Publication Summary

The Spokane River has the highest known PCB levels among Washington State rivers, lakes, and streams. In this report, the data on PCB concentrations in Spokane River fish, sediment, and water are summarized and reviewed, and an assessment is made of the ecological hazard for the river′s aquatic life and fish-eating wildlife.

The Spokane River has the highest known PCB levels among Washington State rivers, lakes, and streams. In this report, the data on PCB concentrations in Spokane River fish, sediment, and water are summarized and reviewed, and an assessment is made of the ecological hazard for the river′s aquatic life and fish-eating wildlife.

Based on the available data and toxicological benchmarks used in the assessment, the primary ecological hazards identified were: 1) possible adverse effects on the sustainability of salmonid populations and fish-eating mammals, primarily in the reach between Trentwood and Nine-Mile Dam; and 2) possible adverse effects on benthic invertebrates in the Trentwood to Monroe Street Dam reach in areas where PCBs have been concentrated in fine-grained sediments, such as behind Upriver Dam. The ecological hazard due to the PCB levels in Long Lake and in the Spokane Arm is low. Fish-eating birds do not appear to be at risk in any part of the river.