The EPA Nitrogen and Phosphorus Pollution Data Access Tool (NPDAT) is a Web-based tool intended to help states develop effective strategies for reducing nitrogen and phosphorus pollution.

The NPDAT consists of an introductory website, geospatial viewer and data download tables.

Data available on the NPDAT include:

• Nitrogen and Phosphorus Loading information from U.S. Geological Survey SPARROW model (SPAtially Referenced Regressions On Watershed attributes)
• Water Quality Data and Information (e.g., Water quality monitoring sites with nitrogen and phosphorus data and National Aquatic Resource Surveys (NARS) Phosphorus/ Nitrogen Values data layers)
• Setting Watershed Load Reduction Goals / Source Control Priorities (e.g., Facilities that are likely to discharge nitrogen and phosphorus to water, waters with N/P TMDLs (Total Maximum Daily Loads) and drinking water sources.)

The first elements in EPA's recommended framework are to:

1. prioritize watersheds on a statewide basis for nitrogen and phosphorus loading reductions and
2. set watershed load reduction goals based upon best available information.

To support states, other partners and stakeholders in this important work, EPA has developed this data access tool, providing downloadable data layers and key information on the following:

• the extent and magnitude of nitrogen and phosphorus pollution in our Nation's waters;
• water quality problems or potential problems related to this pollution; and
• potential sources of these pollutants.