The Mouth of the Columbia River's jetty system was built from 1885 - 1939. The system consists of three rubble-mound jetties with a total length of 9.7 miles, constructed on massive tidal shoals and designed to minimize navigation channel maintenance and provide safe transit between the Pacific Ocean and the Columbia River.
The north and south jetties have been repaired several times since original construction; the latest repairs occurred in 2015 on the North Jetty and 2006-2007 on the South Jetty. Jetty "A" has only been repaired once since initial construction, in 1965. The recent work on the north and south jetties addressed the critical repairs necessary to maintain jetty function until a longer-term maintenance and repair plan was designed. This plan is incorporated into the MCR Jetties Major Rehabilitation Evaluation Report.
Many areas of each structure are 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. The 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.
Of primary concern are critical portions of the jetties, which could breach during a large storm event, allowing sand to be transported and deposited directly into the federal navigation channel. Such an event could shut down commercial navigation at the entrance to the river system, requiring expensive emergency repairs to the jetty and dredging to restore channel depth.