The Corps operates and maintains three jetties and the navigation channel that serves as the border between Washington and Oregon. The north jetty, built from 1913 to 1917, is 2.5 miles long. Jetty “A” was built in 1939 and is 0.3 miles long. The north jetty and jetty “A” are on the Washington side of the mouth. South jetty, built between 1885 and 1895, is 6.6 miles long and on the Oregon side of the mouth.
Many areas of each structure have been severely damaged due to the extreme waves of the Pacific Ocean interacting with the Columbia River. The structures are routinely exposed to ocean waves ranging from 10 to 20 feet high. Increased storm activity and the loss of sand shoal material upon which they are built have taken a toll on the structural integrity of the jetties. The Corps is working to restore the system to acceptable levels of reliability.
Building Strong® at the Mouth of the Columbia River
https://www.nwp.usace.army.mil/Locations/Oregon-Coast/Mouth-of-the-Columbia