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Columbia Slough Sediment Project

The Columbia Slough is located south and parallel to the Columbia River and consists of approximately 31 miles of water way extending from Fairview Lake on the east side to the Willamette River on the west. Industrial, agricultural and urban development along the Columbia Slough has resulted in the accumulation of a variety of contaminants in Slough sediments. Some contaminants, including polychlorinated biphenyls (PCBs) and pesticides bioaccumulate in fish to the extent that resident fish in the Slough are harmful to eat. In 2005 DEQ issued a Record of Decision establishing a program to cleanup sediments at individual release sites, implement source control measures throughout the watershed to prevent further releases, and monitor conditions over the long term to ensure continued improvement.

DEQ is working with many partners to address Columbia Slough contamination including:

  • City of Portland to prevent elevated stormwater discharges associated with City Outfalls and city properties to the Columbia Slough.
  • Private parties at many individual sites to prevent further pollution releases to the Columbia Slough and Columbia Slough sediment cleanup.
  • Multnomah County Drainage District's dredging operations achieve concurrent flood conveyance and remediation of sediment contamination where project objectives overlap.
  • DEQ conducts investigations/sediment cleanups in various Slough segments using settlement funds obtained from private parties in exchange for a liability release for their site's contribution to contamination in Slough sediments.

More information

​Below are resources for properties conducting an upland source control evaluation:

Columbia Slough Screening Level Values

​Industrial, commercial and agricultural facilities located within the Columbia Slough Watershed have contributed to sediment contamination through historical and current wastewater discharge, stormwater runoff, bank erosion and groundwater discharge. The following fact sheet provides additional information to understand Columbia Slough Sediment Liability for owners, operators and prospective purchasers within the Columbia Slough:

Columbia Slough Sediment Cleanup: Option for Liability Release Through Cash Settlements

​Funds available for habitat enhancement

Habitat Enhancements Completed


Environmental Cleanup Site Information: 1283 
County:  Multnomah 
City:  Portland
Region: Northwest  


Project Managers: 
Heidi Nelson - 503-229-6802
Sarah Miller - 503-229-5040 

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