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Posted 8/29/2018

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By Jeffrey Henon

The Columbia River Bar is one of the most treacherous waterways to navigate in the world with more than 2,000 vessels lost, but that hasn’t deterred mariners from crossing it for hundreds of years. The Columbia River, the largest in the Pacific Northwest, has millions of cubic yards of sediment flowing down annually into the mouth, where the river crashes into the Pacific Ocean.

The forces from these two powerful bodies of water push all that sediment around creating shipwrecking sandbars that are continually shifting. The earliest sailors relied on local Native Americans to guide their ships through the bar, but getting through safely was always a gamble.

In 1882, Congress tasked the U.S. Army Corps of Engineers to come up with a plan to tame the Mouth of the Columbia River and manage the shoaling that kept many ships in port until high tide.

Three years later, the Corps’ Portland District began construction of the South Jetty on the Oregon side of the river. To initially place the nine million tons of stone that currently makes up the South Jetty, the Corps built railroad systems along the jetty path six miles into the Pacific Ocean. The metaphor that “they were building the plane while flying it” aptly describes the herculean task the Corps undertook, except that of course, airplanes had yet to been invented.  By 1913, it was clear that the South Jetty wasn’t going to tame the treacherous inlet by itself.

When the Corps completed North Jetty on the Washington side of the river in 1917, it worked in conjunction with the South Jetty to reform the broad and treacherously unpredictable five mile-wide inlet into a stable two mile-wide inlet and increased the average channel depth to 40 feet.

The new 40-foot channel created by the north and south jetties continued to shift northward due to the flow from the mighty Columbia River, ultimately cutting a trench into the North Jetty. The Corps completed building Jetty A in 1939 to redirect the flow back towards the middle of the river.

The pounding that the jetties have endured for more than 130 years required Portland District to make multiple repairs to all three jetties over the years, but the jetty system is showing its age. To ensure that this vital waterway remains open for the $24 billion of commerce that is transported annually, the Corps is rehabilitating the complete jetty system.

Even with modern and powerful construction machinery, the project will take seven to eight years to complete. Working from the smallest to largest jetty, the Corps is scheduled to complete the entire rehabilitation project by 2024.

The Corps completed the rehabilitation of Jetty A, the smallest of the jetties, in 2017. At a cost of around $20 million, the Corps placed nearly 83,000 tons of stone on the 0.9 mile-long jetty.

In March 2018, the Corps began construction at the North Jetty and expects to place 140,000 tons of stone on the 2.5-mile long jetty at a cost of nearly $30 million. Corps employees anticipate North Jetty construction to wrap up October 2019.

Portland District employees are finalizing the design specifications for the 6.3-mile long South Jetty, which is the largest and most difficult to repair because of how far it extends into the Pacific Ocean. They expect to place approximately 360,000 tons of stone with construction scheduled for 2019 to 2024.

The largest stones used to repair all three jetties can weigh up to 42 tons. The companies transporting these mammoth stones use both trucks and barges to ship the stones from quarries. Unlike their predecessors who dumped the stones to create the jetties, today’s workers use modern equipment that allows them to interlock the stones like a puzzle resulting in jetties that need less stone and are more resilient to Mother Nature.

The Major Rehabilitation of the Mouth of the Columbia River Jetty System should extend the life of these jetties another 50 years, helping ensure the reliability of the Columbia Snake River System for future generations.