Factors affecting stream nutrient loads: A synthesis of regional SPARROW model results for the continental United States

Journal of the American Water Resources Association
By: , and 

Links

Abstract

We compared the results of 12 recently calibrated regional SPARROW (SPAtially Referenced Regressions On Watershed attributes) models covering most of the continental United States to evaluate the consistency and regional differences in factors affecting stream nutrient loads. The models – 6 for total nitrogen and 6 for total phosphorus – all provide similar levels of prediction accuracy, but those for major river basins in the eastern half of the country were somewhat more accurate. The models simulate long‐term mean annual stream nutrient loads as a function of a wide range of known sources and climatic (precipitation, temperature), landscape (e.g., soils, geology), and aquatic factors affecting nutrient fate and transport. The results confirm the dominant effects of urban and agricultural sources on stream nutrient loads nationally and regionally, but reveal considerable spatial variability in the specific types of sources that control water quality. These include regional differences in the relative importance of different types of urban (municipal and industrial point vs. diffuse urban runoff) and agriculture (crop cultivation vs. animal waste) sources, as well as the effects of atmospheric deposition, mining, and background (e.g., soil phosphorus) sources on stream nutrients. Overall, we found that the SPARROW model results provide a consistent set of information for identifying the major sources and environmental factors affecting nutrient fate and transport in United States watersheds at regional and subregional scales.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Factors affecting stream nutrient loads: A synthesis of regional SPARROW model results for the continental United States
Series title Journal of the American Water Resources Association
DOI 10.1111/j.1752-1688.2011.00577.x
Volume 47
Issue 5
Year Published 2011
Language English
Publisher American Water Resources Association
Contributing office(s) Maryland Water Science Center
Description 25 p.
First page 891
Last page 915
Online Only (Y/N) N
Additional Online Files (Y/N) N