New Data Added to EPA’s Nitrogen and Phosphorus Pollution Data Access Tool

EPA has added updated U.S. Geological Survey (USGS) SPAtially Referenced Regressions On Watershed attributes (SPARROW) data to the Nitrogen and Phosphorus Pollution Data Access Tool, a tool intended to help states develop effective nitrogen and phosphorus source reduction strategies.

SPARROW is a GIS-based watershed model that integrates statistical and mechanistic modeling approaches to simulate long-term mean annual stream nutrient loads as a function of a wide range of known sources and factors affecting nutrient fate and transport.

USGS recently completed syntheses of the results from 12 independently-calibrated regional-scale SPARROW models that describe water quality conditions throughout major river basins of the conterminous U.S. based on nitrogen and phosphorus sources from 2002.

Two data layers of EPA’s data access tool – one for nitrogen and one for phosphorus – now provide an approximate yet regionally consistent synthesis of the locations of the largest contributing sources.

The SPARROW geospatial layers can be used to prioritize watersheds for targeting nutrient reduction activities (such as stream monitoring) to the areas that account for a substantial portion of nutrient loads, and to develop state nitrogen and phosphorus pollution reduction strategies.

This information is relevant to the protection of downstream coastal waters, such as the Gulf of Mexico, and to local receiving streams and reservoirs.

The nitrogen and phosphorus pollution data access tool, with updated SPARROW layers, is available at:

Data Access Tool – – Launch the geospatial viewer and download data.

Fact Sheet (PDF) (2 pp, 405K)

Tutorial (PDF) (17 pp, 726K) – – First time users are encouraged to review this brief tutorial to become familiar with the functions of the Data Access Tool.
Source: Anne Weinberg
U.S. Environmental Protection Agency
Communications Coordinator Assessment and Watershed Protection Division
1301 Constitution Ave. NW
Room 7417K
Washington, DC 20004

Phone: 202-566-1217
Fax:      202-566-1333

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