The National Water Quality Network (NWQN) for Rivers and Streams includes 105 surface-water river and stream sites monitored by the U.S. Geological Survey (USGS) National Water Quality Program. This data release provides streamflow, nutrient, and sediment data collected and analyzed by USGS for sites on the one Mississippi River site and one Atchafalaya River site used to represent contributions to the Gulf of America for water years 1968 through 2024. This dataset includes daily, monthly, and annual summaries of streamflow conditions, discrete water-quality concentrations, annual water-quality loads, and information on water-quality trends. Water quality data was collected at USGS sites 07373420 Mississippi River near St. Francisville, LA and 07381495 (COE) Atchafalaya River at Melville, LA. Streamflow data was collected at U.S. Army Corps of Engineers sites 01100Q Mississippi River at Tarbert Landing and 03045Q Atchafalaya River at Simmesport.