Analytical data from phases I and II of the Willamette River basin water quality study, Oregon

This report presents trace-element, organic-compound (pesticides, volatile and semivolatile organic compounds, and dioxin and furan compounds), and nutrient concentration data from the analyses of water column, suspended-sediment, and bed-sediment samples collected by the U.S. Geological Survey as part of Phases I and II of the comprehensive Willamette River Basin Water Quality Study in western Oregon. The overall study was designed by the Oregon Department of Environmental Quality to acquire the technical and regulatory knowledge necessary to protect and enhance water quality in the Willamette River Basin.

The data were collected at 50 sites, representing runoff from agricultural, forested, and urbanized subbasins. In Phase I, water samples were collected during high and low flows in 1992 and 1993 to represent a wide range of hydrologic conditions. Bed-sediment samples were collected during low flows in 1993. In Phase II, water samples were collected in the spring of 1994 after the first high-flow event following the application of agricultural fertilizers and pesticides and in the fall during the first high-flow events following the conclusion of the agricultural season.