Posted on September 17, 2026
In order for massive cargo ships and tankers to traverse the Columbia River up to Portland, crews spend up to eight months each year dredging the river bottom so the channel remains deep enough for the commercial ships to pass.
The dredging is a massive operation that most people never see. But the work could come at a cost; local tribes have been warning for decades of the impact it can have on native fish habitats.
The Columbia River is among the Northwest’s most important trade routes, commonly called a “marine highway.” And underneath that traffic, the river is constantly changing.
As sediment build up on the river bottom, crews with the vessel Dredge Oregon work every year to dig it out, keeping the channel excavated just enough for shipping vessels: 600 feet wide and 43 feet deep.
“This is dredge season,” said Don Tjostolvson, director of navigation for the Port of Portland. “You don’t really notice the dredging that much, but you would notice it really quick if we didn’t do it.”
Some of the ships passing through have a draft as deep as 40 or 41 feet — referring to the furthest down the hull goes from the waterline — meaning there is often not much leeway.
“They are very close to the bottom of the river,” Tjostolvson said. “So, you can imagine that if dredging didn’t happen, that material encroaches on that envelope and that stops ships. Our job is to keep that traffic moving.”
Recently, that took the ship out to river mile 34, just above Pillar Rock, about 25 nautical miles from Astoria.
“Here we started with 300,000 cubic yards — we’ve been moving almost 30,000 a day,” said Mark Wrights, captain of Dredge Oregon.
“I think the saying is we are a ‘river of grain,’ we are the largest exporter of wheat in the country,” Wrights continued. “Even though we can’t see what we do, we know we are helping out local economy.”
Wrights’ 44-person crew spends up to three weeks dredging a single location. From June until the end of the year, they’ll hit up to 10 sites, laying miles of temporary pipeline. The ship’s 5,000-horsepower pump churns and pushes material like sand from the bottom of the river, through the piping and to a nearby island.
Crews say the roughly two miles of pipe move an average 25,000 cubic yards of material each day, the equivalent of about 2,500 dump trucks.
“There is a lot of thought that goes into it on how we place the material,” said Wrights.
“We’ve helped establish almost double the count of mating pairs,” said Wrights. “So, we constantly flip-flop sides of an island to make sure that they have prime habitat.”
But there’s another habitat, one under the Columbia River’s surface, which tribal leaders warn is threatened by the dredging operations — operations which contribute to the river’s transfiguration from what it was prior to modern manipulation.
“The dredging operations in the lower Columbia must have the health and well-being of Pacific lamprey, salmon and steelhead, who depend on that environment at its forefront,” said Kathleen George, tribal council member for the Confederated Tribes of Grande Ronde. “Failure to do so puts those populations at an unacceptable level of risk when they are already struggling to survive.”
The U.S. Army Corps of Engineers acknowledged the potential impacts on fish in their habitat in a statement, saying that those concerns informed an environmental review for their recently completed 20-year dredging plan.
“USACE’s responsibility to maintain the Federal navigation channel through dredging and placement can have effects on fish and aquatic habitat, including temporary increases in turbidity, disturbance of bottom habitat and changes in available forage,” the Corps said, in part. “We evaluate those effects and use measures designed to avoid or minimize impacts.”
The Corps formally consults with the National Marine Fisheries Service and the U.S. Fish and Wildlife Service under the Endangered Species Act, they said, to ensure they’re in compliance with environmental regulations before they dredge.
Right now, the U.S. Geological Survey is studying the impact of this relocation of dredged material on juvenile Chinook and coho salmon, the Corps added, in hopes of better understanding “the long-term benefits and tradeoffs.”
“Our job is to balance environmental considerations with our responsibility to maintain a safe and reliable Federal navigation channel,” they said. “Protecting fish, wildlife and aquatic habitat is an important part of how we plan and carry out that mission.”
