Selected elements and organic chemicals in streambed sediment in the Salem area, Oregon, 1999

Analysis of streambed sediments in the Salem, Oregon, area showed anomalously large concentrations of some elements and organic chemicals, indicating contamination from anthropogenic and/or geologic sources. The streambed sediment sample from Clark Creek, an urban basin, had large concentrations of polycyclic aromatic hyrdocarbons (PAHs), organochlorines, cadmium, lead, and zinc. The sample from the East Fork of Pringle Creek, which is a mostly urban basin, had the highest concentrations of DDD, DDE, and DDT compounds. Aldrin was detected in streambed sediment at only one site, the East Fork of Pringle Creek. Ten of the 14 sites sampled had exceedances of the sediment quality guidelines of the Canadian Council of Ministers of the Environment (CCME), and 8 sites had exceedances of guidelines from the Puget Sound Dredged Disposal Analysis (PSDDA) Program.

Trace element concentrations in the Salem area generally were similar to those found previously in the Willamette Basin and nationally. However, cadmium, lead, and zinc concentrations were larger in the sample from Clark Creek than for largest value for Willamette Basin data from earlier studies. Zinc concentrations in the sample from Clark Creek exceeded sediment quality guidelines from the CCME and PSDDA.

p,p'-DDE, which is a persistent breakdown product of the banned organochlorine-insecticide, DDT, was detected at all sites. Total DDT (the sum of p,p'-DDD, p,p'-DDE, and p,p'-DDT) concentrations exceeded the PSDDA screening level at eight sites and exceeded twice the PSDDA maximum level at the East Fork of Pringle Creek. Cis- and trans- chlordanes were detected at about 80% of the sites. The concentration of total chlordane for the sample at Clark Creek was larger than for any sample from previous Willamette Basin studies. The largest concentration of dieldrin also was from the sample at Clark Creek, which was the only site that exceeded the CCME guideline for dieldrin.

The high levels of contaminants in some Salem area streams indicates the need for further study to assess the biological effects of these contaminants. Future monitoring in the Salem area could include bioassays using benthic invertebrates and the measurement of organochlorine compounds, including DDT, DDE, DDD, and dieldrin in fish tissue. Because resident fish may be consumed by humans and wildlife, fish tissue analyses would be helpful to determine the health risk associated with fish consumption.