Upriver Reach Sediment Characterizations

GSI conducted surface sediment sampling from river mile 16 through 26, north of downtown Portland, Oregon.

GSI conducted two focused sediment characterizations in the upriver reach of the lower Willamette River, from river mile 16 through 26. The objectives of this work to uncover (1) potential source areas in sediment that may have contributed to elevated polychlorinated biphenyl (PCB) concentrations in smallmouth bass, and (2) any previously unidentified potential source areas in the Lower Willamette watershed.

Following the surface sediment sampling effort, GSI prepared Field and Data Reports, which were approved by DEQ and the U.S. Environmental Protection Agency (EPA) in May 2018. With the exception of one location where elevated PCBs were observed, the analytical results indicated that concentrations of chemicals of concern in the upriver reach are below concentrations that would warrant active remediation.

GSI's work involved:

  • Working with DEQ to evaluate existing data and identify potential source areas.
  • Preparing work plans and obtaining permits.
  • Conducting sampling efforts in potential source areas.
  • Preparing the Field and Data Reports and submitting them to regulatory agencies for approval.


Portland, Oregon


  • Data gaps evaluation
  • Sediment sampling
  • Sediment characterization

The sediment characterization results showed that, with the exception of one location, concentrations of pollutants in the upriver reach were below the cleanup levels for the Portland Harbor Superfund Site.

Photo Gallery

Marine sampling vessel

GSI and DEQ personnel collecting sediment samples

Power-grab sediment sampling