The South Jetty has been extended to a total length of nearly 7 miles. Around 5.8 million tons of stone were added during repairs in the early 1900s. The North Jetty was next constructed on the Washington side of the MCR between 1913 and 1917. The North and South Jetties stabilized the MCR. The two jetties helped to maintain a 40-ft-deep navigation channel through the MCR. The third jetty in this system, Jetty A, was completed in 1939.