These models will provide a variety of types of information that will be useful in evaluating stream-water quality for management or regulatory objectives.

The models use data on atmospheric deposition, commercial fertilizer applied to agricultural land, animal-manure production, point-source discharges, population density, and land cover (urban, agricultural, and forested). The data describing many of these nutrient sources and watershed characteristics have been refined since earlier SPARROW models.

The models also include nutrient-monitoring data from local, State, and other federal agencies, which substantially increases the number of model-calibration sites. For instance, the South-Atlantic Gulf model includes data from 321 monitoring sites, which is 233 sites more than were used in prior national models (based on USGS monitoring only) for the same region.