National Water-Quality Assessment Program

Nonpoint and Point Sources of Nitrogen In Major Watersheds of the United States

U.S. Geological Survey Water-Resources Investigations Report 94-4001

CONTENTS

Fertilizer
Animal Manure
Atmospheric Deposition
Point Sources

FIGURES

1. Map showing estimated nonpoint-source inputs of nitrogen applied in commercial fertilizer, 1987 (14K GIF)
2. Map showing estimated nonpoint-source inputs of nitrogen in animal manure, 1987 (15K GIF)
3. Pie diagram showing sources of nitrogen oxide emissions in the United States, 1988 (10K GIF)
4. Map showing estimated atmospheric depostion of nitrogen in the United States (10K GIF)
5. Map showing locations of and pie diagrams showing proportions of nonpoint and point sources of nitrogen in selected National Water-Quality Assessment Program watersheds (18K GIF)
6. Map showing locations of and bar graphs showing annual amounts of nitrogen transported in streams and stream discharges in selected National Water-Quality Assessment Program watersheds (17K GIF)
7. Map showing locations of and pie diagrams showing proportions of in-stream nitrogen accounted for by point sources in selected National Water-Quality Assessment Program watersheds (16K GIF)
8. Map showing locations of National Water-Quality Assessment Program study units and their proposed starting dates (26 GIF)

U.S. Department of the Interior, U.S. Geological Survey Maintainer: Kerie Hitt (kjhitt@usgs.gov) Last update: 17:47:39 Mon 09 Jul 2001 Privacy Statement || Disclaimer || Accessibility URL: http://water.usgs.gov/nawqa/wri94-4001/wri94-4001main.html