National Water-Quality Assessment (NAWQA) Program
SPARROW (Spatially Referenced Regressions On Watershed attributes) models have been developed for seven large regions
of the conterminous United States. Results from the models can be used to compare nutrient sources and watersheds that contribute elevated nutrient loads to downstreamreceiving waters, such as the South Atlantic and Gulf of Mexico, inland and coastal waters of the Northeast, the Upper Mississippi and Great Lakes, and Puget Sound. In the southwest, a SPARROW salinity model is used to estimate the spatial distribution of total dissolved solids and the natural human factors controlling salinity. A SPARROW nutrient model is also being developed for California.
SPARROW models for each of the seven regions have been incorporated into an interactive, online decision support system so that water managers, researchers, and the general public can access SPARROW models and map predictions of long-term average water quality conditions, track transport to downstream receiving waters, and evaluate management sourcereduction scenarios.