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Water: Module 3

Basic Course: Key Concepts (Module 3.b)

Introduction: How Are Criteria Developed?

Module 3. Criteria Development

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EPA develops recommendations for many water quality criteria that individual States or Tribe's adopt into their water quality standards. However, States/Tribes develop some criteria that reflect local or site-specific conditions themselves.

EPA develops water quality criteria under the authority of the Clean Water Act §304(a). Consistent with EPA's water quality standards regulation (40 CFR 131.11), criteria that States/Tribes adopt into their standards must meet the following requirements:

  • Be based on a sound scientific rationale.
  • Include parameters (e.g., acceptable concentrations) that are sufficient to support protection of the particular water body's designated uses, including the most sensitive use.

Key Point. EPA's recommended criteria are not rules, nor do they automatically become part of the State or Tribe's water quality standards. EPA develops criteria based on the best available science, extensive scientific literature review, established procedures for risk assessment and management, EPA policy, external scientific peer review, and public input on potentially useful scientific information.


Video Clip View a 2-minute video clip from the classroom session about EPA and States/Tribes working together on water quality.

Key Point. A State or an authorized Tribe can apply water quality criteria to a specific water body or a selection of water bodies or apply the criteria to all water bodies throughout the State/Tribe.

Water quality criteria have no force of law under the CWA until they have been adopted into the particular State or Tribe's water quality standards, EPA has approved them, and they are implemented in a regulatory tool (e.g., a permit issued under the National Pollutant Discharge Elimination System).

For informational purposes only–Not official statements of EPA policy.

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