Project Chief: Dwight Q. Tanner
Cooperator: City of Salem, Oregon
Salem is one of the largest population centers in Oregon, and the area has agricultural, urban/suburban, and industrial activities that affect surface-water quality. Water-quality concerns in the Salem area include salmonid fish rearing and spawning, resident fish and aquatic life, water-contact recreation, aesthetic quality, and water supply.
In streams, trace elements and organic compounds such as pesticides may be either dissolved or associated with particulate matter. The mobility and ultimate fate of pollutants associated with particulate matter depend in part on the mobility of the particulate matter itself. These pollutants may be transported, deposited, and resuspended with or disassociated from the particles in response to different hydrological conditions. There are two main reasons for analyzing the streambed sediment for trace elements and hydrophobic organic constituents: (1) fine-grained particles and organic matter are accumulators of trace elements and hydrophobic organic constituents, and (2) bed sediments in depositional environments provide a time-integrated sample of intermittent or storm-related contaminants.
An interpretative study identifying the occurrence and sources of trace elements and hydrophobic contaminants in stream bed sediments in the Salem area, including Mill Creek, will provide valuable information regarding the identification of potential contamination-source areas, and comparisons to background levels and aquatic-life criteria.
The objectives of this study are to identify the occurrence and potential sources of trace elements and hydrophobic organic compounds (including pesticides) in streambed sediments in the Salem area. The data will be used to assess the variability of streambed sediment quality in small streams draining a complex matrix of a variety of land uses in the Salem area.
Fourteen sampling areas were selected upstream and downstream from anticipated point and nonpoint sources of contaminants. Several of these areas were in the drainage basin of Mill Creek, which is a tributary to the Willamette River. The 14 sites (plus 2 replicates for quality-control purposes) were sampled during low-flow conditions in October 1999, and the samples processed, according to USGS Open-File Report 94-458: "Guidelines for Collecting and Processing Samples of Bed Sediment for Analysis of Trace Elements and Organic Contaminants for the National Water-Quality Assessment Program." Samples were analyzed at the USGS National Water Quality Laboratory for:
Elements and Organic Chemicals in Streambed Sediment in the Salem Area,
Oregon District Hydrologic Studies
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