Posted on September 17, 2025
Disposal sites may impact wildlife refuge
On Wednesday, the Clatsop County Board of Commissioners voted to move forward with plans to create 10 new dredging disposal sites in the Columbia River. Some of the sites have raised concerns due to their locations within the Lewis and Clark National Wildlife Refuge and in aquatic conservation zones.
The dredging process, known as the Lower Columbia Dredge Material Management Plan, has been developed by the U.S. Army Corps of Engineers with the intent of keeping the Columbia River navigable.
The Port of Portland, as a non-federal sponsor of the plan, participates in studies, is obligated to share in the cost of dredging and is charged with obtaining lands and easements when necessary for the project. The Port of Portland has also been contracted by USACE to perform the dredging.
Speaking at the commission meeting, Tom Bullion, planning manager with the Port of Portland, explained why he was before commissioners seeking an exception to the county’s conservation zones.
“The corps has concluded it is necessary to place dredge material outside of the navigation channel at 10 sites within Clatsop County where state and local law would not otherwise allow disposal,” Bullion said.
Despite county staff’s recommendation for the commission to adopt exceptions for the dredge disposal zones, they expressed concern about potential damage to the surrounding environment.
Speaking at a planning commission meeting Tuesday, the Clatsop County Community Development Director Gail Henrikson said based on their analysis, “there could be an effect on river hydrology and morphology within the Lewis and Clark Wildlife Refuge.”
According to county staff reports, the effects on the environment from two proposed dredge disposal sites, O-27.4 IW-S and O-27.4-BN, will be “minor to moderate, long term” for most plant and animal life.
Plant habitats, vegetation, and lamprey larvae would likely be buried in the creation of the sites but would eventually repopulate. However, the real impact would be alterations to river flow and sediment location.
They found that “major, long-term, local effects are anticipated” as a result of the O-27.4 sites. Indirect effects of the disposal zones could decrease water velocity both upstream and downstream, leading to the accumulation of sediment in certain areas and “erosion” between the sites.
In comments to both the county and USACE, the Oregon Department of Fish and Wildlife, which operates the Lewis and Clark Wildlife Refuge, recommended that the site “be removed from consideration or its use delayed until additional studies and hydraulic modelling is conducted.”
ODFW cites cumulative effects from disposal zones that may decrease water flows to the refuge, which could cause not only sedimentation but also “invasive plant growth.”
According to Henrikson, the Port of Portland reasoned the sediment cannot be disposed of in the ocean or on land because it is a “limited commodity” that will negatively impact the “river bottom’s morphology and change how the river flows” if it is not kept within the ecosystem.
It additionally cannot be transferred further upriver because of energy costs.
Environmental impacts a concern
Speaking at Tuesday’s planning commission meeting, Commissioner Jeremy Linder said he was concerned about negative environmental impacts as a result of the disposal sites.
“I’m someone that has spent a lot of time in the Lewis and Clark National Wildlife Refuge,” Linder said. “I do have concerns that these islands out there are used for recreation, but they are filling in; all those sloughs and channels have been filling in … I don’t know if this is going to exacerbate this issue or not.”
Should the sites be approved, Henrikson pointed out that the exceptions would exist permanently.
“There’s no expiration date on them, they won’t expire at the end of the 20-year period, and there’s never a 100% guarantee that a non-federal user cannot use those sites at some point in the future,” Henrikson said.
Bullion said that in the Port of Portland’s view, it is “very unlikely that these sites would ever be used by an entity other than the corps (USACE) or its agents, agents such as the Port of Portland.”
Henrikson said the sites do meet legal qualifications for the county’s exemption and were chosen because their location in the river is “more stable, relatively speaking, than other sites that were reviewed.”
A public hearing and second reading of the ordinances allowing the disposal sites will be held on Oct. 8.
