National Water-Quality Assessment (NAWQA) Project
For information on changes in nutrient concentrations and loads in streams and rivers and how these changes correspond to streamflow and nutrient sources, see the USGS report: Nutrient Trends in Streams and Rivers of the United States, 1993-2003
For information on how trends in total nitrogen and total phosphorus concentrations vary by major geographic regions of the U.S., see the article and supplemental material in Environmental Science and Technology: Regional Nutrient Trends in Streams and Rivers of the United States, 1993-2003
For more information on how nutrients varied from 1993 to 2003 in 244 streams across the Nation, contact: Lori Sprague (firstname.lastname@example.org).
Regional-scale USGS assessments examined changes from 1993 to 2003 in nutrient and sediment concentrations and loads in relation to changes in streamflow and nutrient sources throughout selected major river basins.
Great Lakes, Ohio, Upper Mississippi, and Souris-Red-Rainy River Basin
(contact: Dave Lorenz, email@example.com)
Lower Mississippi, Arkansas-White-Red, and Texas-Gulf River Basin
(contact: Richard Rebich, firstname.lastname@example.org)