Paper No. JAWRA-10-0102-P of the Journal of the American Water Resources Association (JAWRA). Discussions are open until six months from print publication.
Surface-Water Nutrient Conditions and Sources in the United States Pacific Northwest1
Article first published online: 22 AUG 2011
© 2011 American Water Resources Association. This article is a U.S. Government work and is in the public domain in the USA
JAWRA Journal of the American Water Resources Association
Volume 47, Issue 5, pages 1110–1135, October 2011
How to Cite
Wise, D. R. and Johnson, H. M. (2011), Surface-Water Nutrient Conditions and Sources in the United States Pacific Northwest. JAWRA Journal of the American Water Resources Association, 47: 1110–1135. doi: 10.1111/j.1752-1688.2011.00580.x
Re-use of this article is permitted in accordance with the Terms and Conditions set out at http://wileyonlinelibrary.com/onlineopen#OnlineOpen_Terms
- Issue published online: 10 OCT 2011
- Article first published online: 22 AUG 2011
- Received October 6, 2010; accepted May 2, 2011.
- geospatial analysis;
- Pacific Northwest
Wise, Daniel R. and Henry M. Johnson, 2011. Surface-Water Nutrient Conditions and Sources in the United States Pacific Northwest. Journal of the American Water Resources Association (JAWRA) 47(5):1110-1135. DOI: 10.1111/j.1752-1688.2011.00580.x
Abstract: The SPAtially Referenced Regressions On Watershed attributes (SPARROW) model was used to perform an assessment of surface-water nutrient conditions and to identify important nutrient sources in watersheds of the Pacific Northwest region of the United States (U.S.) for the year 2002. Our models included variables representing nutrient sources as well as landscape characteristics that affect nutrient delivery to streams. Annual nutrient yields were higher in watersheds on the wetter, west side of the Cascade Range compared to watersheds on the drier, east side. High nutrient enrichment (relative to the U.S. Environmental Protection Agency’s recommended nutrient criteria) was estimated in watersheds throughout the region. Forest land was generally the largest source of total nitrogen stream load and geologic material was generally the largest source of total phosphorus stream load generated within the 12,039 modeled watersheds. These results reflected the prevalence of these two natural sources and the low input from other nutrient sources across the region. However, the combined input from agriculture, point sources, and developed land, rather than natural nutrient sources, was responsible for most of the nutrient load discharged from many of the largest watersheds. Our results provided an understanding of the regional patterns in surface-water nutrient conditions and should be useful to environmental managers in future water-quality planning efforts.