Willamette River Sediment Study

Between 2008 and 2010, DEQ worked with the City of Portland Bureau of Environmental Services and other partners, including the ZRZ Realty Co. (Zidell), PacifiCorp, Portland General Electric, and TriMet, to investigate sediment quality in the Willamette River in downtown Portland. For over 100 years, various industrial activities have occurred along this reach of the river that may have contaminated sediments. Waterfront and upland facilities also may be currently discharging contaminants to the Willamette River via stormwater.

The purpose of the investigation was to gain a better understanding of the nature and extent of hazardous substances in Willamette River sediments between river mile 12 and 16, which corresponds to the area bounded by the Steel Bridge and the southern tip of Ross Island.

The first phase of Sediment sampling took place in May and June 2008. A report, titled “Field and Data Report, Downtown Portland Sediment Characterization” detailing the results of the investigation was submitted to DEQ in January of 2009. DEQ completed an evaluation of this data documented in the Downtown Portland-Willamette River Sediment Evaluation – Preliminary Identification of Locations of Interest. This evaluation identified 9 priority areas for follow-up environmental work.

Between the summer 2009 and spring 2010, a Phase II evaluation of the downtown Willamette reach was completed focusing on the nine priority areas identified by DEQ. PGE took the lead on investigating two of the nine areas. DEQ, the City of Portland, and Tri-Met jointly funded investigation associated with the remaining seven areas. Phase II included analysis of archived samples from Phase I as well as new samples collected in the priority areas. A report documenting this data was finalized in June 2010, Field and Data Report – Downtown Portland Sediment Characterization Phase II. DEQ completed an evaluation of the data in November 2011.

This study is separate and distinct from the ongoing remedial investigation of the Portland Harbor Superfund Site which is being conducted downstream.

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