DDT, other contaminants persist in Columbia River 1

As the Columbia River runs its 1,200-mile course from a Canadian glacier out to the Pacific Ocean, it passes by one nuclear production complex, 13 pulp and paper mills, and countless agricultural areas, mines, and sewer outflows from major cities.

So perhaps it should be no surprise that the U.S. EPA recently found that the river—which drains a 259,000-square-mile basin covering seven U.S. states and part of Canada—is carrying "unacceptable" levels of contaminants like mercury, DDT, PCBs, and PBDEs.

Although other river systems like the Mississippi and the Colorado contain comparable levels of DDT, PCBs, and mercury, an EPA official said that reducing pollution in the Columbia basin would be a high priority. This is good news for many Northwest tribes who rely heavily on Columbia River fish for their diet. It’s also important news for the region’s salmon populations, which use the Columbia and its tributaries as spawning ground.

So how did these contaminants end up in the river? Here’s a rundown, courtesy The Oregonian:

Mercury

Status: May be on the rise. Levels increased in
osprey eggs in the lower Columbia River and in northern pikeminnow in
the Willamette River in the past decade. Responsible for most fish
consumption warnings in the Columbia basin.

Sources: Most comes from outside the area. Local sources include PGE’s Boardman coal plant and a cement plant near Baker City.

Concern: Can cause neurological and reproductive problems in people and animals.


DDT

Status: Pesticide banned in 1992. Levels decreasing but still found at unhealthful levels in fish throughout the basin.

Sources: Mainly runoff from agricultural lands.

Concern: Thins bird eggshells, causes reproductive and
development problems. Linked to cancer and other problems in laboratory
test animals.

PCBs

Status: Levels of the widely used industrial chemical
banned in 1976 are also declining but still widely found in fish tissue
and sediments.

Sources: Industrial spills and storm water runoff from industrial sites. Also airborne from distant sources.

Concern: Can harm hormonal, immune and reproductive systems in people and aquatic life and increase cancer risk.

PBDEs
Status: Flame retardants present in many consumer
products. Recently banned, at least partially, in both Oregon and
Washington. Data is limited, but they appear to be increasing in fish.

Sources: Still uncertain, but several studies indicate municipal sewage wastewater may be a significant source.

Concern: Harm to mammals’ reproduction, development and neurological systems.

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