95 water samples from 20 subbasins in Oregon's Willamette River Basin were analyzed for 86 dissolved pesticides and conventional constituents during 1996. The study, conducted as part of Phase III of the Willamette River Basin Water Quality Study, found atrazine was detected in 99% of samples. Data collection aimed to characterize pesticide distribution in small streams and relate concentrations to upstream land use categories.
Use Cases
- Analyze relationships between land use categories (urban, agricultural, grass seed crop percentage) and concentrations of specific pesticides like atrazine, metolachlor, and diuron.
- Identify exceedances of water quality standards for conventional constituents (E. coli, nitrate, temperature, dissolved oxygen, pH) across sampling sites.
- Compare pesticide concentration distributions (e.g., median concentrations of atrazine, diuron, metolachlor) between agricultural and urban sites using statistical significance (p-values).
- Investigate the occurrence of unusually high pesticide concentrations (1-90 parts per billion) in small streams compared to larger streams from previous studies.
- Examine seasonal effects on the distribution of dissolved pesticide concentrations and conventional water quality constituents.
Strengths
- Analysis covers a suite of 86 dissolved pesticides, with 36 detected basinwide.
- Samples collected from 20 subbasins (16 agricultural, 4 urban) provide land-use comparison.
- Data includes statistical significance tests (p<0.05, p<0.08) for median concentration differences between site types.
Limitations
- Sample size is limited to 95 water samples collected during a single year (1996).
- Toxicological assessment is limited due to lack of available information on aquatic life response to observed pesticide concentrations.
- Aquatic life toxicity criteria were established for only three of the detected pesticides, limiting regulatory exceedance analysis.
Provenance
- Source
- Willamette River Basin Water Quality Study (Phase III).
- Collection Method
- Water quality samples collected and analyzed for suspended sediment, conventional constituents, and dissolved pesticides.
- Time Range
- 1996
- Geography
- Willamette River Basin, Oregon, USA; small streams with drainage areas 2.6-13 square miles.