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Effects of Chromium in the Columbia River in Spokane, Washington Studied

Date Posted: June 26, 2001

The Service's Upper Columbia River Basin Field Office in Spokane, Washington and the U.S. Geological Survey have completed laboratory studies assessing the potential effects of chromium contamination on chinook salmon in the Hanford Reach of the Columbia River (Reach). The Reach is a unique and biologically diverse landscape, which includes the last 51-mile long free-flowing, non-tidal segment of the Columbia River. About 80 percent of the Upper Columbia River fall chinook salmon (Oncorhynchus tshawytscha) spawn in the Reach The Reach also supports runs of Federally-listed endangered Upper Columbia River steelhead (Oncorhynchus mykiss) and white sturgeon (Acipenser transmontanus). Part of the Reach is adjacent to the 100 Area, one of four Environmental Protection Agency National Priority List (NPL) sites (a.k.a. “Superfund” sites) on the Hanford Nuclear Reservation.

Past operations of nine nuclear reactors at the 100 Area NPL site resulted in the production and disposal of large quantities of wastes and widespread contamination of soils, groundwater, and the Columbia River. Hexavalent chromium is one of the major contaminants of concern. Chromium was added to cooling water to prevent corrosion and clogging of pipes in the nuclear reactors. The cooling water was discharged directly to the River and to trenches and holding ponds, which led to groundwater contamination. During low flow, the contaminated groundwater discharge to the River increases. In the fall, during low river flow, chinook salmon spawn in shallow, near-shore areas. Some of these spawning areas are adjacent to groundwater seeps reaching the river. High concentrations of chromium (up to 632 ppb) have been found in the groundwater near salmon spawning areas.

The results of the laboratory studies revealed that harmful effects to salmon, ranging from poor health to reduced growth or even death were seen at hexavalent chromium concentrations that potentially occur in or near chinook salmon spawning areas in the Reach. The highest concentration of chromium recorded in the groundwater of the Columbia River was more than 11 times greater than the minimum concentrations shown to have harmful effects and more than twice the concentration shown to cause a significant number of deaths in the laboratory studies. Laboratory studies also revealed that chinook salmon were capable of detecting and avoiding concentrations greater than those levels that were shown to have harmful effects. Although these results may indicate that salmon can avoid direct harm from the chromium, avoiding contaminated spawning areas in the Reach can result in a loss of important breeding habitat for the species.

The information collected during these studies will assist the Hanford Natural Resource Trustee Council (HNRTC) in evaluating contaminant threats to fish at the 100 Area. This is the HNRTC’s first set of focused studies to assess the effects of 100 Area contaminants on the aquatic resources of the Columbia River. These results indicate that it is important for State and Federal agencies to ensure effective cleanup of chromium if aquatic life, including threatened and endangered fishes, are to be protected.

Brad Frazier 509-891-0450

Last updated: June 12, 2015