Toxics in the lower Columbia

Toxic contaminants are pervasive the lower Columbia River, but we lack sustained monitoring to fully understand the issues. The Estuary Partnership has partnered on several studies to understand legacy and emerging contaminants. 

Contaminants can impair water quality, affect aquatic organisms like insects and salmon, and impair environmental and human health. Common toxic contaminants found in the Columbia River system include: 

• Polychorinated biphenyls (PCBs)
• Polycyclic aromatic hydrocarbons (PAHs)
• Polybrominated diphenyl ethers (PBDEs, or flame retardants)
• DDT and other legacy pesticides
• Current use pesticides
• Pharmaceuticals and personal care products
• Trace elements. 

The Columbia Basin lacks funding for ongoing toxics monitoring, and no monitoring was done on the mainstem from 2016 to 2022, even as new contaminants of concern have emerged. There is much we do not know about toxics in the river.

Studies on toxics in the Columbia River 

2011 Lower Columbia River Estuary Contaminant Data Compilation and Synthesis Project

The Estuary Partnership contracted with GSI Water Resources to develop an Access Database of the readily available electronic data from local agencies for selected toxics in lower Columbia River. The project brought together existing data on toxics including PBDEs, heavy metals, PAHs, PCBs, and pesticides in water, sediment, and biota (animal and plant tissues). 

One objective of building this database was to pinpoint “hot spots” for contaminants and data gaps in the lower Columbia River, which is meant to aid in identifying target areas for ecosystem restoration, monitoring, and clean up.  The majority of information for the database was obtained from recent studies that were conducted since 2000, although Bi-State Program results were also included.  

Key findings include:

• PAHs accumulate downriver. Both historic and recent data show higher concentrations at mouth of the Columbia, and near the urban/industrial areas of Longview and Portland. The highest concentrations of contaminants were found in the lower Willamette River but there may be a potential PAH source area near Longview also. 
• PCBs also show an urban signature, meaning concentrations are highest around the area from Portland to Longview. 
• There are elevated levels of DDx (DDT and chemicals that are created as DDT breaks down) in biological samples scattered throughout study area, while sediment concentrations are highest in the estuary and within the lower Willamette River. Sediment samples at river miles 10, 35, and 100 in Columbia River and river miles 6 and 7 in the Willamette River show the highest concentrations of DDx. These concentrations have decreased since findings from prior to 2000, but still pose significant risk. 

2008-2010 ConHab Study, US Geological Survey 

The Columbia River Contaminants and Habitat Characterization (ConHab) Study by USGS focused specifically on polybrominated diphenyl ether flame retardants (PBDEs) and endocrine disrupting compounds (e.g. PCBs, phthalates, BPA, etc) in the river and throughout the food chain. The study examined samples of sediment, water, invertebrates, salmonids, resident fish, and osprey eggs, and found these toxic compounds at concerning levels throughout the food web. 

Key findings include:

1. Fish tissues (focused on largescale suckers) showed increased concentrations of contaminants moving downstream with increasing urbanization. 
2. Fish were more stressed at downstream sites, with findings including abnormal morphology, DNA fragmentation, and greater susceptibility to parasitic infection. 
3. Contaminant levels are of concern for communities that rely on subsistence fishing. 
4. Contaminants were present at levels of concern, and PBDEs were found to bioaccumulate in the food web.

2004-2007 Toxics Studies

Our Key Findings:

1.  PCBs, PAHs, and PBDEs are widespread in the lower river­, both geographically and in the food web.
2. Salmon are highly affected by toxic contaminants in the Columbia Basin.
   • Urban and industrial portions of the lower river contribute significantly to contaminant levels in juvenile salmon.
   • Juvenile salmon from upstream areas (e.g. the Snake River) are absorbing contaminants during their time rearing and feeding in the lower Columbia River.
   • Juvenile salmon are accumulating DDT in their tissue and are exposed to estrogen-like compounds in the lower river.
   • Copper concentrations were high enough to potentially interfere with crucial salmon behaviors (e.g. imprinting, homing, schooling, predator detection, predator avoidance, and spawning).
3. The most common pesticides in the water are atrazine, simazine, and metolachlor, which are suspected hormone disruptors.

Bi-State findings (1989-1995)

The Estuary Partnership's predecessor, the Bi-State Water Quality Program, also conducted extensive studies on water quality and toxics. An integrated summary of findings from all of the reports is available here.