty was rehabilitated except for the outer 1,700 ft. 

 1939 A concrete terminus was placed at the end of the rehabilitated 

 section. 



(Continued) 

 113 



