Nutrient Concentrations Remained Stable in Many Streams from 1993 to 2003

The U.S. Geological Survey National Water-Quality Assessment program conducted national- and regional-scale trend assessments (1993 to 2003) of nutrient concentrations and loads in streams and how these trends corresponded to changes in streamflow and nutrient sources, such as fertilizer applications, animal manure, population, and atmospheric deposition. Phosphorus and nitrogen concentrations remained relatively stable in about half of the streams assessed nationwide from 1993 to 2003; however, the pattern did vary in some regions, including increases in phosphorus concentrations in more than half of the streams assessed in the Mississippi/Atchafalaya River Basin. Linking trends in stream nutrient levels to changes in nutrient sources will enhance our understanding of the effectiveness of land management actions.

Regional-scale assessments of examined trends in nutrient and suspended-sediment concentrations and loads in the Upper Mississippi, Ohio, Red, and Great Lakes River Basin, Missouri River Basin, Lower Mississippi, Arkansas-White-Red, and Texas-Gulf River Basin, and the Pacific Northwest River Basin.

For more information on how nutrients vary over time in streams assessed across the Nation, contact:
Lori Sprague (lsprague@usgs.gov).

For more information on how nutrients and sediment vary over time in selected major river basins, contact:
David Lorenz (lorenz@usgs.gov) — Upper Mississippi, Ohio, Red, and Great Lakes River Basin
Lori Sprague (lsprague@usgs.gov) — Missouri River Basin
Richard Rebich (rarebich@usgs.gov) — Lower Mississippi, Arkansas-White-Red, and Texas-Gulf River Basin
Daniel Wise (dawise@usgs.gov) — Pacific Northwest River Basin