Water-quality data for the South Umpqua River Basin, Oregon, 1990-92

Data are presented from a study of algal and nutrient dynamics in the South Umpqua River Basin in southwestern Oregon during summer, low-flow periods from September 1990 to October 1992. The study was done to assist local and state regulatory agencies in determining total maximum daily loads of nutrients for the basin in order to maintain dissolved oxygen greater than 90 percent of saturation and pH less than 8.5 units. Fifty-one sites, including South Umpqua River, tributaries, and wastewater-treatment plant effluents, were sampled during this period. The study included collection of 537 samples or measurements from surface-water sites, 315 samples of wastewater-treatment-plant effluents, 1,262 field measurements during intensive studies within individual reaches, daily mean flow data from 6 streamflow gaging stations, daily mean water-quality data from 2 fixed-station monitors recording hourly, and various biological data including bacteria, algae and macro invertebrates in the river. Also included are notes from field reconnaissance surveys and a compilation of quality-assurance data.