Skip Links

Scientific Investigations Report 2006-5107

About USGS /  Science Topics /  Maps, Products & Publications /  Education / Publication: FAQ

National Water-Quality Assessment Program

Nutrients in Streams and Rivers Across the Nation — 1992–2001

By David K. Mueller and Norman E. Spahr

Link to Report PDF (10 MB)Download Publication
Large File Warning!
SIR 06-5107 PDF (10 MB)
Right-Click to 'Save As' or 'Download'

Nutrient compounds of nitrogen and phosphorus were investigated in streams and rivers sampled as part of the U.S. Geological Survey National Water-Quality Assessment (NAWQA) Program. Nutrient data were collected in 20 NAWQA study units during 1992-95, 16 study units during 1996-98, and 15 study units during 1999-2001. To facilitate comparisons among sampling sites with variable sampling frequency, daily loads were determined by using regression models that relate constituent transport to streamflow and time. Model results were used to compute mean annual loads, yields, and concentrations of ammonia, nitrate, total nitrogen, orthophosphate, and total phosphorus, which were compared among stream and river sampling sites. Variations in the occurrence and distribution of nutrients in streams and rivers on a broad national scale reflect differences in the sources of nutrient inputs to the upstream watersheds and in watershed characteristics that affect movement of those nutrients.

Sites were classified by watershed size and by land use in the upstream watershed: agriculture, urban, and undeveloped (forest or rangeland). Selection of NAWQA urban sites was intended to...>>MORE

Version 1.0

Posted October 2006

*Downloading Suggestion
It is best to download this file to your hard drive rather than open it inside your browser. A standard click may automatically open the file inside the browser but doing so will result in a very slow load. Downloading the file may take several moments but will be worth the wait. Once it is downloaded, open it from your hard drive—it will open in a fraction of the time it would take to open over the Internet.

Part or all of this report is presented in Portable Document Format (PDF); the latest version of Adobe Acrobat Reader or similar software is required to view it. Download the latest version of Acrobat Reader, free of charge or go to for free tools that allow visually impaired users to read PDF files. logo  Take Pride in America button