An Oregon Department of Environmental Quality study of a 150-mile stretch of the Columbia River found water quality is "generally good" for recreational use.
But the study shows that the lower-middle section of the Columbia suffers from fish-habitat degradation, and fish samples contained contaminants, including PCBs, mercury and banned pesticides such as DDT.
The five-year study is the first of its kind for the lower-middle section of the Columbia between Cascade Locks and Bonneville Dam on the west and Umatilla and McNary Dam on the east.
"It helps us better understand general water quality conditions in the Columbia and the extent of contamination in fish in the river," said Aaron Borisenko, manager of DEQ Laboratory's water quality monitoring program, which produced the study.
The study involved collecting water and fish tissue samples at 31 locations. Findings released Nov. 26 include:
* Legacy contaminants that are no longer manufactured, such as DDT, persist in the environment and were evident in fish tissue samples at concentrations exceeding DEQ's human health criteria.
* Every fish tissue sample failed to meet DEQ's standard for mercury.
* All water samples met DEQ's recreational contact criteria for E. coli bacteria.
* The river's habitat suffers from degraded streamside areas, while the river's banks are relatively stable due to riprap and natural basalt.
DEQ plans to use the study's findings to assist local, state and federal agencies, as well as tribes to address Columbia River pollution. The study also will help DEQ target follow-up monitoring in areas of concerns.