Pollution Impact

Experts are still studying the effects of metals pollution on the land and the river. We want to share with you some of the things they have found, and what they are still uncertain about.

The state Department of Health has issued “advisories” telling people to limit how much they eat of several species of fish caught in the UCR/LakeRoosevelt. These advisories are based on how much mercury has been measured in the flesh of each type of fish.

Slag discharge from Trail Smelter, 1992

Slag discharge from Trail Smelter, 1992

Slag is a black sandy material that is very high in metals and was discharged directly in to the river for decades. Sediment in the river and reservoir, especially when it has slaginit, can be toxic to zooplankton, and may have negative effects on fish that are sensitive to metals, like White Sturgeon, Rainbow Trout, and Kokanee, although these effects are hard to measure.

There used to be beds of “pearl shell” mussels in the Columbia River, and in the past they were a staple food source for Tribal members. Today there are no live pearl shells found in the UCR, while healthy populations of the mussels are still found in the Kettle and Okanogan Rivers. Although the link has not been proven, it is suspected that slag caused or contributed to their extinction from the river, because mussels are sensitive to metals.

"Acute and Chronic Sensitivity of White Sturgeon and Rainbow Trout" -  USGS Report 2013-5204 link

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