Surface-water nutrient conditions and sources in the United States Pacific Northwest

Journal of the American Water Resources Association
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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.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Surface-water nutrient conditions and sources in the United States Pacific Northwest
Series title Journal of the American Water Resources Association
DOI 10.1111/j.1752-1688.2011.00580.x
Volume 47
Issue 5
Year Published 2011
Language English
Publisher Wiley
Publisher location Hoboken, NJ
Contributing office(s) Oregon Water Science Center
Description 26 p.
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title Journal of the American Water Resources Association
First page 1110
Last page 1135
Country United States