National Water-Quality Assessment (NAWQA) Program
<-- BACK TO: Changes in Nutrient and Sediment Concentrations in Streams and Rivers of the United States, 1993-2003
Decreases in streamflows from 1993 to 2003 occurred at 22 percent of the 244 sites where nutrient trends were analyzed. Increases in streamflow occurred at only 2 sites during this time period. Nutrient concentrations and loads can vary significantly during different flow conditions. Nutrient concentrations were adjusted for streamflows to allow changes in nutrient concentrations to be evaluated in comparison to changes in nutrient sources, such as fertilizer application, animal manure, wastewater discharges, population, and atmospheric deposition.