Nitrogen and Phosphorus Data Access Tool (NPDAT)

The goal of the NPDAT is to support states, other partners, and stakeholders in their nitrogen and phosphorus analyses by 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.

Actions to Help States Address Barriers to Numeric Nutrient Criteria Implementation (2012–2014)

This document identifies a set of EPA actions to remove obstacles encountered by states as they work to adopt and implement numeric nutrient criteria (NNC).

Causal Analysis/Diagnosis Decision Information System (CADDIS)

This system is an application to help scientists systematically evaluate the causes of harm to plants and animals in aquatic habitats. CADDIS provides basic information on eight common causes of biological impairment including excess nutrients. The tool enables states to pinpoint causes of impairment and target remedial action.

Water Quality Analysis Simulation Program (WASP)

This simulation program model helps users interpret and predict water quality responses to natural phenomena and man-made pollution. WASP has been used to examine conditions of many water bodies for excess nitrogen and phosphorus loading.

Watershed and Water Quality Modeling Technical Support Center

The Watershed and Water Quality Modeling Technical Support center is committed to providing access to technically defensible tools and approaches that can be used in the development of Total Maximum Daily Loads (TMDL), waste load allocations, and watershed protection plans. Many watershed, water quality, and hydrodynamic models are accessible through this center.