Estimated state-wide total nitrogen (TN) and total phosphorus (TP) loads and yields, as predicted by the 2012 regional USGS SPARROW models.Excess nitrogen and phosphorus loading impacts not only local waters, but also downstream waterbodies and coastal systems including the Chesapeake Bay, the Great Lakes, the Gulf of Mexico, and Puget Sound. The data in this indicator table are based on output from the United States Geological Survey’s (USGS) Spatially Referenced Regression On Watershed Attributes (SPARROW) models. SPARROW is a watershed modeling tool which, based on a mass-balance approach, estimates the excess amounts (i.e., amounts beyond assimilative capacity) of nitrogen and phosphorus exported from watersheds and delivered to downstream waterbodies. The models relate in-stream water quality measurements of nutrients taken at a network of monitoring stations to spatially referenced attributes of the corresponding watersheds, such as nutrient sources and environmental factors that affect rates of delivery to streams, as well as in-stream processing of nutrients.