The Decision Tool for Downstream Water Quality Protection is an interactive interface designed to direct states, tribes, and territories to resources and methodologies when developing water quality criteria that provide for the attainment and maintenance of downstream water quality standards. A state-EPA workgroup developed this tool at the request of state partners.

Water quality criteria may be narrative or numeric. States, tribes, and territories have discretion in choosing their preferred approach, based on their specific circumstances. When considering whether a narrative or numeric downstream protection criterion is most appropriate, users are encouraged to read this Tool's companion document: Protection of Downstream Waters in Water Quality Standards: Frequently Asked Questions (PDF) (12 pp, 567 K, About PDF).

Selection and application of downstream approaches recommended by this tool do not ensure Agency approval or disapproval. EPA encourages early and frequent coordination between a state, tribe, or territory and their EPA Region to ensure the most streamlined water quality standard approval process.

• How to Use This Tool
• Use the Decision Tool
• Resources

How to Use This Tool

Identify the pollutant of concern (Nutrients | Aquatic Life Toxic Pollutants | Human Health Toxic Pollutants) and answer the subsequent questions. The Decision Tool will display a record of your selections, and prompt the user with suggested resources at the end - and in some cases, along the way. In addition to the Decision Tool, EPA also provides the following two related resources for developing water quality standards for the attainment and maintenance of downstream water quality standards:

• Templates for Narrative Downstream Protection Criteria in State Water Quality Standards
• Protection of Downstream Waters in Water Quality Standards: Frequently Asked Questions (PDF) (12 pp, 567 K, About PDF)

EPA also provides links on this page to other resources that may be useful in developing water quality criteria that protect downstream waters.

Use the Decision Tool

Resources

• Ask WATERS: Cross-program calculations, examines spatial relationships between programs, and performs nationwide analyses.
• MyWATERS mapper: Displays snapshots of EPA's Office of Water program data.
• How's My Waterway website: Access data on the condition of local streams, lakes and other waters anywhere in the US.
• NPDAT: Data access tool to help states develop strategies to address nitrogen and phosphorus pollution.
• Water Quality Standards in Your Area: State, territorial, and authorized tribal water quality standards that EPA has approved or are otherwise in effect for Clean Water Act purposes.
• EPA's State Development of Numeric Criteria for Nitrogen and Phosphorus Pollution website
• Protection of Downstream Waters in Water Quality Standards: Frequently Asked Questions (PDF) (12 pp, 567 K, About PDF)
• Templates for Narrative Downstream Protection Criteria in State Water Quality Standards
• USGS Streamer tool: Spatially reports upstream and downstream locations of a water body.
• Water Quality Standards Academy: Online courses and information about water quality standards.