The Mouth of the Columbia River's jetty system was constructed between 1885 and 1939. The system consists of three rubble-mound jetties: North Jetty, South Jetty and Jetty A. Constructed on massive tidal shoals and totaling 9.7 miles in length, the jetties minimize navigation channel maintenance and make passage safer for vessels transiting between the Pacific Ocean and the Columbia River.
Both north and south jetties recently required critical repairs to ensure their continued function until the implementation of the Mouth of the Columbia River Jetty System Major Rehabilitation Project, which provides a long term repair and maintenance plan for the jetty system. This plan is incorporated into the MCR Jetties Major Rehabilitation Evaluation Report. The last critical repairs occurred to North Jetty in 2015, South Jetty in 2007 and Jetty A in 1962.
The jetties are regularly pounded by Pacific Ocean waves between 10 and 20 feet high with winter storms bringing extreme waves in excess of 30 feet. Over the years, many areas of each jetty were severely damaged by these waves. Increased storm activity and the loss of the shoaling sand upon which the jetties are built have taken a toll on the structural integrity of the jetties.
If a critical section of the jetties were breached during a large storm, sand could be deposited into the federal navigation channel potentially shutting down commercial shipping. Restoring the channel entrance would require expensive emergency repairs to the jetty and dredging to restore the channel to depth.