National Water-Quality Assessment (NAWQA) Project
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.