Water-quality assessment in the Trinity River Basin, Texas; pesticide occurrence in streams, winter and spring 1994

A consistent, basin-wide set of data for streams in the Trinity River Basin is necessary to provide a baseline for current conditions, to compare with historical data, and to provide a reference for future studies by the National Water-Quality Assessment (NAWQA) Program. In addition, the basin-wide surveys begin the process of addressing the cause-effect relation for water quality in the basin. Effects of land use, geology, vegetation, soils, and reservoirs on water quality were considered by site selection. Seasonal differences were addressed by conducting two surveys, the first during the winter low-flow period and the second during the late spring high-flow period.